I think the larger pixels would only matter for guiding short focal length telescopes, but as the focal length decreases, the guiding becomes less critical, so the inefficiencies don't really matter. I use it currently with my RedCat51 (250mm focal length) and a William Optics 32mm UniGuide scope (120mm focal length) and it works just fine. Actually, I've heard of people with long focal length scopes 2X binning their guide scopes to get more signal for fainter stars, so the larger pixels in this would help alleviate the need for that.

While technically possible to use an OAG with camera lenses, the real problem is lack of back focus distance or "flange focal distance". This is the distance from the camera lens flange to the sensor. It can be a challenge to get these OAGs to work within a 55mm back focus distance, but cameras, especially modern mirrorless cameras have much, much shorter flange focal distances to work with. For your case, the Sony E-mount flange focal distance is only 18mm, so less than the thickness of the OAG itself. I've never seen an OAG for any camera system, even Canon EF mount which has a flange focal distance of 44mm.

There are no spares included in the package, but you can buy spare drawers for $22 each.

@@dalehollenbaugh6084 Thanks for the reply, found them. Thank you very much.

Very true, however, for users of the ASI2600MC you can't use the OAG-L with a filter drawer and achieve 55mm backfocus. It must be used with a filter wheel or with no drawer and a special spacer, due to mounting constraints. I do now have a ZWO OAG-L for use with my ASI2600MM and 7x36 filter wheel, but still want to use OAG on my ASI2600MC with filter drawer. I haven't made a video yet, but think I have a solution. Swap out the M42 sensor tilt plate of the ASI2600MC for the M54 sensor tilt plate and then mount a ZWO M54 filter drawer. This larger M54 filter drawer has threads as well as holes for mounting, so it will fit the Player One FHD-OAG Max, which has a 8x14 mm prism large enough to fully utilize the sensor in the ASI174MM Mini. All this and achieves 55mm backfocus. I bought all of the parts, but haven't gotten a chance to test it out or film yet. This will be my new setup for C11HD with 0.7X for galaxy season coming up.

Let's say you want to connect your ASI2600MC Pro to a refractor with 55mm backfocus requirement and the flattener uses M48 threads. The Celestron OAG body is 29mm thick, then the M48 telescope adapter adds 4.5mm thickness, then the M42 camera adapter adds 12.5mm thickness, and then the ASI2600MC Pro has 17.5mm thickness, so total backfocus length for this setup is 63.5mm, which is way too much backfocus to get clean stars using a 55mm backfocus flattener. And I want to add a filter drawer, so that makes it that much worse. It could be used on a Petzval-style refractor, which have a wide backfocus range or also SCTs or RCs that have a much longer backfocus.

Front and back adapter are 4,5mm, so 2x4,5mm + OAG body = 38mm. Add17.5mm for ASI2600 = 55,5mm. My camera has 12,5mm BF (Touptec IMX571), so I have additional 4mm spacer. No go with filter wheel or drawer, but for OSC it's great. LP filter screwed onto flattener (Apex-D) and IMX174 for guiding. Problematic with other OAGs - easy with Celestron. My Askar OAG stays in the drawer and waiting for mono setup... someday... @@dalehollenbaugh6084

I suggest if you rent a car in Fairbanks specifically to drive the Dalton Highway, fill the fuel tank to the top even if it says full on the gauge. We assumed our rental was full, but we barely made it to Coldfoot and was running on fumes. I used a GoPro 8 to record. I did 5X time-lapse at 30fps (doesn't do 60fps), and then post processed the footage to get 15X 60fps.

@@dalehollenbaugh6084 I was wondering about the fps. Looked like 60 fps, but had a cleaner look. Nice work. Yes, my plan is to rent a car out of Fairbanks. I’ve researched which ones allow travel on the Dalton Highway. Thanks for the travel tips. Good information to have.

Yes

I think about 25 MPH

@@dalehollenbaugh6084 thanks. I ended up going closer to 20mph and was driving a Class C motorhome. Road conditions weren’t too crazy a few days ago although a minor landslide happened on our way back.

@@josephandrews6684 We actually found that the Dalton Highway was in better condition than the McCarthy Road, at least when we drove them. Wasn't expecting that.

@@dalehollenbaugh6084 uh oh I can hear my next trip happening shortly…

A fast-onset aggressive cancer (hemangiosarcoma). He seemed fine and happy on his 10th birthday, and then three weeks later, he was gone.

