Dustobub wrote:
I've now spent some time with three new lenses on the A7s: M-Hexanon 28mm f/2.8, Zeiss 25mm ZM f/2.8, and the very intriguing M-Hexanon Dual 21-35mm f/3.4-4 and I wish I had better news to report. On the upside, there is next to no color cast on all three. However, they all still have significant field curvature at short/medium/long distances.
I was most hopeful of the Dual Hexanon as it's a retrofocal design (by M-mount standards). It really is an incredible piece of glass - extremely well built and with a wonderful feel. It would be a great outdoor walkaround lens for the A7s.
In testing it though I've learned a few interesting things. Nothing not known to others I'm sure, but for me it was a bit of a lightbulb and will force me to retest some other wide lenses on the A7s. In my normal shooting with MF glass and an EVF I set the lens wide open (or one stop down), focus, and then stop down to my desired aperture and shoot. This makes focusing easy and is great for normal shooting. Now with a lens that has strong field curvature in the corners, this technique will likely result in very poor corner sharpness. What I've found is that with a lens sufficiently wide enough (21mm on the Dual Hex is very acceptable, but at 35mm it's not great), you can combat the field curvature with smartly placed DOF. For a subject at infinity, this would mean focusing at the hyperfocal distance for your desired shooting aperture. For a subject closer than infinity, first stop down to shooting aperture and then focus at the shortest acceptable distance where your subject is in focus. This slows down the entire process a bit as focusing is much harder when stopped down, but it does lead to better corner performance.
I am going to take a fresh look at the lenses that are piling up in my apartment to see if any of them can perform decently with this technique. If you're looking for good cross frame performance wide open below 35mm with rangefinder glass, the A7s isn't going to be the Holy Grail you want it to be. However, if you're willing to change your technique and are mainly shooting medium to long distance subjects outdoors, there may be hope.
I guess your lenses behave similarly as my ZM 15 (forward field curvature). It's actually not that slow. For landscape, you can just remember the distance on the distance scale when you achieve the acceptable sharpness for both corners and mid-frame. This is hyperfocal distance focusing, quite well known for street and landscape photographers to maximize DOF.
For shorter distance, especially with human subjects, I will just focus on them instead and the DOF is more than enough most of the time.
hiepphotog wrote:
I guess your lenses behave similarly as my ZM 15 (forward field curvature). It's actually not that slow. For landscape, you can just remember the distance on the distance scale when you achieve the acceptable sharpness for both corners and mid-frame. This is hyperfocal distance focusing, quite well known for street and landscape photographers to maximize DOF.
For shorter distance, especially with human subjects, I will just focus on them instead and the DOF is more than enough most of the time.
So I guess you're not going through with the mod?
Yep, at infinity it's just hyperfocal shooting. But it does take conscious effort when shooting closer subjects to stay on the short end of the DOF. Otherwise corners get progressively worse as you focus farther out even though your subject focus isn't changing.
As for the mod, I'm still really tempted. If Dan says he has time to play around with moving the sensor, which he said could be possible over the winter, I might just jump on it.
hiepphotog wrote:
I thought by "the mount", you meant the included adapter mount. Moving the camera mount would be the same but I think it would be more difficult since the mount is directly attached to the mag-alloy front frame. Unless, I'm mistaken. The sensor assembly, on the other hand, was mounted one several small pegs with shims to ensure proper placement.
maybe, I thought I remembered the exterior mount being screwed in place with shims.
The mount is pretty much attached to the front chassis. The sensor assembly is mounted and adjusted for alignment via shims. I guess there is not enough movement after the sensor stack modification.
Taylor Sherman wrote:
I'm curious about the 21 Super-Elmar and 28 Summicron-M.
I think Charles K has the A7S and the 21SEM, though I don't think I've seen a picture with the combo yet.
Hi Taylor,
I have done some initial testing with the 21 SEM, but I cannot really draw any detailed conclusions yet as the weather last weekend was not good. The 21 SEM is superb on the M240, so anything less I will find it difficult to compromise. The WATE works great, so for now I not searching for too many other lenses, as I find it very frustrating with lens testing.
Surprisingly the 28 Cron Asph, is not as bad as I first assumed when taking some shots. I will test this further, as for street shooting it would appear to be excellent, but for landscapes I have not decided yet. The 28 Cron Asph is much better on the A7s than the A7r.
Of course the best lenses here are the WATE and 21/24 Lux. There is no cheap option, but fortunately I have kept the WATE and 24 Lux Asph.
I have done some initial testing with the 21 SEM, but I cannot really draw any detailed conclusions yet as the weather last weekend was not good. The 21 SEM is superb on the M240, so anything less I will find it difficult to compromise. The WATE works great, so for now I not searching for too many other lenses, as I find it very frustrating with lens testing.
Surprisingly the 28 Cron Asph, is not as bad as I first assumed when taking some shots. I will test this further, as for street shooting it would appear to be excellent, but for landscapes I have not decided yet. The 28 Cron Asph is much better on the A7s than the A7r.
Of course the best lenses here are the WATE and 21/24 Lux. There is no cheap option, but fortunately I have kept the WATE and 24 Lux Asph.
I've seen some mixed reports on the 28 Summicron ASPH. I even tried one at the Leica store in NYC and quickly dismissed it when I saw similar field curvature to the other 28's. However, I didn't give it much of a chance and maybe should have.
Steve Huff said the 28 cron was the only lens that continued to give him trouble on the A7s but the link below offers a competing opinion.
I got to spend some time at Photo Village in NYC (across from B&H) yesterday. Really a great shop. Highly recommended. I'm pretty sure they have just about every single Leica/Voigtlander lens ever produced. And if you're nice, you can test them out I took a bunch of photos, but I won't be posting corner crops of each and every one, just my personal impressions.
