Peltier cooled ZWO ASI 120 MC

[Corpze]

The thing is, if you open the camera, you break the warranty, so i personally won´t open it... i was just curious about how peltiers work and if they just cost a couple of bucks, it is just a fun experiment

ONE BIG WARNING THOUGH...

Do NOT connect the peltier without any heatsink on the hot side (often the side with the text on it) or else you will burn the peltier in a couple of seconds.

/Daniel

[tonedeaf]

yes, good warning

and regarding warranty...who needs it?

i´m just too curious so a warranty void won´t stop me

oh forgot to say the better the heat dissapation on a peltier (like a better fan, heatsink etc) will give the peltier a better efficiency!

so lower fan speed will lower the differential temperature, on the opposite higher fan-speed (better heatdissapation) will give higher dfferential temperature.

under good conditions with fullpower arctic fan cooler on (oh i see the picture above is without a self made cardboard fan-casing -> this gave mit further ~1-2°C differential temperature) i can get ~30°C differential temperature (after ~20-30min)

[Corpze]

How effective is Atik, Sbig, SE etc. In cooling and how quick are those? Maybe they have proper "cool fingers" to?

[tonedeaf]

can´t say anything about them, but they have 1-2 Step peltier coolers and i suppose they have cooling fingers (as the QHY5II also has)

maybe they even have a "warm" finger -> to lower dew issues.

regarding their speed i think they will have similar cooling speeds (a little faster -> their peltiers are direclty attached to the cooling finger or even to the sensor)

the cooling time for me is ~2 minutes for the first 10°C than ~5min for the next 10°C and ~15min for the next 5-7°C

therefore i don´t try to get as low as possible!

i´ll try to be in a 20-25°C differential temperature

so i can take darks during "daytime" when it´s hotter during summertime!

but even without cooling finger or direkt contact the cooling should give you better results regarding noise!

if i recall correctly the asi120 has the same sensor as the QHY5II.

and there is a real great difference in noise let´s say at 600s exposure between uncooled +25°C and cooled 4°C or even better -4°C

[lensman57]

Hi alll,

I have just had a reply from ZWO to my email , the makers of the ASI 120, that they are indeed working on a cooled version of the camera, lets hope that it would be here soon.

Regards,

A.G

[JamesF]

I wonder if they might do something about the reduction in dynamic range at low gains now I've raised it, too?

James

[Corpze]

OK, new mods, new go

I found a neopren beer cooler at home, cut it so it fits just above all the way in to the heatsink, i just made a hole for the USB.

from room temp (26-27C) down to 5C it just took about 5min, but down to 0,5C it took around 15min, lower than that was impossible for me.

One good thing though is that the neopren insulation prevents all of the condensation where it is covered.

here is the latest photoshoot

PS. i can´t save pictures in Tiff in fire capture, why is that? only possible with the 120MM (Mono) camera?

// Daniel

[shirva]

Hi corpse. .I'm doing peltier cooling mod on the video section of sgl on the Samsung scb2000 cctv camera adapted for astronomy video. ..using same Peltier and heatsink /fan ...have a look at my findings on modded camera using sharpcap.Davy

[Corpze]

Hi, i will do that

[SnakeyJ]

Nice job with the jacket Daniel - I think getting 26 deg below Ambient is a good result with this setup and the deltaT across the peltier is prob 5-8C higher than this dependent on hs efficiency and fan speed. It will perform much better outside over night where ambient is prob 10C lower in summer and will get a lot lower on winter nights.

Once you get below zero ice build up becomes an issue and you will certainly want some set point control to keep things manageable - but -5C to -10C should be manageable provided humidity is not to high and you have effective insulation. Most benefit comes at longer exposure/higher gain, but tonedeaf was getting very impressive dark frames over 300 second subs so no doubt if the ice can be managed then some good live data can be produced. Though well depth and 12 bit sampling will limit performance in comparison to proper lx ccd astro cams.

[Corpze]

Well i am very satisfied with my Delta T, especially with my pad (shown in one of the pictures above) witch has a conductivity of only 0,9 W/mK... with a better pad, i should get below freezing point i hope...

I only use this camera as a planetary/solar cam (as it should) but want to try to get some deep sky images when the sky is dark enough (in two months or so here in Sweden at 60 degrees North)

[SnakeyJ]

Well i am very satisfied with my Delta T, especially with my pad (shown in one of the pictures above) witch has a conductivity of only 0,9 W/mK... with a better pad, i should get below freezing point i hope...

I only use this camera as a planetary/solar cam (as it should) but want to try to get some deep sky images when the sky is dark enough (in two months or so here in Sweden at 60 degrees North)

It'll definitely do the brighter small DSOs, Globs and M31, M42 ,,,,, I'm out now getting LRGB on M13 and the data looks pretty good on screen with no cooling and dark frame subtraction on my QHY5L-II mono (same cmos). This is relatively bright at Mag 6-7, but only using 5 sec subs and 96% gain.

