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10-09-2010, 05:15 PM   #1
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Using the Aperture Ring on Auto Focus Lenses

Using my Tamron 28-75 for action photos gave me really nice results. On the Kx however, there is no TAv mode. Would it be possible to use the aperture ring in shutter priority mode to obtain a greater FOV and let the camera choose the optimal ISO?

BTW I'd like to mention that AF-C works like a charm on the KX with the lens. Could be that the shorter focus throw yields faster response? I'm very happy with not only the quick focusing, but also with the sharp f2.8 results.


Thanks for any advice,
Andras


Last edited by agsy; 08-05-2011 at 06:47 AM.
10-09-2010, 06:26 PM   #2
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I dont have the KX, but I would think the answer is no. Try it and I I suspect that the camera will default to Av mode...or just take pictures wide open.

btw I think you meant to say DOF not FOV.
10-09-2010, 06:32 PM   #3
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That is correct, DOF it is . I just don't understand how would you use an aperture ring on a lens like that. I did try but like you said it took the photo wide open. It would be neat if it would work as a TAv mode .
10-09-2010, 07:38 PM   #4
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Make sure that Use Aperture Ring is set to Permitted in your custom menu.
Take the lens off of the A position and set your desired aperture.
Set the camera to M mode
Press the Green button to get your exposure (the kx has a green button, right?)
Focus and take your shot.

The only thing you are not doing here that Tav gives you, is Auto ISO if I'm not mistaken.

In most situations, you don't need to reset exposure until your conditions really change (going from shade to bright sunlight for instance).



10-09-2010, 07:49 PM   #5
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Thanks for the advice Jeff. It does work in M mode. I really wish Pentax would add auto ISO in manual mode (sort of a TAv mode).
10-10-2010, 05:52 AM   #6
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QuoteOriginally posted by JeffJS Quote
Press the Green button to get your exposure (the kx has a green button, right?)
The K-x has a green button, but the Av button is the one you want here. The green button is configurable and although it can be configured to do the same as Av, there's no point. It's better to use it for Optical Preview (which also light-meters), or digital preview or Raw mode or whatever.
10-10-2010, 09:06 AM   #7
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QuoteOriginally posted by Brangdon Quote
The K-x has a green button, but the Av button is the one you want here. The green button is configurable and although it can be configured to do the same as Av, there's no point. It's better to use it for Optical Preview (which also light-meters), or digital preview or Raw mode or whatever.
What does the Av button do when you've gone to M mode and taken the lens off of "A" (on the Kx)?

FWIW, on my K7 I much prefer to use the Optical Preview to stop down the lens (In M mode), read the meter while adjusting shutter speed (or aperture) to get exactly the exposure I want. The green button just centers the meter and while in typical situations that's ok, I still prefer to Zone it out.

10-10-2010, 12:41 PM   #8
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QuoteOriginally posted by JeffJS Quote
What does the Av button do when you've gone to M mode and taken the lens off of "A" (on the Kx)?
It stops down the lens, takes a light reading, and sets the shutter speed to the correct exposure.

(With the aperture on "A", it switches the e-Dial from changing shutter speed to changing aperture.)

QuoteQuote:
FWIW, on my K7 I much prefer to use the Optical Preview to stop down the lens (In M mode), read the meter while adjusting shutter speed (or aperture) to get exactly the exposure I want. The green button just centers the meter and while in typical situations that's ok, I still prefer to Zone it out.
The K-x doesn't have a dedicated Optical Preview button, but it's one of the things you can configure the green button to do. Then the green button meters and the Av button centres the meter. It's a useful combination, and what I have mine set to.

10-10-2010, 02:44 PM   #9
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QuoteOriginally posted by Brangdon Quote
It stops down the lens, takes a light reading, and sets the shutter speed to the correct exposure.

(With the aperture on "A", it switches the e-Dial from changing shutter speed to changing aperture.)

The K-x doesn't have a dedicated Optical Preview button, but it's one of the things you can configure the green button to do. Then the green button meters and the Av button centres the meter. It's a useful combination, and what I have mine set to.
I know that.. At least they gave the K-x users a way to do it DOF preview IMO, is an essential part of owning an SLR or any kind.

10-12-2010, 10:51 AM   #10
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Just be aware that you will not be able to use any P-TTL flash (either hotshoe mounted or the pop-up flash) as the body will no longer be aware of what aperture you have set on the ring.
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