Next step up

I would say the EdgeHD, but honestly, the non-Edge SCT might be a better value unless you plan to do lots of imaging at native focal length. With the non-Edge, there are better reducers out there than the Celestron Edge reducer, and would probably be the best compliment to what you have.

I'm suggesting the SCT because of the versatility of focal lengths that come with the SCT… you can get the hyperstar and image at f/2 around 400mm. This would be a pretty solid focal length when paired with the 2.9 micron pixels of the 585.

Your current scope is around 900mm. If you can get your hands on a starizona night owl .4 SCT reducer, you're around the same focal length but at f/4.

With a starizona .63 reducer, you're imaging around 1400mm at f/6.3ish (I think it's a little higher for the C8), which would be a bit oversampled of course, but provides a nice focal length extension for smaller targets like galaxies and planetary nebulae. You can always bin your camera if you don't want to be oversampled.

You can image at native focal length around 2000mm again for PN or other small objects. Coma and curvature aren't a huge issue if your object is small and centered in the FOV.

You can Barlow the native FL for planetary work. You can reduce the ROI in sharpcap on your 585 and do solid planetary work.

I have also found that the SCT holds collimation very well, even after being taken in and out every night, and even then, I found collimating and SCT to be much simpler than collimating a newt.

The 8” f/4 newt would be a nice, easy transition for you since you're already using a new, and imaging at f/4 around the same focal length would be nice… but it's fundamentally not much different than what you have, so it may not be worth it.

I'll caveat this with the fact that I don't have experience with a RC, but I understand that they can be challenging to get setup and collimate, but once it's set up, it can provide some very nice results. That said, you would be limited to only the longer focal lengths (I think RCs can be slightly reduced and you can always Barlow). So if you're goal is to only use the new scope for galaxies, PN at 1400-1600mm or maybe barlowed planetary work, then this might be a good option, but you lose out on the flexibility fast, wide field optics you could get with the SCT and a hyperstar.

I'm sure you'll be happy with whichever you pick, but I suppose the age old question is: what's you're primary goal for the new scope? What types of targets?

Interesting comments but I should say I did sell an old Meade SCT a few months ago because I was not happy with the coma, of course I might have felt differenty if I had the Starzona reducer.

On the rest, I really like to do a variety of objects, everything from the moon to PN’s and everything in-between. The only thing I’m not interested in is super-wide field work so I probably wouldn’t go Hyperstar but I do like the way things lay out on an RC or SCT, plenty of back focus and everything hanging off the very solid back plate, close to the dec axis. That’s a very clean setup with an OAG. Unlike some, I’m actually a fan of moving primaries for the flexibility it provides (my old Meade had zero mirror slop).

Jason Fleming · Aug 26, 2025, 05:26 PM

The Edge HD is a good choice (albeit the most expensive). It will give you the most options for additional focal lengths using standardized solutions. For example, I have the 9.25, and can shoot at:

517mm with Hyperstar v4 F2.2

1645mm with 0.7 Celestron reducer

2350mm Native

5875mm with 2.5x Barlow (admittedly theoretical and only possibly good for planetary with excellent seeing)

Of course you would have to scale these values down for the 8 inch.

I also have a 8” F/4 Newtonian and it is a great scope. If you go that route, you may need to upgrade the focuser and many that come default are underpowered for astro equipment and have a tendency to slip under load, especially once you factor in color wheels, off-axis guiders, upgrading to larger cameras, etc. Those might not be considerations for you right now, but I like to plan for the future as I know at some point I’ll be wanting to take it to the next level and add stuff which becomes a force multiplier for complexity, especially when I didn’t plan for the possibility.

Actually I have all that in the image train of my 6” newt. I’m still running the original Crawford without the linier rail and somehow it’s getting the job done with no slipping. I’m not running and OAG or rotator and I’m sure that would cross the line with the Crayford. If I did go Newtonian I would likely do a custom build from the ground up rather than buying an OTA and throwing half of it away

That’s certainly not off the table, I do have the seeing to support the aperture.

