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10-27-2008, 06:30 AM   #1
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K10D exposure w/ AV mode

Ok, I now this is probalbly a simple question but I have to ask.
When I am shooting with my manual lenses (Takumar, Voigtlander) if I have the aperture wide open they always seem to underexpose in AV mode. I get a flashing 1/4000 sec for the shutter speed. Do I need to shoot in M mode or can I compensate in AV.
Thanks for helping a newbie and I know I should have already figured this one out. I know its going to be one of those "duh" things.

10-27-2008, 07:45 AM   #2
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check your ISO setting - you could have accidentally set/left it on high like iso1600.
10-27-2008, 07:49 AM   #3
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I believe you're using lenses that don't have automatic aperture - A setting on aperture ring.
If so, then go to menu and set "use aperture ring" to "enable " or something like that. It's in the custom menu. You'll then have to shoot in manual mode:
Set aperture on lens and pres green button. Camera will then stop down, meter and set shutter speed. You can now press the shutter and correct shutter speed if needed.
10-27-2008, 10:03 AM   #4
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OrenMc,
I think that you may be exceeding the upper shutter speed limit. The flashing shutter speed indicates to me that you need to stopdown or use a lower ISO to reduce the exposure. The Voitlander is a different animal then the Tak 85mm, it is almost fully auto, except for MF. The Tak 85mm must be switched to manual on the lens, if the switch exists. Otherwise the appeture will remain full open, regardless of the setting. I use AV all of the time with fully manual and M42 lenses. AV provides exposure compensation, unlike manual mode.

Dave


QuoteOriginally posted by OrenMc Quote
Ok, I now this is probalbly a simple question but I have to ask.
When I am shooting with my manual lenses (Takumar, Voigtlander) if I have the aperture wide open they always seem to underexpose in AV mode. I get a flashing 1/4000 sec for the shutter speed. Do I need to shoot in M mode or can I compensate in AV.
Thanks for helping a newbie and I know I should have already figured this one out. I know its going to be one of those "duh" things.


10-27-2008, 05:46 PM   #5
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Thanks all for your responses.

For the Takumar: Stopping down I have no problem, this of course allows less light. ISO was set at 100, so can not lower that any more. So I quess I just can't shoot at 1.8 in full light in AV mode. I didn't think to try Manual mode last time out.
For the Voigtlander I quess I also can't shoot wide open at 1.4 either? Same conditions.
Got to be able to shoot wide open for the blurred back ground ( bokeh ) with these lenses.
Different light?
Why does it underexpose in such bright conditions?
10-27-2008, 06:11 PM   #6
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Oren said:
QuoteQuote:
Got to be able to shoot wide open for the blurred back ground ( bokeh ) with these lenses.
Different light?
That's easy Put some neutral density (ND) filters on it. I've ended up taking an ND4 (2 stops down) and ND8 with me for a 1.2 lens for 'any case'. I think this was enough to even get into-the-sun shots with both of them stacked at f1.2. If you can get the ND filters in the biggest size you need and then step rings for the smaller lenses you don't have too much stuff to fumble with. If you don't have ND filters but polarizers, you could start off with these too. You can also stack two polarizers. German Wikipedia states that if you do this and have the front polarizer either being a linear one or a reversed circular one and the back one a circular one then you'd have a 'stepless' ND filter which would not mess up the metering (not more than it actually already is )

As for the over- and underexposure with the K10D, there are several threads for this. Here is one of them.

All the best, Georg (the other)

Last edited by georgweb; 10-29-2008 at 02:20 AM. Reason: edited for correction of ND-stops
10-27-2008, 06:12 PM   #7
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QuoteOriginally posted by OrenMc Quote
Got to be able to shoot wide open for the blurred back ground ( bokeh ) with these lenses.
Different light?
Why does it underexpose in such bright conditions?
I'm confused. If it's flashing 1/4000, that's saying it would like to go to faster shutter speed but cannot. The resulting shot should be *overexposed*, not under. Can you post a sample?
10-27-2008, 08:21 PM   #8
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Heres a sample.
The ND filter sound like a plausable idea since when I stop down exposure is bearable. But thats whats confusing, why isn't it overexposing?

AV mode Aperture 1.8 1/4000 sec ISO 100



Last edited by OrenMc; 10-27-2008 at 08:29 PM.
10-28-2008, 01:24 PM   #9
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QuoteOriginally posted by OrenMc Quote
Heres a sample.
Could you also post a link tot eh Flickr page it came form, so we can see the EXIF info?

