Here is a question for you black belters out there.
There are a lot of CCDs getting around these days and alot of budding astroimagers interested in them. If you only had $3500 Aus to spend (not necessarily in Australia and don't include delivery) on a CCD camera what would you choose and why.
Caveats.
No DSLRs, must be a mono CCD and NABG camera.
To be used with scopes of 400mm FL (f/5) to 1260mm FL (f/6.3) for astrometry and photometry.
Good dynamic range, QE, (you know the usual )
Doesn't have to be selfguiding.
Cooling - min 30 deg below ambient.
Ken, Photometry is the measurement of light intensities (supernova, occultations, etc) and astrometry is the science of measuring the position of celestial objects.
Ken, Photometry is the measurement of light intensities (supernova, occultations, etc) and astrometry is the science of measuring the position of celestial objects.
Oh, in that case I wouldn't bother. Those things don't interest me. I just wanna take pretty pictures of DSO's
Why the SBIT ST-7 Anthony? I'm interested in detail of pros and cons. What would be the benefit of an ST-7 over, say an ST-402ME From a quick look at the specs the only thing the 7 has over the 402 is a guiding chip.
ArtemisCCD will soon announce a new mid-range camera... it will sit between the ART285 (ATK16HR) and the ART11002. It may fit your range but is more likely to be on the AUS$4000 side.
Or the 9XEI for that matter.
Any other thoughts, other than SBIG?
I don't think the likes of the ST9 is designed with shorter focal lengths in mind, it has large pixels (about 20 mu?).
Finding all you ask for at the price is difficult. Certainly, the older ST8 cameras, albeit parallel will suffice. Great cameras, but you also need NAGB, and most were AGB. Good luck.
While I may be looking for a good camera in the near future, this thread is more in the nature of information gathering to see what is out there, how they compare and what sort of match they would have with the outlined FLs.
If you're serious about photometry, you can't simply focus on the camera. You should look at the entire optical train. Certain designs such as the SCT with its corrector plate is useless at the UV end of the spectrum due to optical coatings used.
Unless you have extremely high QE delivered by a back illuminated CCD chip (expensive), you'll need to guide. Guiding and pointing accuracy becomes more important if you intend to to all night supernova searches, imaging 300+ galaxies a night.
You have also not mentioned anything about a filter wheel. You'll need a set of UBVRI filters for photometry.
You don't need a large chip CCD to do this type of work. If you're a beginner at this I would recommend a camera that has the KAF-402ME NABG chip. You can go a larger array if you've got the money. There was an ideal camera that was sold recently that would have meet your needs. http://www.iceinspace.com.au/forum/s...ad.php?t=19581
These chips have a peak QE of 85% which is quite decent - close the realm of the expensive back illuminated cameras that use the E2V technologies and Fairchild imaging chips. Good value for money. You can pick up a filter wheel reasonably cheap. The UBVRI filters are still quite expensive. The 1.25" filter will cost ~A$210 each. So ~A$1050 for the UBVRI set. The 2" versions are ~A$510 each.
So in short, I think you need to look at the big picture instead of the camera alone. Its important to understand what you really want to do. Supernova searches are significantly different to astrometry data collection and analysis. Also question how much time will you be able to give your interest. Blinking images manually takes a lot of effort and time.
I appreciate where you are coming from Jase, and agree totally, but I'm looking at it from a crawl before you run perspective. This is also a thread to inform anyone who may be thinking of getting a camera in this price range or searching for CCD Camera info, so your reply about the SCT is a valuable inclusion.
For me I already have most of the prerequisites (I haven't updated my Sig for a while), including a start on the filters (Ouch! But the deal was good, which is why I couldn't afford that camera you linked to, even though I looked long and hard at it). Company 7 have the Optec Johnson UBVRI filters for $125 US ea at the moment.
The mention of supernova searches was only in context of explaining to Ken what Photometry includes. I am pretty well aware now of the requirements as far as critical tolerances in gear is concerned for astrometry and photometry. (I'm testing and comparing off the shelf, low end ($1000 or less) consumer CCD and CMOS cameras for "scientific measurements" as part of a Uni project this semester)
As for blinking images, I'd much rather let the computer do that. It has a much more discerning eye.
Also note the importance of image scale for astrometry, so match your telescope to CCD pixel size. Astrometry typically requires high accuracy/precision. This does not mean that your image scale must match this, but you should work around the 2" arcsec per pixel margin.
Something that can really assist in research work is a CCD camera that is capable of Time-Delay Integration (TDI). TDI is an imaging technique in which rows of pixels are synchronized and transferred at the same motion and rate as the scene.
"Basically, one points the camera at an area of sky and turns off the telescope drive to let the stars drift across the field of view. The CCD is clocked in sync with the rate of drift and the resulting image has an exposure time equal to the amount of time it takes the stars to drift across the CCD. Depending on the focal length of the scope this can be many minutes. But there is no periodic error and no guiding error." from the optcorp site.
With TDI, the important factor here is that you're astrometry precision is no longer limited by your telescope mount tracking. The telescope simply points and does not track. So there is the potential to make sub 1" arcsecond measurement if the atmospheric seeing is stable.
Thought I'd also add that TDI is what camera manufactures generally call what we know as drift scan imaging. Its has multiple uses, but Astrometry is a key one.
Last edited by jase; 14-05-2007 at 04:56 PM.
Reason: added drift scan details :)
I've been doing a bit of reading about the TDI and it kinda got me shivering with excitement (It doesn't take much, I know ). The level of accuracy and depth of field being achieved using everyday camera lenses (admittedly good quality and above 150mm) is quite amazing. Very interesting potential. I also remember reading somewhere that one of the Mars orbiters use a similar technique for ground scanning to increase surface resolution.
Might be a good new thread to start. Requirements for Astrometry and Photometery.
Yes, I've used drift scan imaging to make some astrometry measurements of Teegardens star - http://en.wikipedia.org/wiki/Teegarden's_star
I actually never thought it would be possible to measure the movement with amateur equipment - I was wrong. I wouldn't bother using drift scans for "pretty" pictures - long exposures are best for these.
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Ken, Photometry is the measurement of light intensities (supernova, occultations, etc) and astrometry is the science of measuring the position of celestial objects.
