Darks Flats ect question

[DSOBug]

Ive seen several people using Dark Filters to take Dark's with instead of using the scope cover any comments on this? it seems it would be easier to just run a process to rotate filter wheel and take dark's with a dark filter during your routine.

[ollypenrice]

15 minutes ago, DSOBug said:

Ive seen several people using Dark Filters to take Dark's with instead of using the scope cover any comments on this? it seems it would be easier to just run a process to rotate filter wheel and take dark's with a dark filter during your routine.

Seems very odd to me. Are you sure? You really do need to exclude all light when taking darks.  I compared darks done on the scope with the lens cap on with darks done with the camera off the scope and its metal scew-fit cover in place. The ones done off the scope were different and had slightly lower ADU values. I can imagine an opaque filter plus a lens cap being useful but some scopes, notably Newts, often leak light from beneath the mirror. Off axis guiders can also let light in.

Olly

[DSOBug]

When you take dark's should you take them at the same temp and environment conditions as your Light shots are taken?

[ONIKKINEN]

7 minutes ago, DSOBug said:

When you take dark's should you take them at the same temp and environment conditions as your Light shots are taken?

Darks need matching temperature, gain, offset, and exposure length. They do not need to be taken in-situ with the telescope and can be reused many times. In fact its better to take them indoors, such as in the fridge to make sure they are taken in perfect darkness. If you meant a DSLR or an uncooled camera its more complicated.

[vlaiv]

Dark filters are useful for remote setups and setups used by different people with different requirements for light exposures.

Instead of creating every dark imaginable or set of darks and limiting exposure lengths to only generated dark exposures - one can use dark filters in their filter wheel.

That way anyone using the remote telescope can take matching darks to their particular exposure (and other settings).

However, in amateur conditions - it is much more sensible to do darks with camera off the scope - in basement or other dark room while it is cloudy outside. That lets you take large number of darks (to minimize noise impact).

[Elp]

I use a dark filter with my HS setup when imaging with uncooled cameras but also make sure to cover the end of the dew shield. The preferred method is to take the camera off with the end covered and face down but if I'm going to leave it setup the dark filter is the method I use. With refractors or camera lenses I just cover the objectives.

Edited November 20, 2023 by Elp