Vignetting on a Nikkor 50mm f1.4 AIS Lens

[Ara Ghajanian]

I was going through some recent photos that I shot with my Nikkor 50mm f1.4 AIS lens and I'm noticing vignetting. Is this something that is common with these lenses when they are shot at wide open aperatures? Is it because it is a f1.4? Could someone explain this phenomenon?

I've never done a lens test to determine what the best aperature to shoot at is. Can someone recommend a basic test I can do to determine this?

Thanks in advance,
Ara

 

[laz]

Something is definatly amiss with your lens! You should be able to shoot all the way to f1.4 without any trouble, I do.

What would be the purpose of paying for a fast lens if you couldn't use it at it's fastest?

 

[Dan Fromm]

Ara, its been several centuries since I had a 50/1.4 Nikkor, but the one I had didn't vignette. And I've shot it wide open.

Have you put filters in front of your lens? Lens hood other than the standard issue?

Why do your own tests? These lenses are very well-known. Find a public library that has back issues of Modern Photography or MP on microfilm from the early '70s through about '85 and search for tests of 50/1.4 Nikkors. If that's not practical, they give best sharpness and contrast in the range f/5.6 - f/8.

That said, the concept of "best aperture to shoot at" is pretty fuzzy. Other factors enter, e.g., DoF and shutter speed. FWIW, my practice is not to stop down too far unless max shutter speed available/film speed/illumination for me to or unless I need more DoF. And not to shoot too open unless I need selective focus or circumstances force me to.

Cheers,

 

[Eric Rose]

You didn't mention if you were using a lenshade. If you were, I suspect that, if not your lens is malfunctioning.

 

[laz]

Begin back-peddling: I did a quick Google of this lens. I didn't get the AIS version, but I did find this very interesting review:

Nikon actively developed their fast normal lenses throughout the '70s. The coatings were improved and the basic double-Gauss formula was trimmed to squeeze even better performance out of the 50/1.4. The last version before the AI epoch featured a shimmering red front element and sported a very capable performance. Wide open there is some softening in the corners that disappears by f/2.8, At f/4 it gives excellent images, and the quality stays basically the same up to f/8. Beyond that f-number the performance declines perceptibly. Flare levels are low, but ghosting can be provoked by pointing the lens towards bright light sources.

Well shut my mouth!

Link to the review:
http://www.naturfotograf.com/lens_norm.htmlNikon

 

[Ara Ghajanian]

I'll post a few negs I scanned that exhibit this problem tomorrow. I didn't use a lens shade and I only used one filter at the most.
Ara

 

[Dan Fromm]

Begin back-peddling: I did a quick Google of this lens. I didn't get the AIS version, but I did find this very interesting review:

Nikon actively developed their fast normal lenses throughout the '70s. The coatings were improved and the basic double-Gauss formula was trimmed to squeeze even better performance out of the 50/1.4. The last version before the AI epoch featured a shimmering red front element and sported a very capable performance. Wide open there is some softening in the corners that disappears by f/2.8, At f/4 it gives excellent images, and the quality stays basically the same up to f/8. Beyond that f-number the performance declines perceptibly. Flare levels are low, but ghosting can be provoked by pointing the lens towards bright light sources.

Well shut my mouth!

Link to the review:
http://www.naturfotograf.com/lens_norm.htmlNikon

"Softening in the corners" isn't what most of us think of as vignetting. Vignetting usually means dark corners. Here's an example. Very compressed, looks awful, should make the point anyway.

 

[Dave Parker]

Alot of lenses will show softening at the corners, depending on the aperture setting, Dan is right, vigetting is a dark corner with rounding showing the shadow of the aperture blades.

Dave

 

[Ara Ghajanian]

"Softening in the corners" isn't what most of us think of as vignetting. Vignetting usually means dark corners. Here's an example. Very compressed, looks awful, should make the point anyway.

What was happening to my negs was a very very subtle version of this example. The only way I noticed it was because I photographed something on a very green lawn and the grass at the bottom corners of the frame (vertical orientation) was a bit darker.
Ara

 

[laz]

"Softening in the corners" isn't what most of us think of as vignetting. Vignetting usually means dark corners. Here's an example. Very compressed, looks awful, should make the point anyway.

