I am going to have problems working out a way to see the Liveview screen, which I use for focusing. I don't want to go to full pc control. Maybe a little thin double glazed perspecs window would work. I am assuming most box users provide remote power as well and do not have to swap batteries. It would be nice to have something small that just cools the sensor.
I am also investigating CO2 direct injection into the sensor space which looks promising - uses standard aquarium or beer making gas systems and regulator/tubing. There would be a gas bottle refill charge but a 1kg cylinder could last a month if regulated.
Another factor that has emerged as I play with this - and that's the effect of the cooler box on the "distance-to-sensor" figure. If you're using an MPCC or some other reducer/flattener which has a tight tolerance for this - e.g. the 55mm of an MPCC - then there will be a problem. The T-Ring will have to sit in the camera and inside the box - meaning that there will need to be some form of external connecting ring. In the photos I've attached below, you'll see I have put such a ring in place. It screws through the box lid and into the T-Ring but at a cost of about 8-10mm added distance to sensor.
I've been following this thread with interest given Melbourne's warmer weather this past fortnight and the fact that I gathered over two hours of five minute subs on the Rosette Nebula last week that were rubbish due to thermal noise.
Then whilst out shopping today at Officeworks I found a usb powered fridge! It only holds a 375 mL can but for only $10 I thought what the hey - has anyone tried the cooling unit off of one of these to maintain a cooler temperature for their DSLR? I'd be interetsted to hear your thoughts.
Another factor that has emerged as I play with this - and that's the effect of the cooler box on the "distance-to-sensor" figure. If you're using an MPCC or some other reducer/flattener which has a tight tolerance for this - e.g. the 55mm of an MPCC - then there will be a problem. The T-Ring will have to sit in the camera and inside the box - meaning that there will need to be some form of external connecting ring. In the photos I've attached below, you'll see I have put such a ring in place. It screws through the box lid and into the T-Ring but at a cost of about 8-10mm added distance to sensor.
Peter
Yes this will be an issue for me Peter, as i use a Baader MPCC, which is one reason for leaning towards the 'cold finger' or gas cooling. The box is looking more and more problematic. As pointed out in a few links on this subject, there is no need to waste effort and money trying to cool the entire camera when its only the sensor that requires it. I will bow out of this box discussion and not side track the thread. If I find a cold finger solution I will start a new thread.
The most difficult issue I have with any design is weight.
My scope is a Newtonian with a rotating truss.
My weight limit will be 1kg max.
I am wondering if a cooler bag or a foam filled plastic lunch box can do the trick here?
Otherwise perhaps I will have to follow Gary Honis way and simply try and build a box out of light weight aluminium and then mount the camera inside this.
I've done a lunch box cooler but it's too shallow for a rear fan and not enough room for sufficient foam to be useful internally.
@PeterEde > It doesn't need much space and in fact the less the better withinn reason. It's just more volume to cool. I'd be more interested in getting more airflow round the whole camera body because the current setup means that only the back is cooled ( best point) but there is a lot of thermal mass to cool so it slows down the process. The author mentions wrapping the camera in foil but there are probably some other options I will look into for my version.
Can I play devil's advocate and propose a variation to the cooler box which is actually a variation to mod #3 - I'm currently on #5, a cold finger.
Using the tripod mount, fix a strip of 3mm aluminium strap to the camera base, cut to size to fit one or two TEC modules with heatsinks and fans. The camera is then set in a smaller box, putting the cooling in contact with the body of the camera, improving thermal resistance, dispensing with volumes of air. It would be necessary to exclude moisture from the box, of course.
If you were concerned about cooling directly to the camera base, a gap of 0.1mm would be adequate, separating the strap from the base. A few holes tapped to fix the heatsink/s.
Can I play devil's advocate and propose a variation to the cooler box which is actually a variation to mod #3 - I'm currently on #5, a cold finger.
Using the tripod mount, fix a strip of 3mm aluminium strap to the camera base, cut to size to fit one or two TEC modules with heatsinks and fans. The camera is then set in a very small box. This should reduce the volume of the box by putting the cooling in contact with the body of the camera and improve thermal resistance, dispensing with volumes of air. It would be necessary to exclude moisture from the box, of course.
If you were concerned about cooling directly to the camera base, a gap of 0.1mm would be adequate, separating the strap from the base. A few holes tapped to fix the heatsink/s.
That's got potential. I like it a lot. And relatively easy to do.
Peter
I've been following this thread with interest given Melbourne's warmer weather this past fortnight and the fact that I gathered over two hours of five minute subs on the Rosette Nebula last week that were rubbish due to thermal noise.
Then whilst out shopping today at Officeworks I found a usb powered fridge! It only holds a 375 mL can but for only $10 I thought what the hey - has anyone tried the cooling unit off of one of these to maintain a cooler temperature for their DSLR? I'd be interetsted to hear your thoughts.
Paul
Hi Paul, I got one of thoese from office works a couple of days ago with the same idea. I am going to try and mount it to the bottom of the camera and power it of the laptop. I dont know if it will be cold enough but at $10 it is worth a try
I had an old Acer laptop in the shed awaiting the next electronics recycle day (the motherboard had failed), and decided to tear into it to see if there was any thin aluminium in the CPU heat shield/cooling system that I could use for my cold finger design. The attached photos show what I found. It had two solid copper cold fingers to draw heat from the CPU and graphics chip and take it to a copper radiator/heat sink (blow through design) which the scoll fan blows through to shed heat). I was pretty impressed, and since a Itel CPU inside a laptop is going to get much warmer than my camera sensor, it seemed a good platform for building a cold finger for the Canon. Even if I just use the CPU copper finger and machine it down to fit behind the sensor it should carry most of the heat out to the radiator/heatsink and fan. It's a very thin assembly so it does not weigh much (most of the weight is in the solid copper parts). If you have an old laptop laying around it is worth a look inside.
