Gary Honis
Vendor-DSLR Mods
Reged: 12/15/04
Posts: 220
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The fogging problem has been fixed. Got out last weekend and cooled the camera down to 5 degrees Fahrenheit for both nights. Took six-minute exposures at ISO 1600 and imaged the Horsehead, Heart, NGC253, 7331 & Double Cluster. Images posted here:
http://www.ghonis2.ho8.com/100308modXSi.html
The dark frames at six minutes were velvet black. Here are some image pixels standard deviation figures of dark frames to give an idea of how cooling improves noise:
Temp_________Exposure____Standard
Fahrenheit___Length______Deviation
77___________5 min_______2602
50___________5 min_______2114
34___________5 min_______1080
05___________6 min_______ 146
To avoid fogging of the front lens of the focal reducer, I used an eyepiece heating strip wrapped around the reducer.
Gary
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Gary Honis
DSLR Modification Service
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Nils_Lars
Post Laureate
Reged: 01/04/08
Posts: 3385
Loc: Santa Cruz Mountains , CA
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Beutiful shot , looks like you have it all dialed in.
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Erik
Orion Atlas Self Hypertuned (EQMOD)
Orion ED 80
Williams Optics VII reducer
Celestron 8" SCT
Orion Starshoot Autoguider
PHD guide
Canon 400D Hap Griffin Mod w/Baader filter
Astronomik clip-in LP filter and 12nm Ha
Stilleto CVF and Bahtinov mask
Tamron 75-300mm&28-80mm lenses
NexImage webcam
http://www.flickr.com/photos/31986095@N05/
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walt r
Post Laureate
Reged: 02/13/07
Posts: 3458
Loc: Doylestown, PA
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Very nice image and great news on dialing in the system. The noise numbers are impressive.
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Walt
Obsession 18" f/4.45 #1370 AN/SC
MK67 Deluxe 6" f/12 Mak-Cass, Super Polaris GEM, JMI MicroMax DSC
DIY 60mm f/6 Achromat
Cookbook 245 CCD
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kingjamez
scholastic sledgehammer
Reged: 10/03/06
Posts: 991
Loc: Washington D.C.
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Gary, are you still on V3 of your cooler? It's getting you all the way down to 5 degrees? Those are some fantastic results!
-Jim
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C8 on Atlas with EQMOD
ETX125 UHTC
Celestron Onyx 80mm
Meade Walmart 60mm guide scope
Canon Xsi Modified w/IDAS LPR
Gen 3 NightVision Eyepiece
Aspiring Optician
Watch my Wiimote control Atlas:
http://www.youtube.com/watch?v=PnmkygmGNiM
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Gary Honis
Vendor-DSLR Mods
Reged: 12/15/04
Posts: 220
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Hi Jim,
Yes, still using Version 3 of the cooler. I can't make it any smaller; it fits the camera like a glove. The reason it was keeping the camera at 5 degrees Fahrenheit last weekend was because the ambient temperature was in the 30's. I actually got less of a temperature drop than usual (up to a 44 degree drop) because I was using a heater to keep the front lens of the reducer free from fogging. So, there was more heat in the camera system for the cooler to dissipate. The heater strip is one I made for my binoviewer from nichrome wire and I'm sure it is putting out more heat than needed when being run flat out without a controller. I'll have to make one for the reducer or buy an eyepiece heater strip and use a controller.
Gary
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Gary Honis
DSLR Modification Service
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cvedeler
Carpal Tunnel
Reged: 12/20/05
Posts: 2155
Loc: Scottsdale, AZ
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Nice image Gary!
Do you find it worthwhile to cool the camera that much? I've been taking darks with my Canon 350 now that we are in a cold snap here in Phoenix (lows in the high 50's!) and find the camera MUCH MUCH more well behaved than when it is in the 90's and 100's where it is essentially useless. I'm so impressed with my darks at 60 degrees I wonder about the advantage of cooling the camera down to 5.
I would also be concerned about the health of the camera operating at those low temperatures. How about battery life or do you use an external power adapter?
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Chris Vedeler
Astro-Physics 160EDF
Astro-Physics 900GTO
Q453HR / QHY8 CCD camera
Canon 450XSi
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www.aznightsky.com
Scottsdale, AZ
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Gary Honis
Vendor-DSLR Mods
Reged: 12/15/04
Posts: 220
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Hi Chris,
Good points. Once the camera is below 50 degrees Fahrenheit I have found in general that noise is very low for moderate length exposures. Normally, at ambient temperatures near freezing I didn't think I would use the cooler; but I had it.....so I used it. Also, I just picked up an Ha filter and plan on taking exposures of 10 minutes or longer.
DSLR camera makers usually list an operating range beginning at 32 degrees F, but I have used my DSLRs during winter here in the Northeast many times to near 0 degrees F without problems. When handheld, you can swap the battery with a warm one from your pocket. At the scope I use the canon power supply for the 450D. Since the camera is in a sealed chamber, moisture is not a problem for the camera since it is in a dry environment and after the imaging session I keep the camera in the sealed container. I use desiccant and a desiccant indicator card that would change color if mositure is detected, but that hasn't happened so far.
