Celestron C5 SCT vs Skymax 127 Mak - Double Star comparison test

In this video I compare the performance of two similar telescopes, the Celestron C5 and the Skywatcher Skymax 127. I've used a dozen double stars that are visible in the spring sky and looked at how the images from the SCT compare with those from the Maksutov.
Screenshots are included from Stellarium.

[@nekite1]

The Celestron has held up pretty well considering it's 40 years old! Good design is never outdated.

[@AndyinMokum]

Thank for making this splendid comparison video. When you said your Celestron C5 was 40 years old, I had to roll back the video and watch again. It just goes to show the superb build quality of these scopes. I have an older blue livery version Skymax 127. It also still works a treat. You're right when you say the 127 is a, "more serious beast..." I'd go further and say it's teetering on the cusp of comfortable portability. I certainly wouldn't want to drag around its beefier: 150 and 180 siblings. It's still a magnificent Mak that does the business. I love mine.

[@JenhamsAstro]

Thanks Andy.

[@BlackThunderRC]

Old but gold.

[@natem7440]

Wow.fast turn around on the comparison request! Very well done. Doubles are a nice test. When planet season is back it will be interesting also!

[@AmatureAstronomer]

Oh, I commented on your comparison between the SkyMax 127 and C90 that it would be better to compare the SkyMax 127 to a 5SE. I see you did it. Good! 👍

[@evertonporter7887]

I have a Skywatcher 127 mak and your tests remind me that I must take it out a lot more. I looked at Jupiter a few weeks ago through this scope and it was absolutely stunning!

[@fazergazer]

Enjoyed the double star comparison! Can’t wait for the planets!

[@MountainFisher]

I have a Sky Watcher 127mm Maksutov. OK, so then I bought the Celestron Nexstar 127SLT 5" Maksutov go-to for my son. The two scopes are the same scope, made by Synta and only difference is the Celestron comes with a 1.25" diagonal. The Sky Watcher ota is $550 and the Celestron was $670 and is a go-to system.

[@user-yh2bn8pb9h]

отличное и очень корректное сравнение..благодарю!!ни один магазин не делает таких тестов..вы лучший!!

[@Astronurd]

The 127 won this one easily IMO. Once the planets are back they will provide better targets and i agree with you that the 127 will stretch it’s legs more

[@ianfoster8908]

Thanks for the video. Like many here the 127Mak and I am very pleased with it, but being new to the hobby I have nothing to compare it with. I have become very interested in DSOs rather than planetary viewing; skies are Bortle 3 here. The rig, with an AZGTi mount, is not exactly Grab and Go but portable enough to live by my front door and be lifted out onto the front lawn for a viewing session. I picked up a little hobby killer as a grab and go to use in those few minutes between getting home from a late night meeting and going to bed. I have been surprised by the quality of the OTA and I am having a lot of fun with it but I doubt that a total beginner would fare so well. Thanks for a few more viewing targets. Clear skies, Ian

[@nicudanciu5758]

Nice, with a perfect radio voice. Congrats for your way to explain and make videos. Thanks!

[@JenhamsAstro]

Thank you.

[@frackcenturion]

the 127 mak is my favorite scope

[@GarnettLeary]

Hey Frack. It’s a fine instrument for certain

[@stew8584]

Agreed the 127 was slightly rounder, but as the optics are newer it did show that should be able to kept for forty years too. Cheers.

[@dunringill1747]

Very nice comparison video. I wonder how a new C5 would compare to the 40 year old one.

[@avt_astro206]

Great Video graham!! Nice Comparison, I bet The Maksutovs Smaller Secondary Mirror provides better Contrast + F12 Focal Ratio. Some Really Nice Double stars, im Gonna Image Cor caroli and Algieba Soon!!

[@JenhamsAstro]

Thanks! I wanted to see for myself if the usual argument about secondary size panned out. The result was closer than I’d expected. Clear skies!

[@andrewldownie]

Another useful video Graham, thanks. Will be interesting to see how the two compare in practice on planetary. Looks like you have the 127 on a Starquest mount there (in alt az mode) - does that hold up pretty well despite being above the advertised payload? Looks fine in the video. Should work OK in eq mode too in that case?

[@JenhamsAstro]

Thanks Andrew. The StarQuest copes ok with the 127 in alt az in terms of ability to counterbalance and smoothness of the slow motions, but the single screw to secure the heavy-ish OTA makes me nervous. Also the mount is so light on its aluminium tripod that the 127 feels too heavy and you need to take care not to tip it. So it works, but the C90 feels a safer payload in either mode.

