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08-03-2015, 03:24 AM   #1
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Verifying an assumption on Av

Almost sure about this one.
M lens, forgot camera in Av mode, camera is metering wide open, and is not closing the aperture lever before shooting, correct?
Lens was set to f/8 and had shutter speeds in the order of 1/250s in M mode, 1/2000s or 1/3000 in Av.

08-03-2015, 03:38 AM - 1 Like   #2
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You are correct. For an M lens you either need to use M mode using the green button to do stop down metering, or adjust the aperture on the lens itself, but this can result is less accurate metering.
08-03-2015, 03:53 AM   #3
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QuoteOriginally posted by MSL Quote
You are correct. For an M lens you either need to use M mode using the green button to do stop down metering, or adjust the aperture on the lens itself, but this can result is less accurate metering.
Yeah, that's what I always do (and what I cope with), but sometimes I have to switch to the 18-55mm WR in order to have a true wide angle, and that's when I forget to turn back the dial...
08-03-2015, 04:13 AM   #4
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QuoteOriginally posted by LensBeginner Quote
when I forget to turn back the dial...
Some of my "best" recent photos ended up as 6Meg JPG files since I forgot to switch back that setting after I took a few shots for a warranty claim (so I didn't want to have to process large DNG files).

I also forget to switch between Av and TAv when opting for no flash/ flash - TAv doesn't like flash much.

One day I may get the hang of this.

08-03-2015, 04:34 AM - 1 Like   #5
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QuoteOriginally posted by MSL Quote
You are correct. For an M lens you either need to use M mode using the green button to do stop down metering, or adjust the aperture on the lens itself, but this can result is less accurate metering.
For an M or K lens (in M mode) you *do* have to set aperture on the lens dial, since there are no contacts to communicate with the camera body. Then use green button metering to set shutter speed. In Av mode, an M lens will only meter and shoot wide open.
08-03-2015, 05:02 AM   #6
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QuoteOriginally posted by MSL Quote
I also forget to switch between Av and TAv when opting for no flash/ flash - TAv doesn't like flash much.
TAv is *the* mode for HSS unless you want to go full M.
08-03-2015, 06:38 AM   #7
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I thought it would meter wide open and stop down to what you had the aperture set Tobin the lens - rendering the exposure inaccurate. But it sounds like you guys are saying that setting Av mode disables the aperture from stopping down at all with an m series lens. Is that correct?
08-03-2015, 06:41 AM - 1 Like   #8
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QuoteOriginally posted by UncleVanya Quote
I thought it would meter wide open and stop down to what you had the aperture set Tobin the lens - rendering the exposure inaccurate. But it sounds like you guys are saying that setting Av mode disables the aperture from stopping down at all with an m series lens. Is that correct?
Yes. An M lens (bayonet, no contacts) will never ever stop down unless the camera is in (M)anual...

08-03-2015, 07:29 AM   #9
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QuoteOriginally posted by UncleVanya Quote
I thought it would meter wide open and stop down to what you had the aperture set Tobin the lens - rendering the exposure inaccurate. But it sounds like you guys are saying that setting Av mode disables the aperture from stopping down at all with an m series lens. Is that correct?
Yes, @paulh is correct. Even in M mode you need to manually set the aperture on the lens. I use m42 lenses far more often than M ones, so this step kind of slipped my mind (as it is clearly mandatory with an m42)
08-03-2015, 08:06 AM - 1 Like   #10
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You can "unscrew" M lens a bit and use it it even in P mode

---------- Post added 08-03-15 at 08:07 AM ----------

QuoteOriginally posted by vonBaloney Quote
Yes. An M lens (bayonet, no contacts) will never ever stop down unless the camera is in (M)anual...
It will if you..unscrew/unmout it a bit
08-03-2015, 08:36 AM   #11
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QuoteOriginally posted by AldaCZ Quote
You can "unscrew" M lens a bit and use it it even in P mode

---------- Post added 08-03-15 at 08:07 AM ----------



It will if you..unscrew/unmout it a bit
Well yeah. You can remove the lever too. But then it is just like an m42 -- you can't meter wide-open...
08-04-2015, 12:45 AM - 1 Like   #12
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QuoteOriginally posted by AldaCZ Quote
You can "unscrew" M lens a bit and use it it even in P mode

---------- Post added 08-03-15 at 08:07 AM ----------



It will if you..unscrew/unmout it a bit
That's what I occasionally do when I shoot a sunset for instance.
If you stop way down, it should reduce the amount of light on the sensor in LV (or on the viewfinder with the mirror down) compared to wide open and prevent damage.
That I only do when the sun is quite low and well in the "red", obviously, better safe than sorry...
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