Nikon 24mm F2.8 AIS infinity focus and exposure

minnnt

minnnt

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David
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Hi all, looking for a bit of advice. A friend has kindly lent me a 24mm ais lens to try on my Df but I can't seem to achieve infinity focus. It focuses close up and is sharp as a tack. What am I doing wrong?

Also, I have found some variation in exposure. Is this normal or not? I'm pretty sure it isn't but thought I would ask anyway.

TIA
David.
 
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What do you mean by "infinity focus?" "Infinity" varies and many lenses have the ability to focus "beyond" infinity... the mark is just a general reference/range.

If you mean "hyper-focus," then that's easy. For your FF camera, when the aperture is set to f/11 the hyperfocal distance is the FL as a percentage of itself... i.e. 24% of 24, or roughly 8ft. If you focus longer than 8ft you loose a little up close and gain a little at infinity. And if you focus short of 8ft you gain a little up close but loose a lot at infinity. Since the 8ft HFD is just a SWAG, and because you will be estimating the focus distance, I suggest estimating a little long unless what is very close is critical to the image... in which case I would bracket the distance.
Hyper-focus does *not* mean everything is in focus and tack sharp, it won't be... there is ever only one point/distance that is actually in focus.
 
Ok, please remember I'm dumb... :D

I do not get the focus confirmation dot when focusing on something 20-30 meters away and the image in clearly oof. This includes f2.8 - f16 inclusive. I wondered if adjusting the MA would make a difference? I know it's a MF lens but i once had a 17-50 which wouldn't achieve infinity without adjusting.

Thanks for the help so far.
 
minnnt said:
I do not get the focus confirmation dot when focusing on something 20-30 meters away and the image in clearly oof.
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Uhm... that's the way it's supposed to work...

Are you trying to say that the lens will/can not focus at greater distances/infinity? That's affected/controlled by flange distance and focus travel... neither is adjustable and flange distance isn't variable w/ Nikon DSLRs. If it won't focus at infinity then the lens is jacked up... AFMA will not help.
 
minnnt said:
Am i being thick?
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Maybe... probably ;)
The dot means the image is in focus... so no dot means OOF. Try ignoring the image and take the picture when the confirmation dot illuminates. If the image is recorded in focus, but it was not apparent in the viewfinder, then you need to adjust the viewfinder diopter setting.
 
Thinking it maybe faulty or in need of a strip down and rebuild. My friend had same sort of issue with an AIS lens and it was stripped, degreased and all realigned and worked perfectly.

Does it work ok on friends camera?
 
Focus travel is adjustable, Steven. It's just not easy to do.

Seems like it needs a service.
 
OK... reading through comments, I have the question "Is he not changing the focus with the focus ring?" ringing in my head, as that is what it sounds like; lens is 'stuck' on a close focus distance and you aren't changing it.... so eliminate dumb questions.....
Old error when swapping camera's in days past, has been people trying to 'focus' with the aperture ring (Or zoom control), rather than the focus.... are you twiddling the right ring?
A follow up from that one, I had a friend once grumbling that their lens didn't focus... the glue that held the rubber grip to the focus ring had gone hard and stopped sticking... they were just twisting the rubber around the ring, not the ring...
There's also a couple of anomalies with Nikon Legacy lenses, regarding the aperture 'coupling' I am none to familiar with. ISTR from a friend way back when who used a Nikkormat when I used an M42 Richoch copy; I had 'automatic' M42 lenses; when I stopped down on the lens ring, the ring didn't stop down the actual iris, it merely pushed a pin into the camera and told the TTL meter to adjust the meter reading; then when I pressed the shutter, the camera pushed the pin back into the lens, which DID close the aperture iris to the set setting. Which is effectively the 'modern' way its done, though these days electronically. The 'automatic' lenses had a switch to engage the iris with the aperture ring 'full time', which meant that the view-finder dimmed when stopped down, but allowed you to see effective DoF.
On the Nikon, the coupling between lens and meter was a small slotted tang on the aperture control ring, and I am not 100% sure exactly how that worked; BUT on a DSLR, there's a good chance that its not engaging with anything, and you are shooting 'wide open' all the time; you may have to find a button or knob to make the aperture iris track the control ring. This wouldn't necessarily explain why you are struggling to change focus though.
If any of that is of any help.
 
Ai lenses are known to have a certain degree of exposure variance as the aperture lever is not linear or something daft. AI-s lenses should not have this issue as they made changes to make it work consistently with the FA. Have you tried focusing in live view and seeing if you still can't get infinity?
 
Right, here are a few examples for people...

I was using auto iso but I don't think that would affect the scene?

F2.8 1/4000 iso 100

24mm ais by David Raynham, on Flickr

F11 1/250 iso 100

24mm ais by David Raynham, on Flickr

F2.8 1/400 iso 100

24mm ais by David Raynham, on Flickr

F11 1/125 iso 280

24mm ais by David Raynham, on Flickr

Crops from above to show OOF longer distances

F2.8

24mm ais by David Raynham, on Flickr

F11

24mm ais by David Raynham, on Flickr

And yes, I'm using the focus ring to focus with... :D
 
They're all private...
 
I've got a really old version of this lens (pre AI with a conversion) and it performs better at infinity wide open but your other shots look similar performance wise.


At F8
Pierhead Building by Kyle, on Flickr

Wide open.
Telegraph ID by Kyle, on Flickr
 
I don't think the lens is stopping down as it should. In the first two images the exposure settings are equivalent yet the second image is easily a 1/2 stop brighter. It could be the aperture blades, the aperture lever (lens), or the aperture arm (camera)... Unless you were using the aperture ring, in which case it could be the aperture index ring (calibration) or the communication lever (camera). It's typically something w/ the lens, but I've heard of the aperture arm on the camera getting bent. If it's a pre-Ai lens that has been poorly modified/adapted, that would do it.

Combine that with the poor focus and I think the lens needs serviced... not sure it's worth it or salvageable.
 
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minnnt said:
Are they not showing on the thread?
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They're showing, but when you keep them private no-one can download them to look at the exif data.

I was wondering what the camera reckoned the focus distance, aperture, speed and so on was, if that was recorded.
 
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