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  #41  
Old 11-08-2016, 09:03 AM
mmalik (Mike)
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Some real-world tests are in; more details & analysis soon...


Note: Small sections of in-camera JPG (3min, ISO2000) zoomed-in at 400%; object is Bubble Nebula
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  #42  
Old 11-08-2016, 09:06 AM
mmalik (Mike)
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Sonly (a7S) noise evaluation [3min x36, ISO2000, Bubble Nebula]; RAWs here...


Note: Baseline in my previous post is with the fan running but pot turned down all the way
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  #43  
Old 11-08-2016, 09:08 AM
mmalik (Mike)
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Notes from the field...


Operationalizing the cooler, in the filed that is, and integrating into my routine were major goals of mine. What I meant is I wanted to develop a cooler that was no additional burden than what it takes to handle the camera, setup and image otherwise. Good news is it was a pleasure to use; fan wasn't noisy at all. There were no vibrations as I have elaborated many posts back how those were mitigated. There was no internal condensation; I had descant solution in place as well which I have also elaborated in my previous posts. Having somewhat of an enclosed sensor chamber with round LPS filter attached to the far end of the camera adapter and desiccant inside the chamber is a good setup in my opinion to prevent any un-necessary condensation in high humidity environments.


Overall quite pleased with the ease of use and non-intrusive nature of the cooler; it let's you setup everything before cooling cable is attached between camera and the PSU. I have extensive inventory of parts if more folks would like to have a go at the testing.


I plan to do more testing in coming weeks as moon cycles and weather permit; I wouldn't call it testing anymore since it is now more of an ongoing use that I would like to get accustomed to so it no longer feels like something extra which it actually isn't. I keep cooler attached all the time so I don't have to worry about detaching/attaching routine and/or handling thermal conducting pads. Battery door is not affected so changing battery is easy. Cooler is not heavy so camera handling feels normal. I think you get the idea... it is the seamless use of the camera that was one of my pet peeves and I seemed to have managed it with your help.


If I have not been able to describe in words, following is what I mean...


Regards
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  #44  
Old 11-08-2016, 09:10 AM
mmalik (Mike)
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Cooling noise reduction is very significant. Here is a NO cooler scenario...


Note: Following are real values from an imaging session where no cooler was attached and ambient was same as above, with the same equipment
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  #45  
Old 11-08-2016, 09:13 AM
mmalik (Mike)
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Here is cooling and no cooling data superimposed.


Note: Shown data is from actual imaging sessions
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  #46  
Old 11-08-2016, 09:13 AM
mmalik (Mike)
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After all the experimentation throughout this thread it is quite apparent that there is a thermal run off (σK) on un-cooled cameras; what cooling does in essence is keep that in check, plus cool beyond the ambient stating point. Regards
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  #47  
Old 14-08-2016, 03:14 AM
mmalik (Mike)
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Here is the processed image from the same session...


36x3min, ISO2000, FF, Dithered+Dk5, Guided, Filtered D1
Sony a7S Cool*


Note: *It was not a full cool session since cooler was started after establishing a baseline with only the fan running; 100% cool sessions soon...

High Resolution...
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  #48  
Old 31-01-2017, 04:29 PM
mmalik (Mike)
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IBIS (In Body Image Stabilization) poses a unique cooling challenge since sensor is suspended in a magnetic field without any physical contacts for transferring heat. Camera I'll be profiling for 'Cold finger Inside' initiative is an IBIS based Sony a7RII


I have coined the term 'Cold finger Inside' that will become evident as you follow this discussion; what it basically means is putting a cold finger inside the camera in such a way that there is no permanent modification or alteration to the camera and can even be reversible if ever need. Plus it is a non-visible modification in itself.


Following is the starting profile of a7RII with Metabones adapter attached...
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  #49  
Old 31-01-2017, 04:34 PM
mmalik (Mike)
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A look at IBIS system (a7RII)
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  #50  
Old 31-01-2017, 04:37 PM
mmalik (Mike)
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Back panels/LCD removed... (a7RII)
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  #51  
Old 31-01-2017, 04:40 PM
mmalik (Mike)
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Panels relevant to 'Cold finger Inside',,,
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  #52  
Old 31-01-2017, 04:42 PM
mmalik (Mike)
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A sandwich view of a7RII...
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  #53  
Old 31-01-2017, 04:48 PM
mmalik (Mike)
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'Cold finger Inside' concept...


Core design idea is to connect sensor PCB window to internal base panel for heat transfer (...eventually via active cooler) and make this connection flexible enough so IBIS functionality stays intact.
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  #54  
Old 01-02-2017, 11:42 AM
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sil (Steve)
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Quote:
Originally Posted by janoskiss View Post
Looking at it naively, I'd worry about temperature gradient across the sensor with a setup like that.
+1

and condensation promotion inside camera case
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  #55  
Old 01-02-2017, 01:34 PM
glend (Glen)
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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.
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  #56  
Old 01-02-2017, 06:53 PM
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I think there is scope for a carefully designed under camera bolt-on cooler, depending on the internal design of the camera in question. It's possible to get some idea of this by looking at the heat conduction paths to the sensor from either disassembling the camera oneself or carefully studying disassembled images/videos of one's camera on the net.

It certainly would make for a good DIY project, with far less complexity and downside risk than an invasive internally mounted cold-finger, as good a solution as that certainly potentially could be. There's no doubt that an effectively mounted internal cold finger would be better thermally, but an externally mounted unit, whilst it won't perform as well, due to thermal resistance at the various interfaces or through different materials, offers a simplicity and conversion back to normal, that is to be admired.

I can certainly see that on some metal bodied cameras (there are plenty of diecast magnesium bodied DSLRs )with good heat conduction paths to the sensor that there would be benefit. Of course the only proof is in the before and after images. As for concerns with internal condensation, one just needs to maintain surface temperatures above the dewpoint of the air inside/around the camera, which to be thorough could be somehow mapped with sensors and controlled electronically or more simply set by prior experiment/hand at some increased risk or performance disbenefit of reduced cooling.

As a DIY project, I think the concept has merit, on a camera specific basis and could easily be housed in or mounted via a camera battery pack grip. As a commercial product ..... it would have some limitations, but I'm sure people would buy it if one could show a photographic benefit in before/after images.

Best
JA
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  #57  
Old 02-02-2017, 06:04 AM
mmalik (Mike)
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Thanks everyone; sorry for the delay. Here is what 'Cold finger Inside' looks like. It is a high quality, flexible copper tape (with heat conducting adhesive). Yellow tape is just a wrapping that serves two purposes; it thermally and electrically insulates the copper tape with the excretion of both ends where copper tape comes in direct contact with the sensor and the base panel. Regards
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  #58  
Old 02-02-2017, 06:06 AM
mmalik (Mike)
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Internal base panel connection of the 'Cold plate Inside'; area in direct contact with the plate is also marked. Regards
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  #59  
Old 02-02-2017, 06:08 AM
mmalik (Mike)
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Before and after view of the sensor connection of the 'Cold finger Inside'. Copper tape comes in direct contact with the sensor in the PCB window; back side is covered first with yellow tape and then with a7RII's native black tape material for insulation purposes. Regards
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  #60  
Old 02-02-2017, 06:09 AM
mmalik (Mike)
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Area highlighted that comes in direct contact with the sensor...

Note: There are additional measures in place (not shown) to thermally/phsically isolate copper tape from native ribbon cable.
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