What CCD camera would you buy for $3500

[[1ponders]]

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.

I look forward to the replies ;)

[ballaratdragons]

I'd like to answer your questions Paul, but what the hell is astrometry and photometry and NABG? I'd just use one for Astrophotography.

And I don't know the prices of CCD imagers, so I suppose the best I can get for $3500.

[[1ponders]]

:lol: Ken, Photometry is the measurement of light intensities (supernova, occultations, etc) and astrometry is the science of measuring the position of celestial objects.

[anthony2302749]

Simply an SIG ST-7

[ballaratdragons]

Oh, in that case I wouldn't bother. Those things don't interest me. I just wanna take pretty pictures of DSO's :lol: :thumbsup:

[anthony2302749]

I should add this image was takebn through a 4" f5 acho, one hour exp.

[[1ponders]]

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 (http://www.optcorp.com/product.aspx?pid=319-320-1116-8312) From a quick look at the specs the only thing the 7 has over the 402 is a guiding chip.

Or the 9XEI for that matter.

Any other thoughts, other than SBIG?

[[1ponders]]

Anyone know these guys? The QSI500 (http://www.qsimaging.com/500seriescompare.html) cameras. What about Starlight Xpress, Apogee (Ascent A1 (http://www.ccd.com/ascent_a1.html)) etc.

[g__day]

Also consider FInger Lakes which from American Astronomy sites - seems to be the main competitor to S-BIG.

[Ambermile]

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.

Arthur

[gbeal]

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.

[[1ponders]]

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.

[jase]

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/showthread.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.

[middy]

I would buy a Toucam and spend the rest on a decent EQ mount, some nice eyepieces and a Canon 400D. :P

[RB]

Andrew you might like to read Paul's equipment list in his signature.
Please keep this thread on topic !

[[1ponders]]

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.

[jase]

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.

Here are some good starting point references;
http://cfa-www.harvard.edu/iau/info/Astrometry.html#sort
http://cfa-www.harvard.edu/~tspahr/astrom.howto (http://cfa-www.harvard.edu/%7Etspahr/astrom.howto)
http://www.nofs.navy.mil/data/FchPix/ - catalog searches - you'll need this.

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 (http://www.driftscan.com/). Its has multiple uses, but Astrometry is a key one.

[[1ponders]]

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 :P ). 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.

[gbeal]

And the good thing about TDI Ponders me old mate, is any old mount will do, LOL.
Seriously though, has anyone here tried it? Jase?

[jase]

Yes, I've used drift scan imaging to make some astrometry measurements of Teegardens star - http://en.wikipedia.org/wiki/Teegarden's_star (http://en.wikipedia.org/wiki/Teegarden%27s_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.

[middy]

Sorry. :ashamed:

I'd had a bad day and felt the need to type something humorous. My money would be on an SBIG purely because of all the good things I read about them from other users.

[jase]

Back onto the photometry thread, similar to what I mentioned previously about SCT corrector plates being next to useless for UV measurements, the spectral response actually applies to all components in your optical train not just the correct plate. Don't get me wrong, you can still use a SCT, but you'd need a way of cross checking the accuracy of the measurements. Perhaps using some offset data from other well known sources.

I know you're still learning to crawl before you walk, but considering you're testing CCD and CMOS chips that would be suitable for photometry, I thought I'd also provide more info on the spectral response.

Typically a CCD or CMOS chip chamber is covered using a type of glass (called a window). I recommend during your testing of cameras that you investigate the glass type the manufacture is using. Normally Schott BK7 is used. It has a reasonable reponse to UV wavelengths, but not the best. You should try to obtain a camera that uses MgF2 (Magnesium Fluroide) as this glass allows wavelengths all the way down to 120nm - well below the start of the visual wavelengths. This is not a major issue as typical U filter only starts at 300nm, but you want to make sure the camera is still sensitive lower than 300nm so no cut-off is experienced. Most glasses will transmit all the way up to 1200nm - IR (700-1200nm) wavelengths. UV is probably the most critical and hardest to reach depending on telescope design.

Obviously, having a camera that allows you to go low into the wavelength spectrum wont make a difference if there is poor spectral response in other areas of the optical train. Hence the reason why I indicated you need to look at the big picture, not just the camera.

