From: R. A. Greiner (ragreiner0_at_antispamdomain.not)
Date: Wed Jun 25 2003 - 16:21:34 EDT
I am making a preliminary comment only on the heating problem mentioned at the end of this post. I am doing some careful measurements on 10Ds right now. One data point with one camera really astonished my.
When the 10D is on, but not exposing it draws 110 ma from the 7.4 volts source. This is a power dissipation of 0.814 watts. When the D10 is exposing it draws an astonishing, to me at least, 370 ma. This is a power dissipation in the camera of 2.74 watts. The later figure is a lot of power to heat the camera. It is the same power as a small night light. I found this hard to believe, but the measurements are firm. I do not know where within the camera the heat is dissipated, but in the long run, it heats the entire camera body.
I am surprised by the comment about the 1Ds not heating up. (In fact, I have doubts about this) If you will send me your 1Ds, I will check this out for you. (VBG)
The power dissipation and consequently heating of the camera is verified in some of the data I am now preparing for posting later today.
Doc G
----- Original Message -----
From: Mike Unsold
To: digital_astro_.at._yahoogroups.com
Sent: Wednesday, June 25, 2003 3:07 PM
Subject: [digital_astro] Re: 10D dark frame comparison
I have the 10D raw to 16-bit tiff conversion working in ImagesPlus.
The converted 16-bit tiffs are looking much better than
JPEG or 8-bit tiff conversion. Additional tweaks can also be done if
necessary based on feedback from others. This will be available
probably on Sunday or Monday since I am currently getting ready for
a Friday night presentaion at the Laurel Highlands star party in the
West Virgina mountains. If your in the area I hope to see you there.
The 10D heatup problem when taking a sequence of say 5 minute ISO
1000 exposures can be effectively managed by adjusting the delay
between each image based on temerature. It is interesting to note
that the 1Ds can take long exposures all night long without heating
up. One real nice feature of the 1Ds is the view finder shutter that
can be closed using a small arm next to the finder.
Mike
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>P
Pertti and all:
Find my comments imbedded within the following text:
--- In digital_astro_.at._yahoogroups.com, "R. A. Greiner"
<ragreiner0_.at._c...> wrote:
> I think a list all in one place is important. This should include
camera model with first part of serial number, The temperature of
the
camera, the vital settings such as RAW, ISO speed, Color settings
and
processing settings in the camera, and of course the post processing
that
is done in the Canon and/or other software.
I think we will have to wait until the Canon FileViewer 16 bit TIFF
conversion
from RAW really works. Until then you need some other piece of
software
(at the moment CaptureOne) to get the real results from the image.
But FileViewer should work really soon now.
________________________________________________________________
I agree that we need to be sure to have a working, correct,
conversion in the
Canon software. I too hope that will be soon.
________________________________________________________________
If we use the RAW format, most of the camera settings lose
significance.
White balance is decided only after the raw data has been captured,
and so are all the "parameters" (sharpening, contrast, etc).
If we use the (working) 16 bit linear TIFF conversion, there is
nothing
that interferes with the raw detector data. In this way we can avoid
the stretching done by the camera for the dark frame. (That would
favour cameras with very hot pixels over those that have uniform,
though
smaller noise.)
> This makes quite a list. Many of the variables are default
settings of
course. I have not yet found all of the settings possible. Since you
have
considerable experience with these issues, can I suggest you start
us off
with a list that you feel comfortable with.
Well, I don't think many variables remain if we use the RAW format.
______________________________________________________
I agree fully with these comments.
_________________________________________________________
So I suggest, as a "standard 10D dark frame test procedure", the
following:
1) remove the lens and put the (plastic) cap on instead,
2) cover the finder (with the cover that is integrated to the strap),
3) put the camera in shadow, anyway,
___________________________________________________________________
I actually put the camera in a changing bag or cover it with a heavy
dark
cloth. A viewing cloth is good for those who remember View Cameras.
( real
cameras) (G)
____________________________________________________________________
4) select the RAW image mode,
4) use ISO 3200 and 30 seconds (from the camera settings)
_____________________________________________________________________
While this is convenient since the camera has these settings, I
agree with
Mike that a setting of ISO 1600 or even 800 might be more realistic.
_____________________________________________________________________
_
5) take the first image with camera that has not been used for a
while
(to remove the effect of warming of the camera electronics)
6) record the ambient temperature,
_____________________________________________________________________
__
This is good practive. The camera does dissipate some power when it
is on
and does heat up. I am now trying to measure this heating effect. It
is clear
there is some heating but I do not know how important it is. I think
it is
significant, but not catostrophic.
_____________________________________________________________________
_
7) convert the file with FileViewer into a 16 bit TIFF, using the
linear mode
and false color filter,
8) use Photoshop to find out the average value in the image as well
as the standard deviation, one set of values for luminance and
one set for each of the colors (R, G and B), a total of eight
numbers,
9) give a verbal description of the stretched image (e.g. uniform
starlike
white noise, predominantly green speckled noise, multicolored noise
that increases to the right, amplifier glow on the left or whatever
the
image looks like).
______________________________________________________________
Excellent amalysis. I wish I knew how to capture and post the
histogram. It
is very telling. I would add a verbal description of the histogram
to a verbal
description of the image.
____________________________________________________________
> We can then attack it with enthusiasm. (G)
I'm looking forward to that! ;-)
_____________________________________________________________
See the attack hardly hurt at all (VGB)
____________________________________________________
> I did by the way do the testing of my two cameras at 22 degrees C
and an
ISO of 1600.
I suggested using ISO 3200 and 30 seconds, because that makes testing
simpler. Based on some experiments with my camera, it gives a good
estimate of the noise at ISO 400 and 300 seconds but it is a lot
quicker
and is also easy to perform in cases where you don't have a remote
timer
available. The time is also short enough to test in a shop or a
friends
camera.
__________________________________________________________
I like your reasoning, but feel lower ISO numbers are more useful.
As Mike
pointed out.
You have to take your desk top and a remote control with you to test
in situ.
__________________________________________________________
> I think we are on the way to getting this evaluation pinned down.
I
plan, soon, to do some testing at various temperatures since I have
a
temperature chamber available. I am very interested in knowing how
temperature affects the noise. I wonder how the camera will function
at
-40C and +40C. (VBG)
Tell us, please. I will be able to tell you in January how the
camera works
in -20C. Based on real-life experiments with Nikon 990, we should see
almost no noise in even several minute exposures at ISO 3200. But
then again,
the temperature behaviour of CMOS detectors might be different from
CCD,
and also advanced Canon processing does also change it.
______________________________________________________
I know the D60 works fine down to 0 F (-18 C) but I have used it
only for
regular photos at that temperature. I no longer have the D60, only
two of the
10D versions.
_______________________________________________________________
I tried making one experiment where I compared 20C with 10C, but I
did
not find any difference - or maybe the time was too short for the
camera
to cool down.
_____________________________________________________________________
___
I can tell you that it makes a difference. I have just taken some
data on a
10D between 26 C and 0 C. I will post the data as soon as I have it
organized.
Probably later today.
Best -- Doc G
_________________________________________________________
Pertti
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