DSLR Coolbox test temperature data

[Screwdriverone]

Hi All,

Well, I have done some testing and data collection on the new DIY DSLR cooler box that I based on Gary Honis' design with an aluminium chamber, peltier cooler and two CPU fans with the external one, mounted on the hot side of the peltier and fitted with a pretty solid heatsink.

I had the camera loaded in the box and tonight installed the dual sensor digital temperature gauge so I could see how the chamber temperature dropped while I was watching some TV.

I didnt have the camera on, however I collected a solid 2 and a half hours of temperature readings, measured each half an hour to plot the results, in case anyone wants to see how this little sucker performs.

My previous readings that were taken off the EXIF data reported by Backyard EOS only and didnt really have any accurate ambient readings to gauge how many degrees drop I was achieving (estimated about 7-10 degrees.)

So, here are the results of my testing. I have combined all the pictures I took at 30 minute increments and also added a chart showing the plots of the temperature and the delta T.

Looks pretty good, I am achieving a passive (inactive camera) stable chamber drop of about 11.8 degrees C below ambient temp :D which is great considering anything above 13 deg C shows up horribly on the sensor of my Canon 1000D.

Whats shown by the data and really good is that the cooler drops to about 10 deg C below ambient after only an hour of run time ;)

Not bad for a knocked up piece of aluminium, some foam, a peltier and some CPU fans from a seconds bin at the local PC shop.... :)

I have attached some pics of the box also.

Hope this is of interest.

Cheers

Chris

[wasyoungonce]

Hi Chris, well done.

What I have read, anything below 10C for the Canons really reduces sensor thermal noise.

From what I found this was around 8C for my 450D so pretty close to what I read.

The Camera thermal load does blow out cool down rates...probably a lot depends upon the peltier wattage used and HSF's. Who was it...."Bert" I think made up a dual peltier cooler box. The extra device really helps. He also uses a proper PID controller. Speaking of controllers ....which I trilled a cheap digital temp controller from fleabay (http://www.ebay.com.au/itm/DC-12V-Digital-Temperature-Controller-Thermostat-Control-Aquarium-STC-1000-/251152766258?pt=AU_B_I_Electrical_T est_Equipment&hash=item3a79df1532).

It's only relay actuator switching but it managed to keep my cooler box to just on 1degreeC of the setting( camera in and running).

[Screwdriverone]

Hi Brendan,

Thanks, I am toying with the idea of upgrading the peltier to a larger wattage one to see if the drop increases, they are quite hungry though, the 48W one runs at 4A and the next two choices are 6A and 8Amp modules :eyepop:. The PSU I have is rated at 7.5A, so I might be pushing it.

The M42 pic I took the other night was achieved with the camera sensor solid at 4 degrees C and this provided VERY little noise on the subs and a smooth pic as a result....

I will give the box a go on some more DSO's and see how it performs at different ambients outside with the camera running hot.

Cheers

Chris

[wasyoungonce]

Hi Chris.

I used a 50W TEC (Jaycar) which drew around 4.8A max. I used a separate power supply to the system so as to not induce noise onto my other 12V equipment.

4C stable is excellent result. Try to keep the camera nose pieces and Drawtube (DT) connection well insulated as well. The OTA and focuser (and ambient) will be sinking a lot of thermal efficiency from this area.

I just wrapped insulation material (like stubbie cooler material) around this area.......crude but worked.

As you have found...cooling really reduces sensor noise. Congrats!:thumbsup:

[multiweb]

For a minute I thought your camera developed some serious symptoms of avandonkatitis ;) Glad it's all working for you. :thumbsup:

[Screwdriverone]

Yep, thats the one I have on there now, this is more than capable of producing ice on any exposed metal. I have insulated up areas around the heatsink where the condensation was, this seems to have eliminated that.

The nosepiece is a little harder though, due to the low profile adaptor I use to reach DSLR focus. its a bugger already to tighten up the grub screws to hold the MPCC in the focuser as the adaptor is pretty much butted right up against the front panel of the aluminium and my Fred Flinstone fingers arent dextrous enough to contort past the foam and tighten them up easily, hence I am getting some funky camera alignments on the sensor. I may simply put some thin adhesive foam in this area to help...



:lol: yep Mark, I have caught the mod bug now, I sit inside and look at the cooler box and plot what's next to add or improve....I have already contemplated redoing the chunky foam for some tidier sheets to pretty it up a bit. Aesthetics are nice, but if I can keep the camera around 11 deg or more below ambient, this will satisfy me for now, especially on the cooler nights, I may even get some negative numbers on the camera.

