I've done my first experiment today and the results look promising.
Here is the Canon with the CCD chip exposed:
(http://www.markshelley.co.uk/webdisk/CanonPelt1.jpg)
Note the copper pipe beaten flat in the lower part of the image. Its thickness in 2mm, which is just slightly larger than the gap between the back of the CCD and the circuit board that fits above.
Here's the conductor held in place with duck tape:
(http://www.markshelley.co.uk/webdisk/CanonPelt2.jpg)
Here's the camera reassembled:
(http://www.markshelley.co.uk/webdisk/CanonPelt3.jpg)
The heatsink is a standard aluminium CPU heatsink and fan.
Here is a graph of the standard deviation of noise on a series of successive 5 minute dark frames:
(http://www.markshelley.co.uk/webdisk/PeltierExpt1.jpg)
The noise level increases at first as the CCD warms up and then drops immediately when the cooling is switched on after frame 13.
The drop in thermal noise is consistent with a temperature drop of around 18C from just before switch on until the final frame. The experiment was conducted at room temperature (around 20C) but no ice formed around the Peltier.
Next time I will shorten the piece of flattened copper tube and use a more efficient heatsink/fan (in copper?)
Nice one Mark - Looks very good for first tests. Out of curiosity what Peltier are you using what volts/ current does it operate at?
John
Quotecopper pipe beaten flat
So the copper pipe is just acting as a heat sink ?
I was expecting a bi-metal "finger" with a voltage applied :o
Presumably I've got it all wrong (Now there's a surprise) and need to re-read "Peltier Cooling" :oops:
Quote from: mickwSo the copper pipe is just acting as a heat sink ?
The copper pipe is the cold finger - it "conducts the cold" from the peltier to the CCD. Unfortunately the Peltier cannot be placed directly on the CCD because there is a circuit board in the way.
Quote from: JohnP
Out of curiosity what Peltier are you using what volts/ current does it operate at?
Just look at the photo - it's a TEC1-12703!
I scavanged it from the 12V Maplin drinks cooler. At 12v it consumes 2.5A and the fan adds a little bit more.
I found a datasheet for it on the net which gives the following:
Imax = 3 amps
Umax = 15.4 volts
Qc max = 26.4 watts
deltaTmax = 68 Centigrade
They can probably be sourced fairly cheaply from China.
Mark
QuoteImax = 3 amps
You're going to take Imax images :o :o :o :o :o :o :o
QuoteJust look at the photo - it's a TEC1-12703!
'cuse me for asking......... :lol:
I was more interested in current draw & figured you'd have specs to hand....
Now I've added a bit of insulation around the copper pipe to prevent some of the earlier heat loss. Results are on this graph - guess at which point I switched the Peltier on?
(http://www.markshelley.co.uk/webdisk/PeltierExpt2.jpg)
Temperature drop is now 24C but this is an underestimate because the initial temperature was still rising. I think that with a couple more modifications a 30C drop would be quite achievable. Although thick ice was forming on the Peltier device, the same was not true of the copper pipe - a hammer beaten copper pipe is not really flat enough to ensure good thermal contact with the Peltier (nor with the CCD).
Here is part of dark frame #17 (immediately before Peltier switch-on) and dark frame #36 (after the Peltier has stabilised):
(http://www.markshelley.co.uk/webdisk/noisebefore.jpg)(http://www.markshelley.co.uk/webdisk/noiseafter.jpg)
The dark frames have been scaled in an identical manner. I think you'll agree this is quite dramatic.
By the way - I've estimated the power consumption of the 350D - it is around 3-4 watts. So the heat generated is not that difficult to dissipate.
Mark
Excellent work Mark, the results are staggering, makes me want to pay you to mod my 40D now ;)
just curious why the blip on frame 34?.
How about taking some measurements with the camera in the fridge to start with?
That way you can get some idea of what the results will be like towards the colder parts of winter,
when your camera is l really cold to start with.
The results are looking fantastic considering the initial start temp of 20~ ish.
what would the outcome be if the peltier were larger and had a greater temperature difference?
Mac.
Mark, you could try some thermal grease on the cold finger, both between the pelt and the CCD. I wonder if it would be possible to grind the copper flatter using a cheap whetstone or diamond knife sharpener.
