My Nikon z7 w/ FTZ adapter just arrived! But what am I missing?

I still don't know how the FTZ works with AI lenses. It's supposed to work but how?

Stop down metering, surely?

Stop down metering, surely?

I am not sure. I read both the FTZ and Z7 manual but still don't know how it works.

Interesting - I can't spot it obviously described in the manual either (though I've only skimmed briefly). The "non-CPU lens data" menu is still present, though, so I don't think Nikon have just forgotten to mention incompatibility.

I imagine either there's stop-down metering, or it's like the low-end bodies and there's no metering at all. It would presumably be the latter unless the aperture lever drops downwards to "minimum aperture position" unless an electronic lens is mounted (which... I don't see why not, I suppose), but the presence of "non-CPU lens data" suggests the expectation of an AI follower ring (at least on some future version of the FTZ adaptor), otherwise I'm not sure what the non-CPU lens data is supposed to do for you - unless there's a copy of the Df's set-the-aperture-twice thing.

I guess it should be easy enough to try out: stick on an AI lens and see whether you get any metering information. Presumably manual mode should just work ignoring the metering question, with the aperture set by the ring on the lens, as for other recent (in the last twenty years...) bodies.

Update: Hypnoken purports to have tried it, and says the FTZ stops down to the shooting aperture in order to meter immediately before taking the shot (so the EXIFs are confused because it doesn't know the aperture, but the metering works for manual mode and aperture priority). I'm pleasantly surprised - I was expecting the aperture lever to dangle so you had to focus at the final aperture, but apparently it actually makes them behave like an SLR with a moving aperture lever.

But doing so you would have to stop it down before you can meter manually and in A mode the it can not display the shutter speed as it wouldn't know which shutter speed will be until it stops the lens down. Still don't know how it works.

But doing so you would have to stop it down before you can meter manually and in A mode the it can not display the shutter speed as it wouldn't know which shutter speed will be until it stops the lens down. Still don't know how it works.

The way my purely manual (no aperture lever) lenses work is that you do, indeed, have to stop them down with their aperture rings prior to metering - which makes the display dark before shooting. These lenses tend to have a quick way of toggling between a set aperture and wide open. I was kind of expecting this behaviour from the FTZ, since using the main sensor to provide live view would avoid the problems a dSLR has with the viewfinder blacking out as the aperture shrinks. However, Ken reports that Nikon did better.

It appears that the FTZ adaptor normally holds the aperture lever open (up) for composition and focus, then, on a manual lens, drops the lever (so you get the aperture selected on the lens's aperture ring) immediately before exposure, and meters from that position. I believe this is similar to the FA's "open loop" metering system. Since there isn't a mirror to flap out of the way, this may not introduce much delay to the exposure. This means you get manual exposure as you would expect (with auto-ISO applied if you enabled it) and that aperture priority mode can work by deducing the shutter speed on stop-down.

It's true that the camera won't know what the actual aperture is, because it doesn't know where you've moved the lens's aperture ring to. If you want to know the shutter speed (or ISO) in advance, you wouldn't. On the other hand, I imagine that the camera could display (predicted) ISO (in auto-ISO), shutter speed (in aperture priority) and meter reading (in manual exposure) if you enable depth of field preview - which it appears you have to program to an Fn button since neither of them is now "Pv" by default. It's not significantly more "predicted" than a dSLR, at least if you can mash the shutter button while depth of field preview is held down, but you're relying on sensor gain to emulate the exposure if you also want to see what the exposure looks like while stopped down - and you're still missing out on the "wide open" depth of field for nailing focus, so you pick your poison. Apparently focus peaking is useful. I've yet to find anything in the manual which says this is what happens, but it would be the obvious thing to do.

I'd be interested to know whether anyone can confirm this behaviour, since I've not actually seen one yet and I'm essentially speculating. You still wouldn't get the shooting aperture recorded in the EXIF, of course.

t appears that the FTZ adaptor normally holds the aperture lever open (up) for composition and focus, then, on a manual lens, drops the lever (so you get the aperture selected on the lens's aperture ring) immediately before exposure, and meters from that position.

My experience has been the opposite sorry to report. As you stop down the aperture ring the monitor/view just goes black.

My experience has been the opposite sorry to report. As you stop down the aperture ring the monitor/view just goes black.

Thanks for the correction, Chris. That's disappointing (from a purely academic, I have no particular inclination to buy a Z7 perspective). I was going to ask whether you had exposure preview turned on (the "ok" button in live view on a dSLR), but after failing to find "exposure preview" in the Z7 manual (and stopping myself searching for "live view"), I'm still confused. Does option d8 make any difference? Does assigning a function button to "preview" and using it?