[@GarnettLeary]

Great video. Really enjoyed seeing the splits. I’m surprised the C5 held its own against the 127. I believe you’re right regarding planets tho. That extra contrast will shine there. When I made a video regarding my thoughts on SCTs vs Maks I was able to draw a conclusion based on carefully studying replies. The guys who were readily defending the SCTs were 1) Edge version owners, and 2) mostly deep sky imagers. The best planetary imagers, like Christopher Go and Mr. Peach, are using large SCTs. That greatly helps the argument for SCTs over Maksutovs but I think it’s unfair. Certainly 11” or 14” are going to wreck a 7” Maksutov but I do think under circumstances. My location wouldn’t allow for such large aperture scopes nor would most peoples. I would love to put the 180 up against a C9.25. I don’t even need to compare it to a C8. I’m 100% sure the 180 would beat it hands down.

[@rbrtck]

Well, there isn't a huge deal of a difference between them. The biggest difference in this case is probably that this C5 is miscollimated, which should have been fixed before doing the comparison. This C5's mirror coatings are also pretty old, although that didn't make a difference in this comparison. MCTs have some slight but noticeable advantages against SCTs, such as contrast, due to their smaller secondaries, but SCTs are a bit shorter and significantly lighter, especially as the aperture gets large. The reason the best planetary imagers use SCTs is because this design scales better, and for what they do and how they do it (and given very good seeing), aperture really matters. Not that there can't be really large MCTs, as there have been a few (20" is the largest I've seen or heard about), it's just that they're rather unwieldy, pretty costly I'd imagine, and usually pretty darn hard to find. EDIT: I don't own either type of telescope, although I have used them some. If one design were simply better in every way, then most likely the other would cease to exist.

[@johnmarler6735]

A 5 inch Refractor and a similar sized Dob added to the comparison and all will be complete.

[@eterenostalgia5088]

Here Italy, fantastic "challenge" congratulations !!!

[@dschenk952]

Thanks, Graham. Nice comparison, and with the planets lining up in the early morning hours I'm taking my 127 out. Still using the mount that came with it, but I might upgrade to a Equatorial goto mount, if I can find one that doesn't break the bank, is sturdy, and is comparatively lightweight. Graham, I'm still confused about backfocus. Looked like you took the diagonal off the scopes, did you have to use any spacer tubes to help with the focus?

[@AndyinMokum]

Sorry for jumping in here. I had exactly the same question. The ZWO and Mak head, Martin Pyott over at: *MP Astro,* gave me the answer. I'm using the ZWO ASI120-MC S colour camera with my Skymax 127. The back focus on this and the ZWO ASI224-MC, is 12.5mm. This is pretty much a standard distance and doesn't present any requirement for extension tubes. Just screw in the nosepiece to the camera, remove the diagonal eyepiece and replace it with your prepared camera. If you're using a x2 Barlow. Simply place that between the camera and the telescope. I use a Celestron Omni x2 Barlow. It works well: however, I'd prefer a shorter 3 element one. I hope this helps - clear skies! 🔭😀

[@sjpp71]

Thanks for sharing your findings. One thing I noticed (mostly because I have been trying to use a C6 to image clusters and deep sky objects) is the star shape is not totally round (between the C5 and the mak, the mak seems to show better star shapes imo) So I'd like to ask you, is coma (or not totally round star shapes) normal (inevitable?) when imaging with a SCT or MCT?

[@JenhamsAstro]

Hi Sergio, yes I did note that some of the C5 stars weren’t round, but others were. But as I centred the stars, more or less, coma seems unlikely, more likely atmospheric effects perhaps? But to answer your question coma is definitely a real thing in SCTs (not sure about Maks as I’m no optical expert). But any effect would only be expected in the outer part of the field. I think RC scopes suffer less than SCTs.

[@kamilmoucka6811]

As these are commercially sold systems, one of the main focuses was on compactness. Both the correction plate of the SCT and the meniscus of the MCT were originally placed in front of the secondary mirror. In the compact version, the correction plate and the meniscus are almost flush with the secondary mirror and also serve as its holder. According to the SPOT diagram, the optical properties of the two systems were almost identical. But for the compact variant, differences between the two systems appear in the SPOT diagram, although not large. For the SCT, the aberrations start to appear slightly from 1/8 of the field of view. Whereas with MCT, it is only from 1/4 of the field of view. This could explain the better star imaging in MCT.🙂

[@croysk]

Nice idea for a video, and well executed.

