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  #81  
Old 09-02-2017, 04:38 PM
mmalik (Mike)
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a7S 'Cold finger Inside' area of interest...
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  #82  
Old 10-02-2017, 12:46 PM
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Quote:
Originally Posted by glend View Post
I have yet to see a design that works as well as Rowland's cold finger. Many cameras are just plain unsuitable for a proper cold finger solution, and attempts are usually a mess with only marginal effect. If you want a properly cooled dslr then pick one of the ones that can support a cold finger attached to the rear of the sensor, with a proven history of delivering sensor temps of 0C. The cameras that are most suitable are Canon 450D, 650D, 1100 etc, basically any of the ones covered in Rowland's thread. Newer DSLRs are too tightly packed and produce more heat when used for astro work. A better investment might be an ASI1600MC-C if you want OSC, ASI1600MM-C if you want mono.
Do you have a link to threads by Rowland?
Who is he?

Greg.
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  #83  
Old 10-02-2017, 01:56 PM
mmalik (Mike)
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I have a different point of view; moderate cooling, 'not' deep cooling is the answer. Rowland's own words below, and I fully agree...

This project is all about moderate cooling with significant noise reduction, consistency, and preventing internal condensation without aggressive de-condensation measures. Regards

Quote:
Originally Posted by RowlandC
Experience tends to indicate that there is no need for very low temperatures. Temperature consistency is more beneficial to a data set. 12C cooling will reduce noise by 4 - 5 times anyway depending on the sensor.
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  #84  
Old 10-02-2017, 02:44 PM
glend (Glen)
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Quote:
Originally Posted by gregbradley View Post
Do you have a link to threads by Rowland?
Who is he?

Greg.
Greg, Rowland is rcheshire here on IIS.
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  #85  
Old 10-02-2017, 03:30 PM
mmalik (Mike)
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Prepping the 'Cold finger Inside' for a7S...
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  #86  
Old 10-02-2017, 03:41 PM
mmalik (Mike)
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'Cold finger Inside' in place...

Note: Sensor end loops over and doubles up (end only); this is mainly to get the adhesive toward the sensor windows given the tape orientation; yellow tape covering is for thermal and electrical insulation
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  #87  
Old 10-02-2017, 03:54 PM
mmalik (Mike)
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A before look at a7S sensor...

Note: While a7RII, being IBIS, was bit more involved in terms of allowing for sensor motion, a7S sensor is quite similar otherwise
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  #88  
Old 11-02-2017, 02:13 PM
mmalik (Mike)
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Sensor bracket in place...


Note: Dip in the bracket keeps tape's looped end securely in contact with the sensor (window) by exerting positive pressure
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  #89  
Old 11-02-2017, 03:00 PM
mmalik (Mike)
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Added a secondary path since it felt logical and convenient given the footprint of the 'Cooler @ the Base'; this is to partially cool sensor bracket itself. TEC being toward the cold finger, makes 'Cold finger Inside' the primary path. Note: Yellow tapes are just for insulation
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  #90  
Old 12-02-2017, 05:38 PM
mmalik (Mike)
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With 'Cold finger Inside' (a7S), putting it all together...
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  #91  
Old 12-02-2017, 06:56 PM
glend (Glen)
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Some important considerations for anyone reading this thread:

1. With DSLR cooling, the only figure that means anything is the actual measured sensor temperature, not the cold plate, not the processor, not internal case. RAW file header temperture data is actually processor temperature.
2. Newer model DSLRs produce more heat than the common models with a proven history of modification. This is due to increased processor workload, in some cases mulitple processors, closer board stacking and battery heat.
3. Consider which DSLRs lend themselves to cooling mods. Rcheshire's excellent thread on camera cooling, here on IIS, is the bible on the process and fully tested, and produces consistent results with sensors at or below 0C.
4. Rcheshire's cooling solution development had no commerical goal and could be built by anyone capabkevof following his well documented instructions.
5. Mr Malik runs a business and is advertising an unproven product solution here on IIS.
6. Mr Malik has a history of this sort of thing on Cloudy Nights, his externally attached cooler is a good example.

If your looking for a properly cooled recent model DSLR, then CentralDS of South Korea has proven products. If you want a very good diy cooled DSLR then read rcheshire's thread. If you want a cooling optimised colour cmos camera solution, the ZWO ASI1600MC-C is more cost effective than almost new model DSLR, and has a proven track record - and can run its sensor down to a delta T of -45C.
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  #92  
Old 12-02-2017, 07:51 PM
mmalik (Mike)
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This is no competition with CCD or race to the bottom. DSLRs/MILCs don't need to be cooled that deep to reduce noise; a different animal altogether. Moderate cooling a modern DSLR/MILC will reap the most benefit without the overhead of condensation (and means to mitigate it) for most environments. [There is an option of chamber desiccant for extremely humid conditions; more in coming posts]

Experts (like RCheshire) agree there is NO need for very low temperatures to reduce most noise in DSLRs/MILCs. The concept is simple yet hard to grasp in a (cooling) world dominated by CCD. Regards

Quote:
Originally Posted by RCheshire
Experience tends to indicate that there is no need for very low temperatures. Temperature consistency is more beneficial to a data set. 12C cooling will reduce noise by 4 - 5 times anyway depending on the sensor.
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  #93  
Old 13-02-2017, 04:16 PM
mmalik (Mike)
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'Cold finger Inside' (a7S) areas at the base...