This in turn will send you on a quest to determine what is the most optimal design/telescope for photometry. I haven't found this yet - but if you do come across it, please let me know. Generally, you can use most types though I read that well corrected refractors are good. Many are corrected down to 360nm. I have not looked into mirror based designs to make any comment.

Finally, the speed of the optical system is not really a big issue with the UBVRI filters as they are not really that narrow. Compared to a 3nm or 6nm Halpha filter they are quite broad. Using a fast instrument such F/2.8 or F/4 camera lens, the light cone that hits a narrowband filter can actually shift the spectral response. So instead of the Ha filter being centered at 656.3nm, it shifts. This results in missing the critical narrow light path of the filter and delivers a poor Ha image. This is the reason why if you have a fast optical system, its best to stay away from really narrowband filters. Its best to go for 10nm or higher so when the shift occurs, the filter will still transmit at wavelength. Alas, you don't have to worry about this with the UBVRI filters.

:thumbsup:

[Terry B]

I have used my camera to take photos of proxima centaurus over the last 7 years using just 20 sec exposures (not drift scan) and have plotted the propper motion and some parallax shift. This is using very amateur equipment in my backyard. It is certainly possible.
My CCD camera is a home built one using a KAF0401E chip (NABG). I have borrowed our clubs old sbig ST7 with ABG version of the same chip. It is nowhere near as sensitive as my camera. I didn't realise that htere would be much difference but there is.
I have attached a plot of the movement.

[[1ponders]]

Just revisiting this thread.

I'm seriously considering the ST-7XME (free CFW8 atm, class 1 chip and pelican case) (http://www.optcorp.com/product.aspx?pid=8202&kw=ST-7XME&st=2) with internal guide chip or the ST-7XEI with Class 2 chip and discount on the remote guide head (http://www.optcorp.com/product.aspx?pid=8209&kw=ST-7XME&st=2)(considerably cheaper than the XME package).

I thought about the ST-9 range but to image at 2 arc/pix I'd need to image at f/10 with my current 8"

I had a look at some of the Apogee cameras, particularly the Accent A1 (http://www.ccd.com/ascent_a1.html)camera (the A2 would be nice but just a bit too much) but even at the lower price feel the SBIG is a better deal. They use the same chip. Would need a guider with this one as well.

Any thoughts. Comments on the Apogee range? Anyone like to suggest any other cameras to muddy the water ;)

[allan gould]

Just remember that these ST-7's are quite heavy and if the optical train is not up to it there will be flexing. For my money (~$AUD2500) the SBIG 402ME would be the best option with class 1 chip and internal filter wheel with filters. Lot smaller in size but same chip dimensions

[[1ponders]]

I looked at the 402ME with the class 1 upgrade. Apart from the weight, what would differentiate it from the 7?

[[1ponders]]

BTW the imaging train at this stage will either be an 8" LX200 OTA or a 12" LX200R OTA on G11 (W/- JMI-CM focuser and 6.3 or 3.3 FR), or an Orion ED80 with Williams Optics 10:1 focuser upgrade.

Depending on what I decide on, if I need a guidescope it will either be the ED80 or a Celestron 102 achro refractor.

[rsbfoto]

Hi,

Take also a look at

http://www.qsimaging.com

[Dennis]

Hi Paul

I have the older ST7E with a parallel cable and it is an excellent workhorse, but the relatively small chip size of 765 x 510 pixels may be an issue for you when imaging at F10 for the 8" and 12" OTA's. It is likely that old favourites like M83 and NGC253 would not fit on the chip, so you would need to take mosaics.

So, if the pockets are deep enough, I would try to get a larger chip if you plan on taking pretty deep sky images.

My ST7E has the smaller internal guide chip whereas the newer ST7’s have the larger chip, making it easier to find a decent guide star. I personally prefer to auto guide with the ST7E guide chip whenever possible – the simplicity of a single ‘scope, one computer and one set of cables compared to a separate guide scope etc.

However, a separate guide scope with its large FOV and ability to be adjusted by the guide rings has a lot going for it.

Cheers

Dennis

[[1ponders]]

Thanks Rainer and Dennis.

Dennis, I wouldn't be f/10ing if very often. There would be one of the focal reducers inline most of the time.