[@JenhamsAstro]

Thanks.

[@markwelsh9068]

Hi again Graham. When it comes to Celestron SCTs, how can one compare the SCT of the "Starsense DX5" with another Celestron 5 inch SCT on another mount? Are they likely to be the same OTA (assuming they are standard)? Put another way, would I be quite sure that they (the OTAs) are built to the same spec and are, in fact, the same product just on different mounts? Just got to the end of your video - so to put it another way (3rd. time) would. the C8 on the Nexstar be exactly the same C8 on the Starsense Explorer version?

[@JenhamsAstro]

Hi Mark, as far as I know they are the same OTA, albeit with different colours. To be 100% certain you would have to ask a dealer. For Skywatcher Maks, bearing in mind that both brands are owned by Synta, I found that there were different spec OTAs for the 102mm. The weight difference was the main clue, plus only one allowed you to collimate, suggesting a different mirror mounting cell inside. I'd say if the OTA weights are very similar then the SCT tubes are likely to be the same.

[@davidletz9123]

Hello Graham, and thank you for this video (recently subscribed). I am new to planetary imaging, as I just started wide field imaging this summer. I have a Skymax 127 on order, as well as the ASI224MC. For a beginner, what power Barlow lens should I get for planetary imaging? I see different folks using different power lenses. I strongly suspect something like a 3X is going to be too much, and not produce good images. BTW, I will be using the ASI Air Mini to do my video. FWIW, the bulk of my time with the scope will be for imaging, at least that is what I anticipate doing. Thanks in advance for your consideration.

[@JenhamsAstro]

Hello David, I’m glad the video was useful. Personally I prefer a 2x. If you dial in the scope, barlow and camera into this site it gives you an indication of whether the image scale is appropriate, or to put it another way, is the angular size of the field captured on a pixel of your camera in a reasonable range for the achievable resolution for your scope’s aperture. Or even simpler, might you missing some details or capturing the same feature many times over adjacent sensor pixels.astronomy.tools/calculators/ccd_suitability I hope this is helpful. Other factors like the stability of the atmosphere and the height of the planet can be critical though - on a wobbly night you are better off inside! Clear skies, Graham

[@davidletz9123]

@@JenhamsAstro Graham thank you. Looks like a 2X Barlow is slightly pushing the resolving power of the scope. Interesting it does not consider the power of the eyepiece. One more question: how essential is the IR cut filter I hear recommended quite often for moon (and planetary?) imaging?

[@JenhamsAstro]

@@davidletz9123 I use an IR cut filter screwed into the 224’s nosepiece. I’m no expert but it helps with colour balance for a colour camera.

[@JoeJaguar]

good review, im also think they are 2 different scope for different reason i have owned both, although not right now again on both. I do have the C6 as a portable light weight for plain travel, bit bigger then the c5 but colects bit more light just a lb or 2 heavier. The 127 Mak for plain travel for me would be bit long abit more heavier etc. I guess thats why we need or want few scope to suit what we want to do and any specfic time. Althou saying all that i still prefer a good quality 4" Ed or apo to a 5" mak unless its only based on portability. Again thx for video. Joe

[@JenhamsAstro]

Hi Joe, I agree it’s hard to beat a 4” apo but cost wise there’s probably a factor of 4 between one and the Mak here in the UK. Pros and cons…I had a C6 a few years ago and probably should have kept it (I’ve got a list of those errors, maybe you have too?) I’m liking the light grasp of my Evolution 8 but whilst it’s an easy job to get it into the garden it isn’t one for a trip. Clear skies. Graham

[@JoeJaguar]

@@JenhamsAstro Yeah I agree with all those points currently I do not have a Mac but if somebody wants high contrast almost as good as an ED scope then yeah I think the mak Has a place if I even the SCT has a place. Anyway good video cheers

[@jesuschrist2284]

Is the square on its point star shape a feature of these scopes? I have a smaller mirror lens and thats what i get but a bit worse, so my focus is off?

[@woody5109]

SCTs are just nice to handle

[@4588ron]

Thank you

[@badmonkey2222]

Binary and multiple star systems are actually the most common as single star systems such as our own are the rarity.

