Author Topic: FTZ limitations: Aperture lever  (Read 1213 times)

Airy

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FTZ limitations: Aperture lever
« on: May 01, 2019, 07:04:32 »
The FTZ adapter has no aperture lever. One is forced to use old Nikon MF lenses, or brand new Zeiss lenses, in stopped-down mode.
This is a mixed blessing (ahem):
+ when focussing a stopped down lens, focus shift is no longer an issue, but
- accuracy of focus is less, and
- the EVF needs more amplification, which may lead to a degradation of the image in dark places, again making the focus more difficult
- no aperture info is provided in the EXIF or in the viewfinder

Point #4 is moderately annoying. I've been shooting that Leitax-mounted Summicron R for a couple of years now, and lack of aperture data is not harmful to pictures. One has to learn "stopping down by feel", leading to some uncertainty or slowing down in the shooting process, but anyway I'd use such lenses for "slow photography situations". Nevertheless, I am not pleased to see the compromizes applying to Summicron and a couple of shift lenses being generalized to all MF lenses...

Point #3 is more annoying (from my short experience), but as annoying a muddy and flickering OVF image may be, it may still provide more accurate focussing info than an OVF in the same dark place, so I'm not sure it is a real handicap compared with MF lens + aperture lever + OVF.

Point #1 is probably going to be a plus with some lenses (50/1.2...); fortunately the focus shift compensation is especially critical in the f/2-f/4 zone, not fully stopped down.

In any case - and back to the topic - an aperture lever would be nice, and is probably feasible, drawing some low power from the camera. Any idea about whether this could become available, either from Nikon or from 3rd parties (... Zeiss, for instance...) ?
Airy Magnien

Hugh_3170

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Re: FTZ limitations: Aperture lever
« Reply #1 on: May 01, 2019, 10:24:51 »
Such an adapter would need a lot of extra electronic "smarts" in order to fool the Z body into thinking that it had a bona fide chipped lens on board, as well as the necessary aperture linkages. 

At a price most things are do-able, but I suspect that it would require a fair bit of investment to bring into reality.  At the end of the day, how strong is the market and what will people with legacy lenses pay for such an adapter?
Hugh Gunn

Birna Rørslett

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Re: FTZ limitations: Aperture lever
« Reply #2 on: May 01, 2019, 10:34:30 »
Better to bit the bullet and chip the lens.

Alaun

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Re: FTZ limitations: Aperture lever
« Reply #3 on: May 01, 2019, 11:12:32 »
At least at the lens side of the FTZ you have the known pins from the F-mount.  So if you put a chip into the FTZ connected to these pins …  Copy the functionality of the chip with a modern maker board -like Arduino-  add two switches to select focal length and max aperture plus a little display   …. and you can use any lens like a chipped lens. Does not sound that difficult, once you know the “language” of the F-mount.
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Birna Rørslett

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Re: FTZ limitations: Aperture lever
« Reply #4 on: May 01, 2019, 12:46:20 »
In fact, Erik and I did this with the FT-1 adapter for F->CX mount (1 Nikon series).  A switch allowed the FT-1 to work in pass-through mode (ie., function as normal), or use the additional CPU (programmable).

This setup would in principle allow any F-mount lens to be attached and operate in "G" mode, that is, with aperture control from the camera side.

Jack Dahlgren

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Re: FTZ limitations: Aperture lever
« Reply #5 on: May 01, 2019, 15:26:34 »
At least at the lens side of the FTZ you have the known pins from the F-mount.  So if you put a chip into the FTZ connected to these pins …  Copy the functionality of the chip with a modern maker board -like Arduino-  add two switches to select focal length and max aperture plus a little display   …. and you can use any lens like a chipped lens. Does not sound that difficult, once you know the “language” of the F-mount.

I agree, a smart FTZ would not be hard to create. Just need to know the protocol. I’m sure some here know the details. If they could share I would try to create such a thing.

Airy

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Re: FTZ limitations: Aperture lever
« Reply #6 on: May 01, 2019, 16:11:26 »
Electronically, yes, you are right. However it is not the chipping and the connections to it I miss, but the aperture lever... (none of my AI lenses are chipped, and I do not miss that).
Airy Magnien

Birna Rørslett

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Re: FTZ limitations: Aperture lever
« Reply #7 on: May 01, 2019, 16:39:41 »
One "super" FTZ could serve all of your lenses ... and provide the EXIF data including aperture setting. The aperture lever and its mechanical linkage can be dispensed of with the appropriate adapter and more streamlined interfacing to the camera attained at the same time.

