Screen shot, Sedna, Voigtlander 17.5 wide open, indoors, window light.

Thanks for the advice, Nick.

RBD

I'm saving for one of the Noktons. I think the 17.5mm might better suit me for handheld. Maybe I'll sell all my stuff and just get both Noktons, but I'm worried I'd miss the autofocus. Still, can't beat them for low light video. The Olympus 45mm is nice, but I haven't used it much. I wish the Noktons were both EUR 900.

I had the pleasure of playing with this lens last week at the local Yodobashi. It just came in, and some fool put the UPC with tape around the clickless aperture selection ring, but thankfully the nice employ removed it for me. I played with the 25mm in the past at the same shop, but beyond the clickless aperture this lens just felt a notch above. maybe it was the size which is closer to my canon fd 35mm which I love so much, but it seemed easier for me to pull focus with, and a tad smoother if that's possible. I kept oohing and awing, and didn't want to put it down. Unfortunately my memory cards were full sans a bit of space for stills I took which I will try to hunt down and upload in a day or two. My only very slight qualm was that with the clickless aperture when it got into the low f stops (high numbers) I had a couple of clickless clicks, meaning there were noticeable jumps downward on light. It was smooth as silk till those last two F stops, but it was clearly there. Maybe the tape gummed it up, but it didn't feel like that was the case. I am hoping this is just an extremely rare case and the rest of the lenses are free of this defect, and no it would stop me from buying one, but it would irritate me a bit if I spent that kinda cash and got a lens with this issue. Everything else about the lens was wonderful. I wanted to taste it, but the lady was already giving me funny looks at my sexual caressing of the lens.

http://admiringlight.com/blog/review-voigtlander-nokton-17-5mm-f0-95/

"On the Voigtländer 17.5mm, this exhibits itself rather severely when focused near infinity.  If you focus using the center of the frame, the curvature is such that objects between 5 and 20 feet on the edges will be sharp, but further objects get soft."

Bang on, and a good review. Nice to see more reviews being clear about its quirks, yet still loving it!

I found the time to do some more testing with professional resolution charts at close distances and a building about 80m away at a carefully measured rectangular position. This is what I found:

It seems to be normal that such a lens has a curved field of sharpest focus, but the effect is much stronger at long distances. You'll need to take this into account if you want to do landscapes with it and you can even use it to your advantage if you learn to tame this behavior.

The effect is far less pronounced at close distances, you can only see it wide open with serious pixel peeping. I can just barely see it at 1 meter when shooting full rez photos, I doubt it can be seen in video at that distance. IMHO, this lens is perfect for low-light interiors!

BTW, it breathes far less than my wider vintage lenses, like a Rokkor or a Takumar at 28mm.

P.S. Did I tell you that I love this lens?

Rather buy some contax zeiss lenses, i am not impressed but these voightlanders.

It was not my intent to offend @jimtreats-

Here's my view:

We all know Thoroughbred horses?

Long legs, high strung, not really good for anything. You can't, for instance, heard cattle with them, a little too twitchy for pleasure riding, etc.

But with a light rider over a distance of about a mile, a little more, they can't be beat.

They're absolutely amazing.

The Nokton is a Thoroughbred.

If you ask it to do something it wasn't designed for, that's your shortcoming, not not the lens's.

RBD

@jimtreats- Perhaps they feel they have more important things to do with their time?

Read a little between the lines: "...for those who spend most of their time photographing test charts and brick walls...."

What do you think the implication is here?

Sheesh.

Not only is it an extremely fast lens, it's a macro.

And you're concerned about infinity?

Use the lens for the purpose for which it was intended.

It's a really wonderful tool.

Let it go, Jim.

The folks at Cosina think you're rowing with one oar out of the water.

RBD

Read something about Gh2 that 1 of the downsides is that it need alot of colorgrading in post... if I see this "Drewnet"Stills it does look good to my eyes!