Also it's important to keep an eye on the hot side of the pelt until you've got your testing sorted. They're capable of self destructing, by heating the hot side enough to melt the solder at the semiconductor junctions...
Marm,
Any of these any good to you....
TEC1-12709T125
TEC1-12706T125
TEC1-12703T125
If so I can get hold of them for about £3 each.
Quote from: Daniel
makes me want to pay you to mod my 40D now ;)
No way would I touch a 40D! A second-hand 350D is cheap enough that a mistake won't be too expensive.
Quote from: Mac
just curious why the blip on frame 34?.
No idea. It might be the dodgy fan - I had it lying around because I removed it from my current PC!
Quote from: Mac
what would the outcome be if the peltier were larger and had a greater temperature difference?
It would require a larger heatsink and fan like the one in the Maplin drinks cooler - it was just too big and heavy for the camera.
Quote from: Ian
you could try some thermal grease on the cold finger ... I wonder if it would be possible to grind the copper flatter using a cheap whetstone
Thermal grease - I've already used a bit. Whetstone is a great idea!
By the way - here's a pic of the current prototype:
(http://www.markshelley.co.uk/webdisk/PeltierPrototype.jpg)
Mark
Quote from: Mike
Any of these any good to you....
TEC1-12709T125
TEC1-12706T125
TEC1-12703T125
Yes please! Would you order me four TEC1-12703T125 - they're identical to the scavenged one I already have.
Mark
4 x TEC1-12703T125 on the way :)
wont the fan take off your left eyebrow when your framing the image? ;)
It's looking good.
Is there anything else you can mod on that camera?
Quote from: Mac
Is there anything else you can mod on that camera?
Pink furry dice?
Mark, what a good job you are doing, hope you will be earthed when starting it up :surprised: :surprised:
I don't suppose you'll be taking photos of Aunt Mabel with that camera, sucking on the brussell sprouts at Christmas, with her teeth in the glass next to her. :-?
Tony G
PS........................I know it maybe a bit late, and someone could have already stolen the idea, but have you patented this yet. ;)
Quote from: Mac
Is there anything else you can mod on that camera?
No - I need to find someone with a spare D3 for my next experiment :evil:
Thanks for the suggestions I have had so far.
Last night I made the following modifications:
1) Stacked two strips of copper onto the first to bring the total thickness of copper to 6mm all the way from the Peltier to well inside the camera body (but not all the to the CCD because there is no room).
2) Used a metal file and a whetstone to make the strip as flat as possible where it contacts the Peltier and the CCD
3) Used thermal paste where the copper strip contacts the Peltier and CCD
4) Added insulation to all exposed copper outside the camera body
Then did a very quick experiment at room temperature. 15 minutes after Peltier switch-on all copper outside the camera body was covered in ice (don't know what was happening inside!). The standard deviation of noise on a 5min dark frame dropped from 40 electrons to 5.7 electrons in the same 15 minute period.
I have verified that the read noise on that Canon is 4.9 electrons so most of the 5.7 electrons noise is actually read noise. This shows that the read noise is now the main limiting factor for a 5 minute exposure at room temperature.
I'll do a proper longer experiment at the weekend but this initial result is much better than I had dared hope for.
Here's the English translation of my previous post:
With cooling switched on, a 5 min dark frame is indistinguishable from a 1/4000s bias frame.
Mark
Quoteall copper outside the camera body was covered in ice
If ice IS (quite likely) forming inside the camera, moisture isn't going to get out in a hurry.
When you are happy with your test results and you've finished your modding, perhaps a strip down and a liberal smear of silicone everywhere.
Halfords sell stuff called "liquid masking tape" (similar to photographic "strip mask") it's a thin rubbery liquid that you brush on, that can be peeled off again once it's set - thicker/more coats peel off easier
Mark your 4 x Peltier's have arrived from China.
If I can get my 350d working again (see fuses post) I might have a go at this, I even have one of those Maplin fridge units in the garage ready to be stripped down.
Thanks Mike! I'll collect some time.
condensation...
I've still got loads of those dessicant packs, if you want to seal the camera in a plastic bag and chuck some of those in to remove all the moisture from in the camera.
Just seal the bag around the copper strip.
Mac,
That's exactly what I intend to do - seal a plastic bag around the camera body with dessicant inside - so a few more dessicant packs will come in useful.
