Nikon Df and non-AI lens overexposing

So I've inputted the lens data and coupling method. I've assigned a function button to select the lens. I've selected it. ( all as per p.164 to 168 in the manual). I have the camera on manual exposure. I've matched the lens aperture to the camera aperture setting. (The lens is a 28mm f4 shift). But when I adjust ISO and/or shutter speed to zero the exposure indicator in the viewfinder -- and take a photo -- I consistently get shots that are overexposed by 2 or 3 stops. (And the stop-down mechanism on the lens works fine).

 

I also have an AI lens, which works perfectly with the camera.

 

Anyone else run across this problem?

 

Thanks in advance.

I've used manual-aperture lenses on my Df, the 35/2.8 PC and Schneider Xenon 50/1.9. As I recall- I did not use the Df's thumbwheel to change the F-Stop, always left it at the maximum setting. Then I set the aperture of the lens to get correct exposure. The method for stop-down metering is different from using uncoupled metering with the non-Ai lenses that have "auto-aperture", ie stop down only at the moment of the exposure.

As a few thoughts:

 

1. This one may be obvious, but it's worth asking since this is a pre-set lens. Are you metering at full aperture and then closing the aperture after shooting?

 

2. KR at least(I haven't checked other sources) claims that the older PC lenses will only meter correctly when unshifted. If you are metering after shifting the lens, it might be worth trying to meter with the lens unshifted.

As I recall- I did not use the Df's thumbwheel to change the F-Stop, always left it at the maximum setting. Then I set the aperture of the lens to get correct exposure.

Thanks Brian. I'll try that. (I have to wait for the battery to charge, since it just died on me).

As a few thoughts:

 

1. This one may be obvious, but it's worth asking since this is a pre-set lens. Are you metering at full aperture and then closing the aperture after shooting?

 

2. KR at least(I haven't checked other sources) claims that the older PC lenses will only meter correctly when unshifted. If you are metering after shifting the lens, it might be worth trying to meter with the lens unshifted.

No, I've been metering while the lens is at the closed aperture. And yes, I'm metering while unshifted.

Just before the battery died -- on a whim -- I changed the camera's setting for the lens to Ai, and took a shot. I think it significantly reduced the shutter speed for the shot.

No, I've been metering while the lens is at the closed aperture. And yes, I'm metering while unshifted.

 

For reasons I don't totally understand, Nikon DSLRs don't do well with any kind of stop down metering.

 

Try metering with the lens wide open.

1. re the Ken Rockwell advisory to meter before shifting: thats the old CYA advisory lifted directly from Nikon's F2-era instruction books. It is actually not quite correct, because obviously you'd often end up with an error. Years later, Nikon indirectly admitted this was a mistranslation or miscommunication: the point they were trying to get across was that the composition changes when shifted, and their film-standard centerweighted meter pattern could be fooled by this.

 

They couldn't quite figure out the tortured phrasing to suggest: if metering before shifting, be sure to place the centerweighted meter circle over the part of the scene that will actually be in that location after the lens is shifted. In essence, the opposite of what they said in the instruction manual: its probably more efficient to meter after shifting, off the final composition. Yeesh.

 

2. re metering 100% manual klutz lenses like the old PCs that have no AI linkage and no auto-stopdown lever: Nikon management has had an unreasoning, uncomprehending, utter terror and loathing of this configuration ever since they switched from film SLR to DSLR. They simply don't fully support it technically, not even on the Df. Its a subtle distinction, that somewhat contradicts their sales pitch for the Df as the be-all and end-all DSLR for pre-AI lenses.

 

It isn't, quite. The Df has meter optimization settings for pre-AI Nikkors, but normal metering is only possible with standard pre-AI lenses with "Auto-Nikkor" automatic stop down mechanics. The tiny subset of non-Auto-Nikkors are not technically supported with metering on any Nikon DSLR, even the Df. This subset includes the PC Nikkors, Reflex Nikkors and a couple old very long teles. So with most Nikon DSLRs mounting old fully-manual PC lenses, the workaround is making informed-guess settings based on the suggested (possibly wrong) meter reading, chimping the rear LCD playback, and re-adjusting exposure as necessary until it looks right.

