4" APO Refractor Shootout

[@NebulaPhotos]

Corrections: 1. For some reason, I kept saying millimeters when I meant to say centimeters when measuring the length of the first 3 telescopes. To be clear the length of each telescope with dew shield extended: Askar 103 APO - 77cm, Founder Optics FO106 - 69cm, ZWO FF107 APO - 76cm, SW Esprit 100ED - 64cm 2. Pricing of the Askar 103 APO is promotional pricing only good through the end of the month - forgot to mention that. Other prices are current USA (non-sale) prices. 3. Askar informed me that since the 103 APO and accessories they sent me were still prototypes, the interior of the 1.0x flattener was an issue with my sample only, and the mass production version shouldn't have that problem with the paint. 4. Not a correction exactly, but something I should have emphasized better in the video: I did use the additional spacer and correct backfocus arrangement with the Esprit 100ED. The elongated stars are only in the extreme corners. If you crop in about 500 pixels on each side (9500px -> 8500px in the horizontal), the stars will look perfect across the field. A link to download the FITS data (both single frames and calibrated stacks) is now in the description. Hopefully, that's it. I'll update this comment if I notice anything else.

[@j.s.3407]

Could you please also post the camera's master-bias, master-dark and each telescopes master-flats and all five subframes?

[@NebulaPhotos]

@@j.s.3407 That would take up a huge amount of my google drive space. I can do it, but only very temporarily (a few days). Is XISF format okay?

[@Adrift555]

This is the review I have been waiting for. Would the Askar 103 apo on a heq5 pro be too much? Also, do you happen to know the scope's weight with the 0.6x reducer?

[@NebulaPhotos]

@@Adrift555 weight with 0.6x reducer is 6.3 kg / 13.5 lb. Might be okay on the HEQ5, at the native700mm f.l. It might be pushing it a bit on that mount. But with good balance and guiding, it might work fine.

[@j.s.3407]

@@NebulaPhotosthat would be perfect!!

[@ColeDedhand]

The Askar really holds its own against the more expensive scopes. It looks like a great option for getting to a 4" refractor without taking a second mortgage.

[@tomb9420]

I was wondering where some of these youtubers get all of this money at ! Me i'm on a low budget .

[@michaelcarman-yv9tm]

@@tomb9420 i agree!! and don't see any REAL differences. they're all great to me. but then i'm not that anal.

[@nikaxstro]

That Askar scope looks the goods, maybe not with an 0.6 reducer but with the 0.8 it seems like a great investment

[@jonrbryan]

I am on my second night out with the Askar 103 and 0.8x reducer, and I'm thrilled with it. I immediately noticed that I had pinpoint stars in my OAG. They were terrible with my previous scope, and I figured it was probably the OAG (I'm relatively new to this), but that doesn't seem to be the case. Askar's spot diagrams show the 103 outperforming the 107PHQ (same as the ZWO 107) by a wide margin at the edge of the field. I splurged and got all three flattener/reducers, and I'm looking forward to trying them out. Askar seems to have gone with an optical design that gives up a small amount in the center of the field to get better performance at the edges on all of their new APOs (103/120/140/185). From my initial experience that seems like a good design decision, especially if it made them so much less expensive to produce.

[@fouriousbanana6966]

Great review! I was looking for someone to do an in-depth review of 4" ED refractors for astrophotography. I'm definitely going to get the Askar, not only being the best for it's price, it's the only semi-proffesional refractor I can buy (because others are more expensive)...

[@doramason]

Great review Nick! Just to give a video idea maybe next time you can make a review of different Chinese manufacturers: Sharpstar, Long Pern (Founder Optics), Synta(Sky-Watcher), Kunming United(William Optics) and Jinghua Optical(Explore Scientific).

[@goose300183]

22:55 - I think the captain's wheel on the Esprit is installed incorrectly. There is a much larger gap at the top than the bottom of the frame. It looks like it has skipped a thread on one side. That would explain why it was so stiff and scratchy. This would also potentially introduce tilt to the system, and may be why it was very difficult to rotate the photo properly, and may also have affected the quality of the final image.

[@amgc6369]

Provide an secondary viewpoint on the Askar 103 APO as I just got mine. The issue with the focuser is resolved by a slight allen screw (2) adjust, very smooth and no noise. I got all three of the flattners/reducers all were in perfect condition. You must have received preproduction models because mine have orange writing. Oh, and my knobs were attached!!. Thanks for your shoot-out Nico!

[@davidheflin5847]

Great video, I was interested in the ZWO, was. Definitely helped my decision.

[@DrewJEvans44]

Excellent review. The Askar 103APO is phenomenal, espcially as it's price point I have had a lot of success with it at native FL and with the reducers testing so far!

[@NebulaPhotos]

Thanks Drew! Yes, very exciting how well it does for the price.

[@amgc6369]

Thanks great news I changed my pre-order to just the .8x and 1x. Will you be going an eval on your channel?

[@simonthorp8565]

I have been following you for several years now and find your videos compelling. This video in particular inspired me to purchase the Askar 103 with both the .8 and 1x FF/Reducers. It helps that you are an absolute clone of my son! Hair and all…Love what you’ve done and will become a patreon supporter in the new year.

