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11-03-2014, 09:21 PM   #1
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Shooting TAv and Av with fully manual lenses

UPDATE: Uggghh... I wasn't thinking straight and clearly my methods were off. Please delete this thread.
As Transit noted, the lens stays open in TAv and Av mode.

I think I have a way of shooting fully manual lenses in Av or TAv mode, but I am checking with you all to see if I am missing something.

I have a K-30 and a bunch of fully manual (ie, manual focus and no A aperture contact) lenses. I've gotten pretty accustomed to shooting in Manual mode. Frame the subject, rough focus, green button to meter, focus, shoot. If I want to use Catch in Focus, it makes it even easier.
  • I know I can shoot in Av mode with a manual lens if I'm shooting with the lens wide open.
  • I know that some people have removed the aperture tab on a lens to be able to shoot in Av or TAv mode, but I really don't want to ruin the lens or even mess with removing the tab.
SO...
I recently acquired a nice Pentax M50 f4 Macro lens. It is very sharp across the frame, even wide open at f4, so I can use Av or TAv mode. It does get even sharper at f5.6, so I was thinking...
If I'm pretty sure I just want to shoot at f5.6, I can use Av or TAv mode by simply adjusting my EV level. I.e., I set the lens at 5.6, but I up the EV (overexpose) by a compensatory number of steps. In this case, I ended up (after some experimenting) at shooting +1.7.
I don't see where anyone has suggested this, but my trials with it seem to work quite well. Is there any reason not to use this method?
The only things I have to remember are not to change the aperture on the lens and to reset the EV when I switch to another lens.


Last edited by mgvh; 11-03-2014 at 09:40 PM.
11-03-2014, 09:26 PM   #2
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I thought I stayed wide open except in M ?

Last edited by Transit; 11-04-2014 at 11:27 AM.
11-03-2014, 09:45 PM   #3
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Green button

The operation of the green button, as I understand it, is to stop the aperture down to your setting, and the Av mode then sets an appropriate shutter speed for that stopped down aperture. Changing the EV setting does not stop the lens down. Instead, you would still be shooting wide open at f 4.0 with a slower shutter speed, resulting in a greatly over-exposed image.

I am a little spoiled with my Canon FL 55 mm f 1.2 lens, which has been permanently converted to K mount. With this lens, you set the aperture you want then hand turn a ring to actually move the aperture blades to that setting. With outside photography with plenty of light, I can just leave the ring setting stopped down and change the aperture to the desired level. Av mode then works because the camera is then monitoring the amount of light actually entering the lens with no need to use the green button. Using the lens is a little less fiddly because you do not have to remember to push the green button. The lens is still manual focus, but if you are doing landscape, you can also just set the focus on infinity, and it is just like using a totally automated lens!
11-04-2014, 11:33 AM   #4
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QuoteOriginally posted by ivanvernon Quote
The operation of the green button, as I understand it, is to stop the aperture down to your setting, and the Av mode then sets an appropriate shutter speed for that stopped down aperture. ..etc
not with an M lens...
green button will stop down and meter in MANUAL then lens will stop down to that aperture on shutter release.
In Av or TAv, wide open all the way.

11-04-2014, 11:44 AM   #5
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QuoteOriginally posted by Transit Quote
In Av or TAv, wide open all the way.
Add P, Sv, and Tv modes to that list with one additional note. When the "A" contact is not detected and the mode is other than M, X, or B*, the camera defaults to Av mode with the aperture wide open. The green button and both e-dials are non-functional other than in M mode.


Steve

* In X mode, the shutter speed goes to 1/180s (non-changeable). In B mode, there is no metered exposure or operational e-dials (duh).

Last edited by stevebrot; 11-04-2014 at 11:52 AM.
11-04-2014, 03:15 PM - 1 Like   #6
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There actually is a way to use a manual lens in Av mode. Mount the lens as usual. Set the aperture ring so that the lens is set to fully stopped down. Press the lens release button and turn the lens as though removing it, but stop when the aperture blades are fully closed down. You can now set the aperture ring to the fstop of your choice and shoot in Av mode.

But it's not my fault if your lens falls off (though it shouldn't).
11-04-2014, 05:35 PM   #7
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QuoteOriginally posted by MPrince Quote
There actually is a way to use a manual lens in Av mode. Mount the lens as usual. Set the aperture ring so that the lens is set to fully stopped down. Press the lens release button and turn the lens as though removing it, but stop when the aperture blades are fully closed down. You can now set the aperture ring to the fstop of your choice and shoot in Av mode.