I agree, I was just shocked that the lens had any wide open problems and thought maybe Ara was seeing softness and just mislabeling what he was seeing.

 

[Dan Fromm]

What was happening to my negs was a very very subtle version of this example. The only way I noticed it was because I photographed something on a very green lawn and the grass at the bottom corners of the frame (vertical orientation) was a bit darker.
Ara

Ara, I realize that there's probably no grass in the upper corners of the frame. But is whatever is there darker in the corners too?

And what filters and lens hood did you use? If you used one of those collapsible rubber hoods, take a shot or two without it.

Dave, the cutoff isn't due to the diaphragm, its due to a field stop (shouldn't be one in a 50/1.4 Nikkor, but there is one in the 75/4 Apo Rodagon D 1:1) or some other mechanical obstruction, usually at the front of the lens or to the lens' design (the 38 Biogon with which I took my example shot). I hang a number of lenses in front of a #1 on my little Graphics, always worry that the shutter's barrel will block the peripheral rays.

Cheers,

Dan

 

[Dave Parker]

Dan,

Seems you and I have learned photography in a different way, which is cool as long as we make the images we want.

Regards.

Dave

 

[Paul_Baker]

Check this page out. It shows the darkening of the corners at 1.4 very clearly.

http://www.physics.montana.edu/students/meng/50mmTest.htm

 

[skahde]

The fast Nikkors of 50mm and wider *all* vignette very obviously wide open and I have and had a handfull (24/2,8, 28/2, 35/2, 50/1,8;1,4;1,2). Use it to your advantage (concentrates the viewers attention to the center together with great swirly bokeh with eg. the 1.2/50mm) or stop down a stop or two.

best

Stefan

 

[Dan Fromm]

Dan,

Seems you and I have learned photography in a different way, which is cool as long as we make the images we want.

Regards.

Dave

Not to quarrel, but when the lens is wide open how can the diaphragm cut off the outer part of the cone of light that the lens projects?

About field stops, take a look at Rodenstock's published MTF and illumination curves for the 75/4 Apo Rodagon D 1:1. They're flat to the edge. I had one, it gave even illumination across an 80 mm circle as claimed, and beyond that all was dark. Its a wide angle lens with a stop.

Regards,

Dan

 

[Ara Ghajanian]

Check this page out. It shows the darkening of the corners at 1.4 very clearly.

http://www.physics.montana.edu/students/meng/50mmTest.htm

This is exactly what is happening. As long as it's not something wrong with my lens, then I'm fine with it.

Stefan,
I can appreciate your advice. I will use it to my advantage and at least I know now that I can stop down to lose the effect. I've taken some great shots wide open with this lens, that wouldn't have been possible had I not had the extra stop.

Thanks to everyone,
Ara

 

[Helen B]

Ara,

Vignetting wide open isn’t uncommon among fast lenses. Broadly, there are two types of vignetting that are inherent in a particular lens design: “natural” and “artificial” or “optical”. Vignetting introduced by filters or lens hoods can be referred to as mechanical vignetting.

Natural vignetting is, not surprisingly, a natural property of the lens that is related to the angle of incidence of rays (the Cos^4 law), and the designers will try to overcome it. As far as my limited understanding goes, they do this by selling their souls to the devil. The wider the lens, the more natural vignetting will occur.

Artifical or optical vignetting is caused by things in the lens getting in the way of the oblique rays but not the axial rays, as mentioned by Dave and Dan. These could be deliberate, like field stops, or they could be mismatches between the location of the entrance pupil and the iris*, or the physical size of the front and rear elements – the effect being to obstruct the entrance pupil when viewed obliquely. As the iris is closed down, the obstruction to the axial rays matches the obstruction to the oblique rays and the vignetting disappears. Poof! It’s gone.

The full cure may be worse than the disease. So it’s not so much a sign of cheapness, more a sign of how much the design is balanced between different goals. One opinion is that a little vignetting at f/1.4 is not such a bad thing in a lens intended for pictorial use, because of the typical circumstances in which f/1.4 is used. The Leica Noctilux (50 mm f/1) has a lot of vignetting wide open, but who would notice it in blurry snaps taken in the gloomy dungeons that typical Leica users frequent?

Best,
Helen

*Which is the answer to Dan's question "...when the lens is wide open how can the diaphragm cut off the outer part of the cone of light that the lens projects?"

