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ais vs ai
Old 11-04-2018   #1
tonyp1
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ais vs ai

How can you tell from looking at a lens if it is ai or ais?

Is this the correct lens for a F3? I ask because it dose not seem like the aperture blades function once the lens is mounted..

Embarrassing but I am guessing because I can not see the aperture blades move through the lens once mounted they seem to close..

This is a tokina 28mm 2.8






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Old 11-04-2018   #2
Phil_F_NM
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The F3 doesn't know Ai from AiS. Only the electronic cameras like the F4 and FA make use of the AiS features.
Mount the lens and look into it from the front. Set the aperture to the smallest setting (f/16 or whatever) then push the dept of field preview button which is to the left of the lens when looking at the front of the camera. If the lens doesn't stop down, then you probably have a problem with it. You can unmount the lens and look to the left side of the flange on the camera then push that button again. A small lever on the inside of the flange should move up and down. If that doesn't with, the problem is the camera. Finally, set the lens on the camera, wind the shutter, set the aperture to a smaller opening, look in the front and fire the shutter. The lens should stop down instantaneously then open up.
Hope this helps.
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ais vs ai
Old 11-04-2018   #3
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ais vs ai

Quote:
Originally Posted by Phil_F_NM View Post
The F3 doesn't know Ai from AiS. Only the electronic cameras like the F4 and FA make use of the AiS features.

Mount the lens and look into it from the front. Set the aperture to the smallest setting (f/16 or whatever) then push the dept of field preview button which is to the left of the lens when looking at the front of the camera. If the lens doeant stop down, then you probably have a problem with it. You can unmount the lens and look to the left side of the flange on the camera then push that button again. A small lever on the inside of the flange ahould move up and down. If that doesn't with, the problem is the camera. Finally, set the lens on the camera, wind the shutter, set the aperture to a smaller opening, look in the front and fire the shutter. The lens should stop down instantaneously then open up.

Hope this helps.

Phil Forrest




Thanks, aperture is closed when looking through the lens unless pressing depth of field.



I guess I’m asking if this is normal?



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Old 11-04-2018   #4
CMur12
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Tony, the aperture should be fully open (for viewing, focusing, etc.) unless you press the DOF preview button. Pressing the DOF preview button will cause it to stop down/close to taking aperture.


You just said the opposite of this, so I don't know if you just mixed up your words or if the camera/lens is malfunctioning.


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Old 11-04-2018   #5
css9450
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Quote:
Originally Posted by tonyp1 View Post
How can you tell from looking at a lens if it is ai or ais?
I'm confused by your post also but in the photo you posted, the lens in question is AIS (an AI lens would lack the little semi-circular cutout near the locking cutout). But as mentioned above the F3 doesn't know the difference.
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ais vs ai
Old 11-04-2018   #6
tonyp1
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ais vs ai

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Originally Posted by CMur12 View Post
Tony, the aperture should be fully open (for viewing, focusing, etc.) unless you press the DOF preview button. Pressing the DOF preview button will cause it to stop down/close to taking aperture.


You just said the opposite of this, so I don't know if you just mixed up your words or if the camera/lens is malfunctioning.


- Murray


Yes this was my mistake. I could not tell if the aperture was functional on this camera.

It is fully functional. I just was worried because I guess I am use to fully electronic cameras lol.

I haven not used a manual lens since my F4 and that was 20 years ago lol.

I can see the aperture is fully operative now.

Sorry. Noob question lol.




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Old 11-04-2018   #7
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Glad the problem was answered, but nobody answered the difference (which is admittedly minimal): AI was original auto-indexing coupling from the days of manual-only and shutter-priority cameras. AI-s was, according to the manual of the FA, introduced for better programmed auto modes. The manual specifically states that it identifies the focal length range to select between the standard and 'high-speed' programs, through that milled notch in the back of the flange.

I've read elswhere that the aperture actuation lever travel was made uniform for more accurate P and S modes. Not elaborated in the FA manual, but does say these lenses 'give you uniform exposure control in any lighting situation."

The manual states that you still can use regular AI lenses in all modes and that should also be the case with the F4. The F3 won't care. Don't know which was the last that could do program and shutter priority with *any* MF lens, but I don't think any current models do.

How do you tell them apart? The milled notch seen in your first image, and the smallest aperture in orange.
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Old 11-04-2018   #8
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Quote:
Originally Posted by Takkun View Post
...but nobody answered the difference (which is admittedly minimal):
Another difference, at least valid for some of the Nikon AI and AI-S lenses I have/had, the focus throw is longer than on AI-S lenses.

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Old 11-04-2018   #9
Sumarongi
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Quote:
Originally Posted by tonyp1 View Post
Yes this was my mistake. I could not tell if the aperture was functional on this camera.
[...]
I can see the aperture is fully operative now.

Sorry. Noob question lol.
Actually, this is a good question *since there are many lenses that behave very very differently:

Automatic M42 lenses have an open aperture, when you remove them from the camera body, unless you have deactivated the Automatic feature (or you press the pin of course).

Some ancient West German Zeiss SLR lenses (Contarex), some West German RF lenses and almost the entire range of DKL lenses basically, all lenses that do not have an own aperture collar , have a closed aperture (f/22) when you remove them from the camera body.

The later Canon MF-SLR lenses (FD) are again a special case, AFAIK...
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