Hello all and Happy Thanksgiving!  I am a recent owner of the AP130EDFGT and in my limited time playing with the scope I am very pleased to say the least.  Here is a link to my "first light" rough draft Ha image.   https://astrob.in/mo0tbs/0/ 
I live in South San Francisco, between SFO airport to the south and San Francisco to the north.  SO.....  light polluted, lol.  I have changed out the focuser on the the scope to the 3.5" and am using the Quad TCC (waiting for the Flattener to become available as well).  I like the speed of this scope with the Quad TCC and am considering purchasing the ZWO2400mc/QHY410c camera to pair with.  I understand that the smaller pixel ZWO6200MC/MM type cameras have a bit of a hard time at the edges (hence folks, myself included looking forward to the AP110GTX).  So my question is, how do the larger 5.9 pixel full frame cameras do with the AP130GT QuadTCC combo?  Thanks in advance and glad to be here!

Tom

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Yes, sorry I listed the wrong cameras. I actually have the QHY version of that cropped frame sensor and plan to try it out on the scope. I meant to say the smaller pixel full frame ZWO6200mm/mc style cameras vs. the 2400mc type. My bad.
Tom

And thanks for the compliments.  We have a couple clear nights forecast in a few day and I want to try and get some OIII data on that area. 

Tom

Tom,

The QTCC will correct about 80% of the full frame IMX455.  It does a really good job within this crop.  The flattener is better of course, and I think if you are planning to crop 80% that it just makes sense to use the flattener where you will get very good stars to the corners.  FOV would be about the same as the cropped QTCC but at a little higher resolution. 

IMX571 would be easy peasy on with the QTCC.  No reservations there.

Regarding the larger pixel 2400... it will likely be better than the IMX455, but I bet you would still have some astigmatism in the corners.  Roland can correct me if I am wrong here.  I think that the QTCC will correct well for the 16803 chip, which is even larger than the IMX455 but has 9um pixels.  I'm not sure where the threshold is in pixel size as far as field correction is concerned with this optic, but the smaller the pixels the less perfect the stars will look.  5.9um pixels are not teeny tiny, but they are also not large.

What it really comes down to, is how demanding are YOU on the optics?  I'm a pixel peeper to an unhealthy extent, and what doesnt satisfy me is perfectly fine for many people.  So what kind of demanding are you?  Here is an uncropped integration with IMX455 chip with the QTCC+130GTX.  https://www.astrobin.com/full/z92j74/0/

Thanks for the photo link Chris.  I would say that I am demanding enough that the corners would be bothersome to me after seeing your pic.  As you said, I could always crop…  I was debating the Full Frame sensor at this time mostly because the sales going on.  Seems like a good time to purchase, but I think I have decided to stick with what I have on hand (QHY268c & ASI533mm w/full set of filters)  and give my hand at mosaics if I want a larger field image.  The faster photon collection with the Quad TCC is really desirable from my light polluted house.  I on the fence of sending this scope remote at some point after I obtain a field flatterer for it.  Depending on how my experience shakes out on the remote imaging aspect, still very new for me. Thanks for your input, very helpful.

Tom 

You're really not collecting photons any faster by using the reducer.  Same rate of photons funneling down the scope.  The reducer is just spreading those photons out over more pixels. So it "seems" faster as you are collecting more signal on a pixel basis.  However, with modern CMOS, you could achieve the same SNR result by simply downsampling the data in post processing.

The QTCC is just getting you a wider FOV and a perceived imaging efficiency at the expense of resolution.

That's why the caveat "to crop or not to crop" is so important.  If you need to crop the QTCC image, then you lose the FOV advantage.  So really in that case it's just a resolution trade-off.

I think your decision is a good one.  The 268 is a great camera and with the QTCC gives you a pretty nice wide FOV (and the resolution aint too shabby either with 3.76um pixels).  I'm running a 268 on a 130GTX and love the combination.  My seeing is lousy, so the image scale is about as good as my skies can support.  For wider fields I use a full frame camera on a shorter focal length scope.