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mmalik
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Re: Understanding STF-8300M & STT-8300M new [Re: MattThomas]
      #5703583 - 02/27/13 02:10 PM

Quote:

...hot side of the TE Cooler.




Ah, that's creative. Thx Matt


And Konihlav thanks for your info above.


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Konihlav
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Re: Understanding STF-8300M & STT-8300M new [Re: mmalik]
      #5703690 - 02/27/13 03:19 PM

thanks Matt for detailed information, that's how it actually is in my camera (optical window heated by resistor)...

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jeffweiss9
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Re: Understanding STF-8300M & STT-8300M new [Re: Konihlav]
      #5703803 - 02/27/13 04:24 PM

Hopefully this sheds more light on this question, not hijacking the thread, but I've been interested in these CCDs, particularly the STT-8300M and following this with interest. However, one thing I don't see mentioned with these 8300 cameras is the very low full well capacity (25500e-) and resulting low dynamic range (2800 for 9e- RO noise). I've read that due to the CCD readout electronics, the full well capacity is well less than twice that when 2x2 binned. Doesn't that mean a real limitation with this chip, in general, or have people found this not to be an issue?
Thanks,
-Jeff


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Konihlav
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Re: Understanding STF-8300M & STT-8300M new [Re: jeffweiss9]
      #5703865 - 02/27/13 05:12 PM

Jeff, exactly. You are right. The 25000e- FWC is just "on the edge" (or a bit over the edge) where it is still just fine for using the camera in bin 1x1 mode due to the 9e- readout noise which relatively high (though for a Kodak chip it's still a perfect result). Binning 2x2 is very problematic. With increased gain (that is usual in 2x2 mode) you are really cut on the dynamics. Therefore it is a real, limiting factor. The other downsides of KAF-8300 are:
- it's neither big nor small chip so you need special 31mm or 36mm filters that are expensive
- it's QE is not best, it's only good (average)
- it's noise is realtively high among cameras with this chip raging from 7e- to 12e-
- using bin 2x2 gives you little of advantage

I am sure I forgot some important detail...

why do then so many camera makers make cameras with this chip? because it is very cheap (means big profit) and it's 8.3Megapixels and this really counts as many newcomers see yeeah 8Mpix that's superb :-) the more Mpix the better and 8 sounds simply great...


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Konihlav
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Re: Understanding STF-8300M & STT-8300M new [Re: Konihlav]
      #5703871 - 02/27/13 05:16 PM

I am not saying that KAF-8300 cameras are simply bad they have their place on the market. For many telescopes, using bin 1x1 they do a good job and that's important. I have one smaller chip camera (SONY) and one much, much larger camera (KODAK) so I do not need this "in-between", but for many it's the Compromise with big C.

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mmalik
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Re: Understanding STF-8300M & STT-8300M new [Re: Konihlav]
      #5703916 - 02/27/13 05:43 PM

Quote:

downsides of KAF-8300 are...




If that were the case, what do you suggest that's superior to 8300M offering? I ask this for knowledge sake.


Jeff, no such thing as hijacking; open dialogue is the idea. All, please feel free to jump in. Thx


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Konihlav
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Re: Understanding STF-8300M & STT-8300M new [Re: mmalik]
      #5705010 - 02/28/13 09:51 AM

I have ICX694 camera (mono Atik 460EXM) that has much, much higher QE and much, much lower noise. But it is smaller chip. In millimeters it's not a big difference 18mm versus 12mm wide so it's not a big difference in FOV, but in surface, square size it's almost 50% smaller that's the only downside of ICX694.

If you want much bigger camera then next level is 36x24mm. This involves many problems with suitable optics (cost like 10.000 USD to be usable for a really full sized camera). It allows to use much bigger aperture scopes (aperture is what matters! based your image scale remains same/similar in order to compare cameras), but that calls for much better mount, again in 10.000 USD price range. So this way is really uneasy. Long cool down times of big scopes...

easiest for begginers is to get a reasonable refractor and nice small noise free camera and just some HEQ-5 (Orion Sirius, or so) to begin with. Easy, transportable, problem free. I started this way 4 years ago, and I would start this way again. I was happy that time. Now I try to work with big mount (heavy beast) and big scope (heavy beast).


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mmalik
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Re: Understanding STF-8300M & STT-8300M new [Re: Konihlav]
      #5705243 - 02/28/13 12:21 PM

Quote:

...but in surface, square size it's almost 50% smaller that's the only downside of ICX694.




Wouldn't that be a big downside? How big of a factor QE is in the grand scheme of things (other features like condensation handling, filter wheels, automation, etc.)? Could it be that KAF-8300 is just getting older; what is the actual QE of ICX694? Thx


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Konihlav
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Re: Understanding STF-8300M & STT-8300M new [Re: mmalik]
      #5705524 - 02/28/13 03:05 PM

I promise to post an new article on QE on my blog on Tuesday next week, now I will be out for couple of days. Roughly speaking for Ha you have QE about 48% for KAF 8300 while it's 68% for ICX694. That's advantage for ICX694 by 40% (factor 1.4). But QE is not the main parameter there is readout noise which matters (and for NB imaging it matters really very much). RN of 9e- vs RN of camera with 5e- makes another difference, roughly speaking by advantage of 324% i.e. factor 3.2times better for ICX694. This really counts in NB imaging.
As this is not so important for LRGB imaging, then I really benefit from having worst ever CCD chip KAI-11000 in one of my cameras. It's worst chip ever, and I purchased it intentionally - it has chip surface many times bigger (not sure now, I think about 8x, for ICX285/Atik314L the factor was 14 times bigger). This really counts in LRGB and also you do not have to make mosaic... but if kodak then get really huge chip. The KAI11000 is cheap and that's why I was open to it...

all best mmalik, I hope that I helped at least to YOU if not anyone else today


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Alph
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Re: Understanding STF-8300M & STT-8300M new [Re: Konihlav]
      #5705696 - 02/28/13 04:36 PM

Quote:

I am sure I forgot some important detail...



