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Cooled Astro Cam Conversion

As it's been guessed, let's make this a build log.

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Neil Wyatt31/08/2019 14:12:44
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Ok, plenty of people will be able to guess the general idea, but armed with a vague idea of my interests can you give a more than just a name to this part?

Clues - the two parts are an interference fit and pressed together in the vice before finishing the central part. There are two more threaded holes to be added either side of the column and in the finished project this will be totally hidden from sight.

Neil

toup 1.jpg

 

Strange distortion on the phone camera, those holes are diametrically opposed!

Edited By Neil Wyatt on 31/08/2019 14:14:01

SillyOldDuffer31/08/2019 14:52:59
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Posted by Neil Wyatt on 31/08/2019 14:12:44:

... armed with a vague idea of my interests can you give a more than just a name to this part?

It's an Industrial Grade Nipple Shield.

Brian Sweeting31/08/2019 15:24:37
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A telescope pivot?

peak431/08/2019 15:32:42
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Considering an interference fit with the copper item; is it a heater to combat dew forming in a telescope?

Bill

Arthur Sixsmith31/08/2019 15:36:15
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Guitar effects peddle?

Nicholas Farr31/08/2019 15:36:39
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Hi, it's a base for a rotating space camera/telescope which is due to be taken up to the ISS on the next launch and then one of the astronauts will do a space walk and weld it somewhere on the outside. nerd

Regards Nick.

Edited By Nicholas Farr on 31/08/2019 15:37:25

Michael Gilligan31/08/2019 16:19:30
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Posted by peak4 on 31/08/2019 15:32:42:

Considering an interference fit with the copper item; is it a heater to combat dew forming in a telescope?

.

With similar, but inverted logic ... is it a cooling stub for a camera ?

MichaelG.

Joseph Noci 131/08/2019 16:29:59
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Posted by Michael Gilligan on 31/08/2019 16:19:30:
Posted by peak4 on 31/08/2019 15:32:42:

Considering an interference fit with the copper item; is it a heater to combat dew forming in a telescope?

.

With similar, but inverted logic ... is it a cooling stub for a camera ?

MichaelG.

Michael's got it...To cool the sensor.

Joe

Robert Atkinson 231/08/2019 16:30:16
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Plus one for camera CCD cooling. Called a "cold finger" .

Biggest issue with coolled LCDs is keeping condensation off the electronics. Hermetic + vacuum with bit of dessicant is ideal but hard to acheive. A separate container with replaceable large (0,5kg) silica gel bag piped to a reasonably well sealled camera head is a good compromise.

Robert G8RPI.

Neil Wyatt01/09/2019 14:45:53
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Michael, Joe and Robert have it.

It's for a 'Toupcam Mono', a very simple mono camera with a small sensor, normally the sensor sits on top of a 'stalk' that is moulded into the case, quite a neat arrangement but only basic passive cooling.

If I cool to zero or below it I will be able to take long exposures with little noise. It will fit on a cheap peltier and heatsink/fan module in place of the small internal fan and heatsink.

I'm 3D printing a 2nd prototype case, obviously plastic with a honeycomb of air inside is a good choice for insulation, with some strategically placed foam above the body of the heatsink.

The final design will need to include a t-thread to attach and adaptor and perhaps a storage space for a silca gel sachet.

Why bother with a tiny webcam sized chip? Well I have a filter wheel and RGB filters (as well as some specialist ones for planetary imaging) but a large-chip mono camera is expensive, especially if cooled. It's also a lot more involved to do mono imaging so this will let me see how I get on with it without having to make a big investment, although I will be limited to small targets.

If all goes well I can contemplate bigger investment... or just specialise in imaging tiny but challenging subjects!

Joseph Noci 101/09/2019 15:07:16
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Won't the fan vibration blur the image a little, esp during long exposures?

Robert Atkinson 201/09/2019 15:53:45
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Joseph akes a good point about fan vibration.. Another issue is the high energy density and thermal gradient of small peltiers. Have you considered liquid cooling? just small pump and tank would be enough, you probably don't even need a heat exchanger if the tank has reasonable capacity and surface area.

Robert G8RPI.

duncan webster01/09/2019 16:13:45
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Do you need a pump? Thermo-syphon might work, then no vibration

Neil Wyatt07/09/2019 19:10:07
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Posted by Joseph Noci 1 on 01/09/2019 15:07:16:

Won't the fan vibration blur the image a little, esp during long exposures?

 

A question many have asked. No-one has ever been able to demonstrate a measurable effect. Does make sense to use sleeve bearing fans though, which have negligible vibration.

Edited By Neil Wyatt on 07/09/2019 19:12:54

Neil Wyatt07/09/2019 19:11:42
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Posted by Robert Atkinson 2 on 01/09/2019 15:53:45:

Joseph akes a good point about fan vibration.. Another issue is the high energy density and thermal gradient of small peltiers. Have you considered liquid cooling? just small pump and tank would be enough, you probably don't even need a heat exchanger if the tank has reasonable capacity and surface area.

Robert G8RPI.

It's been thought of, but it would probably need to be a water glycol mix, working well below zero.

Simplicity and reliability are prime considerations, though.

Neil Wyatt07/09/2019 19:21:46
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Current iteration. Designed to have a Canon ET to T-thread adaptor glued in the end to give the same back-focus distance as a DSLR so it can be swapped across without re-focusing and used with field flattener/coma corrector (although these are probably uneccessary with such a small chip it makes things easier = more reliable).

camera.jpg

I did a little test of the camera on the 'Pillars of Creation', uncooled and the sensor was more than a bit grubby after my experiments, plus not a lot of integration time (software problems left me living with mostly 7.5 second exposures).

So probably not the best ever:

To compare, this is with my modded DSLR and I'd class this as a 'record' image. Note the smaller image scale with bigger pixels:

The scruffy image shows a lot more detail, so it's worth pursuing this.

Edited By Neil Wyatt on 07/09/2019 19:23:45

Neil Wyatt21/09/2019 21:48:35
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Some photos (linked from an astro site - SGL - because it's easier!) to show construction of the camera combining machine parts, 3D printed bits and off the shelf components.

Finished cam, photo a bit shaky!

Inside the boxes:

Heatsink ready to fit:

Most bits of the original camera:

10 minute 'dark' exposure at 25C (i.e. with the camera covered) and no cooling:

10 minute dark exposure after having the cooling switched on for a few minutes:

I think it's easy to see how this will help with imaging faint objects!

Neil

Michael Gilligan21/09/2019 22:39:39
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Posted by Neil Wyatt on 21/09/2019 21:48:35:

[ ... ]

10 minute 'dark' exposure at 25C (i.e. with the camera covered) and no cooling:

10 minute dark exposure after having the cooling switched on for a few minutes:

I think it's easy to see how this will help with imaging faint objects!

Neil

.

That's certainly encouraging, Neil

MichaelG.

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