I had a loaner Zeiss ZE Distagon T* 2,8/15 on loan for a few days, but unfortunately I've had very little time to use it because of work and family. I did however visit a 'summer' cabin this weekend with a few photographers (for beef and beer, not photography) and got the chance to pin it against the bargain beauty, the Samyang 14mm f/2.8 in Canon mount. The testing wasn't very scientific, just decided to do a quick one because the two lenses were in the same room and there probably wouldn't be more chances in the near future. So I used a Gitzo 2531LVL tripod, a 5D III, 2sec timer and the best focusing I was able to do with 10x Live View. I didn't account for focus shift and I probably could have found a better subject to test on, as this is rather dull in colours and at short distance, so keep that in mind. Please don't consider this as an all-round comparison with definitive results. And of course there's much more to images than sharpness :-) But in general these two lenses seem very similiar to me.

Please forgive me for not preparing 100% crops for you to see, as I believe the sample files should be viewed in their entirety to make any sort of conclusion. So here are the RAW files (I hope my Dropbox storage won't be too slow!):

First demos at f/2.8. I focused to the best of my ability to the map in the center of the frame, but the lenses seem to have very different focusing fields, as their sharpness/focus differs incredibly between zones.
zeiss15_vs_samyang14_z15_at_f2.8.CR2
zeiss15_vs_samyang14_s14_at_f2.8.CR2

f/8 demos provide a little easier comparison, I didn't to other apertures unfortunately.
zeiss15_vs_samyang14_z15_at_f8.CR2
zeiss15_vs_samyang14_s14_at_f8.CR2

I'm a huge Zeiss fan, in fact, I'm probably the biggest Zeiss fan(atic) in Iceland. The Zeiss 15/2.8 sure is beautiful. I think if Batman was a photographer, this would be his lens. It's just that cool. But is the $2550 price difference between Zeiss 15 and Samyang 14 justifiable? Yes the distortion is horrible in the Samyang but it's correctable for the most part. At least I see very little difference between the two after the Samyang has been corrected to justify this extreme price of the Zeiss 15. I did another test at work last thursday against the Canon TS-E 17mm and noticed another, very interesting thing. The Canon TS-E 17 and ZE 15 were equals in sharpness for the most part, but to my eyes, the ZE15 seemed very diffraction limited - it became incredibly soft at f/16, much more so than the 17 TS-E. (I'm not so keen on showing those cluttered office images publicly though, PM me if interested ;-)

I hope I won't offend anyone with this post, and I may very well be wrong in my methods or conclusion. But this is what I saw and I wanted to share it, as I've been drooling over that ZE15 since it's introduction.

I can't open these raw files. Is it possible to convert them into another format?

No problem, here are DNG's But Dropbox uploading usually takes a good long while so these links may not be ready at the time of posting, but it's way past my bedtime here in Iceland so I'll post them anyway :-) Should be on-line in less than an hour of the time of this post.

f/2.8:
zeiss15_vs_samyang14_z15_at_f2.8.dng
zeiss15_vs_samyang14_s14_at_f2.8.dng

f/8:
zeiss15_vs_samyang14_z15_at_f8.dng
zeiss15_vs_samyang14_s14_at_f8.dng

Remember to check the whole frame of the f/2.8 versions, I'm not sure if it's focusing error on my part or field curvature, but it's hard to judge that one lens is better than the other based on a single point of focus.

Kiddik
Thank you for posting these. I myself am a big Zeiss fan, but I have been also looking at Samyang 14mm for a while. For me, 21mm is already pretty wide, so 14 or 15 would be really wide, and I don't think I would use it as much, and for the limited use I may have, I am not interested in spending premium price at the moment. ( Although, there is still a chance I may go wtih 14-24 in the end... )

Any way, I only looked at the 2.8 shot, and it seems that focus points are a little different ? Samyang's focus is somewhere on the first aid kit, wheareas zeiss seem to be focused on the bedding in the room beyond ? Regardless, Samyan has a little glow / haze, which I have seen in other test on the net. For the price difference, this to me is not that big of a deal. Samyang's distortion sure is a bit distracting, or the way how zeiss is so clean, that stood out for me. Very nice lens, zeiss is, but Samyang holds its own place.

At literally 10 times the price, it would have been embarrassing for the zeiss to not have beaten it.
This only reinforces how much of a good deal that Sammy is.

The biggest surprise to me is the speaker on the iPod dock. It has moire only on the 14. I didn't realize lenses could impact moire like that.

shoenberg3 wrote:
At literally 10 times the price, it would have been embarrassing for the zeiss to not have beaten it.
This only reinforces how much of a good deal that Sammy is.

I think the Zeiss beats it on all levels, if the Sammy seems sharper it's probably that I didn't nail focus 100% (pretty hard with a 14-15mm lens). However, I think the Zeiss is overpriced, and the Samyang is underpriced :-) This just proves just what a good deal the Samyang is. I recently tested the Samyang against Canon 14L too, and while it didn't win the 14L on all levels, it did on many - and there also was the gigantic price difference.

How odd, I get an error in the Z15 F/8 file (100% unavailable). Rest are ok. DNG versions only. My CS5 does not support 5D3.

I have the Samyang and if landscape is your thing I would carefully watch how far corners look when perfectly focused on infinity. That is (for me) by far the weakest point of all. Dont care too much about the distortion if it's not obvious cityscaping or so. It is plenty sharp, one of the sharpest lenses 100% crop I've put on the 5D2 (except far corners).

(dont have any experience with the Z15, but I have plenty of other Zeiss')

Lee Saxon wrote:
The biggest surprise to me is the speaker on the iPod dock. It has moire only on the 14. I didn't realize lenses could impact moire like that.

Lenses impact moire by being in focus. I think the Zeiss has a flatter plane of focus (focused on more distant objects), while the Samyang's focus curvature happens to put the near, corner objects on the table in sharp focus simultaneously with more distant image center.

That's certainly true of the f/2.8 examples, where the Zeiss is clearly out of focus in that area. But in the f/8 I think the Zeiss is close enough to in-focus in that area that if it was going to moire it would.

Lee Saxon wrote:
That's certainly true of the f/2.8 examples, where the Zeiss is clearly out of focus in that area. But in the f/8 I think the Zeiss is close enough to in-focus in that area that if it was going to moire it would.

I disagree, but it should be close.

15mm @ f8 means an ~ 2mm lens entrance pupil diameter. Assuming the bottom right speaker grill is 1/4 of the distance to the focus plane (crude estimate), this means a 1.5mm object-side blur disk diameter. I'd guess the holes in the grill are only 2-3mm across; they're also 2-3 pixels across in the final image. Thus the blur disk at this location is likely a bit larger than a pixel across --- enough to show most detail, but still avoid moire.