As it is, it seems possible that you were using spot metering and metered off the jacket. Or multi-segment metering and the bright hightlight to the upper right was clipping. If either of these is true, then I'd call this the *proper* exposure for the camera to have chosen, if not the one you might have wanted. When using spot metering, you do have choose an appropriate target, and when using multi-segment metering, you do have to be aware that the camera will try at all costs to preserve highlights, so you are better off metering off an area that does not include strong highlights, or just apply exposure compensation.
10-28-2008, 01:32 PM   #10
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Hi,
This happens to me all the time with my Jupiter-9. The high shutter speed is a result of the well-known non-A metering issue on the Kx0D cameras. In AV mode the solution is to apply a couple of stops exposure compensation.

Alternatively, in M mode you would just use a lower shutter speed than the one indicated.

Steve

Last edited by stevebrot; 10-28-2008 at 01:55 PM.
10-28-2008, 07:36 PM   #11
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I was going to test in manual mode next time out but I'm not sure when thats going to be. We've had some unusally nice weather but the rest of this week looks dismal.
Anyway, I really do appreciate the help thus far.

Marc, the lens in use is an old Takumar so its manual all the way. Center metering is all I get. EV compensation as you suggested or going manual as stevebrot suggests also.

Thanks Steve, I believe your jupiter and my tak is going to respond in simular manner so I will try next time out.

I guess I was just curious why in such bright conditions a lens would behave like this. I would think I would have a problem overexposing .
But if someone broke it down in some mathimatical equation I wouldn't understand it anyway.
10-28-2008, 09:38 PM   #12
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QuoteOriginally posted by OrenMc Quote

Thanks Steve, I believe your jupiter and my tak is going to respond in simular manner so I will try next time out.

I guess I was just curious why in such bright conditions a lens would behave like this. I would think I would have a problem overexposing .
But if someone broke it down in some mathimatical equation I wouldn't understand it anyway.
It would be nice to have an equation or a fudge factor. It would be even nicer to have a good explanation for the weird behavior! Unfortunately, the whole issue is poorly understood. There have been several threads on this forum regarding exposure with non-A lenses and the consensus is that aperture-specific correction factors are applied by the camera if the body has aperture data. If the aperture data is missing, a default profile is used. Unfortunately, that default profile is woefully inadequate (gross underexposure) at wider apertures. On some lenses an issue with very narrow apertures has also been reported.

In practice, the flaky metering has not been too big a problem. I generally chimp the histogram anyway, so compensating is not too much extra effort. I am also fortunate in that two of my lenses are sufficiently slow that exposure is generally pretty accurate using the green button in M mode.

Steve
10-28-2008, 09:43 PM   #13
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Av is Aperture priority. However, with a manual lens (or a lens out of A mode), the camera has no idea what that aperture is. You can't even adjust EV compensation IIRC.

My guess is you MUST shoot in M with old lens and do the metering the old fashion way.

Use stop down metering, read light meter, adjust aperture, shutterspeed, and iso accordingly. If you want assistance with the guesses, you can press the green button in M mode, it will stop down, meter, make guess at the appropriate shutterspeed and open back up.
10-28-2008, 10:10 PM   #14
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QuoteOriginally posted by AVANT Quote
Av is Aperture priority. However, with a manual lens (or a lens out of A mode), the camera has no idea what that aperture is. You can't even adjust EV compensation IIRC.

My guess is you MUST shoot in M with old lens and do the metering the old fashion way.

Use stop down metering, read light meter, adjust aperture, shutterspeed, and iso accordingly. If you want assistance with the guesses, you can press the green button in M mode, it will stop down, meter, make guess at the appropriate shutterspeed and open back up.
AV works fine and is the preferred mode with most M42 lenses (those with the Auto/Manual switch) as long as the lens is switched to manual mode. The only issue is inaccurate metering (the subject of this thread) at larger (and perhaps smaller) apertures. This issue also exists in M mode for ALL non-A lenses (M42, Pentax-K, and Pentax-M) regardless of whether you use the green button.

And yes, EV compensation works fine in AV mode with M42 lenses. I use it all the time.

Steve

P.S. If you want a little first-hand experience with the metering issue, slip the aperture ring off the "A" mark on your FA 50/1.4. Meter off a blank wall at all aperture settings and stare at amazement when the camera says that you have 4x more light on the subject (not the sensor) at f/1.4 than you did at f/5.6.
10-29-2008, 02:18 AM   #15
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Just like Steve said,
apparently there is no stringent behaviour with those metering problems.
One thing though which I found good to try:

Shortcut the cameras' bayonet contacts (all of them is a good starting point) via tin foil or 'blanking' the lens' back at the contact points. Bojidar Dimitrov has a table on his pages that explain exactly the settings. This usually helps metering.

One thing that always strikes me with digital cameras is the lack of more options for user-programmability. It would be so easy to teach the camera individual lens data for better metering (say a test mode with same light and then full open and f/8 shot).

Georg (the other)
edit: DosDan hinted me about my ill-calculated ND-to-f-stops relation, corrected in my post above, thanks a lot!
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