Just so I'm clear, the viewfinder goes black as you adjust the aperture ring, so the aperture ring is directly moving the aperture lever? It won't be the first random inaccuracy on Ken's site, but it's odd that you seem to have significantly different behaviour - he was pretty explicit that metering was working for him.

I gotta say metering, skeetering.... :D

As long as it shuts down to what I have set for the duration of the exposure, like an old preset, and for LV (what else is there?!!) the aperture is wide open for focusing/composition, metering doesn't bother me.

If it 'all goes black', I'm not interested!

Just so I'm clear, the viewfinder goes black as you adjust the aperture ring

The monitor view works as expected AFTER you set the lens aperture ring to the maximum level. In this case of my Voigtlander 125mm SL its f2.5. When you turn the ring towards the minimum level it gets darker to the point you can't see the image i.e. all black. It could be a combability issue as I original stated due to the third party lens, however the lens works perfectly on my D500 using both the aperture ring and the subcommand dial after the respective menu options are set to allow this.

The voigtlander 58mm SL II N lens I own works as expected although that one has a CPU in it. Have to use subcommand dial to work aperture - but it works. Using the lens aperture ring just gives a error as I would expect.

But doing so you would have to stop it down before you can meter manually and in A mode the it can not display the shutter speed as it wouldn't know which shutter speed will be until it stops the lens down. Still don't know how it works.

Nikon adjusts exposure with AI and newer lenses by stopping down known increments from the maximum lens aperture. In other words, the aperture is based on how far to move the lever, and what the starting point is. Since exposure can only be measured with the mirror down, any damage to the lever in the camera or lens will cause a systematic error which cannot be corrected automatically. Older cameras, which sense the position of the aperture ring, can be set manually, measuring exposure in the stopped-down position.

If all this seems like an a-backward solution, it is, but it worked for over 50 years for Nikon.

Does the Z7 allow totally manual operation? ie no lens present (to it's mind at-least)

It does turn on and present icons. I have no idea if it can take a picture though I didn't try that.

Homework for tonight! ;)

I'm sure it should be able to, afterall the Series 1 cams could....:)

Nikon adjusts exposure with AI and newer lenses by stopping down known increments from the maximum lens aperture. In other words, the aperture is based on how far to move the lever, and what the starting point is. Since exposure can only be measured with the mirror down, any damage to the lever in the camera or lens will cause a systematic error which cannot be corrected automatically. Older cameras, which sense the position of the aperture ring, can be set manually, measuring exposure in the stopped-down position.

 

If all this seems like an a-backward solution, it is, but it worked for over 50 years for Nikon.

I'm not sure that's wrong, since it confuses me, but I think I should paraphrase...

Most Nikon bodies calculate the difference between the exposure measured when the lens is wide open (normal mounted position) and the shooting aperture by knowing the number of stops between the two. On pre-AI lenses the "bunny ears" hook onto the meter and communicate both the maximum and current aperture (I believe - I've never actually handled an F or F2). On non-electronic AI lenses, the position to which the lens's aperture coupling ridge moves the aperture following tab tells the camera how many stops down the lens is set to, compared with the maximum aperture; on AI-S lenses there is a "maximum aperture post" used for matrix metering on the FA et al., but most bodies ignore it. Prior to G lenses, this is also the behaviour on an electronic lens if you set the aperture with the lens ring.

Only AI-S lenses and later (prior to E) have a linear relationship between the aperture change and the movement of the aperture lever. For reasons still not completely clear to me, only electronic lenses (which communicate the maximum, but not current, aperture electronically) can have the aperture controlled by a dSLR by partial movement of the aperture lever.

On any lens for which the aperture is being set by the aperture ring, the body will just (I believe) move the aperture lever through its full range of travel. The aperture actuator on the lens moves as the aperture is closed under spring pressure, but stops once it mechanically hits its interaction with the mechanical aperture ring on the lens. This is why you can manually change the current aperture on a Nikon lens by turning the aperture ring, why you need to set the aperture to minimum for the aperture lever on the camera to control the aperture (otherwise you wouldn't know whether the ring or the lever movement was going to take effect first), and why Nikon lenses default to "stopped down" - unlike E-aperture (and Canon EF) lenses, which are wide open when no current is applied to the aperture system (this happens during the exposure).

When you use depth of field preview, the camera similarly moves the aperture lever either through part of its range (if the camera is controlling the aperture) or through its whole travel, relying on the aperture ring stopping the movement of the lens aperture post (if the lens is controlling the aperture). Some film bodies support stop-down metering by taking an exposure lock during depth of field preview, which allows metering to work (sometimes with limits) with a pre-AI lens on bodies that can't engage with bunny ears.

