Hi Mark,
I'll attempt to answer that.
First consideration should be your local seeing conditions and the focal length of your scope. The camera needs to be matched to the scope and seeing conditions.
Here is a free calculator which can work this out for you with different scope and camera combinations (the camera list is out of date but you can plug in the numbers):
http://new-astronomy-ccdcalc.software.informer.com/
What this means is for an RC8 of 203mm aperture and 1624mm focal length an 8300 chipped camera will give .68 arcseconds per pixel.
The 8300 chip has 5.4 micron pixels (smallish) and 3326 x 2504 in the array (or a number very similar).
Assuming average seeing of around 2-3 arcseconds (an arc second =1/60th of a degree ie. a pretty small angle) and assuming sampling theory is correct which states you want a minimum of 2X perhaps 3X times to get an accurate sample. Then you get 3 arcsecond seeing divided by 3 = 1 arcsecond or in better seeing 2 arc seconds divided by 3 = .66 arc seconds.
So .68 is close to ideal sampling. This means then your camera will produce maximum sensitivity and resolution and that the light is not being spread too thin over the chip or not too broadly.
With a refractor of 115mm or so, typically that will mean about 800-900mm focal length so you will get 1.21 arc seconds per pixel again not too far away from the ideal.
The smaller pixels of the 8300 tend to work better with faster scopes.
Now as far as which 8300 chipped camera to get then here are the considerations:
1. Cost.
2. Performance (they are not all the same by a long ways)
3. Accessories available
4. Autoguiding solutions available.
1. is obvious but there are some hidden costs. Say the SBIG ST8300, very reasonably priced and a popular camera. But it needs a filter wheel, filters and an autoguiding solution (no autoguider or dual chip system).
So make sure you factor in the cost of the camera, the cost of a filterwheel (some have filter wheels built in - well really only the QSI)
and autoguiding.
2. Performance:
Not all 8300 chipped cameras have the same performance.
Performance can be broken down into - sensitivity (called QE for quantum efficiency or how efficiently does the chip convert a photon into an electron). You get a bit more QE with no cover slip over the chip. A FLI Microline 8300 or an Apogee U8300 can be specified with no cover slip. This can also reduce annoying small halos around stars.
Without the cover slip a FLI Microline 8300 gives 60% QE which is very high.
Cooling. Cooling reduces noise. Higher cooling then is better than lesser cooling. The best cooling cameras I am aware of are the FLI and the Apogee both slam the 8300 down to -35C easily. The FLI does it very quickly the Apogee very slowly (30 minutes) which some don't like.
ST8300 not sure of but probably 40C below ambient which will give you
-20C most of the time and -25 to -30C in winter. That's quite cool and the chip should be quite clean at that temp.
QSI is the weakest in cooling although I see they have a series 600 with enhanced cooling now to address that weakness.
Next is readout noise. This is the noise the camera generates during the chip reading process. FLI is lowest. Apogee is very low. Not sure where the SBIG is there. It all adds up.
Next would be miscellaneous noise from the electronics. FLI is very clean
(probably the cleanest) Apogee would not be far behind. Now this is where the SBIG probably falls behind. Its not the end of the world as it cleans up with standard processing but it puts more pressure on that being done very well.
3. Accessories:
Filter wheels, compatibility with electronic focusers, ease of getting adapters, adaptive optics unit availability.
QSI are the best here with a combined filterwheel and offaxis guider giving excellent flex free autoguiding so if you have a decent mount you are very likely to get round stars. Which is a large part of the battle with imaging.
So I know FLI, Apogee and know about QSI and ST8300. You would do well with any of these. QSI is probably best bang for your buck as it incorporates the filter wheel and offaixs guider. FLI is the highest quality and highest performing camera. It is the fastest in download time, it has the best cooling, the lowest noise, has a sealed chamber with inert gas so no desiccant and has a no cover slip for the chip option. It is light, extremely well made and rugged. It has excellent jacks for power and USB (the SBIG has very cheap and weak jacks that can fail).
FLI has RBI control. This means residual bulk images or ghost images. That is if you take an image of something bright these chips tend to keep a ghost of that image into the next image. I think Apogee also may have RBI control as well now.
There is also a new Apogee range called Ascent. New and untried but probably quite good and cheaper.
I can't comment on QHY or Atik except that QHY would probably be a lower scale option and would not perform as well as the above. Atik is an up and coming maker as well but both of these guys were small and cheap type cameras now offering more expensive and bigger chips.
Starlight Express is another excellent camera maker and they have a range of options from guiders to adaptive optics. They have really low noise cameras.
Mono versus Colour. Colour is simpler and requires no filter wheel and filters and is therefore cheaper. Results can be great on the brighter objects but dimmer objects starts to show the lack of sensitivity. Typically mono chips are 50% more sensitive - ie 8300 mono is around 60% QE but one shot colour is more like 30-35% QE. A big drop. You'll see a lot of extra noise in your images especially in the dim areas.
But its a good way to start off with CCD imaging. And its cheaper and every shot counts (you need luminance, red, green and blue filtered images with mono cameras to get a colour shot).
Also mono means you can do narrowband imaging more easily - Halpha and others. One shot colour can do them but not that easily and you lose a lot of performance in that area and they are not really suitable for that unless again its a really bright object.
So QSI is probably the least expensive and most integrated package in the 8300 range as it has an internal filter wheel, and an offaxis guider and if you get the later souped up cooling version decent cooling as well.
That would be my pick.
http://www.optcorp.com/ProductList.a...-320-1232-1876
If you want absolute best then its FLI. Best cooling, highest QE, RBI control, fastest downloads, lowest noise. lots of accessories, no cover slip option.
Next is Apogee (similar to FLI but the slow cooling whilst it doesn't sound like much is very irritating and inconvenient perhaps their new Ascent camera does not do that) and Starlight Express. But these all need filter wheels and autoguiders and off axis guider or a guide scope (not recommended especially for the RC8 you will have hell trying to get round stars).
The 4020 chip is also an excellent chip for imaging you should consider.
Greg.
. Well yes but still very effective in tems of QE, cooling, affordability)
