IC1396 Widefield

[iksose7]

Evening SGL, though i would share a image from a couple of weeks ago.

My attempt at the Elephant trunk nebula (it is in there!) This is my first 'proper' attempt using some newly aquired aperture rings which are great, they make processing a star layer so much easier as you dont have to deal with the horrible star spike the EF200L produces!

Only 2 hours 35 minutes of data here because at the moment i am using a ball head on a dual bar which is a pain to balance and an even bigger pain to frame, making re-framing a daunting task! I have now ordered a lens collar to make things easier. Hopefully the microfcuser i have right now is not too big to allow me to use it - i have a feeling it is! May have to replace it.

Anyway, here ya go. Details at the bottom.

Exposure details:

30* 300 second subs, f2.8 (f4 with ring), ISO 800, calibration frames, 200mm

Camera: Canon 600Da

Lens: Canon EF200L 2.8 II

Mount: NEQ6

Guiding: Orion Miniguider

[StuartJPP]

Nice work there. I am always dubious about stopping down a lens because you are effectively halving your imaging time...I would have thought that the 200mm L would be pretty sharp to the corners but obviously not. Aperture rings are definitely better than stopping down because I am not a fan of lens diffraction spikes.

Lens collars/rings are good...What I did with one of my cheap ones was line the inside with Teflon tape which makes rotating very smooth and easy.

[Psychobilly]

Indeed nice work I like this target in the wieder field...

Where in the frame are you placiing the star when your  doing you focusing?

Try placing it on or close to anyone of the  thirds points ( a third in from both edges of the frame ) ... I use this methoid with my 200/2.8L and  shoot wide open... In fac tI use this method with all camera lenses and scopes for astrophotography...

I had a set of apertures laser cut  in approximatley 0.25 stop steps , sized so that they woudl fit in an old filter ring to do some experiments but don't use them anymore...

Peter...

[iksose7]

Thanks Stuart. Yeah, halving imaging time would be nice but i just try not to think about it. I really dont get on with the lens wide open.

The 200L is very sharp to the corner if set at f4 but like i said, the spikes just ruin it for me. When i first got the lens i quite liked them but i cant stand them now!

I've taken your teflon tape tip on board, will put it to good use, thanks.
 

[iksose7]

Cheers Peter. When using the rings i just use any star in the FOV really. I have tried your 3rd point technique in the past but unfortunately couldnt get it to work for me. I always ended up with stars appearing to rotate around a centre point like this:

Forgive the image, i've re processed it since not pushing the data as far.

Happened on multiple nights, i thought it was a DEC problem but it was happening even in short exposures of a few seconds. I would love to try the technique on another lens to see if its my 200L that is the problem (probably just me messing up somehow) Never mind though, i'm not looking back not i have the aperture rings!