I believe only a few cameras will actually meter after the lens stops down automatically; notably, the FA (unless I'm confused) can do this in order to support shutter priority with AI lenses, meaning it can dynamically move the aperture actuation lever with the meter in a feedback loop. It shouldn't need to do this with an AI-S lens, because it should know the relationship between the aperture lever position and selected aperture in the way that modern cameras do with electronic lenses, so it can run open loop. The closed loop system adds a bit of delay. Again, unless I'm confused. I'd kind of like an FA to play with (despite a lot of reading, there are slightly conflicting reports online) but I'm warned that most of them don't work...

Anyway, TL;DR about a subtle point: when the aperture ring is controlling the aperture, the communication between the aperture ring and the camera is how far the aperture will move when the aperture lever is dropped, not how far to move the aperture lever.

At least, all of that applies, to the best of my knowledge, to the SLRs. The FTZ is another matter, and I'm still a bit confused as to what it does with non-electronic lenses. Ken's table absolutely claims it can meter with them, so I can't explain the disparity.

At least, all of that applies, to the best of my knowledge, to the SLRs. The FTZ is another matter, and I'm still a bit confused as to what it does with non-electronic lenses. Ken's table absolutely claims it can meter with them, so I can't explain the disparity.

Thanks Andrew for that great explanation of Nikon lens mount history. However it seem, for some reason, that my setup if "always" in DOF preview mode. Therefor if you move the lens aperture ring to something other than maximum you get a darker image on monitor progressing towards minimum/blackness. Obviously camera has no way of knowing aperture and is indicated by the blinking and bank aperture field on the monitor.

I read somewhere on this site a long time ago that if you, on film cameras that don't have DOF preview, you can partially disengage the lens on the mount to achieve this. While not recommended it does work. This is by far the best explanation of how my FTZ is working even though lens is/was clearly locked in.

Thanks Andrew for that great explanation of Nikon lens mount history.

(Which I hope I got right. But you're welcome!)

However it seem, for some reason, that my setup if "always" in DOF preview mode. Therefor if you move the lens aperture ring to something other than maximum you get a darker image on monitor progressing towards minimum/blackness. Obviously camera has no way of knowing aperture and is indicated by the blinking and bank aperture field on the monitor.

I'd kind of expect this behaviour if the camera decided that, with no electronic contact with the lens, it should just drop the aperture lever to its minimum setting. This would kind of make sense if the camera weren't going to try to meter automatically after stopping down - it would essentially make manual lenses with an aperture lever behave like manual lenses without any coupling to the camera at all, which isn't the end of the world so long as you're not trying to focus on a moving subject in the dark. It doesn't seem to be what Ken reported, though.

Your FTZ does work properly with electronic lenses, does it?

I read somewhere on this site a long time ago that if you, on film cameras that don't have DOF preview, you can partially disengage the lens on the mount to achieve this. While not recommended it does work. This is by far the best explanation of how my FTZ is working even though lens is/was clearly locked in.

(Trying to train myself to use the terminology from here...) That should work because the aperture coupling lever opens the lens aperture by rising upwards, pushing the aperture stop-down lever on the lens clockwise, facing the lens mount on the camera (anticlockwise facing the back of the lens). If you partly "unscrew" the lens, you move the aperture stop-down lever clockwise relative to the aperture coupling lever, so it stops holding the aperture open and the lens stops down.

For one reason or another, it sounds as though the FTZ's aperture coupling lever isn't pushing on the lens's aperture stop-down lever, and the only thing holding the lens aperture open is the aperture ring on the lens. I guess the question is whether this is supposed to happen, or whether there's something wrong.

I'd be interested to know what behaviour Chris sees with other lenses (especially electronic ones that are really supposed to be automatic), and if anyone else reports different behaviour.

I'd be interested to know what behaviour Chris sees with other lenses (especially electronic ones that are really supposed to be automatic), and if anyone else reports different behaviour.

My other Voigtlander 58mm SL II N works as expected. This lens is a newer design and is chipped.

For one reason or another, it sounds as though the FTZ's aperture coupling lever isn't pushing on the lens's aperture stop-down lever, and the only thing holding the lens aperture open is the aperture ring on the lens. I guess the question is whether this is supposed to happen, or whether there's something wrong.

That's exactly what it looks like I'm experiencing.

I'm wondering if anyone else has this experience. When I power up the camera with the FTZ on it makes a wurring noise kind of like it's hunting for something. Don't know if that's normal or not. Doesn't matter what or if a lens is present.

Interesting. Thanks, Chris.

Anyone else?