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JMA

XF35mmF2 Light Loss

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I'm consistently getting 3 stop darker exposures with my 35mm f2, regardless camera used or aperture setting, vs all my other fuji lenses, all being equal.

Other way to see it is  that I get ISO 3200 on the 35mm f2 vs ISO 400 to 640 on 7 different fuji lenses, same composition, same lighting, same speed, same aperture, same camera.

I understand light transmission could be different from lens to lens, but 3 stops? Is this normal for this lens or its defective?

Thanks

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@JMA That definitely sounds like your lens could be defective, possibly a stuck aperture blade. You should be able to see your aperture blades move, open, and close if you look into the front of the lens and click through the different apertures with the aperture ring. You may need to half-press the shutter to move the aperture blades, depending on your camera and settings. You should notice right away if something is amiss with the blades.

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Seems that is the case, at f2 it was stuck somewhere in the middle, after several actuations it fully opened. Now its working ok, but I guess will fail again eventually right?

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Yeah, if it's already sticking now, that's not a good sign for its longevity. I imagine it's still under warranty? Best to send it in for service if it happens again, or preemptively if you're able to be without it for a week or two.

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I was able to reproduce the issue now, does not seem to be stuck blades.

If I use it between f2 and f5.6 it works as normal, it opens or closes.....

If I go past f8 and then go back to f2, blades open only from f8-f16 (at f2 it opens at the same size as f8, and f16 as f16)

It wont go back to fully open the blades until I unmount the lens and mount it again (turn the camera of does not work). Seems to me that unmounting the lens resets or reboots it and then it works again.

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I can offer one troubleshooting suggestion.

The spring-loaded pins on the lens "telegraph" the aperture to the camera

and drive the aperture to set as ordered by the camera.

One of them is "common"(DC-return) to another that completes the circuit.  

They should move without any binding when depressed and released.

If any binding is detected, moving the pin manually thru its entire range of

motion might free it up.

That is the only user test I can suggest.

 

Correction;pins are in the camera body not the lens, so that tends to invalidate my 

suggestion because it seems to happen with only one lens.

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@farrell  Thanks!

after your suggestion, I did see the lens has some play when mounting, so cleaned the contacts and tightened the lens when mounting it and seems the issue is not appearing anymore, not sure if due this action or that I started to use the lens (it was stored for about 1 month)

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