Now THAT would be cool :)

Cheers

Chris

[solissydney]

I tested my cooler box one evening at ambient temp of 15 degrees.
Pre cooled for at least one hour with camera in the box, after 10 exposures @ 5 min. each, ( 55 min) the temp inside the box showed 7 degrees.
When one takes into account a normal temp rise of 13 degrees for an DSLR
I consider that a good result.

[LewisM]

I discarded cooler1 - some reason, the heat from the hot side was transferring through to the cold side and negating! Not sure why or how, seeing I had a heat sink with fan (sucking) on the hot side and a big radial hat sink on the cold side.

Anyway, redesigned it, using plastic this time and high density foam. Using nylon screws too. See how that goes when I have the time.

[solissydney]

I build the cooler box some time ago.
Found it cumbersome and painful to insert it in the focuser.
Lately I tried building a box with the camera at the rear instead of on the side
But gave it away. Too fiddly.
I went back to the original box, improved the insulation and the access to the camera and was able to get the temp down to 10 - 13 degrees below ambient with the camera in the box.
Am now quite happy with the box despite still being a bit of a nuisance, but prepared to put up with it. Now for some clear nights.

[Poita]

I've been wondering if something similar might be possible for solar and planetary work to cool the little ImagingSource or PointGreyResearch cameras to reduce their noise levels.
It would be nice to be able to reduce the number of frames required to combat the noise.

[solissydney]

Image of my cooler box.

[Poita]

Oh and for a separate PSU for cooling mods, grab a second-hand XBOX360 power supply, they are nearly free due to all the dead 360s and put out up to 16amps @ 12volts.
They are small and quiet and quite reliable.

[Poita]

Looks great! Very homebrew.

[solissydney]

You could consider just a small computer fan on its own.
Or, as I tried once, a peltier setup, but with out the box, blowing cold air.

[2stroke]

You guys should try a water block with your tecs if you want to get the best temps, it may be a bit more fuss but would let you get some serious cooling done.

[solissydney]

Thank you, but no thank you

[Screwdriverone]

Hi Ken,

I know what you mean about the fitting of the box to the focuser, with my low profile 2" focuser adaptor and my fat fingers, its near impossible to tighten up the grub screws to hold the MPCC (which is effectively the 2" nosepiece of the camera) into the focuser and get a tight fit with the camera in a good alignment position.

Something else I have noticed, is the weight of the CPU heatsink and fan I have has made the crayford slip when the scope is holding the camera downwards. Not so much of an issue as I normally lock the Crayford when the focus is reached with the Bahtinov mask anyway, but a pain if I forget and slew the scope and the focuser goes "WHUMP" out of its tube to its end stops. Scared the crap out of me when it happened and I wondered why I had no stars all of a sudden.....;)

I need to seal up my chamber a bit better to get some more performance, my AC adapator for the camera tends to take about 4 degrees off my 11.8 measured from an inactive camera, but at least its stable, even if the drop isnt as much as I would like.

I have resurfaced my box with new 13mm foam from spotlight so its looks much schmicker now, and seals better on the corners and edges. Although I havent loaded it on the scope yet and tried it out since.

I might take some shots tonight of the new skinned box and post them here, it is a pretty little thing now. Less bulky and purdy.

Cheers

Chris

[solissydney]

Hi Chris.

What I did with my the past setup was that I drilled a small hole through the t-piece into the nose piece and inserted a pin, that prevented any slip because of the weight of the ?
(you know what). Another solution is to use super glue on the thread.
I have slots in my plywood tube enabling me to move the mirror up or down to suit the position of the focus in the focuser. For example, the focus of the camera in the cooler box is about half way up from the wall of the tube leaving me plenty of room at the back of the cooler box, clear of the finder scope. I have 2 screws I use to tighten the cooler box in the focuser, tight up against the insulation, but it is ok.
Where is the ac adopter located? not inside the cooler box?
You might consider calling in any Friday night at the pony club site in Bannerman Rd
Kenthurst, to look at my setup. Or for that matter, any night, just let me know.

[Screwdriverone]

Nope, the only thing in the cooler box is the camera and the internal fan. The AC "battery eliminator" is shaped like a canon battery and fits in the camera, but the cord comes out of the cooler box and to the "dongle" that is the AC/DC converter which plugs into the AC.

Cheers

Chris

[solissydney]

Ah, the dummy battery. I have one myself.