​@@dalehollenbaugh6084 😢😢

I would not recommend any of the ASI "Mini" cameras for astrophotography. They are best used for guiding. They are all monochrome, not color, and their form factor isn't directly compatible with a filter wheel typically used with mono cameras as well as their connection is USB 2.0 and not USB 3.0, so the speed of the camera wouldn't be good for planetary imaging where you typically want very fast speeds. It CAN be used, but I would recommend one of their color planetary cameras instead (ASI585MC, ASI678MC, ASI662MC are great choices), or a used ASI224MC, ASI385MC or ASI178MC if on a budget. That being said, I did use my ASI174MM Mini camera to take pictures of faint moons of Saturn. I was taking longer exposures than typical planetary imaging and wanted the higher sensitivity of the mono camera and wide field of view of the larger IMX174 sensor to be able to capture more moons in a single frame (got eight moons)

@@dalehollenbaugh6084 Thank you very much, I've heard people say that the ASI178MC can be used on deep space as well, do you know any more about whether that's an option or would it be worth it to eventually buy a camera meant for deep space photography?

@@bencaddoo1777 The main differences between planetary cameras and deep sky object (DSO) cameras is the typical size of the sensor and whether it is cooled or not. The DSO cameras typically have thermo-electric cooling and you can set a constant cold temperature to both reduce noise as well as have a consistent noise level for your your many photos that you stack together for form an image. The cooled cameras typically cost about $300 more than the same sensor camera. The sensors also tend to be larger to capture a larger field of view. Planetary cameras are typically used to take short videos of the planets with many very short exposure images that are typically very small and very high frame rates that can be run through software to stack and create images of the planets. My favorite planetary camera is ASI585MC and it has a relatively large field of view for a planetary camera, and I have used it for DSO work, but it does have more noise than cooled camera. Another option is to use a DSLR or Mirrorless camera like a Canon/Nikon/Sony/etc. These aren't cooled, but typically have sensors that are as large as the cooled DSO cameras and can be a great way to start into astrophotography, especially if you already have one.

Hmm, there are a couple of things that come to mind. First, make sure you are not stacking any of the black extensions on the camera. There is a 5mm thick one meant for C/CS threads and a longer one about an inch. Don't use these with OAGs. Second, it may be hanging up on the compression ring. Unscrew the compression ring clamping screw all the way out. You could also unscrew the entire helical focuser off of the OAG and try to insert the camera from the other end to see where it is interfering. My guess is the compression ring. Perhaps the compression ring is bent and catching?

@@dalehollenbaugh6084 Took off all the extensions was first thing I did, I took off everything I can imagine it is stopping right on the helical focuer Guide pins, it wont go past that. I agree there Is a problem although it is Brand new. agena Astro is ignoring all my inquiries for support.

If you have the original ZWO OAG, made before Aug 2021, with the 5.5mm aperture, then the ASI290MM Mini is probably a bit better. If you have the newer ZWO OAG, with the oblong aperture, then the ASI220MM Mini is a good camera. The 290 has smaller pixels, so would help more for shorter focal lengths. You have a non-Mini camera, and a color one at that, so if you get a mini, get the ZWO helical focuser as well. Actually, the ASI120MM Mini will be more sensitive than your ASI120MC-S, due to the simple fact that it is monochrome and many people still use the budget guide camera very effectively.

@@dalehollenbaugh6084 Thank you very much for your help! I have the new ZWO OAG, so I'll probably upgrade to the ASI 220MM Mini. My telescope is the Skywatcher 150P with a focal length of 750mm.

I also now have all of the "Mini" guide cameras and hope to do a comparison video at some point. Have been using the ASI220MM Mini and it seems to work fine, but using it with 30mm or 32mm guide scopes with my RedCat51. I also just got the new Player One FHD-OAG MAX which can illuminate the full IMX174 sensor. It bolts to the filter wheel like the ZWO OAG-L, but can be paired to the ZWO M54 filter drawer and still achieve 55mm backfocus (OAG-L + M54 filter drawer is 60mm back-focus). If you have monochrome and EFW, then get the OAG-L as it is the best solution I think, but for OSC with filter drawer, the Askar combo works very well. I'm hoping the new combo of Player One FHD-OAG Max + ZWO M54 filter drawer + M54 tilt plate + ASI2600MC Pro will beat them, but haven't opened the box yet to test. Also, some might not want to replace the tilt sensor to M54, but that is required to use this particular setup.

