A new lens, a cold night and a hunter's sword

[FenlandPaul]

I recently acquired a Canon EF 200mm f/2.8 lens from a fellow SGLer and, incredibly, the night after it arrived was stunningly clear and it was a new moon.  

So it was great to give it a go on the Orion Nebula with my modded Canon EOS 450D mounted on a Star Adventurer.

I took 178x 30s subs at ISO800 and stacked the best 90% in DSS with darks and flats.  Processed in Photoshop.

Clearly the central region is blown out, something that I struggled to control in processing and it might benefit from blending with some shorter subs (bit beyond me at the moment, that!).  I wish I'd framed it a bit better to get the Flame, but I was keen to centre the main nebula to counter any dodgy polar alignment.  Maybe next time.

Anyway, keen for any hints, tips etc please!

 

[FenlandPaul]

And here's the final flattened TIFF file (for those who like to explore at high res).

20210210 Orion Nebula (Final - flattened).tif

[tooth_dr]

Really nice, great FOV.  What did you stop the lens down to?  Personally I am not a bit fan of the diffraction spikes.  If you didnt want them, an aperture mask would be a solution.

[FenlandPaul]

1 hour ago, tooth_dr said:

Really nice, great FOV.  What did you stop the lens down to?  Personally I am not a bit fan of the diffraction spikes.  If you didnt want them, an aperture mask would be a solution.

Thank you.

It's a fixed aperture lens (which I hadn't actually appreciated before acquiring it!), so it was at f/2.8. 

I'm actually ok with a level of diffraction spike (long-time Newtonian user!) but these are maybe a bit "busy" - I haven't really decided yet what I think of them.

[davew]

Hi Paul,

If you need to know whether more subs are needed then have a look at a single unprocessed image first. If that's blown out then it's back outside for you but if it isn't blown out then it's a processing problem as you've blown it yourself. 

What is a fixed aperture Canon EF lens ? Is it broken ?

Dave.

Edited February 11, 2021 by davew

[FenlandPaul]

32 minutes ago, davew said:

Hi Paul,

If you need to know whether more subs are needed then have a look at a single unprocessed image first. If that's blown out then it's back outside for you but if it isn't blown out then it's a processing problem as you've blown it yourself. 

What is a fixed aperture Canon EF lens ? Is it broken ?

Dave.

Thank you - great tip.  So it’s the subs that are blown out rather than the processing then.  *looks at tonight’s forecast 🧐*

So I may be wrong on this new (used) 200mm lens, but I can see no way to stop down the aperture with an inbuilt diaphragm - please tell me I’m being incredibly stupid and missing something!!   

[davew]

Damn. Processing would have been a wonderfully warm alternative ! 🥶

The lens stops down via the camera doesn't it ? As a Nikon user I haven't much clue on the operation of the 450D.

I hope happy-kat sees this post. She will know,

Dave.

[FenlandPaul]

13 minutes ago, davew said:

Damn. Processing would have been a wonderfully warm alternative ! 🥶

The lens stops down via the camera doesn't it ? As a Nikon user I haven't much clue on the operation of the 450D.

I hope happy-kat sees this post. She will know,

Dave.

Eureka!!  Mostly I use fully manual lenses (e.g. Samyang) so hadn’t realised that - now all makes sense, and turns out I was shooting at f/3.5 (bit embarasssing!!). Thank you.  That opens up (no pun intended) a lot of possibilities!