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Old 29-04-2017, 09:30 PM
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Lognic04 (Logan)
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External DSLR cooling - worth a shot?

I am thinking of sticking a peltier cooler assembly on the back of my camera, but externally. Would that make any difference at all? only thinking that because i know how bad noise is in summer with 40c sensor temps, and even long exposures can overheat a sensor. worth 30$?
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Old 29-04-2017, 10:39 PM
glend (Glen)
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Externally it will not make much difference to sensor temperature, but will generate condensation. Suggest you read Rowland's excellent thread on internal cold finger cooling. And don 't get caught up in the web that mmalik guy is weaving.
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Old 29-04-2017, 11:41 PM
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If you are not too keen to do a full cold-finger mod, you can also build a cold-box cooling, see here for example. While it is simpler the results are inferior to a proper cold-finger modification.

Also, depending on the camera, usually the "sensor temperature" is not the actual temperature of the sensor but temperature of something else somewhere in the camera. For example, in cold-finger cooled 450D if the sensor is cooled directly to 0 C (measured directly on the cold finger), the camera will still report rising temperature, usually above the ambient. So the values reported by the camera have nothing to do with the real sensor temperature.
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Old 30-04-2017, 05:26 PM
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In Melbourne winter temperatures, I wouldn't bother

Summer would be different. I find the thermal noise objectionable once the ambient temperature is over 15C. Below that and the camera doesn't overheat sufficiently, but it can vary from model to model.
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Old 30-04-2017, 06:00 PM
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Quote:
Originally Posted by Lognic04 View Post
I am thinking of sticking a peltier cooler assembly on the back of my camera, but externally. Would that make any difference at all? only thinking that because i know how bad noise is in summer with 40c sensor temps, and even long exposures can overheat a sensor. worth 30$?
If you have a suitable camera, then yes an add-on / no-cold-finger cooler COULD do well. The camera would need to have a reasonable heat conduction path from its body (preferably base) to the sensor and body to LCD. A good example of what I think would be suitable cameras for such an endeavour, based on the internal design of the camera and existing heat conduction paths, would be a Nikon D800 or 810, to a lesser extent, a Fuji XE1 / 2 or derivatives and the Canon 1Dxyz.... or probably most of the metal bodied/chassis cameras. This is based on trying to achieve a reasonable cooling target in the 0-10 deg C range (or atleast no cooler than the dewpoint for the conditions), and not necessarily record beating, sensor fogging sub zero temperatures. There is definitely a diminishing return for effort in chasing the extremes of cooling and I would be guided by what I could see/measure in the dark frames as noise versus temperature.

I think for any of these cameras a bolt-on device with zero mods to the camera would be possible, within the provisos stated.


Best
JA

Last edited by JA; 30-04-2017 at 06:15 PM.
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Old 06-05-2017, 11:49 AM
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I once bolted a huge heatsink fan peltier combo to the base of a DSLR and soon discovered that if there is any chance of condensation or deposition, no matter the temperature, the camera will eventually stop working.

No matter how you intend cooling you must first protect the electronic components, which requires disassembling and applying water repellent in all the right areas.

Or use a dry air or Argon filled cooler box.
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Old 08-05-2017, 11:51 AM
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I don't think you'll get too much of a noise reduction. Start with what you've taken in the past, if ambient 40C the noise is bad in summer but winter ambient of say 15C its ok it may be worth playing with modifying a small esky you can house your camera in and cool its interior, but don't rely on results approaching the specs on a peltier. Its harder than you think to remove heat. But aim for an airtight housing where you can reduce the interior air considerably and see how you go. I started with a cheap usb drinks cooler which did cool its housing but not a drink sitting in it for days.. I dismantled and attached the peltier directly to my zwo and it works great but yes you get condensation to deal with. If you attach directly to the body of the camera you will create condensation inside the camera. hence the previous suggestion of dry air or argon. you're essentially commiting the dslr to a permanent setup state for astrophotography only. Don't forget as soon as you turn the camera on its generating heat straight off just doing nothing. The finger method is the best way to keep this at bay.

As for the image quality improvement? Dont know if itd be noticeable in the end.
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Old 08-05-2017, 12:14 PM
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Basically if you cannot cool and control the sensor temp you are almost wasting your efforts from what I found. Unless the sensor has direct cooling applied and controlled it soon warms up. For any kind of accuracy in managing temp it has to be a cooled finger mod. Plus moisture management as others have noted.
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Old 08-05-2017, 12:15 PM
glend (Glen)
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In the work Rowland did on cold finger cooling of Canons, it was determined that there was no point trying to cool the sensor below zero - no further impact on Dark quality. Even though my cold finger 450D can drive down to near -20C, i usually stop at -5C.
If your imaging in winter, when nights can get pretty chilly out at dark sites, there is not alot your going to gain; in fact i have run my Canon in winter with just the fan cooling the cold finger. However, in rhe heat of summer the TEC needs full power to get below zero.

