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11-02-2009, 03:29 PM   #1
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FA 100mm f 2.8 macro - defective focus limiter

I just purchased a used copy of this supposedly rugged lens from a German store. Trying the lens out, I find that it shows a somewhat odd behaviour in a couple of respects:
- Using the ”A” setting of the aperture ring, the lens is not stopping down properly during exposure (or during depth of field prewiew). If aperture is set to f 4.0 on the camera, lens is not stopping down at all. If I manually set aperture to f 4.0 on the lens aperture ring, it is stopping down properly, and manually metering properly. The effect of this misfunction is that the lens overexposes when stopped down on camera. At f 2.8 it meters correctly. The needed correction when stopping down to f 8.0 seems to be +1.7 - +2.0.

- The focus limiter is supposed to limit focus range from 0.6m – infinity. If set at ”full” or ”manual” there is supposed to be no stop in the focusing range. However, when I set the limiter at ”full” and then focus at close range (closer than 0.6m), the lens refuses to focus on longer range afterwards – the range is then limited from 0.3 – 0.6m. To achieve the full focus range again, I have to dismount the lens from the camera body and manually turn the focus ring to infinity position. The lens also acts as described (locking in the close range) if i manually focus from infinity to close range, and try to turn it back – it stops at the 0.6m point.

- Focus clamp is as i understand supposed to lock the focusing mecanism however on this copy it only gives a slight resistance, making manual focusing a little damped, not stopping it. Not sure if this is normal.

I wonder if anybody else has similar experiences with this lens? I have apporached the seller telling how the lens acts, and asked for suggestions to a solution. Any experiences or thoughts?

Best Regards
Svein Erik

11-03-2009, 03:10 AM   #2
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That sounds wrong to me. My copy is working fine on the Aperture side. It stopps down correctly i A mode when using DOF preview.

The focus limiter om mine sets a stop to the range of the barrel and AF is then restricted to the range starting from fully inside to somewhere on the midle going out. Turning the limiter to MF or Full opens upp the locking device (or whatever it is named).

The Focus clamp on mine behaves as yours do, exactly. It just stiffens the focus a bit but does NOT lock it. I think its the way it should be. Because if you AF against the a locked barrel maybe you could hurt the focus drive!

Someone told me that its not even recomended to use AF with the clamp turned in.
11-03-2009, 02:43 PM   #3
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FA 100mm macro - interesting developement

Thanks for the confirmation that the lens is not supposed to act like I experienced.

However, doing further testing today, I find that the focus limiter now works OK, and the focus ring turns freely all the way when limiter i set to "full" or "MF"!!! There is a slight sound and feeling of passing an edge when passing the 0.6 m mark from closeup to infinity, but the focusing now seems to run freely as it is supposed to do. Will be interesting to see if this lasts.

However the stopping down problem is clearly permanent. But the exposure ajustment, is, to be honest, pure routine and no big obcstacle shooting macro.

So now I consider keeping the lens as it is - after all it is optically excellent and solid built, compared to the newer plastic version.

A couple of examples shot last weekend can be found here:
http://www.setoien.com/Images-by-lens/FA-100mm-f-28-macro/10206279_gzHFz#698607495_MrdVR

Best regards
Svein Erik

Last edited by SEToien; 11-04-2009 at 12:42 PM.
11-03-2009, 03:16 PM   #4
Ash
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QuoteOriginally posted by SEToien Quote
I just purchased a used copy of this supposedly rugged lens from a German store. Trying the lens out, I find that it shows a somewhat odd behaviour in a couple of respects:
- Using the ”A” setting of the aperture ring, the lens is not stopping down properly during exposure (or during depth of field prewiew). If aperture is set to f 4.0 on the camera, lens is not stopping down at all. If I manually set aperture to f 4.0 on the lens aperture ring, it is stopping down properly, and manually metering properly. The effect of this misfunction is that the lens overexposes when stopped down on camera. At f 2.8 it meters correctly. The needed correction when stopping down to f 8.0 seems to be +1.7 - +2.0.
I wonder if anybody else has similar experiences with this lens? I have apporached the seller telling how the lens acts, and asked for suggestions to a solution. Any experiences or thoughts?

Best Regards
Svein Erik
Hi Svein.
I have the same lens but with the focus limiter taken out, so I can't comment on its function. You say that stopping down causes overexposure when at EV0? It does the same with my copy. But if you're getting overexposure, you would have to turn *down* EV, not turn it up to +1.7. I turn mine down to -1.3 to -1.7 when stopping down to f/11 and beyond. At f/8 - it's good at -1.0. f/2.8-4 - it's good at EV0.

I don't know if this is normal, but mine appears to stop down normally in A mode on the aperture ring.

11-03-2009, 04:17 PM   #5
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Hello, Ash,
you are perfectly right about the exposure ajustment - I have to ajust to -1.7 - -2.0 at f 8.0. My type mistake.

Interesting to hear that you use the lens without a focus limiter. Actually, I don't find focus hunting is a problem with this lens - and shooting macro I find manual focus is preferable anyway...

Best regards,
Svein Erik
11-03-2009, 11:58 PM   #6
Ash
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I do also - it's a fine lens to use manually, solid and smoothly dampened focus ring.
AF is quite zippy too.
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