Attempted Saturn earlier, though the seeing was pretty poor at low elevation and I only shot mono via red filter @ a very optimistic F26, but I did get loads of frames!

[Corpze]

M13 is a good one my thought of using the ZWO as cooled on Deep Sky photos is that i can have a "public" event with new pictures coming in every 5-10 seconds, not just one and one person at the time at the eyepiece.

[moxican]

That's an awesome mod. As a matter of fact I was just thinking about this the other day. One consideration though, isn't the camera too heavy like this?

[JamesF]

If only I could do this mod today! At lunchtime I was running my ASI120 at 50C!

James

[Corpze]

Hi Moxican, no it isnt that heavy, and if you glue the peltier to the sink and secure the camera to the peltier with some tight O-rings ( dont rely on regular rubberbands) it will hold the camera in place!

50 degrees is realy hot, did you see any artifacts? What framerate? I presume you did solar photography?

[moxican]

Sure, I can see the benefits of cooling, what worried me a little bit is that if it gets too heavy, it might strain the nose piece too much. Maybe even break. But if it handles for you no problem I guess I will go ahead and try it myself

[SnakeyJ]

The other thing to watch with this is fan vibration - actually the vibration itself isn't too bad at short focal lengths on my 200P (ok up to around F15/3m), but I do see deflection caused by the torque of the fan blades on spin up which is a nuiscance with the fan switching off and on for set point cooling. PWM fan control is recommended rather than simple on/off. There is also a risk of harmonic vibration at certain speeds which might require some damping.

[JamesF]

50 degrees is realy hot, did you see any artifacts? What framerate? I presume you did solar photography?

None were obvious at the time though I'm expecting quite noisy frames. I've not processed the data yet though, so I've no idea what it's really like.

This was for solar (Ha) imaging, yes.

James

[JamesF]

The other thing to watch with this is fan vibration - actually the vibration itself isn't too bad at short focal lengths on my 200P (ok up to around F15/3m), but I do see deflection caused by the torque of the fan blades on spin up which is a nuiscance with the fan switching off and on for set point cooling. PWM fan control is recommended rather than simple on/off. There is also a risk of harmonic vibration at certain speeds which might require some damping.

That's one thing that does bother me about fitting large fans to small cameras. I could be very tempted to drop the 1.25" fitting in favour of some sort of threaded fitting to give a firmer location.

James

[SnakeyJ]

That's one thing that does bother me about fitting large fans to small cameras. I could be very tempted to drop the 1.25" fitting in favour of some sort of threaded fitting to give a firmer location.

James

Agree with you on the T Threads - definitely better with heavy cameras. A standard CPU heatsink and fan probably adds another 350gms on to the camera, before you consider the trainling cable weight.

Thinking about the fan again - it's probably better, cheaper and simpler to leave it spinning at a constant rate and just control the power to the peltier. This would eliminate the torque deflection issues beyond starting. Other than the torque effect, there was little if any discernable vibration even at F30/6m with the firefly/Expl 200P at least not discernable above the seeing!

[JamesF]

Yes, I can see the sense in running it all the time. And choosing a fan with decent bearings probably makes sense too.

James

[Oddsocks]

To minimise vibration consider using a Sunon Magnetic Levitation Fan (MAGLEV).

These are used in high-end CCD cameras and are not expensive, typically $8 for a 70mm x 70mm, 12Vdc, 0.6W, ~19db.

Where used inside a CCD camera the manufactures tend to use several small fans ~20mm to ~30mm grouped together to keep the mass of the fan blades to a minimum.

Developed for "silent" PC makers, when running, the fan rotor lifts away from the bearing surface and essentially "floats".

Here is a link to the Sunon site that describes the technology:

http://www.sunonusa....nology&p=maglev

And here is a link to one for sale on Amazon (US) today but don't expect the link to be valid for very long:

http://www.amazon.co...s/dp/B006X8VXOK

[JamesF]

Just for interest in case people haven't seen it as it relates to this thread:

http://www.astronomy.com.cn/bbs/thread-242988-1-1.html

It shows a cold finger cooling mod for the 120MM. The text is in Chinese and the images take a while to load, but it's interesting to see. There is some discussion of condensation in the text and messages, but google doesn't translate it well enough for me to be sure I'm understanding it properly.

James

[Brians238]

Corpze (or others),

I recently received a 120MC myself and I am going to make a peltier mod based on your excellent example. I notice the noise on the pix you posted is white, whereas mine in multicolored. I assure that you were capturing in monochrome mode for your example images, is that correct?

I'll post pix of my mod when I complete it (hopefully, later today when the heatsink/fan kit arrives).

All the Best,

Brian