Free C8 with Starizona SCT corrector/reducer? Or save for an Edge HD?

Dave,

I've not tried the Starizona reducer but I have tried the Celestron 0.7 Reducer on the edge and it works well so I'd guess Starizona will be just as good. I'm assuming you are not talking Hyperstar - that's a whole other debate of which I have no experience.

I've just sold my Edge mainly because I wasn't getting any better resolution between it and my refractor and I ran a lot of side by side tests and the seeing was always the limiting factor. Admittedly I was using 660 mm and 930 mm FL on the refractors which is a bit longer than yours.

Bottom line if you have good seeing and guiding you will see a difference between the 8" and your refractor if you don't you wont (assuming 3.7 micron pixels on my ASI 2600)! 

I really enjoyed the Edge HD 8 but it's not cheap, and I'm sure you will get equally good images on chips up to APSC size with the C8 just don't expect a step change over the refractor. So I would go with the C8 and see what happens before investing in the Edge.

John

P.S I'd also say while the Edge is a good scope based on what I see on this site in the images and the forums a good f4 or f5 Newtonian will probably not cost much more than the reducer alone and will meet all your long focal length needs, if your using smaller pixel CMOS cameras.

I have an old C8 (Starbright) with an 0.63x reducer, an 1100 EdgeHD, and an Esprit 100ED, so I can comment on all of the above.

Old C8 with reducer: not designed for photography; field is not flat; stars are seagull-shaped in the corners.  Put it in the basement and use it for visual.  Why anyone would consider this system to be an upgrade over an Esprit 100ED is a mystery to me.

1100EdgeHD: works great with the reducer for a small sensor.  Will make the Esprit look like a toy when you first put it onto a smaller galaxy, but just wait until you try to process the LRGB data.  The stars will be "soft" in LRGB because it is not apochromatic like the Esprit.   Ugly LRGB stars are a problem I have not fixed in 10 years of owning the scope, except with narrowband filters.  Having a lot of trouble here with an APS-C sensor due to chromatic aberrations and distorted stars around the edges.  I am going to try it again at f/10 and the APS-C sensor without the reducer, but do you want to image at f/10?  Requires a heavy-duty mount with excellent tracking, or you can kiss the higher resolution goodbye.  Will obliterate planetary nebulae in narrowband, and you will be very happy - but not a great galaxy scope compared to f/4 imaging Newts, RCs, Dall-Kirkhams, etc.

Esprit 100ED:  Nice star shapes and colors, but stars are actually larger (at the same image scale) compared to the EdgeHD due to the small aperture.  Can be set up with autofocuser more easily.  Vignetting is not a problem with APS-C.  No chromatic aberrations whatsoever.  Takes longer to image small galaxies, and you may want to use 2x drizzle to get a smaller image scale like I do.  Field of view is huge, so you can potentially image multiple galaxies at the same time.


This spring, I have been imaging some very small galaxies with the Esprit 100ED at the native 550 mm focal length.  The tricks are 2x drizzle to get 0.7" per pixel, and using Starnet++ to remove and shrink the bloated stars.  These galaxies are really small - and what's wrong with these results?











Nice galaxy, ugly LRGB stars with the 1100 EdgeHD and the 0.7x reducer:




Tiny narrowband stars with the exact same system: 

I have an old C8 (Starbright) with an 0.63x reducer, an 1100 EdgeHD, and an Esprit 100ED, so I can comment on all of the above.

Old C8 with reducer: not designed for photography; field is not flat; stars are seagull-shaped in the corners.  Put it in the basement and use it for visual.  Why anyone would consider this system to be an upgrade over an Esprit 100ED is a mystery to me.

1100EdgeHD: works great for a small sensor.  Will make the Esprit look like a toy when you first put it onto a smaller galaxy, but just wait until you try to process the LRGB data.  The stars will be "soft" in LRGB because it is not apochromatic like the Esprit.   Ugly LRGB stars are a problem I have not fixed in 10 years of owning the scope, except with narrowband filters.  Having a lot of trouble here with an APS-C sensor due to chromatic aberrations and distorted stars around the edges.  I am going to try it again at f/10 and the APS-C sensor without the reducer, but do you want to image at f/10?  Requires a heavy-duty mount with excellent tracking, or you can kiss the higher resolution goodbye.  Will obliterate planetary nebulae in narrowband, and you will be very happy - but not a great galaxy scope compared to f/4 imaging Newts, RCs, Dall-Kirkhams, etc.

Esprit 100ED:  Nice star shapes and colors, but stars are actually larger (at the same image scale) compared to the EdgeHD due to the small aperture.  Can be set up with autofocuser more easily.  Vignetting is not a problem with APS-C.  No chromatic aberrations whatsoever.  Takes longer to image small galaxies, and you may want to use 2x drizzle to get a smaller image scale like I do.  Field of view is huge, so you can potentially image multiple galaxies at the same time.


This spring, I have been imaging some very small galaxies with the Esprit 100ED at the native 550 mm focal length.  The tricks are 2x drizzle to get 0.7" per pixel, and using Starnet++ to remove and shrink the bloated stars.  These galaxies are really small - and what's wrong with these results?

I wouldn't go so far as to say that any SCT would be an *upgrade* over the Esprit 100. I love my Esprit 100, but its wheelhouse is not shooting the small stuff. I have a C6 right now with the Celestron 0.63x reducer, and the Celestron reducer is really not good for AP use, which is why I'm considering the Starizona corrector, which people seem to think highly of.

I kept this topic opened as I haven't completed the image until a couple of days ago.
My SCT is a Celestron C9.25, not a C8, but the Starizona reducer/corrector does a much better job than the Celestron reducer/corrector.

Check this image for star shape: https://www.astrobin.com/58ifv6/
It was a bit cropped and reduced to a pixel scale of ~1 arcsec/pixel.
You can ignore the C6 + Celestron reducer/corrector contribution to the image, I used it mostly as a test for iR, but it wasn't too different than the R channel and it only contributed starless.

Yeah although I've used it on the 8se and not the C8, I can also vouch for the Starizona corrector being not just slightly, but significantly better than all others (celestron, antares, meade). It has enough internal optical elements to not only correct the coma to essentially perfection, but also to prevent ghosting from reflections off of the camera sensor back to the glass, and back to the sensor again. This produces a substantially cleaner field in terms of gradients, and helps the flat frame calibration work much better.

I genuinely don't know if this will behave the same way on the C8, but I can't stress enough that it perfectly corrects abundant coma in my 8se; if it's intended to also be used on the C8, you will get a killer scope with a very flat field and great low gradients. See a detailed review for it on my site here.

As for the 8" EdgeHD, this scope kicks butt and has a perfectly flat field. It's much more expensive (I was lucky to get it at a steep discount second hand, or else I wouldn't have one), but it does its job. Here's the kick though, it depends on if you want to focal reduce your 8" SCT or not! The EdgeHD is great natively, but the focal reducer built for it (which cannot be the starizona one) also has gradient problems, just like the lower quality reducers did on the 8se, so I don't use the EdgeHD when I want to lower the focal length. I still have the 8se with the starizona corrector too, and I use this setup for lower focal lengths! It produces EdgeHD-quality results at the lower focal length (no coma, flat field, etc.).

This applies to you, because if you want to focal reduce it, don't bother with the EdgeHD! Just use the starizona on your free tube, assuming it's compatible with the C8. Truthfully I imagine it is.

Great to know! I'm going with the Starizona reducer (if it's ever back in stock). Thanks for sharing your experience with it.