That's a good point as well. The C9.25 is a sail in the wind, and if you're imaging at higher focal lengths, the impacts are even more pronounced. In any event, you'll want to make sure your setup is shielded from the wind as much as possible. I've struggled a bit at longer FL (about 1400mm with the reducer) where I've had to toss about half my subs due to them being impacted by (what I assume is) wind. I've since made a temporary windbreak I can put up and take down each night which has worked well when I aging with the hyperstar (I've only thrown out subs due to clouds). I'm eager to try it out at 1400mm to see if it helps enough at that FL or not.

I have to assume that due to the sizes of the OTAs, a RC and 8” to 10” newt will also be impacted by wind (my 8” newt was, but not to the same degree my C9.25 is). Certainly something to consider as you weigh your options.

In combination with an IMX585 I would recommend the RC. The 8” should deliver a sufficient flat field up to Micro 4/3 sensor size without a corrector, so the stars should be perfect for the IMX585. This opens up imaging in Far-UV and/or Near-Infrared. You can use additional UV, NIR and clear glass (instead of IR-cut) filters and boost your SNR.

I started to use my RC like this and got an image of M102, where my red channel is mixed 50/50 with NIR data. It’s fun.

Edit: Forgot to say; it seems that my AP 0.67x RC reducer has very good transmission in the VIS and also the NIR spectrum, so “reduced” (f/5.3) infrared imaging is an option, too.

Yup, I already saw your cocoon because I follow the ATR585M camera so I can see what results other people achieve with that (HDR) sensor. And your result is really nice I must say, especially how the stars are rendered.

How much exposure time does the iris have? Considering the contrast and all the dust I would speculate it must be tens of hours because of Bortle 8.

Yes, the collimation can be complex if you do not have any prior experience and it depends on the mechanics of your particular scope. At the back of the 8 inch model you can only collimate the primary and its cell is coupled with the focuser. So if you have any focuser sag you will get problems. Me coming from two RCs (10” steel tube [sold] and now a custom made carbon 10”) I would always buy an additional tilting unit for the focuser. This will prevent further collimation “headaches”.

On some units the default GSO focuser is not rigid enough and can cause sag/slippage depending on angle your scope is pointing at the sky. I speak of experience as the standard focuser of my steel tube RC was downright useless. So I advise to plan in some additional €€€ for a tilter + focuser.

The good thing with GSO RCs is that the collimation is really stable. Once it is dialed in, you don’t have to touch it again for weeks/months. This depends also if you’re shooting in the backyard or mobile.

I travel with my fatty scope a lot and collimation holds up until today.

Another “negative” advantage of the RC is, that you can buy them used at a very affordable price. That’s what I did with both of my RCs.

I tried out a decent number of scopes (APO, Newtons, RCs) and the RC is the most fun to use with the newton coming in 2nd. I do not have any refractors anymore because I sold them.

Regards

Such a result with 4.65h in B8 feels like cheating, especially with the IMX585. Just shows how awesome this sensor is.

For what it’s worth, I’m tossing in another recommendation for the EdgeHD 8. The HD8 is my favorite of my 6 telescopes. The optics are good and the size still allows decent handling in lights breezes with a good mount. It has enough aperture and focal length to open up a whole new range of targets.

Tony Gondola · Aug 30, 2025 at 12:03 AM

So, I’m really down to an 8” RC or 8” F/5 Newt. The RC has a great form factor, and the fact of not needing a corrector is certainly a plus. I’m sure it would be a lot of fun. Still, the Newtonian rig comes in at half the price which is hard to argue with.

You could choose to shoot without a coma corrector with the newt too - I have attached two raw subs (just stretch applied) from my 200PDS to show how much coma there is without a coma corrector at f/5: A full frame from an IMX533 and a crop to simulate the rough dimensions of a 585.

There is obviously coma there, but BlurXterminator - if you use it - corrects it completely.

Now I know people will says it’s always best to correct the coma optically but coma correctors are such a faff and suck some of the fun out of image capture - too much messing with backspacing, tilt, reflections etc. Not to mention the light loss from those extra lenses. Running with no filter and no corrector gives you the absolute maximum signal you can get. Also cheaper end coma correctors may actually reduce the sharpness on axis.📷 M63-533.jpg📷 M63-585.jpg