Let me just preface this by saying that I'm not expecting these lenses adapted on the A7s to be 100% equal to their performance on a Leica body. I'm not looking for perfect flat field sharpness wide open. That's not what most of them provide even on a Leica. But I am looking for reasonable performance wide open to the degree that I feel comfortable shooting wide open. I also would like decent corners by around f/4, and very good to excellent corners by f/8. Everyone's standard for acceptable is different. Those are mine, and they seem to be a tall order from what I've seen over these past few weeks.
These are the lenses I was able to test on my A7s yesterday at Photo Village:
Voigtlander Color Skopar 21 f/4
Voigtlander Ultron 21 f/1.8
Voigtlander Ultron 35 f/1.7
Summicron 28 f/2 ASPH
Elmarit 28 f/2.8 V3
Super Elmar 21 f/3.4 ASPH
Summicron 35 f/2 ASPH
Summilux 35 f/1.4 ASPH FLE
Wide Tri Elmar (WATE) 16/18/21
Initially, I went to Photo Village to pick up the Color Skopar 21 f/4 as I was hoping to keep a small 21 in my kit after I part with the Hexanon Dual, but it wasn't meant to be. No color casting, but it has much stronger field curvature compared to the Hexanon Dual. No amount of stopping down was enough to fully compensate for it. Bummer, it is such a neat little lens.
I gave the Summicron 28 ASPH another chance as I was now seriously considering it out of frustration with all of the other 28's I've tried. However, I saw exactly the same thing I had initially seen a few weeks ago at the Leica store - lots of field curvature. Sure it works reasonably well stopped down to f/8, but for the price, I couldn't live with it.
Long story short (well, somewhat short), there were only three lenses in the list above that performed above my set standards: the Summilux 35 FLE, the WATE, and the Voigtlander 21 Ultron. All of the other lenses exhibited more field curvature than I personally could live with.
I was actually surprised the FLE performed so well. I've seen some conflicting reports online, but take a look below. These are both at 2.8 focused dead center. Top one is the FLE, and the bottom is the Summicron 35 ASPH - full size here. Huge difference.
The FLE performed so well that I actually caved and am in the process of trading my Voigtlander 35 1.2 v2 for one. I should have some comparisons by next week.
Regarding color casting, none of these lenses, nor any other lens I've tested on the A7s has exhibited strong color casts - the A7s seems to be almost entirely immune. However, the field curvature that the A7s imbues to wide lenses seems to be almost identical to the A7r/A7 - likely due to the same ICF/AA glass thickness. So if a lens is smearing (probably just due to field curvature) on an A7r/A7, it's most likely going to perform very similarly on the A7s. For the most part, in my opinion, it seems the only thing the A7s solves is the color casting.
Like with the other A7s, the field curve could fool a person. Shooting a figure in a room at 2-3 meters, and the lens may look fine. Great photos can be made. But the long landscapes can make things really clear.
Made exactly the same experience wi8th the Summicron 35 ASPH on my A7R body - decent for close distances, but extremely bad in the corners plus visible field curvature when focused to infinity. Too bad because it is a lens which I liked a lot by its size and built.
Had a couple days to play around with the 35 FLE. It really is a spectacular lens and does perform quite well on the A7s. Compared to the Voigtlander 35 1.2 v2 it's almost identical past 2.8 with only the tiniest lead in the far corners and edges. At 1.4 and 2 however, the FLE runs circles around the Voigtlander, not just in the corners, but throughout the entire frame. It certainly should considering its price. Take a look through the full res photos here.
As for how the A7s compares to an M240 with the FLE, well that's a different kind of story. More to come on that front soon.
Quick crop comparison of the A7s vs. M240 with the Summilux 35mm FLE wide open. The FLE performs very well in the corners on the A7s even at large apertures, but it's really not equal to the M240 until around 5.6 or 8. Full resolution here.
Hmm the A7s looks worse, but it is also much lower resolution. If you downsize both to, say, 8MP, then maybe they wouldn't look so different. Here the M240 benefits more from the downsizing than the A7s. Having said that, the M just has more resolution, so this is really what you get.
carstenw wrote:
Hmm the A7s looks worse, but it is also much lower resolution. If you downsize both to, say, 8MP, then maybe they wouldn't look so different. Here the M240 benefits more from the downsizing than the A7s. Having said that, the M just has more resolution, so this is really what you get.
I'm sure that's a factor, Carsten, overall.
But there's a fuzzy corner thing goin on there with A7s which is not present on M240, no?
Most subtle with the FLE: no surprise since that lens even "worked" on the A7r.
But the fuzzy edge on the cron......well
Too be fair it's 2.8 and we should see a M shot to compare, it looks like the ubiquitous sensor cover induced SA to me.
Yes, I agree about the corner, that is what I meant with "looks worse", but there is more to the result than just the corner performance, that's all I meant. The Cron is just horrible on the A7*. Too bad, such a nice lens.
Dustobub- I'm not all that familiar with the M240, but doesn't it apply software corrections to RAW files? I'm not suggesting it's fully responsible for the improvements. I'm more curious to see if the correction can be turned off and, if so, if it was off or on for your test shots.
Thanks for testing and posting the results of the Leica 35 mm f/2 and f/1.4 ASPH lenses. Bummer....I was thinking of getting the 1.4/35, but after seeing still issues with corner sharpness on an A7 camera I won't invest this amount of money for the lens. Better performance than the 2/35, but by far not perfect.
Is there any Leica 35 mm lens which works really fine with the A7 series?
I took a bunch of photos, but I won't be posting corner crops of each and every one, just my personal impressions. 