[@DannerPlace]

Very thorough review with lots of details. Would like to have gotten your relative rating amongst the four refractors. I think the ASKAR won.

[@MichaelA-j6k]

Great review Nico! I'm purchasing today the Askar 103 with 1.0 and .8x flatteners...it perform well from your review at a much lower cost than the rest of the field!

[@dasimcoes]

The stellarvue svx 102 is a great scope and stellarvue will list the strehl rating of their scopes.

[@nadirteymurov1]

Huge work done ! Thanks, Nico !

[@janossowski1490]

Thanks for this, very helpful. One thing that might be worth mentioning is that the zwo apo series is simply askar PHQ series sold under zwo brand so in reality 2 of these scopes were askar :) If anyone would ever be trying to decide between the 2, simply go for the one which is currently cheaper/ on promo, or the one which is more appealing to you color wise

[@KingLoopie1]

Another cool scope shootout for me to ponder on. Great reviews, Nico! 👍

[@darrellburke3108]

Thanks Nick. That's helped me a lot. Being budget conscious and with financial limitations - this a no brainer now. At $1000 compared to $2500 - $3000+ I'll be going ahead with my pre-booked Askar purchase (All-Star up in Canada). That it has some minor build quality issues is to be expected at that price point and nothing that can't be fixed or worked around ... I have lots of allen wrenches :) The fact that it was close to/equal to or even superior to the others on the various tests was a pleasant surprise. I already have a Starfield 0.8 reducer flattener so unless for some reason there are issues mating the two - all should be well.

[@MountainFisher]

Have you ever looked at Astro-Tech's scopes for $1000? Made in Taiwan and Oklahoma and I bought an 80mm ED refractor and even though it is a doublet there is next to zero fringe with it. It was $369 at the time, but a little more now I'm sure.

[@haggish7100]

I decided after this comparison to go for the SW Esprit100 ED Pro, And after testing with the recomended backfocus w/flattener I found that it is very critical down to 1/10 of a mm. I then bought an Askar backfocus adapter, which has a resolution of 0.05mm. After a simple adjustment and test, the result is very good. Actually better than the stated 40mm image circle.

[@haggish7100]

I can't seem to post a link here, but search for "Getting back focus SW Esprit 100Ed?" on cloudynight forum for pictures

[@gregb5149]

Thanks for this review. I've been struggling with star quality on my 4" APO (Explore Scientific) but I see now that this issue is common and occurs in varying degrees in all scopes - maybe not is very expensive ones.

[@simonthorp8565]

Hi Nico, Big supporter here. Frankly, you look like my son! I personally purchased the 103 and am very happy with it with both the .8 and 1x FF/Reducers based upon your review. As to your relationship with All-Star Telescope, I have only had horrible service from them and found them to be deceitful and misleading and when any non 5 star, but fair, review is put on their site, they delete it. I would NEVER do business with them again. Both telescopescanada and astronomyplus in Canada out class them in service quality exponentially! Best wishes, Simon

[@CoVoltage]

Askar scopes generally have very good support for large image circles, but I did notice they produce slightly hazy stars compared to FPL-53 scopes (and chromatic aberration when stars are saturated). They're surely a great budget option, and I'm honestly surprised about the pricing for the 103apo (plus the preorder option where you can get 3 reducers+guidescope for 1600). Esprit 100 are known to have astigmatism on corners for full frame sensor, so you are not wrong about the back focus. Although Esprit 100 is a great premium scope, I did find its dew shield to be a lot sloppier than the Askar.

[@licho52]

You're spot on regarding low star quality on these scopes.

[@anata5127]

Lovely! I just started to watch. My prediction - Esprit. Let’s watch and see results. Inconclusive, differences are small. I have esprit 120mm, and use with APEX L reducer. The main drawback of scope is focuser. Good but not good enough. It will become apparent when you get AP Mach2 and start to build sky map for unguided session.

[@steveb.7593]

Hi Nico Thank you for your laborious work. The number of parameters that influence the image quality is diverse. The SkyWatcher Esprit image result at minute 30:45 looks more like a typical backlash tracking error. The EQ6 is known for this due to the gear transmission. The AZ EQ6 with belt drive is less vulnerable. Nevertheless, I have gotten into the habit of never bringing the telescope into exact balance. I also have to say that manual focusing is hopelessly inferior to automatic focusing. In my opinion, you can make every effort and still not achieve the result of electronic focusing. The same applies to polar alignment. In my experience, conclusions about optical performance can only be reliably assessed when all of these criteria are exactly met, regardless of the camera.