 

[Dan Fromm]

Helen, don't you mean the exit pupil?

In some lenses vignetting is clearly intentional. I have two ~ 4 inch reversed tessar type macro lenses -- 90/6.3 CZJ "M" and 100/6.3 Reichert Neupolar -- with rather small rear elements located well behind the exit pupil. At fairly small angles off-axis the rear of the lens barrel obscures the exit pupil. As a result, both have small coverage at infinity but more than enough closeup. I really regret this property of the Neupolar, since over the field it covers -- wider near than far -- it does very well at all distances.

About cos^4 dropoff of illumination, Brian Caldwell has asserted repeatedly on usenet that he has designed short rectilinear lenses that are brighter at the edges than in the center. His trick, if I understand it correctly, is to design the lens so that on the image side of the lens the edge rays are nearly parallel to the central ray.

I'm not sure that Ludwig Bertele sold his soul to the devil, even though some of his designs smell a little of hot sulfur. I have in mind the 44/5.6 Super Aviogon I once got to hold. I held it out in front of me, and as I rotated it from "straight ahead" to "lens' axis 90 degrees off straight ahead" its beady little exit pupil wouldn't stop staring at me. Brrr!

Cheer,

 

[Ara Ghajanian]

The full cure may be worse than the disease. So it’s not so much a sign of cheapness, more a sign of how much the design is balanced between different goals. One opinion is that a little vignetting at f/1.4 is not such a bad thing in a lens intended for pictorial use, because of the typical circumstances in which f/1.4 is used. The Leica Noctilux (50 mm f/1) has a lot of vignetting wide open, but who would notice it in blurry snaps taken in the gloomy dungeons that typical Leica users frequent?

Helen,
Thanks for the good answer. I'm figuring if a rediculously expensive Leica lens shows some vignetting, then a $150 Nikkor shouldn't bother me much. I actually hadn't even noticed it before the last roll of film I just shot, so I'll pretend it never happened.
Ara

 

[Paul_Baker]

Just to clear up a little terminology here, what your seeing is really "light falloff" and not vignetting. As stated above vignetting is ths term usually reserved for something in the way blocking the light. Light falloff is just an optical problem where the light has trouble being uniformly distributed over the focal plane.

Paul B.

 

[gnashings]

Hmmm... I wonder how my 50mm f1.4 SSC Canon stacks up... I just got it recently, so dont have a take on it - but the shots I do have, seem pretty free of visible vignette.

Sorry - I know that partially I am just being a crap disturber but I this thread got me thinking about my own 1.4, though tis not a nikkor

 

[Helen B]

"Just to clear up a little terminology here, what your seeing is really "light falloff" and not vignetting."

Paul,

Do you have a source for that definition? Though what Ara is observing is probably what I know of as 'artificial' or 'optical' vignetting (as I described above) because it disappears when the lens is stopped down, the falloff in illumination according to the cos ^4 (or cos^3 if the Slyusarev/tilting pupil effect is used) is often called 'natural vignetting' as far as I was aware.

Thanks,
Helen

 

[Paul_Baker]

Helen, I'm sure you are correct in differentiating the two as various forms of vignetting, but in reviews of lenses for the average person this is normally referred to as light falloff. In Ken Rockwell's review of this lens, (BTW, I have been looking at this lens to buy, that's why I know where these reviews are) he says:

f/1.4: Spherical aberration lowers contrast. A lot of coma in the corners making them quite soft. Falloff

In fact he recommends to bypass this lens altogether and get the 1.8 instead.

Paul B.

 

[skahde]

in reviews of lenses for the average person this is normally referred to as light falloff. In Ken Rockwell's review of this lens, (BTW, I have been looking at this lens to buy, that's why I know where these reviews are) he says:

For what it's worth I made good experiences with not taking one single source too serious. I'd rather have a look at several sources if possible, look where they agree and what doesn't fit the picture and trying to find out why things might disagree. Ken is not very fond of 50mm lenses after all and says "I no longer even own any 50mm lenses". I think that is a good reason to take his judgement with more than the usual pinch of salt.

best

Stefan

PS.: Neither vignetting nor falloff should be reagerded an exact term as used buy photographers. If you try to do so you will run into trouble faster than you can say Waxahatchie.