brixx84 wrote:
Hi everyone and thanks Fred for this forum.
I recently bought the Voigtlander 18 2.8 and find it very interesting and fun, but I'm having an "issue".
At f2.8, with focus set to infinity all is good, enough sharpness in the center slowly fading away towards the edges. As I focus back from infinity I immediately lose sharpness, so infinity mark is right.
Already at f4, but even more visible at f5.6 and f8 (and up) I got a strange behaviour (focus at infinity). The very center looks sharp enough, but then there is a big area around the center that loses sharpness (f8 is much less sharp than 2.8). Moving towards the edges (and closer to the camera in the low part) the sharpness gets much better! Focusing ever so slightly closer (my X-Pro3 says 10m on the display) the situation evens out a lot, increased sharpness in that area and a bit less sharpness on the edges. Again the area I'm talking about is phsically closer to the camera. An example here, f8 focus at infinity: www.matteobricchi.com/private/pictures/XT509312.jpg
Could it be field curvature? So strong? But it's like a wave, sharp in the center, then much less sharp and sharp again on the closer middle/edges.
This is so annoying to me, I cannot focus at infinity f8 and just shoot, I got that weakness which is really bad and pretty visible even without zooming. I always have to focus at infinity and step back that half millimeter to compensate...! Is it a "normal" behaviour of the lens or do I have a bad copy?
And yes one of the annoyances of this behavior is you have to balance the performance across the frame and another annoyance with this lens is it varies with focus distance. I think there is nothing unusual about your lens. It is just the way the lens was designed and likely was a compromise to keep such a wide lens so small.
Yes, I thoroughly read the review, but I didn't think field curvature was so strong—especially with focus at infinity!
This is the difference:
It's a HUGE difference in sharpness over a large central area of the picture. So basically, to really have everything in focus at f/8, I have to rotate the focus lever back by just a millimeter… pretty difficult to do and check every time! It cancels out the convenience of simply setting f/8, focusing at infinity, and shooting!
This is the full image from which i took the crops above, this is the one with focus at infinity:
Nov 15, 2025 at 11:51 AM
Steve Spencer Offline • • • • • • • Upload & Sell: On
It's a HUGE difference in sharpness over a large central area of the picture. So basically, to really have everything in focus at f/8, I have to rotate the focus lever back by just a millimeter… pretty difficult to do and check every time! It cancels out the convenience of simply setting f/8, focusing at infinity, and shooting!
This is the full image from which i took the crops above, this is the one with focus at infinity:
From these examples, I think your lens with your particular camera may be focussing a bit beyond infinity when set to infinity focus. I have that with several lenses (and most lenses on an adapter) and yes you do have to pull back the focus from infinity a bit with such lenses and it takes some care. Sometimes, you can add shims to the lens to address this issue. I don't know if you can with this lens and I doubt that you can easily given its compact size, but maybe you can. You can also add a little mark short of the infinity mark at the spot that works for best infinity focus and just focus to there before you bring the camera up to your eye when you want to shoot at infinity. Still not ideal, but I have never found that to be too big of a hassle.
Steve Spencer wrote:
From these examples, I think your lens with your particular camera may be focussing a bit beyond infinity when set to infinity focus. I have that with several lenses (and most lenses on an adapter) and yes you do have to pull back the focus from infinity a bit with such lenses and it takes some care. Sometimes, you can add shims to the lens to address this issue. I don't know if you can with this lens and I doubt that you can easily given its compact size, but maybe you can. You can also add a little mark short of the infinity mark at the spot that works for best infinity focus and just focus to there before you bring the camera up to your eye when you want to shoot at infinity. Still not ideal, but I have never found that to be too big of a hassle. ...Show more →
I don't think this is the case, because at f/2.8 with focus set to infinity I get the sharpest result, while with focus set to 10 m the sharpness already becomes slightly weaker.
Also, at f/8 the edges are sharper with focus at infinity than with focus at 10 m, even though the loss of edge sharpness at 10 m is far less severe than the difference in mid-field sharpness when comparing focus at infinity versus 10 m
Nov 15, 2025 at 07:42 PM
Steve Spencer Offline • • • • • • • Upload & Sell: On
brixx84 wrote:
I don't think this is the case, because at f/2.8 with focus set to infinity I get the sharpest result, while with focus set to 10 m the sharpness already becomes slightly weaker.
Also, at f/8 the edges are sharper with focus at infinity than with focus at 10 m, even though the loss of edge sharpness at 10m is far less severe than the difference in mid-field sharpness when comparing focus at infinity versus 10 m
Then that sounds to me like your lens is experiencing focus shift as you stop down. If a lens is well focused at f/2.8 at infinity but no longer is In focus at f/8 that is focus shift. So although the lens might not be focussing past infinity at f/2.8 that does not mean it isn't focus past infinity at f/8. With focus shift that is totally possible.
Steve Spencer wrote:
Then that sounds to me like your lens is experiencing focus shift as you stop down. If a lens is well focused at f/2.8 at infinity but no longer is In focus at f/8 that is focus shift. So although the lens might not be focussing past infinity at f/2.8 that does not mean it isn't focus past infinity at f/8. With focus shift that is totally possible.
Yes, indeed if I focus at f.2.8 (close subject) and close down to 4 I have to refocus otherwise I lose maximum sharpness. What souds strange though is why the edges are sharp when focused at infinity while they lose a bit stepping back, but the central area improves? Might be field curvature. At the end I'd just like to know if my lens is ok...it would be very nice to campare two, but not easy to do of course, very rare lens to find, at least here in Italy
Fred Miranda wrote:
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Field Curvature
The Voigtlander 18mm f/2.8 Color-Skopar has a field curvature shape that varies depending on the focused distance. When focused up close, the curvature seems to extend outward, while at medium distances, it becomes flatter. At longer distances beyond 5m, the curvature shifts inward, similar to the 27mm f/2 Ultron. This typically results in better out-of-focus rendering towards the corners of the frame, and also makes it a preferred field curvature shape for shooting landscapes where the distance center and foreground sides appear sharper.