BTW - how does one "recharge" a dessicant pack? Stick it on a radiator?
Mark
Quote from: Dunc
If I can get my 350d working again
Good luck!
QuoteBTW - how does one "recharge" a dessicant pack? Stick it on a radiator?
some of them can be stuck in oven's or a microwave, but im not sure about the one's i've got.
Put them in an oven on the S setting for about 30 mins.
Mac,
Yours are Desi Paks : http://www.sphinxadsorbents.com/desipak1.htm
They contain clay (not silica gel) and Mike was right - they can be reactivated in an oven:
http://www.agmcontainer.com/desiccantcity/pdfs/reactivation_GDT2.PDF
Mark
QuoteThey contain clay (not silica gel) and Mike was right - they can be reactivated in an oven:
excellent, that'll save a few quid.
Project is now finished apart from sealing the camera body in plastic bag containing dessicant. I settled on a single thickness of copper (instead of 3) because it was getting rather heavy.
A couple of final images:
(http://www.markshelley.co.uk/webdisk/CanonPeltier2.jpg)
(http://www.markshelley.co.uk/webdisk/CanonPeltier3.jpg)
Graph of the pixel standard deviation for successive 5 minute dark frames - experiment conducted at room temperature and the Peltier was switched on directly after frame 21:
(http://www.markshelley.co.uk/webdisk/PeltierGraph.jpg)
Here's a comparison of the above frames plus a comparison with a 1/4000sec bias frame:
(http://www.markshelley.co.uk/webdisk/PeltierFrames.jpg)
Mark
Wow Mark, that is amazing!! How well you have done
How will you support the extra weight?
The added copper pipe plus heatsink and fan doubles the weight from around 1 pound to 2 pounds. I'm hoping that this won't be a problem for the scopes.
Mark
With an extra 1lb hanging out the side, you might find the camera will try and rotate.
Perhaps a support from the dovetail supporting the heat sink or could you set up the camera with the heat sink down and straighten things up in processing ?
Looks excellent Mark - I am really looking forward to first light - If performance graphs are anything to go by it should be excellent. I hope condensation isn't an issue...
John
Mark, I agree with Mick, the one big fault with my Art285 is the shape of the case. Off axis loading is a pain in the ***. It can unscrew adapters, cause alignment issues and give you something else to worry about when making sure all the screws are tight...
I'd try and use it vertically if you can.
Mick, Ian,
Off-axis loading is something I hadn't really thought about. It won't be a problem on the heavy C11 but it might be an issue with the ED80 I suppose.
If it becomes a problem I'll simply(?) re-site the Peltier onto the rear of the camera, which is inconvenient because I won't be able to use the viewfinder or rear LCD.
Mark
Even on the C11 it'll try and unscrew your t-ring. Upside down, or vertically, it won't though...
I've now weighed this properly.
The mod takes the camera from 600g to 850g so the torque problem is nowhere near as bad as first appeared.
Mark
Further details on my website:
http://www.markshelley.co.uk/Astronomy/Projects/canon350peltier.html
First light is here:
http://forum.orpington-astronomy.org.uk/index.php?topic=5409
Mark
Now it looks like I will have two 350Ds (when No1 is fixed) I will have to have a go at this, along with the Ha mod. I might need your help Mark.
Mark, wasn't the original intention to remove the CF holder and take the heat sink through the slot ?
Quote from: mickw
wasn't the original intention to remove the CF holder and take the heat sink through the slot ?
Yes, that was the original intention. But then I realised a could bring the copper strip out the opposite side just by unsoldering a couple of sockets and it would be far less risky than unsoldering all the legs of the CF socket (which might easily have caused a short circuit). So I get to keep the CF socket and the copper strip takes a slightly shorter path to the Peltier - a better solution all round!
Quote from: Dunc
I will have to have a go at this.
Dunc,
I'm going to buy a 2mm sheet of copper. I can cut strips from it that will be properly flat and will give better thermal contact for improved performance. You'll be welcome to a strip.
Mark
That would be great Mark. Thanks.
I have got my second 350D now and want to mod my first one when it comes back from the repairers, then I have fall back position if the mod mucks up!