I also salvaged some thin aluminium heat shield and some aluminium/copper metalic tape and some other bits that could be reused.
All I need now is a TEC I think.
Hi Paul, I got one of thoese from office works a couple of days ago with the same idea. I am going to try and mount it to the bottom of the camera and power it of the laptop. I dont know if it will be cold enough but at $10 it is worth a try
Rick
Paul/Rick,
I suspect the can cooler probably only has a small wattage TEC cooler, 10-20w range
I'd go for something around 40w range to have faster and deeper cooling. Just my 2c
Bo
Paul/Rick,
I suspect the can cooler probably only has a small wattage TEC cooler, 10-20w range
I'd go for something around 40w range to have faster and deeper cooling. Just my 2c
Bo
It's worth noting that the TCU used bythe pampuskies guy linked in post #2 in this thread has only a Qw of 15 watts and still produced an 18C drop in sensor temp after an hour.
Peter
The thing that got me with these units is there are two screws to remove and it is a ready made usb powered /fan cooled heat sink device that can be zipp tied to the camera and offers some cooling?
Can I play devil's advocate and propose a variation to the cooler box which is actually a variation to mod #3 - I'm currently on #5, a cold finger.
Using the tripod mount, fix a strip of 3mm aluminium strap to the camera base, cut to size to fit one or two TEC modules with heatsinks and fans. The camera is then set in a smaller box, putting the cooling in contact with the body of the camera, improving thermal resistance, dispensing with volumes of air. It would be necessary to exclude moisture from the box, of course.
If you were concerned about cooling directly to the camera base, a gap of 0.1mm would be adequate, separating the strap from the base. A few holes tapped to fix the heatsink/s.
I'd be concerned with maybe uneven cooling effect from the base but worth looking into for sure. I've also have got heaps of laptop cooling units from chuckouts at work. Might look into that as well.
No luck findinga similar enclosure to Garys at Bunnings, I'll go see a big electrical wholesaler tomorrow maybe. I think it's the best option for efficient cooling to lowests temp.
I had an old Acer laptop in the shed awaiting the next electronics recycle day .
Ditto: with an old IBM Thinktank. With a 386 CPU - gives you an idea of the vintage - and I just took the CPU cooler out of that. It's similar in most ways to the one you photographed (but it doesn't have the additional graphics CPU cooler). And I notice that the direction of the fan exhaust is down - i.e. towards the heat source (the CPU in these instances but the cold source in the cooler design) which means the cold breeze we want to use seems to be pointing 180 degrees away from the thing we want cooled. Doesn't matter if you reverse the polarity of the motor either. Whether its pushing or sucking air, it seems to be doing so the wrong way.
Well I built V2. At short notice I couldn't find an enclosure similar to Gary's and ended up with another lunch box but deeper and smaller. Wasn't much room for insulation but it was a better build. Took ages to cool down, nowhere near as efficient and only got about 10* delta at best. Temp also climbed quite rapidly when in use for longer exposures, only ran at about 5* delta to ambient. I'll play with it a bit more and improve the insulation and sealing but I'm on the hunt for a better sealed and lightly bigger enclosure. Air cooling is far different animal compared to contact cooling as I used on the AS! 120.
Much tidier on the scope though.
That's a serious heat sink hangin' out the back there! I notice that Gary has put the insulation on the outside of his box - presumably to keep the heat out and the cool in. Might be worth sacrificing a little 6-pack esky to try it.
Peter
I'm still waiting on a couple of thermoelectric assemblies to arrive (one from China - 60watts air-to-air and another rated at 15W same design but from the US). But I've already moved into design two - hopefully a lighter and with much smaller volume inside.
I've used the light aluminium tub that was inside the car-fridge I had used in design #1. So it's smaller in all dimensions and extremely light. Of course its open at the top so I got the tin-snips out and massacred the lid of an old biscuit tin, pounded some lips on the edges and it sits nicely on top of that tub. Holes for the DSLR in the lid and a hole in the base of the tub for the peltier.
As luck would have it, the distance from the back of the camera to the bottom of the tub is 60mm and the height of the cold side of the peltier device/fan/etc is 54mm so there'll be a small clearance only and the cold will blow directly onto the back of the camera. I've got the polystyrene lining that comes from the car-fridge and can easily trim that to fit inside this design so there should be good insulation. I may later put some on the outside as well if the temp doesn't drop enough.
The good thing about using the biscuit-tin for the front face is that it is thin and light. So I can attach the T-Ring to the optical train without having to insert another coupling/adapter/ring and screwing up my backfocus.
The whole box is just held together by ZIP-ties but that's not a biggie.
So far, design #2 is looking to have most of the boxes ticked.
Yeah, it's a big one. Trouble is air to heat sink transfer is pretty pathetic. There is a fan inside but the heat sink being small isn't shifting enough BTU's to be really useful but it was the only one that would fit. Really needs a deeper enclosure, 100mm or more to get a decent sink inside.
Gary's enclosure is plastic, already an insulator, then he has filled it with expanding foam and he has a big enough heat sink inside to be reasonably effective in collecting the internal heat allowing it to be shifted by the TEC to the outside radiator. I'd be using a plastic enclosure rather than metal. His has good seals as well.
My problem is being unable to collect enough BTU's to really make use of the big outside sink. When it was strapped onto the AS! 120 at 12volts you could really feel the warmth as it was cooling the whole camera body and a bit of the scope. Much more efficient. I might look at trying to pull it down with a sink attached to the camera base to get some metal to metal contact. Back to the drawing board.
Last edited by ZeroID; 23-12-2014 at 12:18 PM.
Reason: Added pic