[@NebulaPhotos]

Hi Steve, I don’t think so. These were stacks of 5 presented, and I also watched the guiding the whole time. 0.4” RMS with no spikes in guiding. I used the EQ6R which like the AZEQ6 uses a belt and has no issue with backlash. I also watch focus for every sub-exposure as it comes in and make sure the HFR doesn’t go up. If it does, I refocus. I can’t put automatic focusers on for these tests as it would slow me down too much and then I wouldn’t be able to get the objects for all scopes when high in the sky and free from atmospheric issues. Polar alignment is also done electronically with a polemaster followed by sharpcap pro to double check. I’ve practiced this testing methodology over several years of doing the channel to be confident I’m not introducing the most common kind of errors you mention (tracking, focus, PA, etc.). Cheers, Nico

[@steveb.7593]

Okay, then I'm really surprised by the image errors in the Esprit. Apparently there are significant manufacturing tolerances in the manufacturing process, although it is claimed that SkyWatcher offers really good telescopes with the Esprit range and is therefore different from the rest of the market. In any case, my Esprit 100 images the stars exactly round right down to the corners, provided the back focus is exactly at 55 mm and all other parameters are also perfect. If I see more or less short lines at the edges of the picture, especially in the corners on the right and left of the stars, this is without exception a tracking error. But thank you very much for your explanation. I like your channel and the content seems soothing, calm and practical. Many thanks for that.@@NebulaPhotos

[@NebulaPhotos]

@@steveb.7593 hi Steve, good to know! Are you using the same sensor (IMX455 - full frame with 3.76 micron pixels) that I used here? If I had used a crop sensor OR full frame with larger pixels, it would be a different story. In talking to a representative from Sky-watcher, they felt the Esprit 120 and 150 would handle correction to the corners with that sensor (IMX455), but the 80 and 100 would struggle a bit in the corners. It’s not a huge deal when you have so much resolution to work with. I could crop in a few hundred pixels on both the left and right sides and have a perfectly round stars. I have the 120 coming next so looking forward to seeing how that one does. Cheers, Nico

[@steveb.7593]

The only impression I have with full-format chips is the Sony A1, which has slightly larger pixels than the Asi 6200, but has a similar resolution and should hold up in comparison. As a rule, I use the ASI 2600 MC. However, if the setup is set up correctly and precisely, there are no significant differences in terms of round stars in the corners of the image. The situation is different with the 1000 mm f4 Newton, which is an extremely delicate matter overall, and I almost despair at the eternal construction site. The only reason I'm sticking with the Newton is the spikes, which I really like as a style element, and the color imaging due to the lack of chromatic aberration. Nevertheless, I tend to replace the Newton with an APO of the same focal length. Patience and persistence are crucial in astrophotography, but at some point you just want to get up and running. All in all, I can say that, in my set up contrary to expectations, imaging errors with the Esprit and the Newton are most often caused by tracking errors.@@NebulaPhotos

[@briankotak403]

Very nice comparison Nico. You always do such a thorough job! Much appreciated. Dr B from Manitoba, Canada 🇨🇦

[@NebulaPhotos]

Thanks Dr. B!

[@alandyer910]

Another excellent comparison test, thank you! I was curious how well the new Askar 103 would perform at f/4, and you answered that. The high speed comes with more vignetting and some longitudinal CA. To be expected. A point - the ZWO FF107 is a rebranding of the Askar 107PHQ, so one presumes they perform the same. It’s a matter of whether you like your scopes in red or green!

[@NebulaPhotos]

Thanks Alan!

[@offraed6156]

@alandyer910 So is this the case with all the ZWO triplets? That they are just rebrands? Who makes the original? Is it Long Perng or United Optics, Synta or Ningbo? This is what is confusing about these Chinese refractors, it seems a great many of them are simply the same scope just branded by someone else.

[@doramason]

@@offraed6156 ZWO is sharpstar

[@waldemarwitt764]

Great job Niko!

[@kevinhanley3023]

My Esprit 120 focuser, current production model, fell apart after 5 years. There are Teflon strips used for centering the tube. The Teflon fell off while I was imaging. I had nice rectangular shadows in each image. I have suspicions that all of the focusers in the video have long term reliability issues just due to the economics. I’d rather have a focuser that works and has some “friction noise” as opposed to one that falls apart. I installed an American (Indiana) focuser.

[@realmcerono]

Please point me to your focuser... mine is getting 5 years old and I know exactly what you are talking about.

[@NebulaPhotos]

Thanks for the report Kevin - one of the weaknesses of this style of review is I have no clue how well these hold up in the long term, so these kinds of comments are very welcome!

[@desmcmorrow2978]

Setting the standard for objective and systematic YT Astro reviews. I appreciate the fact that you left it up to the viewer to draw his or her own conclusions. I was thinking of getting the FF107 but now will consider the 103 as a budget option. What about shooting NB nebula at F4 and using stars from a better corrected but slower scope at similar Fl? Many thanks, Des

[@enriqueboeneker]

Love this reviews, Nico. They are indeed useful. Thanks! Great job.

[@vicinvesta8349]

The smoothest talking drug dealer. This guy. 😂

[@arielbarra]

I wish I had any money left for drugs after getting into Astrophotography 😂

[@paulk119]

Haha

[@TheReadDesultory]

@@arielbarraExactly… in this case the first one is NOT free! 😂

[@hunter133official]

Astrophotography is complicated (simplest way to put it)

[@togray619]

Mr. Nico, very nice review and informative video. Thanks for putting in the time for this review.

[@dmintz88]

Great video, Nico!

[@BurningFlame1999]

Very nice comparison. How about a similar video with achromats vs APOs at the same price ? :) I wonder which would produce better images at the same price, a 70 mm APO or a 127 mm achromat?

[@gaborbartha612]

I love these reviews. Another suggestion is to review 4 identical scopes to look at manufacturing variability.

[@Anthony1102www]

this is the thing i really need thanksssss for the video appreciate all your effort!!!

