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06-27-2008, 11:58 AM   #1
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Non-electronic lens: Why can't Av mode just trust me?

I just got a Lensbaby 2.0, which is an all-manual no-electronic communication lens. It uses aperture disks to change the aperture, so it's not like I'm going to be flipping apertures a lot. I therefore assumed that I could just put the camera in Av mode, set the aperture to match what the lens says, and go about my business. This doesn't seem to work the aperture is listed as "F--" and turning the dial does nothing. (Which is what, on closer reading, the manual tells me will happen.) Is there a way to tell the K10D "trust me" and make it work? If not, whyever not?

06-27-2008, 12:03 PM   #2
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I should add: of course, it works perfectly fine to go into M mode and use the green button to take a meter reading, which is what I'm used to doing with my old Pentax lenses. I'd never even tried Av mode with them.
06-27-2008, 12:13 PM   #3
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Why can't the camera just trust you?

I can think of a couple of reasons.

I don't know about the lensbaby, but the K10D has a real issue with lenses not in apature mode, and metering.

I have reported this before, but the camera applies I believe, a correction factor to the reading, as a function of the maximum apature of the lens to correct for this problem.

If you were able to put apature values into the camera, how would it work out the metering? what apature have you entered, maximum or set value? etc.

it is better to leave it blank.
06-27-2008, 12:50 PM   #4
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Normal to had F_ _ _, simply put the camara in av mode, set the f stop on the lens press the green button, make focus and release shutter, don't forget to enable the USE APERTURE RING option in user menu (36)

06-27-2008, 01:04 PM   #5
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QuoteOriginally posted by lequynorm Quote
Normal to had F_ _ _, simply put the camara in av mode, set the f stop on the lens press the green button, make focus and release shutter, don't forget to enable the USE APERTURE RING option in user menu (36)
Not to upset you but this does nothing at all

In Av mode the camera meters and shoots wide open, it does not stop down the lens regardless of where the apature is set.

YOur process works in manual only.
06-27-2008, 04:44 PM   #6
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QuoteOriginally posted by Lowell Goudge Quote
Not to upset you but this does nothing at all

In Av mode the camera meters and shoots wide open, it does not stop down the lens regardless of where the apature is set.

YOur process works in manual only.

The camera can not shoot wide open cause you set the f stop at first, the camera did not control the lens, i always shoot like i exlain with my k20d and all my shoots are ok, the camera set the speed accordingly with the light passing by the lens at the aperture you have set on your lens
06-27-2008, 06:30 PM   #7
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QuoteOriginally posted by Lowell Goudge Quote
If you were able to put apature values into the camera, how would it work out the metering? what apature have you entered, maximum or set value? etc.
The lensbaby's aperture is changed by physically switching an aperture disk; effectively, it's a fixed-aperture lens. (As are many mirror lenses, right?) So, I guess it actually happens to just work out because the Av mode sets the shutter speed and ISO automatically based on the wide open reading so the only thing to be gained would be that the exif would record the aperture correctly.

The quirk that it took me a long time to figure out is that front dial wasn't working for EV compensation even though I had it set to be so. Apparently those 1.1 firmware settings didn't make it all the way into every mode of operation I can still change the EV by holding the button and turning.

This makes Av mode way more useful than M for the lensbaby, because the meter is operating constantly, without having to go through the motions of "stopping down".
06-27-2008, 08:52 PM   #8
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Am I correct in remembering that the LensBaby uses magnetic disks (fixed aperture) that you swap out per need? If so, all you need to do is to put the camera in AV mode and shoot (same as with any other manual aperture lens e.g. M-42). Ignore the F____ warning.

Steve

06-27-2008, 09:03 PM   #9
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QuoteOriginally posted by stevebrot Quote
Am I correct in remembering that the LensBaby uses magnetic disks (fixed aperture) that you swap out per need? If so, all you need to do is to put the camera in AV mode and shoot (same as with any other manual aperture lens e.g. M-42). Ignore the F____ warning.
Yeah, turns out this is indeed the case. I was mostly perplexed because in this state the front dial wasn't working to change EV, and so I assumed it wasn't working at all. Turns out that's just a (unfortunate) quirk, and EVbutton+dial works fine.

I still wish the Av dial worked simply for the purpose of setting the Exif. But I suppose having it wrong would be worse than no information.

Anyway, first results:
https://www.pentaxforums.com/forums/post-your-photos/30934-first-lensbabies-shots.html
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