taking darks

[Daniel-K]

ok i know your suppose to take darks at the same settings as your light frames but what would happen if i done 90 sec light frames with 30 sec darks??

[ScubaMike]

I'm not knowledgeable, But I would assume that you wouldn't capture the same amount of sensor noise with 30 second darks as 90 second darks.

Please correct me if I'm wrong, as I like to try to paraphrase what I try to learn - it helps me understand things.

[Bizibilder]

Darks need to be the same exposure time as your light frames and should also be (more or less) at the same temperature. If you have 90sec lights don't worry! Just run off some (at least 24 or so) darks by setting your camera somewhere at the right temperature (I often take darks in the garage and save them for when I need them).

Just put the lens cap on and click away!

[Daniel-K]

but what if the dark exposures time = the same time of the lights?

last night i managed to take 21 subs at 90 secs but i only done 30 sec darks is this why my picture is noisy?

[Bizibilder]

As ScubaMike said a 30 sec dark is not the same as a 90 sec dark. You must use darks that are the same exposure time as your lights.

You need to take some 90sec darks. Don't delete the 30sec darks - just file them until you need them.

You don't say what your target was so I cannot comment on the "noise" you refer to.

[Daniel-K]

it was the north american nebula i have detail there but when i procss it i cant get much out of it i think its the noise tbh

[Bizibilder]

Yes - You only have 30mins of data. I recently ran around 2hours with an unmodded DSLR through an ED80PRO and there was still quite a bit of noise there (or rather not very much signal ).

[todd8137]

deep sky staker will tell you that are do not match give it a go "the computer says no"

i did the same last night took 60 pics 0f M13 got back in the house on the camera screen on the 10d they looked mega got them on the pc with 30 darks and 30 flats and bias with light box ect tried to stack no joy at all got the star count at 15 gave me about 40 stars (with meri filter box ticked no joy) what a pain biut will save all took the tempreture out side filed them andfor later what a pain

[Daniel-K]

mines modded piggy backed but my adapter is coming tomorrow so will be taking subs through the WO66 after that. could i see your picture ?

[Bizibilder]

Take a look here:

http://stargazerslounge.com/imaging-deep-sky/144488-north-american-pelican-nebulae.html

For a 2 pane mosaic each of two hours of 2min subs.

[OzDave]

What you could do is take some bias frames and produce a master stacked bias. Use that to subtract from your 30 second darks. Then stack your bias-subtracted darks. Finally, multiply the stacked dark by 3 and you'll have something usable on your light frames. I.e a 90 second dark.

If you go this route, you'll need software that can perform these image manipulations. I know that nebulosity can do it, but not sure of other software.

You'll need to use both your stacked bias and stacked/scaled dark on the light frames.

It wont be perfect but might be a lot better than alternatives.

David

Sent from my iPhone using Tapatalk

[Daniel-K]

thnaks oz but might just taked some 90 secs darks insted lol im rather new too ap