Alistair,
Ah - the eternal compromise !
Cost Vs performance, Vs weight, Vs purpose, Vs FOV, Vs image scale, Vs compatibility, Vs features . . . .
I'll toss in my thoughts here.
What is the image circle of the 10"F4 ?
How well corrected is it ? - ie how much of it will be useful ?
How much weight can your OTA/focusser support ?
Are you set on only ever using the camera on the one telescope ?
If not what would be the focal length of your possible other ? - Longer or shorter ?
If you are set on this combination of CCD/OTA then that will determine the largest CCD diagonal you would buy - so this will potentially limit your field.
The image scale of the KAF8300 chip is 1.09 arc sec/pix
The image scale of the SXVR-H814 is 0.75 arc sec/pix
I would say for a 1m fl instrument that you are over sampling for your average likely seeing conditions (say 1.5 to 3.0 arc secs/pix), but if you have great seeing and can see yourself deconvolving then maybe its worth it.
That oversampling may come at the expense of FOV, but I dont know what your image circle is so cant comment.
I am assuming that with only 1000mm you arent intending on making faint fuzzies your subject matter (so you are not aiming at 0.5 arc second resolving capability !) - so its a midfield rig
If it were me I would be considering a chip that has maybe from 7 to 9 micron pixels - yielding an image scale of around 1.5 to 1.8 as/p but maybe 6 to 10 microns
So this may help you determine what image scale you want or need
But if the FOV is quite small then maybe you are better off oversampling anyway since you may not actually be paying much for the extra real estate (that you cant use) !
The next thing I would be thinking about is the performance of the camera for that image scale.
An assumption being that you want an anti blooming camera for "pretty pictures" rather than for photometric style of use
The bigger the pixels, the deeper the wells, so you will generally get better dynamic range with the larger sized pixels - but of course the internal read noise is a real consideration and this is where seemingly the Sony HAD cameras seem to perform (at least anecdotally since their specs are hard to unravel).
Can you calculate this out ?
But choosing a camera based on dynamic range can be an exercise in frustration - they nearly all want to quote their A/D output in bits which is really meaningless in terms of what the real dynamic range output of the chip actually is when read noise is considered.
Then there is the other stuff :
Is it compatible with the software you use or intend to use, are there good drivers, that work all the time, and are they likely to be supported in the future versions of the operating systems - there are some that will not !
Do you want to guide internally, in front of the filter wheel, do you want to use AO (probably not at 1000mm), do you want an integrated internal or external guiding system, are you going to use off axis guiding or guide scope, do you want the minimum cable count for cameras, filter wheels, power supplies, is weight a consideration, what about electronic focussing and rotation, maximum cooling, download times, binning capability etc etc - all considerations that are individual to you and your gear and directions.
I have no idea on the QSI range
But if you can narrow down what your intentions and your gear will allow - the field will likely have been narrowed down sufficiently to make your final selection based on what is actually available in your budget.
Its always a compromise and you have to draw the line.
On the other hand more is better so buy two cameras !
Don't forget that second hand opens up the field considerably
Plenty of cheap STL11000's about these days !
Rally
Quote:
Originally Posted by alistairsam
Hi,
I know this topic has been done to death here and there are several options, but after a year of experimenting with my 10inch F4 and a one shot colour, I've decided I need to go down the mono path and am looking for suggestions on what would suit a 10inch F4 in terms of illuminating the chip and providing good resolution.
My primary targets would be nebulae in narrowband and RGB or HaRGB, but I would want to image galaxies as well and be able to resolve details.
The area which I'm not clear about is the fully illuminated circle. Do I just use what newt provides and look for a sensor size that matches?
is it worth going below 4.5micron pixels? there are a few models like SXVR-H814 that have 3.69 micron pixels. would that be sampling over seeing limits?
Is there a chip than the KAF-8300 that has better dynamic range and decent well depth?
I'd like to keep it under $4k. I was hoping to use a 7 position filter wheel as well.
I love the QSI range, but they go over my budget very easily and they all use the KAF-8300 chip.
Is the qhy9 the only decent option for this budget?
Thanks
Alistair
|