Darks from the Fridge?

[KenMiller]

I am currently (for just two more weeks - right Brian?) limited to imaging with a DSLR.

I'm trying to come up with a way to keep shooting darks from cutting into my imaging time.

From what I've read, it appears that darks that are within five degrees F from the temperature the lights are shot are good enough.

I was thinking that it might make sense for me to shoot nothing but lights during my session and then put the camera in the refrigerator and shoot whatever darks are necessary at whatever temperatures.

Since my outside ambient this time of year is between 45F and 65F I should be able to get the correct temp in the fridge with no problem.

Since it's not uncommon for the temperature to drop during the night from 65F to 45F this technique would have the added advantage of being able to provide me with ample darks at any and all temperatures I desire.

Does anyone have an idea of the rate at which dark noise changes over time in a typical DSLR?

I'm thinking I could create a library of darks and just reuse them but understand that the dark noise in a sensor changes over time.

[Gary Beal]

Sounds like a plan Ken, and given the actual length of a two week period, it may be beneficial, LOL.
I have just started back into using the Canon 20D (non-modified), and with the lack of auto-guiding been using shorter exposures, of about 180 secdonds.
With that in mind, I have simply shot my darks as I unpack the gear, as even 5 darks at 3 minutes each is only 15 minutes, and I normally have a couple of scopes to pack away.
Try it, and see perhaps. Shoot some at varying temps, but obviously at the temps you envisage imaging at. Grab a light and try the varying darks, and see if you can discern any real difference. I for one would be very keen to see/hear what you find.
Gary

[KenMiller]

I have been doing something similar in that I set up the computer and camera first and then shoot darks while setting up the rest of the gear and doing polar alignment.

When done, I shoot another set of darks while I'm taking everything down. I usually get plenty of darks while setting up because good polar alignment takes a while even with TPoint but when taking down I usually have to leave the camera outside for a while and go back later and bring it and the computer in.

But in addition, because the temp typically drops 20F from start to finish I shoot a set of darks in the middle and that cuts into my imaging time.

Based on what I've read, the darks should be within 5F of the lights. I have no way to do that currently.

I'm thinking a fridge would solve that problem.

[Gary Beal]

Sounds like you have to at least try this Ken, even for others sake. The only snag I can see is that the temperature isn't recorded by the DSLR, like it is with the "real" CCD's. Good to see what gives though.
Gary

[budguinn]

My only question: How long is two weeks?

[KenMiller]

Originally Posted by budguinn

My only question: How long is two weeks?

I ordered an STL11000 in November and was quoted a 2 week delivery time. When I checked 15 days later I was told it would be 2 more weeks. After another 15 days I was told it was on the way but when I checked back a week later... you guessed it - two weeks.

Today marks 16 weeks. I asked again last week. Two weeks.

[KenMiller]

Originally Posted by Gary Beal

Sounds like you have to at least try this Ken, even for others sake. The only snag I can see is that the temperature isn't recorded by the DSLR, like it is with the "real" CCD's. Good to see what gives though.
Gary

I have a USB memory stick size stand-alone recording thermometer that I can use to record the temperature.

I wonder which manufacturer's refrigerators offer the narrowest temperature control?

The biggest question I have though is how frequently I'd need to repeat the process - i.e. how quickly does the dark noise change in a DSLR?

[Gary Beal]

Originally Posted by KenMiller

I wonder which manufacturer's refrigerators offer the narrowest temperature control?

Cripes, if you have to go out and buy a fridge just for this, why not just buy a cooled camera, maybe one of those STL11000's LOL.
Still keen to see what you can achieve.
No idea of the "shelf life" of the dark, and as I said, I am convinced the easiest way is to simply shoot them every time I image.
Gary

[budguinn]

Well gosh, as to darks I have a whole library of them and I............Oh, wait a minute....I have SX cameras and they don't require darks. Never mind.

[KenMiller]

Let me see if I have any more wounds you can grind some salt into

Bud, any comments on my last post here? I took your recommendation and gathered more data but it looks like it was to no avail.

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