 

The one-off Df, as the only DSLR with a dedicated "pre-AI" meter setting in its menu, may or may not be easier depending on lens used and your shooting circumstances. My suggestion: follow Nikon's instructions re the menu settings (focal length, maximum aperture, and pre-AI flags), but ignore the part about setting exposure by matching the aperture on the lens with the second command wheel. Instead, set the body aperture wheel to the maximum aperture of the lens, and leave it there. Set aperture only on the lens, so that the camera interprets aperture changes as changes in ambient light. This should get you within a stop or so of correct exposure, but you'll likely still need to chimp the rear LCD.

 

Unfortunately there is no possible way to set the meter specifically to stop down accuracy mode on any Nikon DSLR. You could do this on most of the manual-focus film SLRs by mechanically zeroing the meter coupling shoe or AI tab before mounting the lens, which programs the meter with a default (false) max aperture of f/5.6 for any attached lens, and a compensation factor that kicks in as you stop the lens down for a reading.

 

Most Nikon AF film bodies, and all Nikon DSLRs, omit this dedicated stop-down mode. They all assume a mounted lens is coupled in some way that the meter interprets as open-aperture with later stop down: AI mechanical follower, or electronic aperture feedback from AF or chipped lenses. The Df flip-up AI tab is deceptive: it does absolutely nothing beyond protecting itself from the intrusive flange of pre-AI lens mounts. That's why the Df has an additional menu function that couples a pre-AI flag to the aperture command dial: you're basically still making full aperture readings, compensated by matching the body and lens mechanical positions. This crude matching fails when the attached lens does not have an auto stop down lever: the meter will read 1 to 4 stops out depending on the lens aperture setting.

 

Long story short: metering goes AWOL when mechanical, film-era PC lenses are used on Nikon DSLRs. You save a lot of money with the older shift glass, but you pay for it with tedious multi-step guesstimate metering. The modern pricey PC-E lenses add electronic feedback compensation that tricks the meter into thinking a perfectly ordinary lens is attached: much more convenient. Also, some of the older film-era PC Nikkors edge smear when shifted: their ray angle clashes with the sensor cover glass to create faux LoCA. Modern electronic versions are optically designed around the sensor glass, and/or work with the camera raw algorithm to auto-compensate it in software.

Edited February 16, 2019 by orsetto

Didn't have time to use the old 35mm 3.5 PC I bought in December very much before the Winter weather settled in, but didn't encounter any exposure problems using it on the DF, the shots were properly exposed indoors & out. Looking forward to better weather and opportunity to work with it more. If the effects are at all consistent, even in a given situation, the exposure comp is readily accessible.

You should meter with the lens wide open. If you meter with the lens stopped down then in the lens setting you will have to set the lens maximum aperture at that stop. For example if you use f/8 then you in the lens data you should set it at f/8 28mm. Set the aperture also at f/8 with the wheel then shoot. Of course this technique is a pain so you should meter with the lens wide open and then stop the lens down before taking the picture.

 

Ben, the reason that Nikon DSLR doesn't meter stop down because of the matrix metering algorithm. It needs to know the actual scene brightness. That is why the F5 won't meter in matrix if you use AI lens because it doesn't know the maximum aperture of the lens.

Well, I did a bit of experimenting with all the possibilities: stop down, wide open, telling the camera it's either an Ai or a non-Ai, using the command dial or not using the command dial to inform re aperture, manual vs aperture priority, as well as the 3 different metering modes. But nothing works. And I did compare with the same lens on a Sony A7s (with adapter), since I know it handles exposure well. The only two routes the Df takes are either quite over-exposed or quite under-exposed. This is even though Nikon explicitly states that PC-Nikkor lenses work with the Df ( Nikon | Imaging Products | Lens compatibility - Nikon Df ).

