C9.25 XLT opinions pls

Hi, I doubt you'll find many people on here who have tried both and I'm in that group but it's definitely a tough choice. I'd very highly recommend the HyperStar as your first purchase over a reducer (although it's effectively a reducer). If you're in to DSO then the HyperStar is a game changer. If it doesn't fit in your budget then for got the 8 inch and HyperStar. I'm not sure you'll notice much between the XLT and EdgeHD, there IS a difference but certainly not worth the upgrade for planetary as you're not using the edge of the field. Get a Barlow for planetary.

Hope that helps a little…

I had a guy at Celestron tell me that an XLT is a better option than the Edge if you are shooting with a reducer. There’s less glass in your optical train with the XLT.

I had an 8 (came on a Nexstar originally) and upgraded to the 9.25XLT. The 9.25 is slightly faster yielding 1480mm and .528”/px with the Starizona v4 vs ~1450mm and .535”/px with the 8/v4, both with the ASI2600MC. Apparently the 8” scopes are closer to f/11 than f/10.

As John Davies mentioned above, for planetary the Edge has no benefit when paired with a small sensor.

I cannot comment on how well the mirror locks work on the Edge or if they can be used with an autofocuser, and I do find that I need to refocus more with my XLT than my 10” Newtonian, I assume because of mirror shift inherent to SCTs.

Unless you intend to shoot DSOs without a reducer, I think the XLT is the way to go, and 9.25 has a few advantages over the 8.

My older C9.25 is not compatible with Hyperstar. If you're buying secondhand you should check this.  Having said that, the C9.25 works very well with camera formats from 4/3 and smaller; I use an ASI 533MC.

I also have an older 9.25 that is not Hyperstar ready but I do have a Starizona focal reducer.  I initially used it with a Celestron .63x FR.   The Celestron FR  worked pretty well but the Starizona is better.  On the Starizona,  you do have to be sure you have the 90 mm backfocus spacing correct and the scope collimated to get the best results.    I use an Askar OAG for guiding.   Before I used that OAG I would get a lot of pixel drift in my exposures.  I don't know if that was due to mirror flop in the 9.25 or flexure in my guide scope but the OAG basically eliminates that.   Supposedly the Edge with its locking mechanism doesn't have mirror flop, but there are some comments to the contrary.    While I can't compare my 9.25 to an Edge since I have never used the latter, overall,  I am satisfied with what I have.

I Have Carbon Fiber C9.25 XLT, C11 XLT. I also have an Edge 8. I imaged for years with the C11 Hyperstar 3 at F2. Hyperstar is a whole ano1thern game. I did mono with a filter drawer.

Also in another post it was said that Hyperstar was a Reducer. It is not a reducer. It is a Flattener working off the primary F2 spherical mirror. Celestron 8 &11 SCT's primary mirrors are F2. The secondary mutifies x 5 giving a F10. The C9.25 primary is F2.5 and consequently not needing to be multiplied as much by the secondary. Consequently, the longer tube. I have used the Sarizona 3 F7.5 reducer/Flattener with both the C9.25 & C11.

Other than magnification, I didn't see any more resolution in the C11 to justify the additional weight. I NOW use the Starizona 4 F6.3 Reducer/Flattener on the C9.25. With the C9.25, the Starizona 4 will render F6.5. It will correct ASP-C chip. I have a QHY268M. HOWEVER, I use a Starlight Xpress Trius SX694 with 4.5 pixels for better sampling. That chip is large enough for most galaxies that I image with the C9.25. 

I have always used Starlight 2" Feather Toutch Crayford focuser at the rear when 1using the Starizona R/F. I highly suggest you use either a Starlight or Moonlight 2" focuser, rather than the Celestron primary mirror moving focuser. Always end final stardard Celestron focus with upwards mirror movement. The Starizona R/F will slide into the Crayford focuser. 

 I only image galaxies with the C9.25. Due to it's longer focal length. I have done planetary at F20 with it. You can also image small Planetary Nebula with it at F20 using RGB.

 I only use the Edge 8 for casual visual on Evolution mount. It will render round stars to Edge with Televue Delos eyepieces. 

I prefer refractors or imaging. I leave in Bortle 7 skies and can only do narrowband imaging. My Takahashi FSQ106ED at 106mm aperture at F3.6 will out perform the C11 Hyperstar 280mm aperture for resolution. 

Lynn K.

  Do consider weight when choosing between 8, 9.25 & 11 SCTs. The 9.25 &11 will require a heavier mount. Also consider the field of view.

I have the 925 XLT with Starizona reducer and am super happy with it. The Edge increases cost so there needs to be some advantage to recommend it, and I have never seen any issue that would make me want to change. Indeed, some say the 925 XLT has the best performing optics in the Celestron line, though I cannot confirm that.

I run my XLT only with the reducer (or hyperstar). There are no issues that I have had at f6.3 with the Starizona reducer, though I do only use an APSC camera, so I don't know if there would be issues with the reducer with a full frame camera. The Edge will put you at a disadvantage at f/7 with the reducer, reducing your signal by 20% for nebula and other extended objects (lower Entendue) compared to the XLT.

Not sure why one would use an XLT or Edge without a reducer, f/10 is really too high for deep sky imaging, and makes no sense in terms of sampling anyway, unless perhaps you are on a mountain top with great seeing and a camera with small pixels. The lower F/ratio of the XLT has great sampling at near 1500 mm with around a typical 4 micron pixel, which is perfect even if the seeing is good.

For planetary imaging the FOV required is small, and you would add a Barlow, so the Edge has no edge over the XLT. As far as I know, near center for XLT and Edge have identical performance, Edge is only useful for wider fields if you want to image at F/10. Field flatteners, as there is in the Edge are great, but unfortunately flattening an image at F/10 is not that useful, unless you meet amazing imaging conditions. If you want to do deep sky, F/10 is a non-starter for most of us.

I use the Hyperstar occasionally. Both the recent XLT compatible models and Edge can use it equally well. With Hyperstar the two are identical performance, as the Edge lens is not used in this configuration. Thus, whether or not you want to do Hyperstar, it doesn't play into your decision on which to purchase.

I would not worry about mirror flop. The XLT holds focus well. After the meridian flip I do a focus, which changes slightly. But on either side of the meridian, unless temperature is changing a lot, I do not need to refocus for 2 or 3 hours. For focus and collimation I use a tri-bahtinov mask, I do not see any shift in collimation after meridian flip.

As an XLT user, I would never switch to Edge, as I can no reason to do so, and many reasons not to.
CS
Rick

Am I hearing correctly that you need to use a 2” compression connection with the starizona .63 reducer on the 9.25?!?

sounds like a recipe for tilt

Alright, debate over. I ordered the edge 8. 

for ONE reason. 

Space in the jeep.  I finally realized that the 9.25 would cause packing problems haha.  Would love to have had the extra resolution though. 

Thx for all the replies!