[@qbaxcpu]

Good Stuff! liked before I watched , as usual! THX

[@astrodoc4163]

Amazing review and effort in this video. Wow.

[@mjhouse1955]

Great job Niko! I would like to see the scopes you review checked for collimation accuracy. Can you set up a collimating test stand? Would be nice to see how these collimate out in each of your reviews! Take care, Mark

[@NebulaPhotos]

What do you suggest for that? A laser interferometer? I feel like it would be hard to figure out what is real and what is measurement error

[@mjhouse1955]

@@NebulaPhotos I don’t know how to do it, I was hoping you knew.

[@NebulaPhotos]

​@@mjhouse1955 It's something I've looked into, but no promises I will get something like that sorted soon. I currently live in a very old house with no central AC and I've heard that even humid air and air currents can mess with the results when using an optical bench.

[@MountainFisher]

I asked my son for an Astro Tech 102 ED and he bought me the Explore Scientific 102 carbon fiber triplet. I do visual mainly and it is nigh on perfect for that.

[@grigoryvidishev1810]

Nico thanks for the video. I own Esprit 100. The manual rotator very bad and if not tight, it introduces tilt. However, overall it is great scope.

[@PhotoGuyOmaha]

You convinced me to get an Askar 80phq in a previous video (back ordered for over a month now). What I haven't been able to figure out is the comparison between the different families that Askar/Sharpstar make. Should I get the Askar 103apo or the 107phq? Sharpstar... FMA... FRA... APO... PHQ... etc... how do I know what to buy? Right now, I am assuming more expensive equals better. Can you do a review of the different families? Even if you don't do imaging, can you just explain the differences

[@richfavinger]

Agreed!!

[@psuaero100]

The rotator on the Esprit (100) is my biggest peeve about the scope. Optically, I think it's excellent but rotating and framing is a PITA. It doesn't help that it's not easily replaced with another manual rotator due to the threads that Sky-Watcher chose. There is a drop-in motorized unit from Prima Luce Lab but it's expensive ($1400). I'm not ready to commit to that when the scope is in my backyard. Maybe if it were at a dark site observatory far from home that would be a necessity.

[@haggish7100]

Why not just rotate it in the tube rings, then you don’t need extra flats ✨🔭🙏

[@danieljohnson6044]

Thanks for your review do you do a break down in another video that explains field flatners and the other parts? Oh and I like your point of view that you are coming from the photographers POV, not punning.

[@radioparisment628]

Mine is the Askar 107PHQ. Results are better than with my 10 inches newt.

[@marcomancilla6232]

Hello Nico, Thank you for your prompt reply. I have an EQ6-R pro and an EOS 1DX MarkII, but I plan to purchase a dedicated full-frame Astro camera. I now take images with an EOS 70-200 mm 2.8 lens and utilize Kstars for software. Thank you for being so helpful.

[@NebulaPhotos]

Hi Marco, if you want to use a full-frame astronomy camera, I’m not sure either of those telescopes is the best choice. I think they both correct better for an APS-C sized sensor (ASI2600). Check out Blackwater skies imaging toolbox to visualize different combinations of telescopes and sensors to get a feel for what field of view you want. This is a good first step. After that, if it’s still unclear, feel free to email me and we can chat further about it.

[@marcomancilla6232]

Hello Nico, My apologies for the delayed response. Last night, I was trying to capture the fireworks galaxy with my 200 mm lens and DLSR camera. I will be sure to look into the website you suggested. Thank you. By the way, where can I make a small donation? @@NebulaPhotos

[@NebulaPhotos]

@@marcomancilla6232 Hi Marco, Feel free to email me if you have more questions: [e-mail]. I accept donations three ways. There is a 'Thanks' feature here on youtube if you've linked a credit card to your google account. I am on Patreon (comes with benefits): patreon.com/nebulaphotos And I have paypal: paypal.me/nebulaphotos

[@rodwatkins145]

Thanks Nico, great video. Any ideas what is causing the Founder tilt? Is it in the focuser? The lazy geek also reported tilt with this scope so it seems to be common.

[@microreniassance2929]

Great shoot out video!! Many thanks! I have a question though. You said something about using the EQ6 model Star Watcher mount for this Askar scope. It looks to me that this scope can work with an EQ5 mount based on load capabilities. I know you should over compensate for weight, but would you consider DSO work with the Askar scop and an EQ5 mount--with the belt upgrade? I really like that scope now and would like to have one, I simply can't afford the 1600 for a new mount to go with it. Any thoughts on this would be appreciated. My total weight would be approximately 20lbs including scope, guider, camera, etc. Thanks for perfect videos again and again!

[@NebulaPhotos]

Yeah, I think it would likely work okay with guiding, especially reduced. At 700mm f.l. (native) you might be pushing it, depends on how much your belt upgrade has helped reduce the mount's periodic error.

[@alfredobeltran611]

Thank you for this extensive review. While all of them cover a full frame sensor, clearly not all of them perform similarly.

[@skye7690]

Would be nice to see the AT102EDL here.

[@AstroDragon33]

I absolutely loved my AT130EDT. I really want another one.

[@johnreilly8672]

Be nice see a Stellarvue in the bunch also. But my guess is Vic (Marris) wouldn't just loan one for review, they are very pricey.

