Cygnus Milky Way region from Dordogne Region - Samyang 14mm (Reprocessed)

[coatesg]

Quick process of 12x5min from my modded 350d using a Samyang 14mm lens at f2.8 from last night, taken from our campsite near the Dorgdogne Valley - tracked using a GM-8. 

Flats, Darks and Bias applied (oh, flats are fun with this lens...!) - and rudimentary processing in PI (BPP, DBE, Background Calibration , CC, Histograms, etc), will have another go when I get home on decent internet with a proper monitor. 

One thing is that I'm not 100% convinced about this lens - think I'll be doing some further testing as I think it has some decentering. I'm not expecting the world with it wide open, but it's worse to the lower portion than upper if you zoom in (looking for some advice from owners of this lens perhaps!)

Thanks for looking

(EDIT: See reprocessed version below!)

[Peco4321]

Wow, beautiful. I'm camping in the dordogne in a few weeks. Can't wait for some widefield shots, won't get close to this quality though, no tracking so maybe 20-30 sec max. 

Breathtaking picture. 

[MarsG76]

Phoa.. count the stars.... that's heaps of Milky way shine,..... 

On my monitor it looks like the blackness of space is green shifted.

 

[MARS1960]

Very nice.

The image does look like the lens has the decentering problem, i wouldn't say it's common but it does affect a few of these lenses, the one i bought off ebay had the same problem, a brick wall test will confirm it for sure.

[coatesg]

54 minutes ago, MarsG76 said:

Phoa.. count the stars.... that's heaps of Milky way shine,..... 

On my monitor it looks like the blackness of space is green shifted.

 

Very possibly - processing on a laptop is not the greatest for colour shifts! I'd used Background Neutralisation in PI but might have chosen a poor sample...!

 

 

[coatesg]

35 minutes ago, MARS1960 said:

Very nice.

The image does look like the lens has the decentering problem, i wouldn't say it's common but it does affect a few of these lenses, the one i bought off ebay had the same problem, a brick wall test will confirm it for sure.

Thanks - I'll test it when at home, but shouldn't be an issue to return via Amazon. Annoying though!

[coatesg]

1 hour ago, Peco4321 said:

Wow, beautiful. I'm camping in the dordogne in a few weeks. Can't wait for some widefield shots, won't get close to this quality though, no tracking so maybe 20-30 sec max. 

Breathtaking picture. 

20-30s should be enough at high ISO and with wide aperture/short f.l., stack if necessary! V dark in places - bring binos!

[MarsG76]

6 minutes ago, coatesg said:

Very possibly - processing on a laptop is not the greatest for colour shifts! I'd used Background Neutralisation in PI but might have chosen a poor sample...!

 

 

True that Laptops aren't the best to use for color balancing or black levels, too much variances as the screens tilt, but it doesn't matter, its a great looking image nonetheless.

 

[Peco4321]

1 hour ago, coatesg said:

- bring binos

I'd take my full set up if it would fit!  Seriously though, family holiday and me up till the early hours would not be very good would it. I'll settle for my camera and gorilla pod tripod, and my 15x70 bins. Can't wait. 

[geordie85]

Looks like your having the same issues I'm having with this lens. Apparently de-centering on this lens is quite common, ive read about others who've had 4 or 5 of these lenses before they got a good one. 

I currently have a thread that I'm asking for help with diagnosis. 

As you can see my 2nd lens isn't as bad as the first but it's still not perfect. I'll probably keep the 2nd one till after the persieds peak then send it back for a replacement until I get a good one. Just hope it doesn't take too many attempts. 

[newbie alert]

On 30/07/2017 at 17:51, MARS1960 said:

the one i bought off ebay had the same problem, a brick wall test will confirm it for sure.

Brick wall test..not heard of that one before..ivr got the same lense but I'm more than happy with it..so far..

[coatesg]

Fiinally got round to reprocessing this on a half decent monitor! I got rid of a few gradients and hopefully have been a bit more sympathetic in terms of how far it's pushed and the black levels. Still a fair amount of coma over the bottom portion of the image from the lens, but as long as you're not pixel peeping, it's not *so* bad (helped by scaling the image down a bit too!). To give an idea of the scale of the image, I've also added a solved image from nova.astrometry.net with the constellation lines included (interestingly, it doesn't handle the lens distortion over this scale particularly well - the lines don't quite match up with the stars!  :-D)

Thanks for looking!

 

Annotated version:

 

[Notty]

On 10/08/2017 at 17:11, newbie alert said:

Brick wall test..not heard of that one before..ivr got the same lense but I'm more than happy with it..so far..

Lovely images there Coatesg, but newbie alert could you possibly explain this "brick wall" test for me please?  I've just got one of these lenses and I'm showing some strange behaviour on some images and I'd love to be able to work out what's what. Thanks!

[newbie alert]

57 minutes ago, Notty said:

Lovely images there Coatesg, but newbie alert could you possibly explain this "brick wall" test for me please?  I've just got one of these lenses and I'm showing some strange behaviour on some images and I'd love to be able to work out what's what. Thanks!

I had to Google it as is never heard of it either..heres a link I found..

http://www.tomgrill.com/brickwall/