Orion Widefield

[Galactic Wanderer]

To be honest, I am not extremely happy with this image because I thought more nebulosity would appear in the image - such as the horsehead nebula. Perhaps my exposure is too low (140 secs) , or there is simple too much light pollution. 

Anyway, I'd thought I'd share it as it was taken as part of a weekend trip to Norfolk.

Thanks for looking Seb

Equipment: EQ3 pro mount, Canon EOS 60D 30x140 seconds (unmodified)

 

[Knight of Clear Skies]

That does seem very noisy, what aperture setting did you use please? Other details such as ISO and calibration frames would be useful as well.

[gnomus]

43 minutes ago, Knight of Clear Skies said:

That does seem very noisy, what aperture setting did you use please? Other details such as ISO and calibration frames would be useful as well.

The flame is there and there is just a hint of horsehead.  However, as Knight says, it is a bit noisy.  I'm not seing much colour either.  Did you use calibration frames?  These are quite important.  What about lens and exposure details?  And how did you stack these? 

[Galactic Wanderer]

8 hours ago, Knight of Clear Skies said:

That does seem very noisy, what aperture setting did you use please? Other details such as ISO and calibration frames would be useful as well.

 

Thanks for the replies.

I used ISO 1250 and F13, is that too drastic?

I haven't used calibration frames for this one, which I know is slightly stupid - but will that completely change the image/ boost colour?

 Thanks again, Seb 

[Knight of Clear Skies]

F13 is the problem, as each stop in the aperture scale results in half the light hitting the sensor.

Making F13 about 12 times (I think) slower than F4, many people don't realise it's an exponential scale. Finding the best aperture setting for a lens can take a bit of experimentation, most of mine work best between f3.5 and f5. At f3.5 the Horsehead shows up quite well in a two minute exposure, un unmodded one will require more time but can still pick it up OK.

Dark bias and flats can help, I usually don't bother with DSLR darks as if their temperature profile doesn't match the lights they can potentially introduce more noise. Hope that's some help.

[happy-kat]

Very crudely you would need to expose for 169 minutes to get the same from f4 in 12 minutes. It gives an idea of the impact of stopping down.

[Galactic Wanderer]

Thanks. That is very useful for next time. I was confused when I saw this done with an unmodded camera and taken at a dark sky site (same as me!).

Seb

 

[happy-kat]

Not really comparable as you used f13 and that post the OP uses f5.

[Galactic Wanderer]

1 minute ago, happy-kat said:

Not really comparable as you used f13 and that post the OP uses f5.

Exactly.

[happy-kat]

The most light is with a lens wide open but this will be where a lens shows it's weak points be it CA or lens aberration in the corners or both or a bit of both or none of either depending on quality of lens. As I crop my images during precessing I'm less bothered about aberrations (poor star shape) and CA on one of my lenses is always present. Generally one or two stops from full wide helps. Try and see what works on your lens.