Quote from: Dunc
I have got my second 350D now and want to mod my first one
Happy to help when you're ready. Strongly suggest you buy the Baader-ACF 2 filter (model specific for the 350D) for the conversion because, if you don't, you'll have to use a 2" IR/UV filter with it. Unless, of course, you want to try your hand at IR photography.
Mark
From start to finish, Exactly how long would you say it would take to get an unmodded 350
Into the current state of your one?
Including the IR mod ect.
Mac.
Quote from: Mac
From start to finish, Exactly how long would you say it would take to get an unmodded 350
Into the current state of your one?
First time I did the H-alpha mod it took me about 3 hours - I can now do it in 2. Whilst it's in bits, the additional overhead of the Peltier mod is another couple of hours at most - assuming the copper is already cut from a copper sheet.
Let's say 4-5 hours in total.
Mark
hmmmmmmmmmmmmmm,
Looks like i might have a go at modding my 350D.
can you remember where you got the glass replacement.
Just found the link i was looking for.
http://astro.ai-software.com/articles/mod_350D/mod_350D.html (http://astro.ai-software.com/articles/mod_350D/mod_350D.html)
Mac.
Go for it, Mac!
The one piece of advice I would give is that the ribbon cables are very fiddly to get back in position - they need to go all the way into their "sockets". That part is a patient and careful operation that can't be rushed.
Will you use glass or the Baader replacement?
Mark
i'll probably go for just the glass replacement, and stick the necessary filters in the scope and /or lenses.
Where did you get your glass from?
I got it from Edmund Optics.
A 48mm x 84mm rectangle of anti-reflective glass:
http://www.edmundoptics.com/onlinecatalog/displayproduct.cfm?productID=2402
Cheers.
Ordered.
hurah, the glass turned up today,
so as soon as i strip the camera down please expect perfect viewing conditions,
Im looking to do it this weekend.
Hopefully
Mac.
A really interesting project, have you used it in anger yet outside? Earlier posts suggested you were going to use desiccant packs to keep the sensor dry, has this worked? I built a Artemis 285 CCD (now prebuilt and sold as an ATIK 285L (I think that is the model No)), the biggest problem I had was drying out the air in the area between the chip and the glass front and the CCD icing up, after a few experiments I was able to seal the unit successfully, but the reason I mention it is the volume between the glass and the CCD was kept dry by as reservoir of silica gel in a syringe connected to the air volume by a short hose, if you have trouble with icing this might help give the little space you have to work with.
Good Luck,
Simon.
It worked perfectly the first time at -17C:
http://forum.orpington-astronomy.org.uk/index.php?topic=5409.0
But the second time it had problems at only -9C:
http://forum.orpington-astronomy.org.uk/index.php?topic=5467.0
I like your syringe idea - I might give it a try.
Mark
Mark isn't there anyway you could seal the camera but still leave the battery compartment exposed or can't you get one of those adapter things for the 350D that would enable you to make the battery connection outside or better still use an external 12v source - no need to worry about opening at all then.. Something like this...
http://astronomiser.co.uk/canonpower.htm
John
John,
Yes I have one of those (a DIY version) but I was using it on the other camera. I will have to make another then I can keep the camera sealed.
I'm also waiting for some 2mm sheet copper to arrive so I can make a Mk2 of my mod.
My earlier Orion subs were all OK - I'll process them at the weekend 'cos I'm busy finishing off Thursday's presentation on digital imaging noise.
Mark
QuoteI'm busy finishing off Thursday's presentation on digital imaging noise.
....................... and the perils of cooling ;)
I have got one of those adaptors Mark
I've just taken delivery of the Astronomiser power adaptor. Nicely made.
I'm now the proud owner of a sheet of copper. Very shiny! :D
QuoteThursday's presentation on digital imaging noise.
Looking forward to it Mark.
Carole
I performed the MkII mod yesterday.
Here's the copper strip I soldered together and cut to shape:
(http://www.markshelley.co.uk/webdisk/StripMkII_1.jpg)
I've made the strip wider than the previous piece of copper pipe. That and the double thickness means it transfers the heat much better. Since it is completely flat it gives excellent thermal contact.
I had to then do a bit of extra shaping so it would not collide with other components:
(http://www.markshelley.co.uk/webdisk/StripMkII_2.jpg)
In position in camera:
(http://www.markshelley.co.uk/webdisk/StripMkII_3.jpg)
Here are two 15minute subs before and after cooling (same scaling on both) - all done at room temperature.
