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Old 16-05-2007, 12:30 PM
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h0ughy (David)
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Cooled 350D, anyone ordered/owns one and some darkframe comparisons?

I am astounded by the results Scott Alder has achieve with my cooled canon 350D.

I do know that there were some other orders being filled by Yun to Australia at the time I got mine so its time to fess up!!

Who has ordered or now owns a cooled 350D or 400D?
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  #2  
Old 16-05-2007, 01:07 PM
Dennis
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If you would like to gather data on those who have not yet purchased, do not currently own, nor intend to acquire a cooled Canon 350D, then I havenít got one!

Cheers

Dennis
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Old 16-05-2007, 01:50 PM
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Quote:
Originally Posted by Dennis View Post
If you would like to gather data on those who have not yet purchased, do not currently own, nor intend to acquire a cooled Canon 350D, then I havenít got one!

Cheers

Dennis

LOL thanks Dennis. Remember we are going to attach it to your scope in August

No I am sure there are some sleepers out there who either have got one or have ordered one.
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Old 16-05-2007, 02:30 PM
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i was considering of getting one.. maybe when my pocket gets abit bigger first i was wondering, what is the total weight of the camera now with the fan?

i woudl love to see a dark frame comparison with this unit and a Hutech modified version.
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Old 16-05-2007, 02:40 PM
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i was considering of getting one.. maybe when my pocket gets abit bigger first i was wondering, what is the total weight of the camera now with the fan?

i woudl love to see a dark frame comparison with this unit and a Hutech modified version.
well Scott can do that as he hasthe hutech modified camera.
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  #6  
Old 16-05-2007, 04:31 PM
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What I will do on next day or 2 is take a 1 hour cooled, and a 1 hour uncooled shot with my own Hutech 350D and compare.
Scott
EDIT:
Taking a 1 hour dark ISO1600 RAW with each camera now.....
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  #7  
Old 16-05-2007, 04:39 PM
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that will be great. cheers scott .
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Old 16-05-2007, 04:54 PM
Dennis
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Is Scott more than 1 person? His output seems too prodigious for 1 man?

Oh…..just realised…..he is a Novacastrian - right!

It will be quite interesting to compare the dark frames of the Hutech and cooled 350D's.

Cheers

Dennis
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  #9  
Old 16-05-2007, 05:01 PM
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I may even do a 1 hour dark from my 20Da just for comparison.
Say at ISO 1600 RAW, with and without N/R.
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  #10  
Old 16-05-2007, 05:02 PM
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we should stick a thread with all the dark frames gathered from different cameras/ccd's etc for comparison. Will be interesting and a good resource/reference.
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  #11  
Old 16-05-2007, 06:48 PM
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While I agree that a comparison of camera dark frames would be a good idea, won't the conversion to jpeg and then resizing and compression to 150 kb void their usefulness? If you are going to do uncooled frames some planning may be in order? Don't take this as a nay saying, I just think it needs a bit more thought and planning.

Something along the lines of, but not restricted to, select an agreed temp for the non-cooled models, specify ISO and exposure times, select exposure condition (darkened room or with something covering the camera viewfinder for example). Once the RAW exposure is taken, the manner it is converted to a Fits or Tiff file should be considered. I know that AIP4WIN and ImagesPlus deal with their RAW to FITS and TIFFS conversion differently as does Photoshop. The files could then be sent to a central person (either Raws or fits/tiffs) who can use a standard method to measure the means and standard deviations, noise etc, of the darks. Bias frames would also need to be included for subtraction from the dark frames.

The results could then be tabulated to give a better comparison. Including this with the compressed jpegs or better yet a small crop of an uncompressed image would make better sense to me.


jm2cw
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Old 16-05-2007, 07:07 PM
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Quote:
Originally Posted by tornado33 View Post
What I will do on next day or 2 is take a 1 hour cooled, and a 1 hour uncooled shot with my own Hutech 350D and compare.
Scott
EDIT:
Taking a 1 hour dark ISO1600 RAW with each camera now.....
Are the results available yet, ?



S
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  #13  
Old 16-05-2007, 07:21 PM
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Here are the results, one guess what one is cooled and what isnt.
Both 1 hour ISO 1600, ambient temp round 22 degrees. sensor temp of Houghys 6 degrees. Amazing isnt it??
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Click for full-size image (IMG_5181.jpg)
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Old 16-05-2007, 07:26 PM
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Note, the extra bits of pink glow in the corners of Houghys might be IR light leaking through the plastic body cap, whereas mine had a 50mm lens and cap on. Either way they dont appear at all in any processed images Ive done.
Scott
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Old 16-05-2007, 07:28 PM
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Quote:
Originally Posted by [1ponders] View Post
While I agree that a comparison of camera dark frames would be a good idea, won't the conversion to jpeg and then resizing and compression to 150 kb void their usefulness? If you are going to do uncooled frames some planning may be in order? Don't take this as a nay saying, I just think it needs a bit more thought and planning.