@@dalehollenbaugh6084 I'm debating between the Redcat 51 and Askar FRA300, but either way, I think I've made up my mind to go with OAG rather than a guide scope. As for guide camera, I'm a bit torn between the ASI290 and ASI220 - the 220 seems to have better specs overall, but for the 250mm - 300mm focal length where I plan to shoot (at least initially), I suspect the ASI290's smaller pixel size might benefit me more - not sure. As for main camera, I've settled on the ASI2600MC. I don't have the time / patience / experience to deal with mono, at least not yet - I'm still quite new to the hobby, only working with a star tracker and mirrorless Sony + Tamron zoom lens at the moment!

@@johnposavatz I had narrowed it down to the same two scopes, RedCat51 vs FRA300. If you haven't seen it yet, check out Nico Carver's (NebulaPhotos) video review of the FRA300. He compared it to the RedCat51. Both great choices, but I think the RC has less chromatic aberration than FRA300, at least in his sample. RC51 does use FPL53 glass and FRA300 doesn't, so that could be the reason. Some people might not like the helical focuser, but if you buy a kit to connect ZWO EAF, then it works just fine. In the end, I chose RC51 and couldn't be happier. Images are fantastic. Since it is also my portable scope to take on the road, I wanted something as small and light as possible. I have Samyang 135 and Stellarvue SVX080T (480mm focal length @ f/6, but 312mm focal length with 0.65X reducer), so the RC51 fills in the gap better. As for the ASI220MM Mini, I wouldn't necessarily call it an "upgrade". It is cheaper, has larger FOV and more sensitive in IR, but larger pixels. As you said, the ASI290MM Mini smaller pixels might actually be better for small focal length applications. Of course with smaller focal lengths, the differences become almost pointless. For longer focal lengths, the ASI220MM Mini does become a better choice I think, so still probably would get that if you plan to upgrade to a larger scope down the road. Or pick up a cheap used ASI120MM Mini like I did and keep using it for the smaller focal length scopes. I would say that it is much easier and cheaper not to use OAG for such a small scope in the 250-300 range. Get a small 30-32mm guide scope. I have four small guide scopes to compare in a video when I get a chance, but my initial impression is that they all work about the same with only minor differences. OAGs become more important at longer focal lengths - I'm going to say at 1000mm or above. Also, anything with a movable mirror (to focus) like a SCT will benefit from OAG, so my C11. Not that you can't use OAG with shorter focal lengths, but it won't be any better and could be worse - depending on the scope and conditions. You may not get as many stars for multi-star guiding and out at the periphery of the image circle, there is more coma and field curvature to deal with. But, once you set it up, you could move the OAG + filter drawer + camera to another setup easily. And with Petzval designs like the RC51 and FRA300, you don't have to worry about backfocus distance either.

Any and all of these OAGs can work, but you will have several challenges. First, since your scope is a non-Edge HD model, it isn't corrected for coma and field curvature, so with the OAG picking up light at the periphery, there is likely to be significant coma and field curvature. Perhaps using a field corrector like Starizona SCT Corrector IV could help, but I'm not sure how well it will work with OAGs given its small 27mm image circle. The other issue is that OAGs are best used with the "Mini" style of guide cameras since you want the sensor focal plane typically pretty close to the prism. You can remove the helical focuser and screw the 174mm directly to the OAG stalk, but it is difficult to co-focus with the primary camera, but can be done. If you keep the helical focuser, you can screw the camera to the top and have an easy time focusing, but will have to space the primary camera back significantly more (42.7mm farther) in this configuration. This can be done, but you may go over your back-focus distance. Back focus on C9.25 is natively 139mm, but adding a field flattener will change this. Back focus with Starizona SCT Corrector IV is 90.3mm. I wouldn't recommend the ZWO OAG since most of the 174mm sensor is wasted as shown in my video. The Askar OAG is better, but still doesn't fully illuminate this. The Celestron OAG is best of this batch, but the helical focuser can't be removed. If you are careful with your back focus, this one can work the best.

@@dalehollenbaugh6084 thanks appreciate the inputs.

@@dalehollenbaugh6084 I forgot to mention. I use an external moonlite focusing Flange inside which I have a Meade 0.63x Reducer corrector. Would this change the dynamics of your suggestions. Pls let me know.