You should meter with the lens wide open. If you meter with the lens stopped down then in the lens setting you will have to set the lens maximum aperture at that stop. For example if you use f/8 then you in the lens data you should set it at f/8 28mm. Set the aperture also at f/8 with the wheel then shoot. Of course this technique is a pain so you should meter with the lens wide open and then stop the lens down before taking the picture.

 

Hmm. That seems to have done the trick. I metered wide open, but then I stopped the lens down and also made sure the sub-command dial was set to the stopped down level also. Thanks Bebu!

You should meter with the lens wide open. If you meter with the lens stopped down then in the lens setting you will have to set the lens maximum aperture at that stop. For example if you use f/8 then you in the lens data you should set it at f/8 28mm. Set the aperture also at f/8 with the wheel then shoot. Of course this technique is a pain so you should meter with the lens wide open and then stop the lens down before taking the picture.

 

Should this also only be done with manual exposure and manual ISO selection?

Should this also only be done with manual exposure and manual ISO selection?

I just did a few more test shots, and this seems to be the case.

You should meter with the lens wide open.

Only if you're going to use the lens wide open.

 

There is no communication of aperture between old PC-Nikkors and the camera. They use manual preset aperture rings. So you cannot meter wide open and expect to get the correct exposure when the lens is stopped down.

 

From Nikon's Df lens compatibility guide, WRT older PC-Nikkor lenses:

 

"Exposure determined by presetting lens aperture. In mode A, preset aperture using lens aperture ring before performing AE lock and shifting lens. In mode M, preset aperture using lens aperture ring and determine exposure before shifting lens."

 

IME it's easier to just use the exposure computer built into your head, and put the camera in M mode.

 

"I consistently get shots that are overexposed by 2 or 3 stops."

 

- Check that the AI coupler isn't binding on the mounting ring of the lens. You should latch the AI coupler up when using these old non-coupled lenses.

Edited February 17, 2019 by rodeo_joe|1

Only if you're going to use the lens wide open.

 

There is no communication of aperture between old PC-Nikkors and the camera. They use manual preset aperture rings. So you cannot meter wide open and expect to get the correct exposure when the lens is stopped down.

 

From Nikon's Df lens compatibility guide, WRT older PC-Nikkor lenses:

 

"Exposure determined by presetting lens aperture. In mode A, preset aperture using lens aperture ring before performing AE lock and shifting lens. In mode M, preset aperture using lens aperture ring and determine exposure before shifting lens."

 

IME it's easier to just use the exposure computer built into your head, and put the camera in M mode.

 

"I consistently get shots that are overexposed by 2 or 3 stops."

 

- Check that the AI coupler isn't binding on the mounting ring of the lens. You should latch the AI coupler up when using these old non-coupled lenses.

 

It should work with lens wide open. You meter with lens wide open. you tell the camera which is the max aperture by entering lens data. You tell the camera which aperture it you would actually used for the exposure by setting the aperture with the wheel. Of course you also have to set the aperture on the aperture ring after you meter and AE lock.

BeBu is correct. The lens gets stopped down manually, and the camera also gets told -- via one of the command dials -- which aperture the user just stopped down to.

BeBu is correct. The lens gets stopped down manually, and the camera also gets told -- via one of the command dials -- which aperture the user just stopped down to.

That sounds over-complicated.

All I've ever done with both my 28mm f/3.5 and 35mm f/2.8 PC-Nikkors is use A mode with stopped-down metering, or take an open aperture reading and set the aperture and shutter speed manually after working out how many stops difference I need to adjust the shutter - which takes far less time than it's taken to type this.

 

I have never had a 2 or 3 stop overexposure error with either lens; unless I've actually forgotten to close the preset aperture!

 

"You tell the camera which aperture it you would actually used for the exposure by setting the aperture with the wheel."

 

Can you even do that on the Df?

No other Nikon DSLR allows body control of aperture unless a chipped lens is fitted. And anyway, what's the point of adding that extra step when you can just as easily adjust the shutter speed from an open-aperture reading?

