dark and bias frames help needed

[LeeWilky]

Hi all as the title states im looking for a little advice on dark and bias frames.

My problem is i only have one battery at the moment for my DSLR and this limits me to about an hour and half exposure time.

My question is where i to shoot all light frames until the battery dies then drive home and recharge the battery whilst leaving the camera in my car to stay cold then pop out and shoot my dark and bias frames say about an hour or 2 after my lights is this ok?

Also would i need to connect the dslr back to my scope or could i just shoot them with just the camera body with the protective cover over where the lenses go?

thanks for any help as im struggling to find a straight answer on Google.

[Leveye]

The dark frames should always be taken directly afterwards. The ambient  temperature of the camera might not be the same as when the lights were taken but i have gotten away with what you're doing. Sooner or later you'll want that extra battery though just saying. They also make a cigarette adaptor style for most Nikon dslr cams now. A nice gell cell 18 Mah battery is about 35 dollars. that'll last you all week.

[Zuben Elgenubi]

Easiest solution is probably to buy another battery. I bought a cheap (less than £10) one for my 1100D from eBay. Only used it a couple of times so far but it seems to last about as long as the genuine Canon one. It may not last as long in the longer term, but for the cost I'm not too worried.

[LeeWilky]

Cheers guys yep a new battery is on the list but pretty skint until next month and tonight is looking good so i was looking for a temporary fix just for the next few weeks until i get paid.

Cant go wasting a clear sky they are very rare these days lol!

[ollypenrice]

There's no problem at all with using library darks made at another time. They just need to be as closely temperature matched as possible, so note the temperature at which they're made and build up a bit of a range then use the most appropriate. You can make them in a fridge or on a cloudy night. The thing about DSLR darks is that they are hardly ever going to be a perfect match because the temperature changes during the night and the chip temperature rises during the sub. For this reason I can't see any real virtue in doing them at, say, the end of a session. Surely you could get just as good a match, or possibly better, from a library dark.

Olly

[LeeWilky]

There's no problem at all with using library darks made at another time. They just need to be as closely temperature matched as possible, so note the temperature at which they're made and build up a bit of a range then use the most appropriate. You can make them in a fridge or on a cloudy night. The thing about DSLR darks is that they are hardly ever going to be a perfect match because the temperature changes during the night and the chip temperature rises during the sub. For this reason I can't see any real virtue in doing them at, say, the end of a session. Surely you could get just as good a match, or possibly better, from a library dark.

Olly

Thats great thanks mate

The temp is going to be a steady 4 degrees all night tonight so ill just use all the battery up on whatever im going to shoot (still undecided) and then make my darks and bias later.

The Moon isnt going to rise until after midnight tonight and the forecast say mostly clear and clear skies until then so with any luck ill get better results thn my poor M81-M82 shot from last week.

[ChrisLX200]

If you get a power adapter to use an external battery you'll remove a source of heat in the process - the battery itself gets warm and trasmits that to the camera body. One of the better accessories to buy, and saves changing batteries too.

ChrisH