You do need to put a temp sensor on, or as close to as possible, the sensor. Never rely on the RAW image header temp data, as that is recorded inside the camera processor not at the sensor.
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Old 08-05-2017, 01:56 PM
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You do need to put a temp sensor on, or as close to as possible, the sensor. Never rely on the RAW image header temp data, as that is recorded inside the camera processor not at the sensor.
Just like any electronic device, the thermal sensor is a small electronic component and usually gets soldered onto the board as close to the heat source as possible and rarely touching. Like a computer motherboard has one on the board sometimes under or directly next to the cpu. Maybe these days they are built into chips directly that rely on cooling. So don't believe the values themselves they tend to be meaningless. You want to see differential though, so you know the cooling is working at all times. Just turning on your camera itself may negate the cooling effect. Its not about cooling to a target temp so much as displacing the generated heat quickly. Don't forget thermal greases and glues need to be applied particular ways otherwise they become insulators.
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Old 09-05-2017, 08:56 AM
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I have recently made a peltier powered external cooler and have been using it on the few clears nights we have had here in Mackay. Its quite warm here and and my camera has overheated on several occasions. With the cooler attached the sensor temp is definitely a bit cooler and temp is generally more stable. Because the cooler is at the bottom of the camera any condensation has been dripping away from the camera body and I have not noticed any internal condensation. My unit is salvaged from an el-cheapo drink can cooler, powered by a usb phone charger. The original pelitier module has been replaced with a larger 12v 60w unit. The heat sink and fan are too small to handle the extra heat generated when running at 12v but it works ok with the 5v usb power. It simply screws onto the tripod mount hole of the camera, slightly offset to still allow for battery changing.
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Old 09-05-2017, 04:40 PM
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Just like any electronic device, the thermal sensor is a small electronic component and usually gets soldered onto the board as close to the heat source as possible and rarely touching. Like a computer motherboard has one on the board sometimes under or directly next to the cpu. Maybe these days they are built into chips directly that rely on cooling. So don't believe the values themselves they tend to be meaningless. You want to see differential though, so you know the cooling is working at all times. Just turning on your camera itself may negate the cooling effect. Its not about cooling to a target temp so much as displacing the generated heat quickly. Don't forget thermal greases and glues need to be applied particular ways otherwise they become insulators.
In the 450D I got the small temp probe for the cooling system hard up against the side of the imaging chip and on the metal frame that supports it. Other than thermal gradient across the sensor it should have picked up the sensor temp as accurately as was possible.
It was sensitive enough to detect very small changes quite rapidly when I adjusted the power to the Peltier. About 5-6 volts gave me a steady 5* C and about a 20 *C delta dependent on ambient temp of course.
This was enough to be effective in managing chip noise but without causing condensation problems.
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Old 10-05-2017, 09:07 AM
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with my peltier experiment on asi120mc, I was confident with the thermal reading from the camera the firecapture gives. The camera housing frosts up but mainly just watching the temp graph with and without peltier turned on for 10-15min each in the garage . Its reassuring to see the temperatures level out flatly with little to no visible variation (0.1C only ). I've never felt as asi120 needed cooling for me and I didnt notice noise change with my recent planetary captures. Maybe come summer it'll show its hand, but glad it works and confident the camera is usable if the peltier fan fails or battery pack dies.
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Old 10-05-2017, 05:23 PM
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Based on experience, an external metal surface does reduce condensation internally. Just be careful water is not seeping into ribbon connectors (in the cooler regions of the camera) corroding the contacts. Might last a lifetime depending on the design or it might just pack up after several hours use.

On temperature sensors. Cold finger temp is close enough for our purposes. If you are using darks temperature consistency is more important.

While I think of it. If you are imaging at say 0C to -5C or even lower over a night, with or without temperature control, you can omit darks. Just use a Superbias and flats. Temperature is academic in this case.

You may not get terrific results with a regular master bias. Superbias produces much better results. Take flats and bias at the camera's lowest ISO to further limit noise.

Last edited by rcheshire; 11-05-2017 at 05:40 AM.
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Old 24-05-2017, 07:50 PM
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Hi,
I have recently completed constructing the "Martin Pyott" external peltier cooler for my Canon 650D

I am most pleased with the simplicity of the project and the fact that the camera is left intact.

I was able to keep my sensor to a stable 13 degrees C the other night when photographing Carina. Outside temp was 18.5.

To prevent any condensation from finding its way into the adjacent buttons i used a piece of plastic from a glad bag between the peltier cooler and the back of the camera which extended past the sides of the cooler by about 20mm all way round forming a shield for any water to run off but not into the camera.

John
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