Do you dither?

[tornado33]

Howdy all
Id like to ask, do you dither, that is move the scope or lens slightly after taking each exposure of a stack? I did, then tried not dithering, just taking sucessive shots without moving the scope, and sure enough, I get more noise by not dithering, I guess each pixel responds slightly differently, and dark subtraction is never 100% accurate, so dithering can help smooth over non random noise.
I think dithering might be especially important for narrowband imaging as only certain colour pixels (eg red for Ha imaging) will be illuminated, the rest will be dark, so moving the camera/scope at least a few pixels each time will, when the images are aligned and stacked, help smooth out the pixels, at least thats the theory anyway.
For fast lenses and shorter exposures perhaps dithering is not necessary.
Scott

[Octane]

Scott,

Real men don't dither. :)

Regards,
Humayun

[h0ughy]

:rofl: :rofl: :rofl: oh dear you'll get him in a dither with that one H!!!

Personally what he says almost make sense, oh there goes rthe cork again, fathers day is great! I like the principle of what scott says, and I think there is merit in it!

[[1ponders]]

Dithering is recommended buy many authorities.

[Striker]

Scott,

I remember you mentioning this at Lostock.....I automaticly Dither because my images slightly moves down over the period of the night....so thats my Dithering.

[tornado33]

Heres some links on Dithering
http://www.stsci.edu/hst/stis/documents/handbooks/currentIHB/c11_datataking4.html
http://www.adass.org/adass/proceedings/adass99/O6-02/
To dither or not to dither, that is the question :)
Actually dithering may not be so necessary from dark sites, as the sky background will be so much darker anyway. Humayun's excellent shots from Kulnura speak for themselves.
Scott