You did not consider a shot noise limited image which is what you normally want to achieve. Once the photon noise is dominant the difference between ICX694 and the KAF-8300 in terms of photon efficiency is a wash.

The math is brutal: 4.5*sqrt(77) = 5.4*sqrt(56)


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jeffweiss9
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Re: Understanding STF-8300M & STT-8300M new [Re: Alph]
      #5705738 - 02/28/13 04:55 PM

Glad I asked my question, although I didn't follow why sky-noise limiting your images cancels the issue of QE. Since an 8300 involves significant compromise although highly popular, what other CCD's do people think are better, or at least make different compromises, in the price range of an STT-8300 with guide chip and filters (~$5K). I'm looking for a big step up from my interline ST-2000XM in image size, cooling, probably slightly smaller pixel size. Any recommendations for other camera choices to make that step (but not to have to go up to $10K+)?
Thanks,
-Jeff

Edited by jeffweiss9 (02/28/13 11:15 PM)


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Alph
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Re: Understanding STF-8300M & STT-8300M new [Re: jeffweiss9]
      #5705844 - 02/28/13 05:48 PM

Quote:

Since an 8300 involves significant compromise although highly popular,



The KAF-8300 does not compromise much. It is 40% larger in diagonal than ICX694 and it gets sensitivity boost from larger pixels. There is no other mono CCD in your price range that can beat it .


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mmalik
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Re: Understanding STF-8300M & STT-8300M new [Re: Alph]
      #5705889 - 02/28/13 06:09 PM

Following is side-by-side comparison of STT-8300/KAF-8300 and 460EX/ICX694; missing/additional specs welcome.

Note: One thing that stood out for me was that 460EX only supports 1.25" filters (correction welcome).



Edited by mmalik (03/02/13 08:35 AM)


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Mike7Mak
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Re: Understanding STF-8300M & STT-8300M new [Re: mmalik]
      #5705950 - 02/28/13 06:42 PM

Quote:

Note: One thing that stood out for me was that 460EX only supports 1.25" filters (correction welcome).




I think it would be more like 'only needs 1.25" filters'. That's a good thing, for the wallet anyway. Unless you already have 36mm filters.


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mmalik
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Re: Understanding STF-8300M & STT-8300M [Re: Mike7Mak]
      #5708306 - 03/02/13 08:21 AM

Quote:

I think it would be more like 'only needs 1.25" filters'.




True; but I think there is more at play here than just needing 1.25" filters. ICX694 is only 15.99mm compared to KAF-8300's 22.5 mm diagonal.

To put things in perspective FSQ-106EDXIII... has an image circle of 88mm; ICX694 is going to miss a lot of it. Unless SONY comes up with something larger, this doesn't look very impressive?




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mmalik
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Re: Understanding STF-8300M & STT-8300M [Re: mmalik]
      #5708341 - 03/02/13 08:48 AM

To be fair, KAF-8300 doesn't look that large either compared to say full frame DSLR.

How old is KAF-8300 in terms of its lifecycle; is it going to get updated anytime soon? Maybe not in diagonal, but in technology (to meet or beat ICX694ís QE, etc.)? Thx

Edited by mmalik (03/03/13 04:46 AM)


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Mike7Mak
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Re: Understanding STF-8300M & STT-8300M [Re: mmalik]
      #5708856 - 03/02/13 01:39 PM

Quote:

...this doesn't look very impressive?



I guess that's another reason to not start out in AP with a dslr. Any subsequent move to a ccd astro cam is gonna 'feel' like a step down unless you can spend $10k+ on a camera.

I honestly don't get the appeal of huge chips. They place more demand on the optics, massive file sizes increase processing time and storage space, and the pics don't fit on the monitor.

Aside from extreme wide field imaging most objects will fit any chip with an adjustment of focal length. Coming from DSIs and the ST-402 this Atik 314L seems huge to me.


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Konihlav
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Re: Understanding STF-8300M & STT-8300M [Re: Mike7Mak]
      #5709044 - 03/02/13 03:56 PM

let's put it this way: do you want to image narrow band? then get ICX694. Do you want to image LRGB? then get KAI-11000. This is obvious choice :-) I've spend last 4 years doing camera research and this is where I ended myself. And I want only the best for myself. But it's you who evaluate your needs and wishes. It's impossible to give you an answer within one post. Try yourself to study the plenty of valuable information available on Internet, but rather then reading forums (that are full of myths and false information) try to locate some real tests and their results (of experiments).

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pfile
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Re: Understanding STF-8300M & STT-8300M [Re: Konihlav]
      #5709468 - 03/02/13 07:56 PM

i started with a dslr and moved to an STT-8300M and the smaller size is not that big of a deal. it's really not that much smaller than my 50D's APS-C sensor. i believe the KAF-8300 is 4/3rds format - a lot of 'large' pocket cameras use that form factor.

the 8300M is so much more sensitive than the DSLR it's not even funny. what would take me 10s of hours with the DSLR i can accomplish in just 2-3h of integration time with that sensor.


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Hilmi
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Re: Understanding STF-8300M & STT-8300M [Re: pfile]
      #5709847 - 03/03/13 01:41 AM

The right camera for the right use for the right budget for the right skill level. For some of us, An 8300 is the best camera we can get for our limited budget, bad skies etc... There is always a better camera out there if you can afford it. I bet they thought exactly the same thing when they last upgraded the Hubble telescope's cameras. I can just about imagine the guys at NASA complaining that even after pooling their lunch money, they where only $200,000 short on the next model up camera.

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