(http://www.markshelley.co.uk/webdisk/mkiiframebefore.jpg)
(http://www.markshelley.co.uk/webdisk/mkiiframeafter.jpg)
The cooling is so dramatic that I can't meaningfully measure the noise reduction - I'll have to do 60min subs to measure it. It's well over 30C of cooling. The "after" picture is almost indistinguishable from a bias frame except in the amp glow areas. I really need to do an amp-off mod as well to get rid of it.
Mark
Looking good,
I'll probably start mine in the new year.
I'm busy untill then, Birthday, Degree, Concerts, and that thingy some where around the 25th :lol:
QuoteI really need to do an amp-off mod as well to get rid of it
Is there such a mod?
also is it necessary?
i know it would reduce the amp glow
but, , what would the length of time be to fill the wells up?
considering their depth.
if this is only say 9 mins, what is the effect of the amp glow after this time?
Mac.
Once again, impressive stuff.
How does this compare with the Mk1 mod for an exposure of the same length ?
Have you just tack soldered the outside edges or did you "tin" one or both surfaces ?
Tacking may introduce an air gap (a very small air gap)
That is an impressive difference Mark. I can't wait to see this camera used in anger.
Mick,
The 15min darks with Mk2 are very similar to the 5min darks with Mk1. I'll have more acurate figures later today.
I coated the internal surfaces with plumbing flux (makes the copper very shiny), clamped it together, heated it and then introduced plumbers solder at the join until it was "sucked" into the gap. I carried on adding solder until I could see it appearing at all the edges it had internally flowed to.
Mark
Quote from: Mac
what would the length of time be to fill the wells up?
considering their depth.
It's not a question of how long the wells take to fill up. The problem is that those brighter areas contain greater noise. The brightness can be subtracted with a dark but it leaves the extra noise behind and this extra noise drowns the faint details in your image.
It's a shame you missed my talk - I explained it all there.
Mark
Great results. Payback for all your hard work on this.
Don't suppose you made a template of the copper strip for next time? I got my second 350d back and hope to start Ha modding one as soon as I can get some Edmunds glass or a Baader pane ordered. Since the cooling is so impressive that will have to follow shortly after!
I've now done a couple of cooled 60min darks at room temperature.
The standard deviation of the pixels in the difference image between the two is 8.9ADU.
Compare this with a standard devation of 6.9ADU for a diffence image between two 1/4000s bias frames.
I'm pretty happy with this 8)
35C is the estimate I have for the cooling (vs approx 24C for the MkI version) - this is the difference in CCD temperature between cooled and uncooled.
Roughly speaking this means the cooled CCD temperature is approx 28C below ambient.
Duncan, I've made a template - I just need to transfer it to squared graph paper for repeatability and ease of use.
Mark
Have you had any more problems with keeping the moisture (and hence ice) out ?
Quote from: RobertM
Have you had any more problems with keeping the moisture (and hence ice) out ?
No, I opened this up after 4 hours, while it was still running cold, looked at the CCD and there was no hint of dewing up.
QuoteI opened this up after 4 hours, while it was still running cold, looked at the CCD and there was no hint of dewing up
Cool.
Yup pun intended. ;)
How much would you charge to mod a camera?
I've got the glass.
Need to purchase the copper,
Just thinking about the amount of time i currently lack.
Even the UDSC is looking problematic, but im digging in deep.
Mac.
I've just peltier modified my second Canon 350D. My 60x60mm heatsink didn't arrive in time so I had to buy a 70x70mm from Maplin.
Big difference! It's 80g heavier but it's given me an extra 5C of cooling. I did a couple of cooled 60min darks (at room temperature) and reckon the amount of cooling is now around 40C from it's level without cooling.
The only annoying feature is the remaining amp-glow. I'm seriously wondering if the 400D maybe the ideal camera for peltier cooling (sorry Mick for all the nasty things I've said about the 400D in the past!). Even though it's dark current is higher than the 350D, it has no amp-glow after cooling. Even better, it is probably just as easy to peltier mod as the 350D. I'm very tempted ...
Mark
Strangely I have one for sale.........................
£1000 :lol:
I'm actually tempted to (try to) mod them both - Ha at least.
Time and patience (or lack of) will tell