Nikon Photomic FTN finder problem

Stephen Furley · Sep 4, 2022

About 11 years ago I put all of my cameras into store because failing eyesight was making it almost impossible to use them. Recently I have got them out again and am trying to use some of them. I generally prefer the non-professional Nikons but I do have one professional one, a F from 1970. The camera itself is working but I have a Photomic FTN finder which has a problem, or maybe I'm just doing something wrong; I'm not sure if I ever actually used the camera with this finder fitted. Thr problem is that when I try to mount a lens fitted with the 'rabbit ears' coupling shoe this pushes the coupling pin upwards into the body ot the finder where it remains so that it is too high to enter the slot in the coupling shoe, and so the lens does not couple. The manual says that the coupling pin should be pushed up in this way when mounting an uncoupled lens, but does not say how to get it down again, and it shouldn't be in this position when mounting a coupled lens. At the moment the only way I can get a lens to couple is to remove the finder, set the aperture to f5.6 and then re-fit the finder so that the pin enters the slot.

Thanks for any help you can give

reddesert · Sep 4, 2022

Roughly speaking this is how it's supposed to work, for the FTn finder (the last of the F finders, which has the large release lever on one side):

- at rest, with no lens attached, the coupling pin is in the center.

- if you push up on the coupling pin with your finger, you hear a spring-firing noise inside and the indicator in the maximum-aperture window on the front of the prism moves to f/5.6. This is what they intend you to do for lenses with no aperture prong, as (I think) in this position the prism will meter in stop-down mode (you use the DOF preview to stop down the lens and take a reading).

- when you mount a lens, twist the aperture ring toward larger f-numbers and the pin will ride over the prong, then engage the center notch and follow the prong. Then twist the aperture ring to the maximum aperture (smallest number) and the indicator in the window on front will follow, showing f/2.8 if you have an f/2.8 lens mounted, etc. This sets the meter up for open-aperture reading, and is slightly simpler than the twists required by earlier versions of the prism.

If the pin is not engaged by the prong as you twist the aperture, then it sounds like the spring that pushes the pin down and into the notch is not functioning. It is possible that the mechanism has been damaged by someone wrenching on the pin while dismounting a lens in an uncouth manner. It could be as simple as an unhooked spring or a bent piece of metal.

Stephen Furley · Sep 4, 2022

reddesert said:
Roughly speaking this is how it's supposed to work, for the FTn finder (the last of the F finders, which has the large release lever on one side):

- at rest, with no lens attached, the coupling pin is in the center.

- if you push up on the coupling pin with your finger, you hear a spring-firing noise inside and the indicator in the maximum-aperture window on the front of the prism moves to f/5.6. This is what they intend you to do for lenses with no aperture prong, as (I think) in this position the prism will meter in stop-down mode (you use the DOF preview to stop down the lens and take a reading).

- when you mount a lens, twist the aperture ring toward larger f-numbers and the pin will ride over the prong, then engage the center notch and follow the prong. Then twist the aperture ring to the maximum aperture (smallest number) and the indicator in the window on front will follow, showing f/2.8 if you have an f/2.8 lens mounted, etc. This sets the meter up for open-aperture reading, and is slightly simpler than the twists required by earlier versions of the prism.

If the pin is not engaged by the prong as you twist the aperture, then it sounds like the spring that pushes the pin down and into the notch is not functioning. It is possible that the mechanism has been damaged by someone wrenching on the pin while dismounting a lens in an uncouth manner. It could be as simple as an unhooked spring or a bent piece of metal.

Thank you. Sounds like I'll have to get it looked at. No spare money until May when I get my state pension. No chance I could dismantle it myself, my eyesight is now so bad that I couldn't see what I was doing. This is type 2 diabetes related.

beemermark · Sep 4, 2022

I've had an F2 with the same problem. Looking closely I could see that the pin arm was pushed back slightly and dragging on the finder body. Very light tweak with my pocket knife set things right.

Nikon Photomic FTN finder problem

Stephen Furley

reddesert

Stephen Furley

beemermark

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