Register now to gain access to all of our features. Once registered and logged in, you will be able to contribute to this site by submitting your own content or replying to existing content. You'll be able to customise your profile, receive reputation points as a reward for submitting content, while also communicating with other members via your own private inbox, plus much more! This message will be removed once you have signed in.
Recently Browsing 0 members
No registered users viewing this page.
As I haven't had any sessions for a while I needed something to do with my astronomy before I forgot what it was all about. So, (don't you hate it when people start a sentence with "So"!) having read an article in Astronomy Now about building a Peltier controlled coolbox for a DSLR camera I thought I would give it a go. My main reason for doing this is that I am not too keen on taking my DSLR apart to do the more radical Peltier cooling that some members have done. Yes Gina, I'm looking at you!
My coolbox is slightly upgraded from the one in the article as I have put a copper ribbon cold finger from the Peltier exchange heatsink to around the DSLR body (bottom and back).
The Peltier cooler was purchased off of the internet and came all the way from China in a plastic bag with a bit of bubblewrap around it so needless to say it was damaged when I received it, but nothing I couldn't fix and I wasn't going to send it back for only £8.
The insulation was from an old camping mat that I bought some time ago to make a dew shield from but was too floppy! The box was one of those food storage boxes that locks twice and the copper was 'rescued' from the scrap bin at work!
The power to the DSLR is via the battery hack that can be found in this forum.
After completion I ran a test indoors and recorded the results via APT which give a cmos temperature reading from the RAW file. Room temperature was a steady 23.5 deg C throughout the test. I set up APT to take 100 frames with a 60 second gap between each frame. The first few readings were at 24 deg C, by the time the test ended APT was reporting a cmos temperature of 13 deg C. That's an 11 deg C drop in temperature over the course of the test and a 10.5 degree drop over ambient temperature.
All I need now is a clear night to test it out in the real world.
I thought I would share with you last summer's project to add set-point cooling to my DSLR. It took about 3 months and wasn't actually required much over the cold winter months. I've made a few minor changes since the winter. The original white-on-blue display packed up so I replaced it with this black-on-green one. And the original ball-bearing fan introduced vibration when using my SCT (not apparent on my other scopes), so I've replaced it with a MagLev/vapo type. Unfortunately I haven't had any clear skies to test the new fan...
My main design criteria were:
Cold-finger/peltier cooling As little 'destruction/deconstruction' of the camera as possible - I wanted it to still look like a DSLR Achieve 5-10 C set-point cooling, as I felt this gave acceptable low noise Include a dew heater/indicator for the front filter Arduino controlled with display to provide useful feedback on settings and simple controls I give due credit to Gina and Rowland Cheshire, having read their many inspirational posts on cooling (both here and on Ice in space) which helped me to hone my design.
Image with the camera shows fan-heatsink-peltier-bracket construction. The connection box is screwed to the tripod mounting. The white sensor measures ambient temperature and RH. The controller images show approaching the set-point and at set-point. A red LED above the main display lights up when the dew heater is active. The display shows:
Set = desired set-point temperature CMOS = temperature of cold-finger close to sensor Fltr = temperature of front filter Dew = number of degrees above the dew point to maintain the dew heater TEC = heatsink temperature (hot side of peltier) PWM = percentage output sent to the peltier (I've limited it to 90% max) Am = ambient temperature, DP= dew point, RH = relative humidity At some point I will tidy the heatsink side to conceal the cables, etc.
Had another look at my files and I seem to have got a bit more detail out. Thank you everyone for your advice.
Mars, Saturn and Jupiter. Taken using QHY5L-II colour planetary camera and 8SE, using a Celestron X-Cel LX 2 x barlow. All AVIs stacked in RegiStax6 and processed in PS Elements 11 (composite image)
Stacked and processed image of The Sun and AR2542 (formerly known as AR2529) taken this afternoon using William Optics FLT-110 refractor, 1.25" Lunt Herschel Wedge, Celestron X-Cel LX 2 x barlow and QHY5-L-II monochrome planetary camera.
800 frame AVI processed through RegiStax6 to stack and select best 25% of frames and then wavelets added.
It was good to see what was left of fabulous sunspot AR2529 which I previously imaged on 17th April prior to it's journey around the farside of the sun.