4 replies to this topic

[jkobservatory.net]

Hi All,

 

Not sure if appropriate topic but need help some advice on CCD recommendations for a Celestron C11 HD using 0.7 reducer + Essato 2 inch focuser 

 

 

I seen some post but are a few years old and wonder if the tech has changed in cameras since

 

Seeing conditions are average in the UK.

COLOUR CCD recommendations 
 

[Ron (Lubbock)]

I've made out really well with my 2016 era QSI 660ws.  It's still alive and ticking, though the field of view is a little small for my tastes.  Being able to use small 1.25" filters is nice to keep the cost down.

 

The new APS-C CMOS cameras (such as the QHY268M) are a different matter.  Most C11 EdgeHD users report that the 0.7x reducer and the larger sensor don't play well together.  Chromatic aberrations appear on the edges and corners, at least with my telescope and several others I have seen.  Edge stars are ugly, soI ended up cropping the image down to the same size I would have gotten with the CCD camera.  I gave up on trying to get good star colors and shapes around the edges with the QHY268M after 10 months of experimentation with the 0.7x reducer in place, even though the camera is a beast and easily out-performs the old CCD camera based on noise.  If you take the reducer out in order to use the APS-C camera, then you're at f/10 and the field of view shrinks - so why not just keep using the CCD camera with the smaller sensor at f/7?  I'm still dying to use the QHY268M with this rig at f/7, but the refractor is doing just fine on galaxy images, so my C11 EdgeHD remains married to the QSI 660ws.

[Louis@minus28South]

What do you want to image?  Deep sky, planetary?
 

CMOS cameras have leapfrogged CCD cameras in terms of noise, sensor size, download speed, etc.

[jkobservatory.net]

Hiya

CMOS is good

Mostly deep sky object's

Sent from my SM-S928B using Tapatalk

[dhaval]

The image scale is going to matter with CMOS cameras and C11 EdgeHD. At native 2800mm you are at 0.28"/px. In most cases, that will be significantly over-sampled. If you have a solid mount, I wouldn't be too worried about this though. Additionally, with recent advances in image processing tools, I think the effect of this gets minimized - meaning, you can process things out rather easily. So, if you are trying to decide between CCD and CMOS, I think it will be OK to use CMOS with this particular scope at native focal length. 

I would not use the reducer with this scope - the QA for these reducers is a bit flaky. Some are good, others not as much. Regardless of CCD or CMOS, my suggestion will be not use the reducer.

The last question then is, you are in the UK. You probably don't have as many nights to image. Do you truly want to image at F10? If you do, then you are much better off with CMOS cameras given the higher QE. But, you're still collecting light slowly than at F7. Just something to consider.

 

NOTE: You can look at my images on Astrobin. They are with a CMOS, but were taken from really good skies.

 

Thanks and CS!