First Milky Way shots with new Samyang F2.8 14mm

[Barnjet]

Some advice please.  Last night was my first attempt at the Cygnus area of the Milky Way using my brand-new Samyang F2.8 14mm connected to Canon 70D with a Skytech CLS filter fitted.    Settings were:  15 sec exposure ISO 6400 F4.0 and saved as RAW and JPEG.  I used LiveView on Jupiter to achieve focus, but was concerned that the focus ring was nowhere near the infinity mark; it was between 2 and 3 feet!    Is this unusual?  I know the seeing wasn't that good last night, but I  don't think the stars are particularly sharp either.  JPEG attached.   I'm a bit worried about the quality of new lens - should I be?

 

[FenlandPaul]

Hey there, I’m by no means an expert but I do use the same lens a lot and I love it. It looks to me like your focus is sound (certainly the stars don’t seem overly large), but it seems you might have some coma towards the edges - nothing horrendous but certainly detectable.  I don’t know why the focus mark is so off - mine is bang on infinity.

Is there a reason you shot at f/4?  It should, of course, sharpen things up a bit.  I’d be interested to see what the same image looks like at f/2.8.

I know that Samyangs can have patchy quality.  I’ve not heard too much wrong with the 14mm, though, so if you’re not happy it might be worth contacting the dealer from whom you bought it.  😊 

[wxsatuser]

The coma is not good if that is f/4.

Try the focus without the clip filter and see if it comes to infinity.

[Barnjet]

Thanks for getting back.    I removed the CLS filter and tried again, but this time using Vega and not Jupiter as my focussing aid.  This time the focus ring was pretty much bang on the infinity mark.    I also took some shots with standard Canon  kit lens (18-55mm/F.3.5) at 18mm.  Here are the single shot comparisons, kit lens at 18mm F4 ISO 1600 25 sec first, then the Samyang at 14mm, F2.8 ISO 1600 25 sec.

 

And now the Samyang

Critical views welcome!

BTW these are JPGs, but can I post photos in RAW (CR2) format?  When I did, I didn't see a thumbnail, so not sure if they can be seen by others?

[wxsatuser]

Some star trailing, focus seems good but in that test I would go with the kit lens at those settings.
Not what you want to hear no doubt but the Samyang has the obvious coma.
You should be able to shift the chromatic aberration with software and a lens profile.
Do this on the RAW file.

BTW the filter will shift the focus point as it's another piece of glass in the way.
I wouldn't worry about it as long as you get good focus.

[Barnjet]

20 hours ago, wxsatuser said:

Some star trailing, focus seems good but in that test I would go with the kit lens at those settings.
Not what you want to hear no doubt but the Samyang has the obvious coma.
You should be able to shift the chromatic aberration with software and a lens profile.
Do this on the RAW file.

Thanks - I will try to use my Vixen Polarie for the next image capture to reduce the star trailing.    I downloaded the latest Samyang lens correction data and have applied it to the the RAW Samyang image, shown below as a JPG 

I think it has improved?    

However, as I specifically bought the Samyang 14mm to take Milky Way shots, am I flogging a dead horse with this lens? 

[Mike73]

1 hour ago, Barnjet said:

However, as I specifically bought the Samyang 14mm to take Milky Way shots, am I flogging a dead horse with this lens? 

Definitely not! That Samyang lens is all but a classic for any body that's enjoyed landscape astrophotography.

Yes it has coma and moustache distortion but that's something you just have to live with unless you want to pay +£800 fo a lens.

The good news is that in the centre its usually pretty sharp and since it has a very wide field of view you can crop the worst of the edge coma out. Also, when you start tracking and stacking and the Milky Way is a lot more prominent in your image your eye is drawn to the Milky Way not any kinda of lens distortions.

[wxsatuser]

That is better.

The worst area is bottom left, as above crop it out.

Unfortunately all Samyangs are not equal, some are better than others.