@@sreeshab4093 It can change the backfocus. Typically on an EdgeHD model, the focal reducer is mated directly to the back of the telescope and any accessories, including external focuser, are added after that, taking up back focus. But with the non-Edge SCTs, I think you can put the field flattener after the external focuser and it will still work well. I've read there are several different versions of the Meade 0.63X field flattener/focal reducer with three separate back foci: 72.6mm, 85mm and 105mm. I think all three can work with OAGs, but you'll need to do some testing to see how much vignetting and coma are in your pictures. I think with the EdgeHD models, with their built-in field flatteners, the back-focus numbers are more rigid, but with the other SCTs, there is more ways to do it and a wider sweet spot, but also more work testing.

Optec sells the Lepus F/6.3 reducer corrector with a 105 mm recommended distance to chip. They will custom cut a camera adapter to whatever attachment size you need for around $75. I’m going to test mine next week. I’m using a QHY 268m with medium oag and large cfw.

I doubt that's unique to this camera, but rather common to all the ZWO cameras. What tracking software are you using?

@@JethroXP It's a little home-writen app that I wrote to get my scope to do some ISS/satellite tracking, nothing fancy like Goto or any of that... just bare bones optical dot-location .. it sees a dot/blob and tries to keep it in the centre of the CCD...

@@IIIRotor That's cool!

ZWO doesn't sell a M54 OAG. They have their original OAG, which I show here, the M68 OAG, which is discontinued and the OAG-L, which I don't own, but show some of the specs here, especially the prism size. The ZWO M68 OAG had a larger opening to be able to be used with their full-frame cameras, but had the small 8mm prism with presumably same small circular aperture as their regular OAG, so the OAG-L that replaced it worked well, but the way it is connected to the cameras means that it works well with the monochrome camera setups with filter wheel, but not with the color cameras with the filter drawer. The filters have nothing to do with the OAG, but can be very useful for the cameras. You don't need to use a filter or filter drawer with an OAG, and in that case you could connect the ZWO OAG-L with their 20mm special spacer for use with it and the ASI2600MC Pro and it will work, but I always want a filter drawer.

M42x0.75 female thread

@@dalehollenbaugh6084 so how would I go about connecting it to the Coma corrector that comes in the quattro 150p deal? It's m48, Would the ZWO m42 to m48 adapter work?

@@Orbit_3_astronomy so, your coma corrector needs 55mm of backfocus and has M48x0.75 male threads. The camera sensor is spaced 12.5mm back from the flange, so 55-12.5 = 42.5mm, so this is what you need to come up with. There are numerous ways to reach this with spacers, adapters, filter drawers, 3D print, etc. If you just want the basic, I would get the ZWO M48 female to M42 male 16.5mm adapter, the ZWO M42 female to male 21mm spacer and the Stellarvue M42 male to female 5mm spacer. The Stellarvue spacer has a deeper 4.5mm female spacing and will fully thread onto the adapters and some other 5mm spacers might protrude a bit. agenaastro.com/zwo-m48x0-75-female-to-t-t2-m42x0-75-male-adapter-set-with-37-5mm-extension.html and www.stellarvue.com/42-mm-extension-tube-5-mm-long-sfe-m42-005/

@@dalehollenbaugh6084 will I need both these items or are they just 2 different options

All three adapters. 16.5mm + 21mm + 5mm. Two from ZWO and one from Stellarvue.

There are very few accommodations along the road. Basically, at the halfway point, in Coldfoot, you have a hotel called Slate Creek Inn, but also known simply as the Coldfoot Camp, as that is the original camp from when the pipleline was constructed in the 1970s. It offers very basic rooms and that is where we stayed traveling in both directions. In Wisemen, the tiny village just north of Coldfoot, there are two bed & breakfast type lodging options, Boreal Lodging and Arctic Getaway B&B. I think next time we drive, we'll try one of these instead of Coldfoot. In Deadhorse/Prudhoe Bay area, there are actually about a half-dozen or more hotels/camps that mostly cater to the pipeline industry workforce. Most rooms are single rooms for the workers, but at least some of them offer rooms for tourists. We stayed at the Aurora Hotel and would recommend that. Food and laundry were included.

@@dalehollenbaugh6084 oh wow! thanks for the detailed reply! I'll use these as references for my trip. Thank you 😁