Gary
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Gary Honis
DSLR Modification Service
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walt r
Post Laureate
Reged: 02/13/07
Posts: 3458
Loc: Doylestown, PA
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Even with winter temperatures there is the advantage of the "cooler" in that one can maintain the camera temperature at a set point. This helps ensure the Dark frames match the Flats and Lights for good correction. Makes processing easier and results in a better final image.
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Walt
Obsession 18" f/4.45 #1370 AN/SC
MK67 Deluxe 6" f/12 Mak-Cass, Super Polaris GEM, JMI MicroMax DSC
DIY 60mm f/6 Achromat
Cookbook 245 CCD
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Gary Honis
Vendor-DSLR Mods
Reged: 12/15/04
Posts: 220
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With cold winter temperatures having settled in here in the Northeast, the peltier DSLR cooler can take the 450D below 0 degrees Fahrenheit. Don't really need to go that low for noise reduction and I have some fear of operating the camera that cold for extended periods. So, I bought a variable power supply ($30) for controlling temperature of the cooler and posted some notes here:
http://www.ghonis2.ho8.com/rebelmod450d16g.html
Gary Honis
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Gary Honis
DSLR Modification Service
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cvedeler
Carpal Tunnel
Reged: 12/20/05
Posts: 2155
Loc: Scottsdale, AZ
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Very cool Gary! 
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Chris Vedeler
Astro-Physics 160EDF
Astro-Physics 900GTO
Q453HR / QHY8 CCD camera
Canon 450XSi
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www.aznightsky.com
Scottsdale, AZ
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Gary Honis
Vendor-DSLR Mods
Reged: 12/15/04
Posts: 220
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Chris,
I was thinking maybe you wanted to try this power supply to see if you could get more cool out of your working DSLR cooler. The 15 volt setting is very tempting, but since you already burned up one peltier, I can understand the fear. 
Gary
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Gary Honis
DSLR Modification Service
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cvedeler
Carpal Tunnel
Reged: 12/20/05
Posts: 2155
Loc: Scottsdale, AZ
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Actually Gary I'm going to try a different approach entirely. I'm going to design the insulation around the box to allow me to place dry ice behind the copper box. I'm thinking that since I really don't need to cool the camera to -100F I will put a thin layer of insulation between the dry ice and the copper box to slow the cooling down. This will also prolong the life of the dry ice. According to my early web research I may be able to go 8 hours with a single 1" to 2" packing of dry ice. This will eliminate the need for an extra bulky battery in the field, as well as one less wire to the camera.
I'll run tests as to how much cooling I get with how much ice for how long to test the feasibility of the idea. It may be a pipe dream, but it won't cost much to test it out at this point.
My fears at this point are cooling the camera to much to fast and actually damaging it. I'll probably place a block of wood inside the box with my initial testing to see how well it performs with that before subjecting my camera to a test.
I'm thinking ahead to my 100F nights next summer. If I can design a system that can drop the camera temps to below 20 - 30F under those conditions I'll be quite happy. I don't think a standard peltier cooler is up to such a task.
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Chris Vedeler
Astro-Physics 160EDF
Astro-Physics 900GTO
Q453HR / QHY8 CCD camera
Canon 450XSi
----------------------------
www.aznightsky.com
Scottsdale, AZ
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cvedeler
Carpal Tunnel
Reged: 12/20/05
Posts: 2155
Loc: Scottsdale, AZ
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Here is some of my thinking regarding using dry ice.
It costs about $2 a pound so is quite cheap and is readily available.
A 1 inch by 6 inch by 4 inch area of dry ice (the area I'm planing on making behind the box) weighs 1.3lbs and contains 331 BTU of cold.
A 45 watt Peltier cooler is at best 10% efficient meaning it could generate only 15 BTU of cold per hour.
If the dry ice lasts 8 hours before it has sublimated that is 41 BTU per hour or almost 3x the cooling power of a 45 watt Peltier. Higher power Peltier's require a much more robust cooling system as I discovered with my 138 watt cooler making them impractical for this application.
Dry ice will probably weigh more than a Peltier and heat sink but it will not require any additional wiring to the box or a robust battery to run it all night.
Of course this is all theoretical at this point. I hope to modify my box in the next few days and run some tests with dry ice to see how feasible this idea is in real life.
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Chris Vedeler
Astro-Physics 160EDF
Astro-Physics 900GTO
Q453HR / QHY8 CCD camera
Canon 450XSi
----------------------------
www.aznightsky.com
Scottsdale, AZ
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cvedeler
Carpal Tunnel
Reged: 12/20/05
Posts: 2155
Loc: Scottsdale, AZ
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Dry ice is some powerful stuff! I haven't modified my box yet but decided to just put a 2" x 3" chunk of it in the box and put my thermometer probe hanging in the air. It went from 73F to -34F in less than 8 minutes! My box was crackly and popping along the way.
So we know it is cold, but can it last? I hope to modify my box for a real test tonight.