But it's not my fault if your lens falls off (though it shouldn't).
By golly, that works! I can use it a bit like a preset. Focus with it wide open then close down and shoot.
And I won't blame you if the lens falls off!
11-04-2014, 08:33 PM   #8
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QuoteOriginally posted by mgvh Quote
By golly, that works! I can use it a bit like a preset. Focus with it wide open then close down and shoot.
And I won't blame you if the lens falls off!
And this is easier than the green button? Go figure.


Steve

11-04-2014, 10:36 PM   #9
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QuoteOriginally posted by stevebrot Quote
And this is easier than the green button? Go figure.
Steve
I suppose it is just as easy for me to forget to change the aperture ring as it is for me to forget to use the green button...
11-04-2014, 11:34 PM   #10
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QuoteOriginally posted by mgvh Quote
I suppose it is just as easy for me to forget to change the aperture ring as it is for me to forget to use the green button...
Now you have me really confused. You don't have to change the aperture ring before or after using the green button when using a K-mount lens. The flow goes like this:
  • M-mode
  • Set aperture using ring on lens
  • Frame subject and press green button to set shutter speed based on the meter's center-weighted reading
  • (Optional) take test shot and adjust shutter speed as needed to suit
  • Shoot until either light or subject changes. The lens will stop down automatically for each frame.
Note that you only need to meter once per set of photos. This is the same general flow that was used with earliest TTL stop-down meters on cameras such as the Pentax Spotmatic. It is also the same general flow used with a hand-held meter. Real time metering is highly overrated and not needed for most subjects.

Note that the flow for adapted M42 screw mount lenses is a little different in that the automatic diaphragm actuation is not available with those lenses.


Steve

P.S. Using the menu to enable the aperture ring need only be done once and there is no real need to change it back. Why the default is set to "off" is anybody's guess.
11-05-2014, 08:22 AM   #11
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stevebrot: My point was that I realized that there is another step (setting aperture ring) when using that 'Av mode and twist the lens partly off' trick. I.e., it's the same number of steps as using M mode and the green button. >> It really is best just to use M mode.
But I do also enjoy using the M42s in Av mode...
11-05-2014, 09:17 AM   #12
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QuoteOriginally posted by mgvh Quote
stevebrot: My point was that I realized that there is another step (setting aperture ring)...
Cool! I was just making sure. We get a lot of questions where the user is jumping through hoops that are not there and it is not clear until late in the thread.


Steve
11-12-2014, 02:46 PM   #13
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I had an identical problem with my Kx and manual lenses. I found that in the Av, Tv, and P settings that the lens took pictures at full aperture, which resulted in over-exposure. In some cases the exposures were in the 1/5000 sec. range. In a recent thread I asked for help and was advised to set the camera and lens to M and then press the Green Button which would set the lens to the chosen value and give the appropriate expose time. When I first tried it, it didn't because the lens still didn't stop down. I found that I needed to reprogram the Green Button to ""Action in M Mode-Tv Shift". On pressing the Green Button I heard a loud click and the lens temporarily stopped down and the exposure was measured. On clicking the exposure button I got a perfect exposure at the selected aperture.
11-12-2014, 03:07 PM   #14
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QuoteOriginally posted by P. Soo Quote
I had an identical problem with my Kx and manual lenses. I found that in the Av, Tv, and P settings that the lens took pictures at full aperture, which resulted in over-exposure. In some cases the exposures were in the 1/5000 sec. range. In a recent thread I asked for help and was advised to set the camera and lens to M and then press the Green Button which would set the lens to the chosen value and give the appropriate expose time. When I first tried it, it didn't because the lens still didn't stop down. I found that I needed to reprogram the Green Button to ""Action in M Mode-Tv Shift". On pressing the Green Button I heard a loud click and the lens temporarily stopped down and the exposure was measured. On clicking the exposure button I got a perfect exposure at the selected aperture.
Normally if there is no lens data in manual mode it does thenTV shift any way. Alt least that's what I have found. It is only with A lenses that you need to be careful with program curves , at least in my experinece
11-12-2014, 03:59 PM   #15
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QuoteOriginally posted by Lowell Goudge Quote
Normally if there is no lens data in manual mode it does thenTV shift any way. Alt least that's what I have found. It is only with A lenses that you need to be careful with program curves , at least in my experinece
Thanks Lowell.
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