Anyone know any fast 50s with a flat field?

[Bjørn Rørslett]

I mentioned the AIS 50/1.4. It is a manual-focus lens ...

[David H. Hartman]

What about the early or mid AF 50/1.8 Nikkors made in Japan? These are both non-D type AF lenses. If those aren't flat field enough what about a 50/1.8 AI or early AIS?

Dave

[Bjørn Rørslett]

Most of the slower f/1.8 models have flatter field than their f/1.4 siblings.

However, if perfect flatness of field is a primary concern, get a Micro-Nikkor.

[Øivind Tøien]

I wonder if the mentioning of field curvature and effects in out of focus areas early in this thread is confused with cropping of the blur circles by the front aperture of the lens causing "cat-eyes" as shown in Børge's the last posted image from the 50/1.2? These are typically be oriented in a circular pattern that can be used to provide focus to the center of the image ("circular bokeh"), but can of course be unwanted. Would you perhaps post an image Tristin?

I am however quite familiar with the field curvature effect in my Nikon 12-24mm. Focusing on a subject 50-10 m away with slightly blurred background will cause center to be sharp almost to infinity, but edges more blurred - not nice (perhaps tendency for front focus has been part of the equation too). It is then better to set the lens to the known infinity position and use depth of field together with field curvature to provide focus on close subjects.

[Frank Fremerey]

I mentioned the AIS 50/1.4. It is a manual-focus lens ...

yes the latest 1.4AIS is better than the 1.4G, yet the current 1.8G is very near to the classical 2.0AI. I was really
surprised using both of them side by side on the D600.

[pluton]

I will shoot an image soon that shows what I speak of, as replies are making it clear that there is a good amount of confusion on the issue itself. 

Please do.  In your initial post, you mentioned shooting wide apertures, but then later mentioned night time exposures with the lens stopped down.  Please show both if both have the annoying curvature artifacts.

[Tristin]

I mentioned stopping down  as I don't care about coma because I shoot nightscapes at f/8+.  I have no field curvature issues at narrow aperatures.

Will provide a pic tomorrow.

[Akira]

Airy, it is not that I shoot flat subjects.  It's that I find curved focus fields at wide aperatures quite nauseating in appearance.  You do not need flat subjects to see this, it makes the bokeh induce a look of smeary distortion to the scene that I label "barfy".  When doing close portraits it is not noticeable or an issue.  At other ranges though, it is extremely noticeable.

Is the "barfy" bokeh you mention similar to those "swirly" ones for which the old Petzval lenses, Zeiss Biotar or some CCTV/cine lenses are famous?

[Erik Lund]

Well in that case it would have exactly nothing to do with field curvature,,, 

[Bjørn Rørslett]

The tell-tale signs of field curvature are loss of sharpness at the out parts of the frame (when shooting a flat subject), and peripheral veiling due to spherical aberration.

[Tristin]

Thanks all, to be honest I felt that this thread was a pipe dream from the get go.  It seems I would have to go to a f/1.8 or f/2 at minimum to get a flatter field, this is something I will just have to accept.  Was hoping there was some fast 50 that I had yet to hear of somehow.

[Airy]

It would help everybody if you could illustrate what you call field curvature and its nauseating effects. Just to remove the misunderstanding.

[John Geerts]

Yes, I think so.        I see the Voigtlander 58mm 1.4 was not mentioned but I never 'tested' it's 'flat field'.

[Tristin]

It would help everybody if you could illustrate what you call field curvature and its nauseating effects. Just to remove the misunderstanding.

I have none to show currently as the offenders were all promptly deleted.  When I happen across a scene that can portray it I will take a picture.

Akira, no it is not the petzval look.  Though I do find that look to be a bit nauseating as well haha!

[Roland Vink]

It seems I would have to go to a f/1.8 or f/2 at minimum to get a flatter field, this is something I will just have to accept.  Was hoping there was some fast 50 that I had yet to hear of somehow.

As others have suggested, the problem may be  mechanical vignetting, not field curvature. In extreme cases, such as with the Nikkor 50/1.2 and 55/1.2 wide open, the result is "swirly bokeh", which I generally don't find pleasant.

If this is the case, it may be worth looking at the Sigma 50/1.4. Due to the oversize front element it has lower vignetting than other 50/1.4 lenses, so is likely to have less of a swirly look.

But until you can post some images which show the effect, I'm just guessing.