Airy

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Re: FTZ limitations: Aperture lever
« Reply #8 on: May 01, 2019, 19:16:21 »
Not sure I understand. In any case I need a mechanical device to keep the iris open, then release it to the (mechanically) selected f-stop, then open again. That device could be contained in the adapter, the latter receiving the power and the triggering signal from the body.
Airy Magnien

Birna Rørslett

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Re: FTZ limitations: Aperture lever
« Reply #9 on: May 01, 2019, 19:40:52 »
The FTZ already contains those components. There is a aperture stop down lever and a camera-controlled spring to keep the aperture set at a required position. These provide the means by which the camera can set aperture on the lens. The flow of information however is in direction from Z camera to lens, as there is no aperture follower on the FTZ. Thus the camera needs a feedback from the lens via a communication protocol if stop-down shooting is to be avoided. A lens with CPU performs this task.

The main difference between the mount on an F camera and the FTZ is the latter only can operate in "G" mode whilst the former, given the lens has a CPU, can be either in "P" or "G" mode depending on the user's settings.

Roland Vink

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Re: FTZ limitations: Aperture lever
« Reply #10 on: May 01, 2019, 22:52:05 »
Hopefully Nikon release another FTZ adaptor which also has the AI linkage (and maybe a pre-AI aperture linkage as well) so that the aperture of non CPU lenses can be recorded in EXIF data. To keep it simple it could even omit the aperture stop-down linkage, which would mean such lenses would be limited to stop-down metering. This adaptor would give better support to non-CPU lenses and retain full capability with "E" lenses with electronic aperture. On the other hand it wouldn't work with "G" lenses, but the current FTZ can be used for those lenses.

The only disadvantage is the EVF needs more amplification, especially at small apertures in dark places as noted by Airy. You could work around this by focusing at perhaps a medium apertures to let in more light, and stopping down fully just before taking the picture. Composing at a medium aperture, perhaps 2 stops down from wide open should eliminate most problems with focus shift, there is not usually much more shift when stopping down further.

Birna Rørslett

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Re: FTZ limitations: Aperture lever
« Reply #11 on: May 01, 2019, 23:05:09 »
This is not likely going to happen as the Z system has no provision for the "P" mode of aperture operation as far as I can ascertain.

Nikon, on the other hand, has silently tried to move away from the mechanical linkages by introducing "E" lenses and sooner or later these will be the dominant Nikkor species. That change in policy makes the release of an FTZ with aperture linkage even less likely.

pluton

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Re: FTZ limitations: Aperture lever
« Reply #12 on: May 02, 2019, 01:17:32 »
To keep it simple it could even omit the aperture stop-down linkage, which would mean such lenses would be limited to stop-down metering....
The only disadvantage is the EVF needs more amplification, especially at small apertures in dark places as noted by Airy. You could work around this by focusing at perhaps a medium apertures to let in more light, and stopping down fully just before taking the picture. Composing at a medium aperture, perhaps 2 stops down from wide open should eliminate most problems with focus shift, there is not usually much more shift when stopping down further.
This is all coherent reasoning, Roland, but in my experience with *Fuji EVFs*, focusing stopped down is pretty much as annoying and inaccurate with EVFs as it is with OVFs.  I wouldn't buy such an adapter.  I would rather meter by trial and error(checking the histogram), and once having ascertained a good exposure, continue setting exposure by dead reckoning the light on the scene.
Keith B., Santa Monica, CA, USA

Roland Vink

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Re: FTZ limitations: Aperture lever
« Reply #13 on: May 02, 2019, 01:42:39 »
Stop down metering is probably more accurate in good light since there is no discrepancy between the dialled-in aperture and the actual aperture, and it eliminates focus-shift too. But when stopping well down in poor light the meter will struggle since it has very little light to work with. How often do you use small apertures in poor light? Most of the time I would use wider apertures to keep shutter speeds up and ISOs down to a reasonable level, but there are always exceptions... :o

When I was at Grays of Westminster last year we discussed the possibility of an AI FTZ adaptor. He said it might happen if there was enough demand, but I have no idea if it is technically possible, and how does Nikon gauge "demand" for these things anyway? :)

Airy

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Re: FTZ limitations: Aperture lever
« Reply #14 on: May 02, 2019, 06:51:29 »
Apparently, I started from the false premise that FTZ has no aperture lever. So, stopped-down metering is not mandatory. Fine then.
Airy Magnien