[@bowrudder899]

Dante has a special ring in hell for the person who decided to put the finder scope shoe in that position.

[@ENKI7477]

You can compare any equipment and give reviews. Good luck

[@gabrielrobles5288]

Is it hard to focus on the C5? I remember reading that you had to rotate the back of the scope (like if it was a camera lens)to reach focus

[@JenhamsAstro]

The C5 has a conventional focusing knob so is no more difficult to focus than other scopes. The old C90 models from the 70s/80s had the helical focus you are thinking of. I’ve got a video of this scope on my channel. Focusing on of those is tricky unless the mechanism is well lubricated.

[@gabrielrobles5288]

@@JenhamsAstro thank you Jenham, I love your content

[@joeimbesi99]

Wonder what the LIGHT LOSS on the C5 is due to very old deteriorating coatings which surely over is well over 10% in all these years

[@JenhamsAstro]

Yes that must be a factor. The C5 looks shiny but then you look at the 127 and realise that it’s REALLY shiny.

[@jgfrjhgrz-fgkjh]

I'm wondering why there isn't a small ring around the stars because of the obstruction?

[@JenhamsAstro]

The secondary isn’t seen in a focused star image but you can see it as a black dot when the scope is of focus. the scope is bringing rays from a position at infinity, and any part of the mirror can focus these rays, not just the middle part.

[@amaury1264]

Have the quality of the optics changed over the years with the C5? Better lens coatings for example?

[@JenhamsAstro]

Yes, that’s a good point. In general C5s have a good reputation, aside from a period in the mid 80s where quality dipped, apparently. But certainly the coatings on the Skymax will be superior to the old C5.

[@davepastern]

Yes they have. Significantly. 40 years ago, no StarBright XLT coatings. Graham, try the test again with a well collimated new C5.

[@amaury1264]

@Jenham's Astro it would be interesting to do a three way comparison between the old C5 and a new C5, and then look at the new C5 against the SW 127 Mak. Would be useful especially as newer doesn't always mean better; maybe cheaper to produce and a smarter design, but what matters- the optics-are they of a better quality than previous models?

[@davepastern]

@@amaury1264 The XLT optics have much better light transmission (~95% from memory) vs the old Celestron SCTs (~86-88%). Reference source: www.bintel.com.au/wp-content/uploads/2016/08/StarBright-XLT-Tech.pdf new is not always worse than old - quite often it is better, but nostalgia ruins perspective.

[@davepastern]

@@amaury1264 of course, mirror figuring should also be considered too. modern optics are mass manufactured of course, but typically, QA is pretty high (unless you are Meade lol).

[@mastercaptain8695]

what mount are you using for the skywatcher mak?

[@JenhamsAstro]

It’s on a Skywatcher Eq-Avant mount.

[@ericbarnett6771]

What AltAz mount is the Skymax sitting on?

[@JenhamsAstro]

It’s from a StarQuest 102 package. It was available as a standalone mount called the Az Eq Avant.

[@phakeacount2228]

The magnification on the MCT is slightly higher than on the SCT.

[@JenhamsAstro]

Yes, the MCT is f/12 and hence has a longer focal length (1500mm) than the f/10 SCT (1250mm).

[@phakeacount2228]

@@JenhamsAstro Well, sure. I meant that in comparing them on doubles, its not an exact comparison because they are at two different magnifications.

[@JenhamsAstro]

@@phakeacount2228Yes that’s a good point. The resolving power should be the same but the magnifications favour the 127.

[@daviddesmondyork6306]

Good video. However some of the star images in the C5 looks as if they suffer from some coma.

[@JenhamsAstro]

I agree, something not quite right there. I think the collimation may have been a little off.

[@davepastern]

weight isn't a fair comparison - by design, the Mak will always be heavier due to the meniscus lens used. The C5 didn't look properly collimated imho and that could be easily seen via the binary star videos.

[@johnshropshire3399]

👍👍👏

[@StereoSpace]

Canes Venatici: Ka-ness Wena-tichi

[@Mark-MensHealthandPT]

The mak would have superior light transmission due to modern era coatings, not really a fair comparison. Line up a current production C5 with a current production mak 5... Most people aren't going to be able to find, let alone buy, a ancient C5. Review the current productions for a legitimate comparison.

[@ossiaaltonen2176]

Tähtikaukoputkeen sopiva kamer

[@dragosniculescu6877]

Useless comparison. Try again with a proper collimation.