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DSLR Cooling to Near Ambient with Fan Cooler

Gina

By Gina
in DIY Astronomer

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Gina

Gina

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Couldn't you just set up some CPU fans to blow on your passive cooling?

Do you mean fans blowing onto the mounting plate? If so I don't think so because the plate felt really cold - but I didn't measure the temperature so it's really just conjecture. I do know that the 60mm cooler with lots of closely spaced fins really works well :)
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Gina

Gina

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I take back my comment questioning the sturdiness of the ali plate, it looks thicker than I first thought, in my head 3mm didn't initally seem thick enough:D

3mm is about an eighth of an inch - pretty solid. But aligning Ha and OIII images will prove it one way or the other I reckon.
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Gina

Gina

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Now have a cooler on the second camera. It would have been great to have had the same model as for the first camera but failing that I've had to use a bigger unit but (by calculation) a slightly lower total surface area of heat shedding fins. Hopefully this will be made up for by a bigger fan. This cooler also has a poorer heatsink as it's all aluminium whereas the smaller one has a copper heat spreading pad. Time will tell if this larger 80mm cooler is as good as the smaller 60mm one. I still have a 12v supply cable and connectors to add, to power the fans before it's ready for use.

Here are some photos.

post-13131-0-74525100-1350592951_thumb.jpost-13131-0-49128700-1350592955_thumb.jpost-13131-0-95853000-1350592959_thumb.j

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Gina

Gina

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Assembly now weighs 1.67Kg so that's 170g for the coolers compared with the copper bits. I'm hoping to sort out fan power today and get it back out on the mount and run more tests.

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russellhq

russellhq

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Gina, just a though, have you tried passive cooling with the heatsink attached? I read earlier you tried passive cooling but this was without the heatsink. You should get a performance gain on the passive cooling with the heatsink attached.

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Gina

Gina

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Gina, just a though, have you tried passive cooling with the heatsink attached? I read earlier you tried passive cooling but this was without the heatsink. You should get a performance gain on the passive cooling with the heatsink attached.

Interleaving the copper plate between the cold finger and the cooler would add thermal resistance - not sure there would be any gain. Might try it later. What I really need to do is set up some digital thermometer chips to check temperatures. I'm not sure where the problem was with the passive cooling but I suspect all the junctions even with thermal paste.
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Gina

Gina

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What I meant was to try it with the cooler fan turned off so you can measure the effect of just the cooler heat sink.

Oh I see :) Can do that easily enough.
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Gina

Gina

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Added 12v power cable and took assembly out to obsy. Problem - fan of bigger cooler catches on the mount :( May be able to get over it by moving the dovetail but could have balance problems. More to sort out... Can't check the balance yet because I'm altering the scope camera box, so don't know yet what the weight will be - but I don't think it'll be much different. Meanwhile, I'll see if I can move the dovetail in the mount so that the WF assembly will fit.

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Gina

Gina

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Just been out and looked at the problem. I can't move the dovetail enough for the cooler fan to clear the mount. So either I need to find a smaller cooler or get a bigger piece of aluminium to move the camera further out from the centre line. Nothing I can do tonight other than order another ali plate - which I've just done (100mm x 250mm x 3mm).

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Gina

Gina

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Gina the two fans I ordered from the link you put up are nice and small, and a cool anodised blue colour:D

Yes, they do look quite good :) In fact I have now ordered one (the last one they had) to try on my second camera. Not expected to arrive before next Wednesday though. Have to say, I don't like the 80mm cooler - looks far too big! :(
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Ags

Ags

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I find the screen on the back of my camera quite useful, so I would not like to replace it with a block of copper :-) but now you have me wondering if I could knock some air vents in the camera and rig up a fan to blow air through the system?

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Gina

Gina

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I find the screen on the back of my camera quite useful, so I would not like to replace it with a block of copper :-) but now you have me wondering if I could knock some air vents in the camera and rig up a fan to blow air through the system?

I tried this with very little success. I also got dust on the filter :( However, cold finger cooling may be possible by taking it out through the bottom of the camera as I think I described earlier in this thread. I may look into this later (just for fun and maybe to help others) on one of my spare cameras. I have two currently non-working 1100Ds (I went just a bit too far in modding) that I can play with. Having spare cameras is useful in proving or disproving an idea before going ahead on a working camera.

Also, when I was testing out cooling earlier I brought the cold finger out through the side. This worked to an extent but the length and thermal resistance of the long cold finger meant I was losing a lot of cooling from the Peltier TEC outside the camera.

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Gina

Gina

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Now have the little blue CPU cooler so will be trying it out shortly. Have brought the WF assembly indoors to play with and taken the cameras off the mounting plate and tried the new cooler on the cold fingers. There are little raised edges on the part that contacts the CPU but I think these will be OK on camera 1 as the coldfinger is slightly further out.

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Gina

Gina

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Now have the blue cooler on one of the cameras and running a test. It was quite east to fasten to the camera using the spring clip on the heat sink. A couple of small self tapping screws into the plastic case of the camera were all it required. I drilled a couple of 1.5mm pilot holes for the screws.

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Gina

Gina

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It's not bad - ambient temperature = 23.9C and EXIF T has settled down to reading 26C with continuous 3m subs according to APT.

Now running 5 minute subs at ISO 3200 which is what I generally use.

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Gina

Gina

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Results are now in :)

With ambient temperature varying between 23.5 and 23.9C the EXIF T has varied between 25 and 26C :) Been running my darks sequence of 10 seconds to 1 hour in logarithmic progression, and it's just finished the half hour exposure. The noise is showing well now as expected with half an hour at ISO 3200 and 25C.

Latest 40m 25C EXIF T with 23.8C ambient.

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Gina

Gina

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Better than I expected :) I don't think it's significantly worse than the 60mm MicroFin cooler. It's certainly much easier to attach. I would have bought two of them if they'd had two left to have a matching setup. But I missed the boat yet again :mad: Still the 60mm is alright anyway.

I guess I could have set up APT for two cameras and run both side by side.... Maybe I'll do that tomorrow. Could set it up in my obsy - cooler out there :D

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