[@jimwaters304]

Not sure what's going on with the Esprit 100ED scope. The FF looks like it needs additional backfocus. My Esprit 100ED scope has perfect stars in the corners. The color is well corrected. The Askar 103 w/ the FR/FF looks to have 'cross' stars in some corners. BlurX cleans them up.

[@shamrockisland]

Interesting. Was hoping for a "in conclusion" section to get your definitive thoughts.

[@alexindub]

Awesome review as always Nico! Curious if you tested the Askar 103 @ 700mm without the flattener? I'm thinking of just getting the scope and the 0.8x reducer. If I shoot at 700mm I'll be cropping quite a bit anyway as the target would be smaller galaxy. Hoping the very center will be corrected enough to save a bit of cash and skip the 1.0x flattener. Max sensor size I have is APS-C.

[@NebulaPhotos]

I didn't unfortunately. From past experience, I wouldn't be happy with the stars with an APS-C and no flattener on a triplet. If using a smaller sensor like the ASI585, or maybe even the ASI533, I think you could get away with it.

[@alexindub]

@@NebulaPhotos That's great, thanks for the feedback! I'm thinking of using the scope with 0.8x reducer with APS-C sensor and possibly getting a smaller pixel camera like the 183 or 678 for extending the reach a bit. Appreciate your thoughts and the quick response!

[@southbronxny5727]

What I hate is how the cases are not modular so I could store the scope with the focuser, filter wheel and camera still attached. Great reviews again.

[@kurosumomo]

True, I dislike that with most scope products, but it is expected as they ship - as is. I got over this by telling myself, if I already spend $1000+ on my scopes, I might as well invest in a good case, and have different foam inserts for different scopes I want to take on a "tour", so I bought a large NANUK hard case and just cut the foam for new scopes and accessories.

[@glennvanrooij5571]

Thanks Nico, great video's !!

[@physmc1]

This is great work. Thanks for taking the time to go through this analysis. Any plan to review the new 151phq scope from askar? 😊

[@Poketronics]

I'm honestly shocked by how well that Askar 103 with the 1x corrector performs, especially for its price. Saturating that stacked image you provide shows no real bloating in the blue channel, and the stars look very nice.

[@robertmcgrory3464]

Hi Nico, thanks for the thorough review. I watch it through to the end. I got the impression that you liked the Askar 103 APO despite the focuser. Which of these telescope did you like based on the test? You were not entirely explicit with judgment but my impression is that the Askar 103 APO performed well relative to the other models or did I misunderstand?? I would greatly appreciate you feedback. I am considering this model paired with the Sky-Watcher EQ6 - R. Any thoughts? It would be my first telescope.

[@NebulaPhotos]

Yes, I thought it performed well and is the best value proposition of this bunch. I probably would only get the f/4 reducer for narrowband, and stick to the other configurations for broadband.

[@robertmcgrory3464]

@@NebulaPhotos Thanks for your specific feedback. Very helpful for me. Cheers

[@3dfxvoodoocards6]

Like! Would be interesting to see a similar video with an achromat vs apochromat vs maktusov vs newtonian at the same aperture or price :)

[@waldemarwitt764]

Now we need a review of the Askar 140 mm f7 and Askar 130PHQ and Askar 151PHQ with the full-length ZWO Color Astro Camera ASI 6200MC!!! I’m sure you would get an excellent review!!!

[@dumpydalekobservatory]

Great comparison Nico all sadly out of my budget though especially the full frame camera but still interesting to see all the differences

[@M42-y8l]

Same with me, I like to dream.

[@msacco]

Amazing video, honestly with BXT that we have now, the stars could be rather easily be corrected for the 103 apo at f4, besides the star colors which are bad at f4, it seems to be very well illuminated and at f5.6 or f6.8 the scope seems to work amazing for full frame, which is impressive for that price point. Extremely detailed, thank you.

[@darrellburke3108]

BTX? Not familiar with that that term.

[@haggish7100]

@@darrellburke3108 BlurXTerminator an addon In Pixinsight ✨🔭

[@msacco]

@@darrellburke3108 Actually meant BXT = BlurXTerminator

[@JohnStone-g8j]

So I went and tried BXT on the 103APO F4 image. I set it to maximum halo reduction and maximum star shrink. The spherical chromatic aberration is too great for BXT to correct. I'd suggest trying the Starizona Nexus-L 0.63x reducer/flattener to see if it works better. @NebulaPhotos Do you have that reducer? Could you give it a try?

[@msacco]

@@JohnStone-g8j Just learn how to use BXT. Stars look perfect after BXT.

[@teslar1]

Chances are that Askar scope has been out for review and someone fitted an EAF to it. That’s why the knob was loose

[@framed-tales]

Hi Nico, very informative and resourceful as always. I am impressed with the Askar 103 APO for its performance vs. Price. I have a Stellarvue Access 102 FCD100 and Lanthanum Doublet (similar to AT102EDL). I noticed bloating on big stars and it gets somewhat irritating during stretching the data. Do you think getting Askar 103APO triplet would resolve this issue, or I need to improve my data processing workflow? Also my mount is CEM26 and camera is ZWO 533 MC Pro. So I am afraid I may overstress my mount with 103APO and accessories. But with that price tag and performance, I am really inclined to buy a triplet. All good triplets are north of $1500+ 😢

[@Wilfredos_Astrophotography]

Awesome comparison. This was a huge help. Overall, how would you rate the ASI6200 and is it worth trying out?