To demonstrate this effect, I've processed a sequence using the "find edges" technique. The sequence shows how the lens behaves as it's focused from 1m to a point far into the distance, approaching infinity, in a GIF animation.
Hi Fred, sorry I do not completely get your field curvature explanation, does it explain the behaviour of my lens, as I described in the previous posts? Many thanks!
Fred and others - I own both a Sony and a Fuji system. What in your view is the superior lens, the 28mm 1.5 Voigtlander for Sony FE or the 18mm 2.8 Skopar for Fuji ? How different is their performance? On the face of it to me it looks as if the Sony FE mount lens is sharper in the corners and a nicer manual focus experience as the focus has more throw to it? But the Sony FE mount lens is nearly twice the price (as will be the new APO Lanthar). I am a bit worried that the short focus throw on the Skopar for Fuji will make it hard to use for zone focus street photos ?
Hawkmoon wrote:
Fred and others - I own both a Sony and a Fuji system. What in your view is the superior lens, the 28mm 1.5 Voigtlander for Sony FE or the 18mm 2.8 Skopar for Fuji ? How different is their performance? On the face of it to me it looks as if the Sony FE mount lens is sharper in the corners and a nicer manual focus experience as the focus has more throw to it? But the Sony FE mount lens is nearly twice the price (as will be the new APO Lanthar). I am a bit worried that the short focus throw on the Skopar for Fuji will make it hard to use for zone focus street photos ?...Show more →
I own the Fuji and in my experience it's not a problem at all the short throw, I'm annoyed much more by not being able to fucus infinity and forget it, as I mentioned in my previous posts
Nov 17, 2025 at 06:28 AM
Steve Spencer Offline • • • • • • • Upload & Sell: On
Hawkmoon wrote:
Fred and others - I own both a Sony and a Fuji system. What in your view is the superior lens, the 28mm 1.5 Voigtlander for Sony FE or the 18mm 2.8 Skopar for Fuji ? How different is their performance? On the face of it to me it looks as if the Sony FE mount lens is sharper in the corners and a nicer manual focus experience as the focus has more throw to it? But the Sony FE mount lens is nearly twice the price (as will be the new APO Lanthar). I am a bit worried that the short focus throw on the Skopar for Fuji will make it hard to use for zone focus street photos ?...Show more →
I have the Sony FE mount 28 f/1.5 but I don't have the 18 f/2.8 for Fuji X mount. At least not yet. I think they are really different lenses. The Sony is two stops faster and a lot bigger and heavier. It has a longer focus throw, but not a lot longer (I have the 27 f/2 for Fuji X mount, which has a similar focus throw to the 18 f/2.8). Both lenses have quite a bit of field curvature that varies with focus distance.
This thread isn't about the 28 f/1.5, but I really like that lens but it has to my eyes a really distinctive character. I am in the process of moving to shoot mostly with Fuji and I will miss the lens and particularly its fast aperture. I will like get the Fuji 18 f/1.4 for that reason even if I get the CV 18 f/2.8. I am still on the fence about the little CV lens.
Nov 17, 2025 at 06:45 AM
Steve Spencer Offline • • • • • • • Upload & Sell: On
brixx84 wrote:
Yes, indeed if I focus at f.2.8 (close subject) and close down to 4 I have to refocus otherwise I lose maximum sharpness. What souds strange though is why the edges are sharp when focused at infinity while they lose a bit stepping back, but the central area improves? Might be field curvature. At the end I'd just like to know if my lens is ok...it would be very nice to campare two, but not easy to do of course, very rare lens to find, at least here in Italy
Yes, It sounds like your lens has both focus shift and field curvature. That means you will need to focus at shooting aperture and get the best compromise across the shooting plane, which means probably checking focus in several spots. That can be a pain as you have recognized, but that is how some lenses perform. You could mark on the lens where typical best compromise is for long range shooting, which may work for you, but having both issues definitely is a bit of a pain as I find focussing at wider apertures with field curvature can be useful for setting focus and you can't do that with a lens that has focus shift.
Hawkmoon wrote:
I am a bit worried that the short focus throw on the Skopar for Fuji will make it hard to use for zone focus street photos ?
I haven't had the Color-Skopar for too long, but the short throw is, for me, a non-issue. You get used to it quickly if you're looking through the viewfinder for focus and zone focusing is not a problem in my experience.
I will like get the Fuji 18 f/1.4 for that reason even if I get the CV 18 f/2.8. I am still on the fence about the little CV lens.
I've tried many 18 mm lenses for Fuji, and ended up with the Fuji 18 1.4. I'm just too picky I guess. But that lens is amazing. It's my most used lens.
This lens caught my attention, as it would be nice to have a small compact option. But the already slower aperture has made me hesitant. But now I'm even more hesitant because I've seen various reports of things like this Infinity focus, and weird curvature. I guess I would just have to try one to know for sure, but everything about the 18 1.4 always makes me want to gravitate towards that lens. So I worry that I would buy this and not use it as much as I think even though it's small and light... But then it's small and light. :-P
Did anyone found a solution for the obnoxious screw(ed) lens cap that comes with this lens and the 27mm? (I have the 27…). A solution that keeps the low profile?
vallejo wrote:
Did anyone found a solution for the obnoxious screw(ed) lens cap that comes with this lens and the 27mm? (I have the 27…). A solution that keeps the low profile?
I bought an aftermarket, screw-in lens hood that accepts the normal lens cap. You just have to check to make sure what you get doesn't cause any extra vignetting.