Something along the lines of, but not restricted to, select an agreed temp for the non-cooled models, specify ISO and exposure times, select exposure condition (darkened room or with something covering the camera viewfinder for example). Once the RAW exposure is taken, the manner it is converted to a Fits or Tiff file should be considered. I know that AIP4WIN and ImagesPlus deal with their RAW to FITS and TIFFS conversion differently as does Photoshop. The files could then be sent to a central person (either Raws or fits/tiffs) who can use a standard method to measure the means and standard deviations, noise etc, of the darks. Bias frames would also need to be included for subtraction from the dark frames.

The results could then be tabulated to give a better comparison. Including this with the compressed jpegs or better yet a small crop of an uncompressed image would make better sense to me.


jm2cw

load the lot onto Paul's personal space, ahh I mean the IIS large file area
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Old 16-05-2007, 07:31 PM
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Quote:
Originally Posted by tornado33 View Post
Here are the results, one guess what one is cooled and what isnt.
Both 1 hour ISO 1600, ambient temp round 22 degrees. sensor temp of Houghys 6 degrees. Amazing isnt it??
don't know scott, its hard to pick, the one on the right looks well......but then the one on the left does have some glow as well. Gee its close
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  #17  
Old 16-05-2007, 08:15 PM
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Heres some full res. crops, with Levels adjusted the same for both, the crop taken from near centre of both images, and converted tp CFA colour with IRIS as I would with an astrophoto
Scott
PS, with IRIS, the remaining "Deviant Hot Pixels can be removed easily, and other software can do the same. Its mentioned here
http://astrosurf.com/buil/iris/roadmap/help2_us.htm

FIND DEVIANT PIXELS INTO THE THERMAL MAP

Some pixels are affected by a high value thermal parasitic signal. The rate signal of "hot pixel" can be non-linear. A special procedure permit to erase bad effect of this pixels in the final result.

This cosmetic correction apply the local median to a set of pixels on the image of a CFA image, around each hot pixels (a separate procedure is used for red, green and bleue pixels). The coordinate of the hot pixels are in an ASCII file. This file, known as cosmetic file, is then used by Iris to correct certain systematic defects during the preprocessing of the deep-sky images. The extension of the cosmetic file is .LST (list file).
For construct the cosmetic file use the in-line FIND_HOT command on the dark frame master image. So, the produced file will contain coordinates of the pixels affected by an abnormally high dark current, up to a given threshold.

First, reload the dark frame:
>LOAD DARK
then:
>FIND_HOT COSME 150

The first argument of FIND_HOT is the cosmetic file name (here the file COSME.LST is created onto the working directory). The second argument is the threshold. The command return the number of hot-pixels found up to 150 intensity value in the example. Try successive values for this threshold and examine the result in the final image. The typical useful number of hot pixels listed is between 0 and 500.
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Old 17-05-2007, 09:11 AM
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Paul's correct about conducting these tests in a standard format but so that we can just get a rough idea of these cameras' capabilities, here's the two dark frames taken last night using the 20Da.

The first is one hour without in cam noise reduction.

The second is one hour with in cam noise reduction switched on.

Notice in the first, there's no amp glow since it gets switched off for the duration of the exposure.

Both done at room temp of 20C, at ISO 1600 and no processing apart from resizing and saving for the web from the original jpg's, not the RAW's.
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Old 17-05-2007, 09:36 AM
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Quote:
Originally Posted by Rocket Boy View Post
Paul's correct about conducting these tests in a standard format but so that we can just get a rough idea of these cameras' capabilities, here's the two dark frames taken last night using the 20Da.

The first is one hour without in cam noise reduction.

The second is one hour with in cam noise reduction switched on.

Notice in the first, there's no amp glow since it gets switched off for the duration of the exposure.

Both done at room temp of 20C, at ISO 1600 and no processing apart from resizing and saving for the web from the original jpg's, not the RAW's.

interesting to note the noise in both Andrew! Scotts was also done at 22 degrees, which would be pretty close in result to the 20degrees, not like its 40degrees . LOL stick it in the fridge andrew for an hour then do a shotin the fridge
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  #20  
Old 17-05-2007, 10:08 AM
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Quote:
Scotts was also done at 22 degrees, which would be pretty close in result to the 20degrees
For every 6 degrees rise in temperature the dark current approximately doubles, so 2 degrees is a significant increase. More important than ambient temperature is chip temperature, which can depend on how long the camera has been switched on, whether it has been actively capturing an image a reading it out (more reads / time = hotter chip) etc.
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