[@briandiaz3758]

I own a zwo 6200mm pro , you can use it on ROI aps-c and full frame , but with full frame I use all M54 , the big challenge with the full frame mode is the OTA and reducer or flat, otherwise need crop imaging , Most of the OTAs say they are for full frame 43mm, but it is not entirely true, except AP, Taka and others

[@gaborbartha612]

More of these reviews please. It would be nice to see lighter scopes like the Explore Scientific ED102-FCD100 Series Air-Spaced Triplet Telescope in Carbon Fiber in the line up some day.

[@afryhover]

Well done Nico 👍👍 As a long time Esprit owner.... our case and plate is so bad! LOL But, it's ok.

[@Chorge1972]

I’d loved to see how the Askar performs with its 0.8red

[@remiferrieri2603]

Very nice video as usual. One question: How do you set the backfocus for each scope ? Do you just follow the recommendations of the manufacturers (often 55mm) or you set it precisely for each scope by trial and error?

[@NebulaPhotos]

Yes, I'm just using the recommended distance as suggested by the manufacturer. There very well might be some gain in performance by dialing it in more precisely, but I have so few clear nights, I'm not able to do that for these tests.

[@remiferrieri2603]

@@NebulaPhotos thanks for your answer. That's what I thought but was just to make sure.

[@johannesrockmann5169]

Hi Nico, thanks for the great review. I´m currently considering which refractor to buy in future. The Askar 103 Apo is an intersting option. The only thing which bothers me is the performance on bright stars. Do these rays only appear in the corner areas or as well in the middle of an image? Regards Johannes

[@ssfalk41]

Nice haircut! Great video!

[@ssrattus]

Thanks Nico!

[@pierspinelli8352]

Hey Nico would you like to consider to do a shootout between all your RC telescopes?

[@kenfrank2730]

Would love to see you review the Stellarvue 102T Raptor.

[@shinyy187]

Is the Esprit 120 or Askar 130PHQ worth it over the much cheaper Askar 103APO? I’m at the point of upgrading from my first and only scope, the Redcat 51.

[@captaincook6666]

Great review. Its not put me off the askar 103 so thats good! When you say f/4 for NB would you also include duoband OSC? The promo deal here is all 3 reducers or the 1 & 0.8. Do you think the 0.6 is a novelty or worth it? I have a 360mm already...

[@Adrift555]

what speed is your current scope?

[@captaincook6666]

​@@Adrift555it's f/6 at 360mm

[@Adrift555]

@@captaincook6666 at f4 420mm I think it will gather light twice as fast. If you are getting the scope anyways I'd recommend getting the 0.6x. If I get this scope I think I will end up leaving my Z61 inside more unless I want the wider field and slightly cleaner stars

[@captaincook6666]

@@Adrift555 yeah I know you're right just looking to save a few quid. I think I might go for it...with a new AM5 $$$$$$

[@j.s.3407]

I'm not sure a dual-narrow band filter would be best with the 0.6x F/4 reducer since it can't seem to focus both red and blue colors at the same time. Mono narrowband would probably work great. There's a guy at Askar who's put up a couple images like that.

[@TheHemiphil81]

I had a 4 inch apm apo refractor i used for 2 years. I sold it for what I paid for it and bought a 6 inch apm apo and to me their was some difference in observing between the 2. I personally think a good 4 inch apo is an all out great telescope for observing and astrophotography.

[@Rotceh-r4g]

Niko, so if you were to buy one, which one would you pick? (I think I'll keep my APOs small (50mm 242/5 & 62mm 400/6.5), and continue using my C6 SCT for 950mm to 1500mm focal length work.) Nice review. Thanks for posting it.

[@NebulaPhotos]

I’m not really in the market for any more telescopes, but if I imagine I was, I’d probably get the ZWO FF107 (or the Askar 107 PHQ which is the same scope with green trim). All the scopes performed well enough for my standards, but I like the simplicity of a quad where you don’t have to worry about dialing in backfocus.

[@the_astro_guyy]

​@@NebulaPhotosI'm more interested to know if we can achieve flat field in founder optics and espirit especially apsc frame size because the stars look stretched

[@drithen]

How does the 103 APO compare to the Askar V in build quality and optics? I realize they do different things with some overlap, but what I'm curious about is how well they do what they do compared to one another.

[@GaryMCurran]

Nico, maybe in another video, if you haven't already, can you describe the function of the flattener in a APO telescope? I would have thought with three elements, the image should have been flat. I'm guessing I am wrong on that. In a related question, do you need a flattener on a quad scope?

[@musa7606]

Apo means apochromatic, meaning it does a better job of focusing the light bands together. What it doesn't mean is that it keeps a flat field, ie the image will still have distortion, esp in the corners. An extra element (or 2) in the form of either a flattener or reducer, or a 4+ element scope is required to flatten the distortion.

[@GaryMCurran]

@@musa7606 I understand the concept of Apo versus achromatic, but I guess somehow I just got the impression that the third element also did some flattening. Thank you for your answer.

[@iamjessieray]

Nico, would you have interest in doing a similar video with ED refractors in the 70-80mm range?

