Darks and Bias How Many

[cp255]

So I am just wondering how many darks do your guys take. Do you have a fixed number or do you decided based on how many lights? Also is there any point in using Bias frames with a DSLR if the bias is contained in the darks?

[Gina]

When I was using a DSLR I usually took around 35 darks - I set up APT to take the darks automatically after an imaging session and then went to bed.

[RikM]

I used 20-30 darks when using a DSLR. I also shot bias frames (about 80 of those because you can reuse them). The separate bias frames are needed to properly calibrate the flats when using DeepSkyStacker. If you are not using flats (and you should be!) you will need separate bias frames.

The number of calibration frames you use is not dependent on your number of light frames in any way. You want enough calibration frames that they don't add significant noise to your image.

[cp255]

I also shoot usually 50 flats and 50 dark flats. I figured the darks flats would contain the bias signal as well.

[RikM]

I also shoot usually 50 flats and 50 dark flats. I figured the darks flats would contain the bias signal as well.

dark flats do contain the bias signal, yes. In practice, flats are usually of such short exposure that a straight bias frame will do the same job. You probably don't need both bias and dark flats.

[cardconvict]

i agree i never use dark flats, but i use 50 or more dark files. as i have some software that works with deep sky stacker, it is called dark,s library and i collect all the dark,s so i could use them again. This software match,s the exposure times and temperatures of the lights and finds the dark,s from the library to match with the lights to be stacked.

[nephilim]

i agree i never use dark flats, but i use 50 or more dark files. as i have some software that works with deep sky stacker, it is called dark,s library and i collect all the dark,s so i could use them again. This software match,s the exposure times and temperatures of the lights and finds the dark,s from the library to match with the lights to be stacked.

Hi, do you have a link to this software as it sounds like it will save a heck of a lot of time.

Steve

[cardconvict]

i will pm you link

[M00NMonkey]

I may have confused myself doing my own research on here, there and everywhere, but I was beginning to get the impression that everything in the optical train had to be exactly the same as when the light frames were taken, when it comes to taking the darks flats and bias, including the orientation of the camera. This makes sense to me, as the noise will be located in the correct position for the light frames. Surely this software wont know of of this details?

Forgive me if I have this totally wrong, Im still new

Jez

[cardconvict]

the flats have to be the same as the lights in orientation, but not the darks or bias. when i make darks i could leave the camera outside all night with just the cap on taking darks.

[nephilim]

i will pm you link

Great link thanks, the cooler for the Canon 350D looks good & as i've just bought a 2nd hand 350 it'll be something to think about when I'm a little more confident with it's workings.

[cardconvict]

Great link thanks, the cooler for the Canon 350D looks good & as i've just bought a 2nd hand 350 it'll be something to think about when I'm a little more confident with it's workings.

Yeah i think it is a good idea to do. i did mod my canon 500d myself with taking the filters out but i do not think i could go any further than that.

[M00NMonkey]

the flats have to be the same as the lights in orientation, but not the darks or bias. when i make darks i could leave the camera outside all night with just the cap on taking darks.

Thanks for clearing that up for me Cardconvict.

Any chance of a PM'd link to that software too please, good sir?

[nephilim]

Yeah i think it is a good idea to do. i did mod my canon 500d myself with taking the filters out but i do not think i could go any further than that.

I know what you mean, I'd have to do a lot of research before even thinking of doing filter/cooler etc as i'm not experienced with anything like that. For now I'll just be using it the way it is until I start getting to know my way around it etc.

Steve

[cardconvict]

if you wanted to have a look at modding your 350d with filter replacement just google gary honis i believe, he has a good site and instructions on modding cameras

[nephilim]

Thanks, I'll have a look at that as i've heard his named mentioned quite a few times around the forum.

[kirkster501]

Gee whiz, 50 x 5 min darks? How to do that when you have to break down every night?

Sent from my iPhone using Tapatalk

[RikM]

You don't need a clear sky to shoot darks

[kirkster501]

You don't need a clear sky to shoot darks

You know, I never thought of it like that....... Yes indeed. So could create a library almost of dark frames at differing temps and exposure lengths? Would be a PITA doing them all though but once done..... 99% of time I use ISO 800 at 300secs. So just fire a load of them off at say 0,4,8,12,16C and a-ok? what do you think?

[RikM]

That's what I did.

I actually shot one set by sticking the camera in the fridge Worked a treat though