Samyang 85mm f/1.4, any use for astrophotography?

[Space_Plane]

Hi all,

I have recently been looking at the Samyang 85mm and considering using it with an ASI 178.  Has anybody got any experience with it? 

I know the 135mm is rather famous and well regarded, unfortunately also twice the price 😀 

Thought this lens might be worth a try for the slightly wider fov and hilarious f ratio, and hoped maybe the tiny chip on the 178 might "skip" the worst of any potential edge of field aberrations? (if i understand that correctly).

Cheers

Chris

[Alien 13]

I think some people have used that lens successfully but it might need to be stopped down a little. I doubt that Samyang would know how to even make a bad lens......

Alan

[vlaiv]

Size of 178 will certainly have an impact even if lens is not "sharp to the edge" at F/1.4 - because you won't be using it "to the edge" with such small sensor. I think that you could possibly get away with imaging with it fully open with such small sensor.

[vlaiv]

I just looked at some test shots with this lens, and hm, it looks like it is better at F/2.0 than at F/1.4 even at center field. You might need to stop it down a bit, but still - if it is cheaper and you are ok with focal length - you still get F/2.0 manual focus lens - which is very fast and suitable for wider field shots even with small sensor.

[Space_Plane]

Many thanks for the input everyone.

I was never 100% sure vlaiv if a smaller sensor kindof, sits in the middle / "best" part of a lens and only the bigger sensors receive the worst of the aberrations at the edges, or whether the lens acts like a funnel and all sensors get all aberrations regardless of size.  Fascinating 🙂

Do you remember where you saw some test shots?  I quite like the idea of it for the price, but the combination results in 5.82"/ px.  Wasn't sure how badly that would affect images, maybe things would be a bit, blocky?

Thanks again!

[vlaiv]

Don't think results will be blocky, at least not as much. It is small aperture and that increases PSF, so although there will be some oversampling - it will not be enough to make things blocky. Worst you can get is single pixel stars and those won't look blocky even when viewed at 1:1 (well, I guess it depends on screen pixel sizes - but most displays today have sufficiently small pixels)

I stumbled upon test on a retailer website I visited to see local price of this lens, here it is:

http://www.fotodiskont.rs/test-modela/samyang-85mm-f-14-if-mc-aspherical-za-canon-1878.html

It is however in serbian so you probably won't understand a word of it, but I don't think you need to. Images will be self explanatory. There are three sets of images - close focus, medium focus and long distance focus. As far as I can tell - all three show some softness at F/1.4 at center field. Interestingly enough - edge of the field feels sharper (at least at close focus). Here is one of such images (far distance focus). FYI, "centar" - stands for center of FOV, while "ugao" means corner - so first row is center of the field, while second is corner.

One more thing noted in the review - This lens when wide open - produces quite a bit of chromatic aberration. Seen in these test shots:

 

[Space_Plane]

Thanks  for that vlaiv, was an interesting read (google translate helped me out a bit 😀 )

Certainly gives me lots to consider, and typically the lens has increased in price in a "sale" lol, so I have time yet to continue my research!