[@NebulaPhotos]

Already done! 65-70mm refractors: kzbin.info/www/bejne/jXWvhqlnfL5md7M 80mm refractors: kzbin.info/www/bejne/oqS2Z4Oop7yhnqs

[@iamjessieray]

@@NebulaPhotos Thanks! I'll give that a watch!

[@jimwaters304]

The Esprit Captions Wheel still confuses me. The Captions Wheel on my Esprit 100ED is difficult to use and required a strap wrench to loosen. Why not just rotate the entire scope in the rings if you want the focuser on top?

[@licho52]

Very good and in-depth review. Color reproduction comparison was very helpful.

[@michaellorentzen1672]

Fantastic work. I’ve been eyeing a refractor in this range, and for the price, I’m surprised that the askar 103 is so competitive. Will be Preordering from agena

[@EvenTheDogAgrees]

Correction at 5:16: 77 centimeters, or 770 millimeters.

[@jasonalexander4565]

Fresh cut homie!

[@haggish7100]

Thank you very much Nico🙏. This test is exactly what I wanted. I have the same camera and have considered the Esprit 100ED, but when I saw the Askar 103APO coming on the market, I wanted to wait a bit. I'm still a bit in doubt, but think the Esprit scores a bit on sharpness, while perhaps the weight of the 103APO speaks in its favour. So my choice is between Askar 103 APO with 1x and 0.8x and Esprit 100ed. I have asi6200mc camera. Which would you choose? ✨🔭🙏🙏

[@NebulaPhotos]

To summarize what I saw: Esprit - build quality and quality control are great, optically it's very sharp, but stars were elongated/distorted in the far corners with the ASI6200MC (could easily crop in) Askar 103APO - build quality / QC seem suspect - note the focuser knob coming off and the uneven finish inside the flattener. Optically - better corrected in the corners of full frame, but blue transmission seemed lacking. 1x flattener and 0.8x reducer were both decent options - personally I'd only use the 0.6x reducer for narrowband

[@haggish7100]

Thanks, yes you have to crop a little bit in the length direction since the image circle is only 40mm the image, but I can live with that. 🙏

[@Astroterrat]

For my APX60 camera, I prefer Askar or FSQ scope. I have an Esprit 150 and I changed my FF camera to Aps-C because I found aberration in corners😊

[@haggish7100]

I’ve owned both the FSQ106N and the FSQ106ED in the past, but that’s now in another budget game. Now I’m looking for a good 4" at a lower budget. The Askar 100APO will cost me about $1600 w/ 1x and .8x flatner/reducer and the Esprit 100ed w/ flatner about $400 more. I believe the Esprit is a bit sharper an more well built, and when you crop of about 500 pixels at each end the stars are good in the corners. The 100apo is tempting because it’s lighter, as I’m travelling to an Astro farm I Namibia next year ✨🔭🙏

[@NebulaPhotos]

@@haggish7100 yep, that all sounds right, and sounds like you are leaning towards the Esprit. You are right that is surprisingly heavy for a scope of this size. Must be less expensive where you are located. In the US, there is a $1500 price difference between the Askar 103 with those 2 accessories and the Esprit with flattener.

[@QuantumRads]

Would you recommend the Askar 103 APO as a first refractor telescope? I already have a EQ6-R Pro mount. I currently have a Celestron C5 SCT and a ZWO ASI678MC.

[@DD-gi6kx]

you are the one using them, sure would be nice to get more of a comparison summary

[@NebulaPhotos]

What comparisons did you want to see that were missing from the video?

[@jamespeirce2582]

Quite unusual corners on the Esprit. It should be able to render pretty round stars. An odd question, but did you happen to include the spacer that comes with the telescope and is mean to land backfocus at 55mm and use the corresponding 55mm backfocus optical train?

[@NebulaPhotos]

Yep, that’s exactly what I did. The spacer + 55mm backfocus. Have you used the Esprit 100 with this chip (IMX455)? Something interesting I’ve found from lots of doing these telescope tests is that pixel size makes a HUGE difference. If I test full frame, but with large pixel pitch (6 micron), the corners will look perfect. It’s only full frame + small pixels that reveals these kinds of aberrations. Even very good telescopes like the Takahashi FSQ series have a hard time with the IMX455.

[@jamespeirce2582]

​@@NebulaPhotos Yep, for the Esprit 80ED (sold some time ago, but such a lovely telescope) and the 120ED, but I have not owned the 100ED. But having owned the other two is why I wondered if you may have missed that poorly-documented spacer. A buddy of mine has a 100ED and it seems to perform inline with the other two, as one might expect. I have had quite respectable results up to full frame from those telescopes at 3.76μm (6200). I agree your backfocus clearly *looks* like it needs adjustment, and unusually so starting out with the proper spacers. Curious. To really dial things in I did need to make a few fine adjustments to the backfocus (despite starting at the specification) and make sure tilt was corrected out of my optical train. But that seems like a pretty normal thing to do with a modestly fastish focal ratio and that demanding sensor. And I did not start in either case with the star elongation or cross-hatch aberrations that seem to show up in your test image. I own a Takahashi FSQ-106EDX4. You are spot on. One fair concession to it, though, is the native f/5 focal ratio. Thank you for the lovely channel. I believe you are the finest educator for folks learning the ropes in this crazy hobby.