Agreed with BeBu, if my understanding of the Df is correct: the Df knows the maximum lens aperture (because you told it in a menu) and how far you're going to be stopping down from that aperture (via what you've fed into the aperture dial). During exposure, after the meter reading is taken, the camera will drop its aperture lever and assume that the lens will reach the aperture you've told it - and, critically, that the image will get darker by the specified amount. On most AI (and indeed pre-E) lenses, dropping the aperture lever makes the lens stop down - but not the PC lenses. On those, you have to stop the lens down manually. There's no reason you couldn't use auto-ISO or aperture priority - but because you're going to change the amount of light coming through the lens when you manually stop it down (before the exposure), you'll need AE lock to tell the camera not to change its settings.

 

You can meter with the lens stopped down (by setting the aperture dial on the camera to suggest maximum aperture, so the camera doesn't expect light to change between metering and exposure). The matrix meter won't know the absolute brightness, but it shouldn't affect other modes. I'm less sure whether stopping down could cut enough light from the finder to cause confusion; I've never quite been clear how the limited visibility of depth of field in a typical finder affects the viewfinder metering process. I remain a bit disappointed that you can't do the "DoF preview + AE lock" trick on the Df, which would avoid replicating the aperture setting in two places - but would mean you wouldn't know some of the exposure settings until you stopped down.

"You tell the camera which aperture it you would actually used for the exposure by setting the aperture with the wheel."

 

Can you even do that on the Df?

No other Nikon DSLR allows body control of aperture unless a chipped lens is fitted. And anyway, what's the point of adding that extra step when you can just as easily adjust the shutter speed from an open-aperture reading?

 

I believe you can only do it on the Df. And the camera can't control the aperture (though again I'm not clear why in the case of an AI-S lens) - you still set the aperture on the lens, you just have to tell the body as well because it has no way to know the set aperture on a pre-AI lens with no AI coupling ring connection.

 

You can meter with the lens stopped down (by setting the aperture dial on the camera to suggest maximum aperture, so the camera doesn't expect light to change between metering and exposure). The matrix meter won't know the absolute brightness, but it shouldn't affect other modes. .

 

In this case the matrix meter does know the absolute brightness. It thinks that you use the lens wide open and the maximum aperture is what you set in the lens data.

In this case the matrix meter does know the absolute brightness. It thinks that you use the lens wide open and the maximum aperture is what you set in the lens data.

 

Oh yes. Sorry, not my brightest moment. I vaguely wonder whether the matrix meter knows about expected vignetting at different apertures, but I'm probably over-thinking it.

All I can say is that stopped-down A mode has worked perfectly well with a D700, D800 and a D7200 with my 35mm f/2.8 and 28mm f/3.5 PC-Nikkors, and using matrix metering.

 

I could understand under-exposure if the camera thinks the lens is still at maximum aperture, but not overexposure.

 

The Df system sounds over-complicated. I suspect that the camera's doing a double think, and metering at the preset aperture, but expecting it to be at open aperture until the shutter is tripped. And then the image brightness doesn't change to the programmed-in aperture, because the lens is already at that aperture.

 

My reasoning is that with lenses that have no auto-aperture control, you have to leave both the non-cpu lens data and the aperture wheel at the lens's maximum aperture. Just like with a 'normal' Nikon DSLR.

All I can say is that stopped-down A mode has worked perfectly well with a D700, D800 and a D7200 with my 35mm f/2.8 and 28mm f/3.5 PC-Nikkors, and using matrix metering.

 

I don't have PC lenses, and the only sort-of-kind-of preset lens I have is a 500mm Reflex-Nikkor.

 

In any case, I get perfect exposure in A mode also on every DSLR I've tried by putting 500mm and f/8 in the non-CPU lens data. Of course, that's the only aperture available on that lens, but none the less it works fine.

 

(a preset lens would REALLY make me wish for the old D2/D200 system where you could hold the Fn button, use one command wheel to set the focal length, and the other to set the maximum aperture).

As far as I know the non-CPU lens data affects only the EXIF information. If you forget to select the correct lens, or use an unlisted lens, the exposure does not vary. Since the listed aperture for a preset lens will be only what you set, and not what you use, it's really only useful if you need to be reminded later what lens you were using.

 

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