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Chris Vedeler
Astro-Physics 160EDF
Astro-Physics 900GTO
Q453HR / QHY8 CCD camera
Canon 450XSi
----------------------------
www.aznightsky.com
Scottsdale, AZ
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Kentari
scholastic sledgehammer
Reged: 11/19/06
Posts: 794
Loc: Belgium
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Make sure not to make it airtight or that box is going to pop real hard!
Cool experiment though... I look forward to the result.
I'm pondering the purchase of a second 40D to mod and freeze  ... The are becoming interesting on the used market.
Koen
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Darkstar 355 f/5 Dobsonian
Orion UK 8" f/4.5 Newtonian and WO ZS 80 FD on Losmandy GM8
Canon 20D DIY mod with Baader filter
A bunch of lenses: 10-22mm f/3.5-4.5, 17-40mm f/4, 50mm f/1.4, 70-200mm f/2.8, 300mm f/2.8
www.koenvangorp.be
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cvedeler
Carpal Tunnel
Reged: 12/20/05
Posts: 2155
Loc: Scottsdale, AZ
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Yea Koen I've watched those Youtube videos where kids explode pop bottles using dry ice and water. Air tight = bad. However I need to keep it sort of tight so it will cool the camera slowly and evenly and stay as cold as possible as long as possible. I figure with my engineering aptitude, if I try and make it air tight it will be just leaky enough...  
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Chris Vedeler
Astro-Physics 160EDF
Astro-Physics 900GTO
Q453HR / QHY8 CCD camera
Canon 450XSi
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www.aznightsky.com
Scottsdale, AZ
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Strgazr27
Vendor - Deep Space Mods and Composites
Reged: 10/04/04
Posts: 6984
Loc: StonyHill Observatory
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Chris,
Although that is some wicked cooling your treading on "Dry Ice" so to speak. There is no regulation, no safety net and man have you ever grabbed a pice of dry ice without gloves on Lol. My biggest fear is cooling the components way faster than they can handle.
Good luck with your tests....I see a QHY8 in your future Lol.
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Bobby
StonyHill Observatory
Skywatcher EQ6 Pro (On it's way)
AT 130 F/6 Prototype
Royce 10" f/4 Astrograph (Under Construction)
Self Modded 40D
70-200 F2.8 L IS
SSAG
YAHOO TMB 130SS Group
Astronomy Technologies Yahoo Group
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walt r
Post Laureate
Reged: 02/13/07
Posts: 3458
Loc: Doylestown, PA
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Interesting idea. As posted above I too would be concerned about cooling too low and too fast. Maybe have the dry ice in contact with the back (component) side of a heat sink with the fins in the camera compartment. A fan on the fins could circulate the camera compartment air to cool the camera. Like the TE cooling except with the dry ice on the cold side.
Any thoughts anyone?
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Walt
Obsession 18" f/4.45 #1370 AN/SC
MK67 Deluxe 6" f/12 Mak-Cass, Super Polaris GEM, JMI MicroMax DSC
DIY 60mm f/6 Achromat
Cookbook 245 CCD
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cvedeler
Carpal Tunnel
Reged: 12/20/05
Posts: 2155
Loc: Scottsdale, AZ
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Thanks Bobby. I had no intention of putting dry ice in the camera compartment because I think you are right that it would be too much cold too fast for the camera to handle. Plastic would likely crack and the camera could very easily be damaged. The dry ice would also disappear far to fast to be useful for several hours of astrophotography per target. My plan is to have a separate insulated compartment behind the copper box to slowly leak the cold to the camera. I will try different amounts of insulation (something between paper to 5mm of foam) between the copper box and the dry ice until I can maintain perhaps a 50F difference between ambient for as long as possible. This will also prolong the life of the dry ice making it more feasible in that regard too. I also plan on using an internal fan just like Gary's to help circulate the cold within the box just like you suggested Walt. In practice I'm just modifying the source of cold and not the application that Gary has proven with his great project.
My test this afternoon was just to see for myself what kind of cold power I was dealing with. Now I have to figure out a way to tame it.
I'll hopefully get it all put together in the next day or so (perhaps tonight) and post pictures and results here.
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Chris Vedeler
Astro-Physics 160EDF
Astro-Physics 900GTO
Q453HR / QHY8 CCD camera
Canon 450XSi
----------------------------
www.aznightsky.com
Scottsdale, AZ
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Freddy WILLEMS
Carpal Tunnel
Reged: 11/13/05
Posts: 2546
Loc: Hawaii, Honolulu
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I'm working on one to, will post images soon.
Freddy
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Freddy
Meade 14" LX200 GPS UHTC GPS on permanent pier
Celestron C 14" Peltier cooled for planetary imaging.
Meade 10" LX200 & TITAN 50:1 mount Gemini 'go to'
Meade 127 mm f/9 APO & TITAN 50:1 mount Gemini 'go to'
W/O 102 mm f/7 APO doublet
Orion 80 mm f/7 ED
DFK 21AU04.AS
ToUcam 840 II pro
Canon 10D Unmoddified
Canon 40D Hutech moddified
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