@nomad, nice research. I will have a go at testing on something bowl shaped next week. If this is just how the lens is then its fine. Hardly noticeable in normal use, focus on your subject and go. Would prefer to not have it perhaps but if it's just the way it is then ill still take it as the FOV is lovely, the shallow DOF nice, nearly as pronounced as the 25mm, footage handheld is steadier due to the added wideness, the stepless aperture is really nice!

@Ralph_b, @RBD glad to give you info on this lens, fair enough if it's not for you though genuinely in the typical usage of this lens, up close and wide open it's a non-issue.

I think the review I linked to earlier nailed it best, and it's the ONLY review I've found so far that mentions this curvature and that this lens can punish the hell out of you if you try to use it against what it's good at. Use it in harmony with its strengths though and there is little like it.

I just wanted to know if my copy was a bad one, once I know it's just how it is ill move on and just learn to work around it.

To be continued...

@jimtreats

Got it. You're right. That is very significant field curvature. I was seriously considering this lens, but now, I don't think so. Thanks for the test.

@nomad. Sorry to say but i'm glad to hear that you have the same issue, not no issue at all. Would suck if its noticably off-centred. Though can't say whether mine is or isn't as all my testing has been a bit informal.

If we all have the same issue then at least it becomes just a property of the lens. Will wait and see what Voigtlander have to say when they get back to me.

I'm happy to have the lens with that issue, though it does sting a little that your £800 lens can't focus reliably at infinity!!! It's perhaps just a quirk and once you know it you can work around it. Some of my stopped down tests last night seem pretty good... if you pixel peep you can see a difference at the edge, but its very close. More testing on this front is key perhaps... the best way to test that would perhaps be to do some true landscape photography with it, where EVERYTHING from edge to edge is relatively at infinity. I think this lens' resolution peaks about f5.6 before diffraction takes its toll... it'll be around here and f8 where perhaps you have to be for infinity shots.

I'm about to go shoot a wedding reception with the lens this evening, the subjects will all be much closer, but if there is any nice shots of the setting i'll either stop down and take my chances or change lenses! :)

One test i'd like to try now is a formal measurement of just how curved it is. My thinking is perhaps to get something bowl shaped, relatively close focussed (where DOF is shallow... and see if i can get anything at the extents of the bowl in focus where it's obviously MUCH closer and can only be explained by this curvature... if you were lucky you may be able to get a lot in focus in this odd shape, a bit like that Rokkor lens mentioned earlier in the thread... Obviously this lens is just missing the afore mentioned ring to control curvature :)

I look forward to further testing results nomad... i still love the lens, but notably my copy of the 25mm doesn't exhibit anywhere near this level of curvature, if any. I've googled and found some people saying their 25mm did, and hoping the 17.5mm would be better... i think we can pretty safely say its worse! As I said before though, its never really what the lens is for, and i do still love it... let's see what more we can find out. Cheers.

I just looked at google maps and the distance of my distant subject is getting on for 300m +, for the houses at the very top of the road.

Just processed 4 shots and added them to the earlier flickr album, shot on the pen.

http://www.flickr.com/photos/jimbobuk/sets/72157630781100484/with/7661898064/

It IS noticeable on the computer, i guess the pen's lack of EVF makes it really hard to see.. It's certainly a worse camera than the GH2. But reassuringly i see the same things going on in the images so i think i can exclude my camera from the equation.

In my photos i've noticed that the neighbourhood watch sign is a nice thing to look at and see the sharpness difference between the two shots. It's probably more like 150m away.

Another way to look at this is focus past infinity till the lens stops and take some photos or look around the edges, and as you can see in my shots the right and left 1/5 edge of the frame is sharp, regardless of its depth away from the lens.. the grass and driveway on the right of some of my shots is barely 5m away yet is sharp at the same time as the distant object. It's like its behaving like dofmaster predicts at this setting.

It is strange! :-/