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04-15-2007, 03:36 PM   #1
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Question about my "A" lens...

OK, I just got my Tokina 28mm "A" that I altered from a Ricoh mount to fit my DS. Works great, have no complaints (about the workings, still getting used to the lens...)

But, when in auto aperture, the camera never shows an aperture of less than 5.6 even though he lens will go to 2.8. Is it just reading wrong? The aperture will adjust automatically as I make changes on the camera in shutter priority.

But if it reads wrong, doesn't that mean I can't ever use aperture priority? That is, if the lens is at 2.8 but the camera thinks it's at 5.6, won't the shutter compensate with a longer exposure, and therefore be too bright?

I have been using this in manual mode mostly, and just noticed this the other day. Ideas?

slinky

04-15-2007, 03:39 PM   #2
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Sry I can't get a complete pciture of your situation but this is what I think you are getting at.

Ok, if you are on "A" setting on the aperture, you can shoot in "Av" or Aperture Priority. Just roll the dial and the camera will change the aperture.

If you are in Manual, rolling the dial will only change your shutter speed. To change the aperture, roll the dial (with the lens set to "A") while holding down on the exposure compensation button. (+/-)

Hope it helps!
Pete,
04-15-2007, 03:49 PM   #3
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Sorry, let me try to be clearer...

In the Av setting I can change the aperture with the dial. But, although the lens can open up to 2.8, the camera will not go "above" 5.6 on the read out. Is this a limitation of the Av mode, or a mis read of a Ricoh lens on a DS?

If it's a mis read, won't my shutter speed be affected in Av, when I'm really at 2.8, but the camera "sees" 5.6, or will internal stuff make it all work right?

(I really should just play with it a bit more and figure this out, but I am not near the camera now, and was wondering...)

slinky
04-15-2007, 04:10 PM   #4
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Slinky,

I think what Pete is trying to figure out, is whether or not you aperture ring on the lens itself is set to "A" position? If not, do that, move it to where the "A" lines up with the vertical mark on the lens... If the lens is working properly, and it is set to the "A" position, you should have no issues with dialing your aperture setting through the camera from 2.8 to whatever the min aperture is.

Regards,
D

04-15-2007, 04:17 PM   #5
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here's a link to some info look for ka mount and you can check the contacts with an ohm-meter to see if they are o.k.Bojidar Dimitrov's Pentax K-Mount Equipment Page
hope this helps
tom

the contacts tell the camera body the maximum aperture

Last edited by borno; 04-15-2007 at 06:08 PM. Reason: clarification
04-15-2007, 05:55 PM   #6
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I use several "A" lenses and they all work great with a DSLR, so it's too bad this one is acting up. If the readout never goes below f/5.6 in Av, I would think that the lens wouldn't open up past that in Av, either. If f/2.8-4 work in M mode, you might just have to use M for any apertures larger than f/5.6. I have a lens that acts differently every time I put it on the camera, so I guess some old lenses come with eccentric personalities!
04-15-2007, 07:00 PM   #7
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Finn,

I have the same lens as you, the Tokina 28mm, f2.8 'A' lens, and I have never had any problems with it, as a matter of fact, it is one of my most used lens.

I have never had to make any alterations to it. However, it is the second lens of this type and brand that I have had, and the first one didn't work at all! So I would have to assume that you have a defective lens.

Good Luck,
Bill

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04-15-2007, 07:56 PM   #8
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I have the same problem using my 2X macro teleconverter and the 50mm 1.4 manual. It always reads 5.6 when attached. I think it's just an error with camera and it just says something to say something.

04-15-2007, 08:23 PM   #9
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QuoteOriginally posted by codiac2600 Quote
I think it's just an error with camera and it just says something to say something.
Haha thats hilarious. Yea, just shoot in Manual mode and/or use the DOF preview to verify that your lens is indeed at f2.8 when selected and not dropping to f5.6.
04-16-2007, 06:30 AM   #10
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Looks like a quirky lens, then. Manual is more fun anway.

If I get adventurous I may open it up again to see if something is out of wack with the sensors.

Is it likely that Ricoh lenses would have different wiring?
04-16-2007, 06:39 AM   #11
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Possibly, but then again, I've never have a Ricoh "P" lens.
04-16-2007, 07:17 AM   #12
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QuoteOriginally posted by FotoPete Quote
Possibly, but then again, I've never have a Ricoh "P" lens.
Be careful with Ricoh lenses. They sometimes have a projection that gets the lens stuck on the camera. It has to be cut off to use it on a true K mount.
04-16-2007, 07:28 AM   #13
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Yea I have only used the XR variants but I'll keep that in mind. Haha.

*Walks into a camera store and gets a Ricoh P 24-40/2.8 'stuck' on the camera. :P
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