Lotusm50 wrote:
Yes, quite small fraction of the frame. This is much ado about very, very little, IMHO. This is the least seen, least used, and often cropped 1% (or less) of the frame. As mentioned before, nearly ALL 50mm standard lens exhibit this, why this particular 50mm should be called to task for it is mind boggling.
Comparing it to a 100mm lens is useless. If you need a 100mm lens use a 100mm lens, if you need a 50mm use a 50mm. The 50mm MP is incomparable across 99% of the frame and merely comparable to all other 50mm's over the last tiny fragment of the frame. To dismiss the lens for this is a kin to throwing the baby out with the bath water. Even if the 35-70 might be a touch better in the absolute corner than the 50 MP, the performance of the 50 MP over 99+% of the frame totally and obviously dominates the old zoom. Would you really prefer to use the 35-70 over the 50MP?! I still don't get the point of all this. It's not perfect? No lens is. That is to be expected. So far we've seen nothing that isn't shown in the published MTF's. IMHO, you spent a lot of time and effort obsessing over this for very little insight or gain. If you don't want to use it because of this, that is your prerogative, but you would be leaving a lot of performance on the table that you can't get in another 50mm lens -- performance in areas of the frame that matter a great deal more than the often-unseen absolute corner. Use the lens for real photographs rather that brick walls and fences and it will never fail to impress.
I have the feeling, that you don't really read my posts. Or maybe you just don't understand it.
I said, that i liked the 50MP and will keep the lens. It will probaby substitute my 35-70. But before I make such a decision, I do some tests. Sharpness is best tested on a flat wall. I don't understand your problem with this approach.
And your assumption, that nearly all lenses look like this, is completely wrong. The 50MP is the only lens, that shows this behaviour. No other lens, I own, shows this. And you can't tell me, that it is the most difficult task in the world to develop a 50mm lens with sharp corners.
Bobu wrote:
And your assumption, that nearly all lenses look like this, is completely wrong. The 50MP is the only lens, that shows this behaviour. No other lens, I own, shows this. And you can't tell me, that it is the most difficult task in the world to develop a 50mm lens with sharp corners.
I didn't say "ALL" lenses look like this, I said 50mm lenses (but generally wider lenses also). You should read what I write, as well. I would say show me a 50mm that isn't soft in the absolute corner until f5.6 or f8. They all use pretty much the same type of design (Planar). I have 8 or 9 50mm lenses and they all show this. I would also note that the degree of performance in the corner depends in part on the focus distance. This is probably why users have commented that this has not been a problem in their images produced by the 50MP.
If you are keeping the lens, then I'm really not sure what the point of all the obsessiveness is with the performance in the furthest reach of the corner. We know this is a characteristic of the lens, easily understood from the MTF. Continuing to harp on it doesn't affect it, or make Zeiss run to their lab and change their excellent design. Is there a point to all this effort, beyond what we already understand?
Is it "difficult" to produce a 50mm lens that is sharp and has a perfectly flat field across the entire frame at all apertures? Probably not. It's probably prohibitively expensive, and would be at least twice the size and weight. Even $4000 Leica 50mm lenses don't do it. Correcting that final 1% of performance in the absolute corner would increase the cost of the lens several fold, and produce a lens that you would not want to carry. Most users wouldn't buy it, and prefer to accept optimal compromises and tradeoffs. With the 50MP, Zeiss has kept performance strong across 98-99% of the frame and then lets it drop off steeply into the absolute corner. Other lenses may choose a slightly different tradeoff, where performance drops off more gradually towards the corner. With this you will see compromised performance by the edges of the frame but it may preserve a bit more in the corners (depending on how well it is implemented). The 35-70's tradeoff is like this, it is pretty much downhill across Zone B and into Zone C of the frame (but it's also not a Planar-style design). Quite frankly, I think Zeiss' tradeoff with the 50MP is optimal. They have kept the price reasonable and the the size of the lens usable and sacrifice only the least important (by a wide margin) tiny fraction of the frame -- a fraction of the frame that only rarely you see in a print.
It is, of course, much easier to do with a 100mm focal length, and that is why you see the difference between the 50MP and the 100MP. Of course the 100mm won't do when you need or want a 50mm, and perhaps is one reason why Zeiss makes both.
Lotusm50 wrote:
I would say show me a 50mm that isn't soft in the absolute corner until f5.6 or f8. They all use pretty much the same type of design (Planar). I have 8 or 9 50mm lenses and they all show this.
I agree with this, even the Leica M 50mm ASPH, possibly the best 50 ever made, is soft in the (very) extreme corners until f/4 or so.
philber wrote:
Is that CA which I am seeing in the OOF foreground, Lotus?
I would be amazed if there weren't signs of CA. It was an exceptionally bright, high-contrast scene with bright white snow, taken wide open at f1.4 with a non-APO lens. At the very least a touch of "sensor bloom". Given that crop is a 100% crop, CA seems to be very well controlled, indeed. You might catch a hint of it, but that is all.
I have no other 50mm lens (besides the 35-70mm zoom) to compare, but I have lots of wide angle lenses, that don't show this behaviour. From the pictures I've seen, the Zeiss 1.4/50 has sharp corners at f/4.0 for example (but it has some other disadvantages, like a much stronger field curvature and lower center resolution).
In my opinion it should be easier to design a 50mm lens with perfect corner sharpness than a wide angle lens with perfect corner sharpness. Maybe I'm wrong.
And I think, I'm not at all obsessed with this. It's just a lens characteristic I've never seen before and I just wanted to know, whether this is normal for this lens and then had to decide whether I will keep this lens or not.
From the lens characteristic, I would probably prefer the 35 ZE, but I like the 67mm filtersize and the macro option of the 50MP.
Maybe your are a bit obsessed in defending the 50MP ;-)
Bobu wrote:
I have no other 50mm lens (besides the 35-70mm zoom) to compare, but I have lots of wide angle lenses, that don't show this behaviour. From the pictures I've seen, the Zeiss 1.4/50 has sharp corners at f/4.0 for example (but it has some other disadvantages, like a much stronger field curvature and lower center resolution).
The Zeiss 1.4/50 is indeed soft in the absolute corner until about f5.6 or even f8 (depending how fussy you are), and I have 3 versions of this lens (c/y, N and ZF) so I can speak from some experience. The Zeiss MTF's also confirm this.
A lot depends on the image itself whether you notice it or not. Take a picture of a brick wall or a flat wood fence and you'll see it. Usually, however, images of brick walls is not in my repertoire.
Just got the lens this morning, here are few test shots I took today. Nothing spectacular just quick shots to make sure I got a good copy. I was pleasantly surprised that the colors are very neutral and truthful. All were taken on Canon 5D and are straight exports from Lightroom. I did get a little bit of cramp in my left hand from turning the stiff focus ring for the first hour, but I think I adjusted now. This will certainly be a challenging lens as I am not used to manual focus. That's partly why I bought it, to have something challenging and very different from all my other lenses. So far I'm very happy about the IQ and built quality. Can't wait to try it outside when the weather gets better.
No post processing, just straight Lightroom export. Not sure about the colors on mk2. I assume they should perform the same on both bodies, but without direct comparison it would be difficult to judge.
Here are few more I just took this morning. Again nothing artistic, just merely testing my manual focus skills - I certainly have some learning to do, especially at f/2.
