A "shutter" for imaging Dark Frames?

[Macavity]

Just to establish a basic premise: I have always assumed that to obtain a "dark

frame", it's only necessary to block light at *some* part of the optical path???

Right now, my nice warm (remote controlled) evenings of VIDEO astronomy are

interrupted by a quick dash outside to place a lens cap on my Newt (Exposures

are measured in minutes, rather than hours!). I'm not really THAT lazy... Simply

I fire the dreaded neigbour's "security" lights whenever I open my back door!

I imagine remote *classical* imagers use an extra opaque filter in a USB wheel?

But I'm "too tight" (don't need) one of those. lol. And maybe something simpler?

A kind of "shutter" device? Too much to hope for something commercial? Unless

you know different! Perhaps something "DIY" - Bit like a flip mirror might work?

[D4N]

Would it be simpler to get a thermometer to temperature match the dark frames and build a darks library?

I was thinking you could set up a flip mirror for remote activation but that would probably cost as much as a filter wheel.

TSED70Q, iOptron Smart EQ pro, ASI-120MM, Finepix S5 pro.

[ollypenrice]

Yes, the darks library would be my solution as well. Keeping light out of dark frames is harder than one might think, too. And doing so is vital.

Olly

[Gina]

Oooohhh how I love not needing darks with my Atik 460EX and 314L+ cameras   <smirk>  Sorry folks for those with noisier cameras - no put-down intended   I shall need darks when I get back to my debayered DSLR project   But yes - a darks library is what I used in the past.

[Macavity]

Oh - Not feeling put down! Uz Video Astronomers poach eggs on our camera bodies? 

Indeed - A "library" of Darks, I agree! Genuinely interesting study... So many variables,

So little time? lol. Camera integration time... (hardware) Gain & Gamma - Then there's

software brightness and contrast. I think I'm sussing out the *more* important factors? 

The crie de coeur re. "shutters" was rhetorical? [sure Gina could 3D-Print something] 

I do intend to buy one of those TS filter slider-thingies. I sense they're fairly light tight...

Aside: I seldom (totally) fail with "Darks" recorded under identical conditions to "Lights"! 

Interestingly, Registax has additional settings of 0.5 - 10x (default 1.0) to "scale" darks?

Sometimes I do use 0.5x, when I have over-subtracted ("rivers of black" in nebulae etc).

I have yet to find good use for (seemingly counter-intuitive) values of 1.5x - 10x, but...

P.S. I have learned a lot recently. Maybe we Video Astronomers and Classical Imagers

should get together more often?There's a lot of *good* information out there on Image

Processing. A lot of helpful software utilities too. It can take a while to find sometimes...

[Gina]

If I took darks I would simply put a black filter in my filter wheel I think.  I don't bother with Flats either as I strive to keep my optics scrupulously clean.

Yes, I could indeed 3D print something I guess though stopping stray light getting in can be a problem.

[D4N]

You would have to check that the black truly is black in all wavelengths, steel or Ali would be fine but black glass or plastic may be transparent in IR.

I don't know about the filter sliders but I have a TS filter drawer and that's definitely light sealed, I use it in the day while doing solar so a light leak would be very obvious.

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