This is a great question and I have been awaiting responses...
In general, at the bottom, would be used Nikon ais primes, with an adapter. Alongside these, the Samyang, then onto SOME of the native Sony lenses, then at the top SOME Zeiss etc. That's the brand way of thinking but there is another way to consider the issue; what are the primes you actually need most? I would put it that if I were buying just one lens, it would be a 35mm. Buying two lenses, 35mm and 80mm. Three lenses; 35mm, 80mm and 50mm. Some (perhaps, many) would prefer a narrower standard view and opt for the 50 mm as the first lens if forced only to buy one.
But, there is a problem here; normally, the wider the lens the less sharp. And this starts to become an issue in 4k. Its actually fairly hard to find an inexpensive 35mmn lens that is suitable for sharp 4k. It's quite easy to find lenses above 100mm, even zooms like Nikon 70-200 2.8 are good enough. But the Nikon 35mm ais manual iris as well as the Samyang 35mm are really not all that great - good enough for HD but not 4k. What to do?
If I were in your situation, I would get a Zeiss Loxia (fully manual) 35mm for $1200. It's a stunning lens. For my second lens, I'd get a Samyang 80mm, which is a fairly good lens, much, much better than the Samyang 35mm, about as good as some of the Nikon manual focus 80's, but with mount that doesn't require you to buy adaptors. Eventually, I'd replace that Samyang but I would add a 50mm first - as well as maybe some wide etc etc. Some will grip about the lenses not matching, but I think this is a minor issue in the scheme of things. Use DXO Mark to check lens quality.
And there is another way to think about it; forget sharpness alltogether. Its an overrated criteria and just get either used Nikons with an adaptor or Samyangs without. Think of yourself as creating a 'gentle' style, using the 4k as more info to grade etc.
Edited by Stephen Timpe, 01 August 2015 - 04:04 AM.
I would not assue that just because it's Zeiss that it is great. I was surprised to discover how uneven their line is. So, do your homework, check the DXO site, shoot with them if you can. But, having said that, going in the Zeiss driection (slowly and carefully) is probably a good move. I remember thinking their 25mm was probably the best bet for the focal length - but that is from when I checked a few years ago, I could be confused. As for the Loxia, they are adding to the line and, so far, altogether a notch higher in quality than the average Zeiss slr still lens. Again, though, each lens has it's own strengths etc. don't forget to check out chroma, distortion and lateral fringing as well. And, as you seem to know, totally forget about Batis or anything else without manual fstops and manual (non electronic) focus.
ps Just went to the DXO site. I pulled up Zeiss and Samyang primes. Important when using that site to make sure you use the same 'mounted on' camera - I just used the Nikon 810. Interesting stuff, once you do this. The Zeiss 25mm f2.8 doesn't fare nearly as well as the faster 25mm f2. The Samyangs fare extremely well for the money (this might actually depress you, forcing you to weigh off 'feel in the hand, solid metal, name brand with pure practicality, quality enough, even if it feels like plastic junk). I suggest you go there and play for a few hours before making any decisions.
And then... I would order, for instance, the Loxia AND the Zeiss 35mm from BH and play for a day or so. (Samyang, no matter their merits, will not survive the 'feel good' factor.) Then send back the 'loser'.
Another consideration will be ease of use - the Loxia wins hands down on this as it's electronics are set up to work the Sony's. This will make it much easier to focus. BTW, the DXO doesn't seem to have the Loxia's yet. Pity. I did read all their reviews when they came out - the 35mm and the 50mm. Seems I was left with the impression they were very strong across the board but didn't excel at any one aspect. Sharp as hell, good to excellent bokah, low on the bad stuff (distortion etc). But, so the complaint might go, they lack 'character'.
But, what does that mean? I suppose 'character' is just another word for lack of balance. Certainly the high level cinema primes also lack 'character'. In fact, that is what you are paying for. That something like some Cookes have ever so slightly more 'human' character, proves the point. You can go online and discover that even dp's cannot tell the difference between one lens and another - test after test shows this. Put up the same scene shot with ten lenses (using same focal length, same sensor size), tell the dps which lenses but make them do the matchup, and you will be left with only slightly better than random results.
Nobody will ever know whether your work was shot with a Samyang or Zeiss dslr lens - except you will have the 'feeling' every time you mount it on the camera. What an irrational factor to use in helping choose lenses, yet even knowing that might still not help me choose the Samyangs. And, what happens when they actually fare better in the tests? Gads. I suppose the only way I could past that 'junk' feeling is that if I viewed them as temporary. And if their quality was up to snuff, I would eventually forgive them, tell my snickering buddies to screw off, and get shooting.
The Zeiss 28mm f2 gets a sharpness score of 25, which is respectable.
The 25mm f2 is the one that shines out with it's score of 29. The problem is with the 50's. I am stunned how badly the Zeiss 50's did - and part of me is suspect of the tests. Those are such mediocre scores. It's always good to find multiple sites - and read opinions, like at the BH site. I just did a very quick look there at the 50mm 1.4 ... lots of talk about focus shift and softness, comparisons etc. Maybe those dxo test are correct.
Edited by Stephen Timpe, 01 August 2015 - 07:32 AM.
I've spent some time reading about these lenses as I am considering purchasing. But I've not used them. So, take my opinion for what it's worth.
Yes, I think the Loxia 50 2.0 is clearly superior to the Planar 50 1.4. Basically, for two reasons. The Loxia is much sharper at f2.0 than the Planar. At 1.4 the Planar is really mediocre. In this sense, the Loxia is 'faster'. The Planar 50 1.4 is perhaps the least sharp Zeiss out there- a consideration if shooting 4 k.
The second reason I would go for the Loxia is ease of use. Just grap the camera and lens, start focusing, and you get instant zoom in. Touch the release button and you are back to normal magnification. For stills work, at least, the Loxia is much, much better. And, for quick focusing in video work, it will be better as well. The lens is designed to work well with the Sony A series. Owners seems super satisfied.
Glad, but not surprised, to hear about the build and feel quality of the Loxia.
What to get for the 25mm area. That's the harder question to answer. I suppose I would be looking at the cine Samyangs. They are around $500 new. Used, I would guess, they fall in value more quickly, than, say, a Zeiss. But, beware one issue - the variance in build quality is very large with the Samyang - some samples will be considerably better than others. If you buy used you take a chance on a not very good one - but, you might find a great deal. New, you could order two , test them out, keep the better.
And, I suppose, you could find some super cheap slr lens, and get an adaptor.