[@NebulaPhotos]

Thanks! I added a pinned comment with some corrections, and added a little commentary about the Esprit 100 corners - something I should have mentioned in the video is it's really just the extreme corners. If I crop 500 pixels off both sides of the image, the star field is perfect. I wonder if your buddies may be cropping a bit? But it's also possible a small backfocus adjustment would fix it as you say. Talking to some folks at Sky-watcher, they felt the Esprit 100 was the least equipped to handle the IMX455 and the 120mm and 150mm would work best.

[@G4L4CTIC]

31:58 newb here. I see a angled smudge across the middle…can you explain what that is please?

[@NebulaPhotos]

That is the nebula I was capturing. It’s a ‘dark nebula’ meaning space dust. In the video I’m only showing raw data from the tests I did, but I took all that data and processed it to make this which shows what the nebula actually looks like better: www.astrobin.com/4bi317/

[@G4L4CTIC]

lol sorry....maybe i should pay attention @@NebulaPhotos

[@WRX2001]

Hi Nico are there any difference between Triplett and doublet telescopes as in imaging performance? I know in cost there is a difference,

[@NebulaPhotos]

Check out my video here, where I tested this: kzbin.info/www/bejne/jXWvhqlnfL5md7M In short, a doublet with ED glass + a field flattener will perform very well for astrophotography- the blue stars will just be a little bit bloated, but many people would not even notice.

[@glorbez]

Mines an 8 inch. But it's not the size that matters but the way you use it, right?

[@astronome66]

Ugh, bad Nico! Bad astrophotographer! I'm supposed to be done with buying scopes, and here you are, tempting me into 'needing' one more 😅 But yet another awesome shootout sir. Well done 👍 Will be fun to watch over the next few weeks / months to see of any of them take up a more permanent place in your collection 😁 Cheers!

[@astroventure2221]

Curious, you suggested the HEQ6, but why not the 5? I ask because none of these loads would tax a 5, and the 5 is a lot cheaper. Of course, if the 6 is within your budget, then get it, but I think the 5 would be more than adequate.

[@tyrantworm7392]

A belt converted/tuned HEQ5 perhaps, but you are getting close to max payload with all the gubbins. Guess it depends on environment and exposure length you image at also, even with Apo's and guiding, wind can be the boogieman.

[@astroventure2221]

@tyrantworm7392 I was thinking that with the scope, camera, guide camera, guide scope, and asiar, you're still not hitting 3/4 of the payload.

[@mungus3838]

Nico, when are you taking a road trip North? 30 miles up 95. I'd like to see what you can get with my Nikon Z9

[@MickyMouseLimited]

What is your favorite eye piece for 120 Askar? Do you think 7 mm is too short of an eyepieces. Thanks

[@NebulaPhotos]

Hard to answer without knowing your skies and what you are interested in. I use my 20mm eyepiece most often, but I mostly like looking at nebulae, star clusters, and bright objects. I'm not a 'serious' visual observer. I think a 7mm eyepiece can be useful, but I'd also have a wider eyepiece like a 20 or 25mm.

[@thomasphennigan]

I’m late to the party. I’m a subscriber and just became a Patreon member for your channel Nico . Love your content. Just curious about your experience with the ZWO FF107 Quad . Did you ever figure out what the problem was in the upper left at full frame ? I’m very interested in this scope as it seems to have everything I would want sans fpl53 glass but you can’t have everything.

[@NebulaPhotos]

Hi Thomas, Thanks! I didn't ever figure out what I was seeing in this test, but reaching out to ZWO and others who have the scope, it seems like it was something only happening with my copy. Cheers, Nico

[@Psychlist1972]

I haven't been able to use any of the cases that came with my OTAs. I wish manufacturers would give you the option to get a larger case instead of the small one. I get why they do it (for shipping as much as anything else), but it's wasteful for those of us who like to keep our imaging trains together.

[@christianbowes7907]

Askar for me - such nice stars except for f4. I would’ve been interested in seeing FWHM to gauge which setup produced the tightest stars.

[@NebulaPhotos]

drive.google.com/drive/folders/1zjEhyrzHGMb4omEIBmbbrKxCScsIDLAa?usp=sharing You can check out the data here. I think for me there are too many factors for FWHM to be a reliable measure I'd have confidence in sharing. The change in focal length combined with variable seeing, very limited data (just 5 subs), etc. I've considered taking the best sub from each scope and comparing those numerically, but the reviews are already long, and as mentioned there are several reasons I can't trust the numbers to be really measuring the scopes and not something else.

[@christianbowes7907]

@@NebulaPhotos I tend to agree with you considering how variable seeing can be and how much of an impact it has. We should test telescopes in space. I thought the Askar produced the best stars but I wonder how the rest might’ve performed when backspacing is dialled in. That said, I fully appreciate that that would take way too long, but also that it can make a big difference to star shapes in the corners. Really enjoying the head to head comparisons! Oh and thanks for the link to the data!

[@JohnStone-g8j]

@@NebulaPhotos Can you please also upload the master-bias, master-dark for the camera, the master-flat for each telescope and all 5 subs for each telescope. I'd like to try various processing techniques to see if I can equalize the results between the 103APO and the Esprit 100