Note: There is a seam along the base that separates plastic vs. metallic frames; 'Cold finger Inside' areas reside on the metallic side of the frame
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  #94  
Old 13-02-2017, 04:31 PM
mmalik (Mike)
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Prep for 'Cooler @ the Base' (a7S)

IMPORTANT: Arrow points to a raised point that needs proper alignment/negotiation with hole in the coldplate for a flush contact
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  #95  
Old 13-02-2017, 04:37 PM
mmalik (Mike)
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'Cooler @ the Base' (a7S) and test setup...
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  #96  
Old 13-02-2017, 11:53 PM
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Mike, while I admire your attempt to make a "moderate cooling system" for DSLR, I am starting to wonder where this project is going. It has definitely lost it's simplicity and it has developed from a simple cooling to the camera mounting to something that requires camera opening and modification. It seems to be slowly approaching a full cold-finger mod. You are even mentioning a dew control now (more about that below).

Also, you keep quoting Rowland (rcheshire) but there is a very important sentence that gets quoted and gets skipped over:
Quote:
Temperature consistency is more beneficial to a data set.
Firstly, your cooling is applied to the "wrong place". Your sensor temperature will also depend on the temperature of the camera body and hence on the ambient. Also temperature consistency can only be achieved if a cooling system has a temperature sensor at the imaging sensor (exif data is useless as we know). While your design is simpler than a full cold-finger mod, it lacks all these aspects. Also, the cooling system needs to have the extra cooling capacity to deal with temperature variations that happen during nights and between different nights (30C hot Australian nights come to mind...).

Regarding dew control, your system seems to be more complex than the fully-cold-finger modded DLSR. Instead of cooling the sensor, you will be also cooling the camera electronics and actually the whole camera. Condensation on the electronics can do serious damage unlike the simple fogging up of the sensor. Rowland used a simple resistive heating of the front glass of the sensor to solve the dew issues but you will have to address dew control of the whole camera body. You should have a look at Glen's great idea of packing the whole camera body inside a plastic bag containing silica gel and which is filled with argon gas. But as I already said, this is getting closer to a full cold-finger mod.

Also, I can see that in one of your tests you used ISO2000. You should probably stick to full-step ISO numbers (200, 400, 800, 1600, 3200 etc) as lots of DSLRs still take exposures at full-step ISOs and then use multiplication to get the ISO values in between.
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  #97  
Old 14-02-2017, 03:29 AM
glend (Glen)
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All good points Luka, but i wonder about giving this thread any oxygen at all. His Cloudy Nights thread covering the same ground, was started back in 2014, and he is up to 2757 posts now, and gradually people there have given up on trying to engage in any rational discussion, and walked away. He doesn't listen and the goal seems to be to trap unaware parties into buying from him.
This is simply an "infomercial" thread, much like those annoying TV channels that sream ads 247. He obviously has email alerts programmed so any response give him a chance to come in quickly over the top of it and post another photo with a few words, to push down any unwanted comments or concerns, out of sight of the next casual viewer lured into the trap.

All we can do is keep reporting this thread and hopefully IIS admin will do something about killing it.

Last edited by glend; 14-02-2017 at 03:55 AM.
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  #98  
Old 14-02-2017, 04:22 AM
mmalik (Mike)
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Quote:
Originally Posted by luka View Post
Also, you keep quoting Rowland (rcheshire) but there is a very important sentence that gets quoted and gets skipped over:
Quote:
Temperature consistency is more beneficial to a data set.
Thanks Luka; temperature consistency is at the heart of this effort. I'll show some lab and filed data in coming posts how consistent the temp. remains after initial convergence (i.e., time it takes for sensor to thermally stabilize in terms of noise reduction) which typically has been about 1/2 hour. Regards

Last edited by mmalik; 14-02-2017 at 06:46 AM.
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  #99  
Old 14-02-2017, 12:26 PM
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Glen, as this thread seems to be staying here the best may be to keep posting every now and then. Otherwise your comments will be buried and the newcomers will never see them.

Mike, can you please explain how the "temperature consistency is at the heart of this effort" as your temperature sensor is not "at the heart of the camera", i.e. the sensor. As far as I can see your solution can only keep the cold finger at the constant temperature but not the sensor. The ambient temperature may drop by 10 degrees C overnight and your sensor will do similarly as the camera body cools down although your cold finger may be at the constant temperature. And let's not talk about difference in between nights or summer/winter.

Furthermore, I am guessing that the lab data you want to show is similar to what you already have shown a few pages back. While it shows that the sensor temperature goes down and reaches equilibrium (as it has to), it is not what I mean as it shows nothing about longer term variations.

Also I am curious, have you ever tried measuring the cold finger temperature (or sensor noise) while camera exposing over, say 30min, but without the cooling.
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  #100  
Old 14-02-2017, 04:32 PM
mmalik (Mike)
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Quote:
Originally Posted by luka View Post
The ambient temperature may drop by 10 degrees C overnight and your sensor will do similarly as the camera body cools down...
Luka, I have done some retrospective study of my RAW data going back to pre-cooler days and found that to be NOT the case. It may seem logical to think that as night temp. drops the sensor temp./noise would drop with it, but RAW data speaks otherwise. Yes camera body temp. may apparently drop, noise at the sensor behaves quite differently. And there is a reason for it... will explain as I present some field data in coming posts while folks ponder.

And I am not talking EXIF here [...plus some cameras like Sony alphas don't even log EXIF temp.]; I am talking actual noise evaluation of RAWs (as night goes by) and getting the real picture what's doing on at the sensor level in an un-cooled scenario.

Once I have elaborated that, it will be easier to explain what role cooling plays in terms of consistency. Regards

Last edited by mmalik; 15-02-2017 at 02:28 AM.
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