DSLR Coldbox questions

[frugal]

I have been reading around the subject of banding on images taken with DSLRs and the common feeling seems to be that it is largely a function of the temperature of the sensor. As the camera I use is also that family camera for daytime photos I am not in a position to rip it's guts out and start to put in cold fingers or other kinds of extreme modding (even assuming that I felt confident to take it to pieces which I am not). This just leaves me with a cold box style solution for cooling.

Looking back through the search function there has not really been any discussion of cold boxes since 2012, has this approach fallen out of favour?

Almost all of the tutorials use a metal box with the peltier on the outside, and using the conductive capability of the metal to dissipate the cooling, however they also use a cold-sink on the inside. If you put the peltier in a cut-out so that it is in direct contact with both the heat sink and the cold sink would that provide a better temperature gradient? Like this:

Is there any benefit to having the cold sink directly in contact with the back of the camera (the plastic under the swivel out screen)?

cheers,

Frugal

[Tinker1947]

You could try a mains PSU to replace the battery this could reduce the heat a bit....

[Mick J]

We put together a Gary Honis box a few years ago, I can remember thinking how heavy it all became - camera/box/fans/cables, but we did get much the same temperature drop and performance.

The thinking seemed to be that the aluminum box became cold and conducted to our 450d.

You can pull most of the parts you need from a 12volt cooler, the ones with the electronics in the lid or the small fridge type things.

I think if you were to make a cut out as described it may be a bit quicker to cool, the main trick seemed to be getting the heat away from the hot side of the Peltier as best - big heat sink, big fan etc, I have seen suggestions of second Peltier to cool the first.

You will also be able to remove the family camera easily from the box etc.

All the best with it, an interesting project if you like that sort of thing.

[frugal]

I have been reading Gary's articles along with a number of others, and it looks relatively straight forward, I was just wondering about some of the specifics. Such as, is it better to try to cool the whole case down and effectively have the case cool the air, or is it better to try and have a direct connection to the cold sink and have it do all of the air cooling. The former has the advantage that you do not need to cut another hole in the side of the case to connect the two sinks and the peltier together, the later has the advantage that you can make the case out of whatever you like As it does not need to be thermally conductive.

I am also wondering if the coldsink touching the back of the camera to cool by conduction rather than convection would be a good thing or a bad thing. It should cool the camera down more efficiently, but on the other hand if the cold sink is not directly over the area of the camera that houses the sensor would you end up with a thermal gradient across the sensor?

Has anyone here tried these options, or do I just need to take a punt and see what works.

I have had the camera out in a -30C environment with no ill effects (well other than losing a bit of skin when I mistakenly touched the metalwork of the camera )

[Mick J]

 or do I just need to take a punt and see what works.

I think that's your best bet, for what it's worth we went with a MK1  , Maplin Ali box and odd bits from ebay and old computer fans & heatsinks but needed bigger sinks & fans. The MK2 used parts from a cooler box, Peltier/sink/fan/mounting in a ready assembled lump but much more weight.

Had half a plan for MK3 dumping the Ali box for insulated board to save weight, sink still bolted to base of camera via tripod mount.  We were not above putting the whole assembly in the fridge so the camera was already cool before use.

Found these chunky lumps on ebay that did not seem to be around when we were playing.

[frugal]

Cheers for that Mick, that might make the whole thing a lot simpler. Altough the one thing I have just noticed is that all of these peltiers are all 6 amp, and the 12v power supply I run everything off of is only 5a at most... i think i will have to have a look for 12v 6amp power supplies, which will mean yet another 3 pin plug out in the garden which I was hoping to avoid.

[Stainlesssteve]

I am also wondering if the coldsink touching the back of the camera to cool by conduction rather than convection would be a good thing or a bad thing. It should cool the camera down more efficiently, but on the other hand if the cold sink is not directly over the area of the camera that houses the sensor would you end up with a thermal gradient across the sensor?

I've ordered one of these http://www.ebay.co.uk/itm/GPU-CPU-Heatsink-Cooling-Thermal-Conductive-Silicone-Pad-100mmx100mmx2mm-/171568190502?pt=LH_DefaultDomain_3&hash=item27f242d426 to have a go at this with the 70D.

[ghonis]

What I and members on my support forum have found is that 12 Volt peltiers that operate around 3 to 4 amps work best for a whole camera peltier cooler.  They normally provide a 44 degree Fahrenheit temperature drop.  Higher wattage peltiers require larger heat sinks and cooling fans, resulting in larger and heavier coolers.  

[kalasinman]

I considered doing a Peltier based box for a time. Being a skeptic, it seemed heavy, complex  and expensive.I later saw a post of someone making a cool box out of an insulted lunch cooler bag with a hole cut out for the lens or T ring. Cooling was accomplished by using those gel based bags you throw in the freezer. Camera in a bag with desiccant pak overnight, desiccant in the cooler bag. Guy claimed to be getting 3-4 hours of cooling and gel paks could be swapped in session.

I built one of these. I never used it as I came across the Nikonhacker dark point firmware. Having as wide a range between read noise and thermal noise is the goal. With the firmware my Nikon's read noise is dropped to under 2e at room temp., well below that of many CCD cameras (460ex is at 5e, I believe). Moving the thermal noise barrier up, or the read noise down..the latter was easier and cheaper for me.

[frugal]

Well, the peltier and the power supply turned up at some point today (delivery ninjas snuck them into the porch without ringing the doorbell). The socket to wire the bits and bobs to turns up tomorrow. So now I have no excuse not to start building. It will give me something to do this week as the weather forecast is rubbish

I also have 2 temperature sensors with red LED displays coming from Hong Kong at some point in thenext coupleofweekes so I can monitor internal and external temperatures. Then I can compare them to the camera recorded temperature.