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05-27-2019, 03:28 PM   #1
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Inconsistent exposures in Aperture Priority with K-1

Hi All,
I used aperture priority (Av mode) for the first time yesterday in the hopes of getting some reasonably consistent exposures while there were some spotty rain showers in the area. The model and I found a nice shaded area to shoot in with the hopes that'd further stabilize the ambient light, but for some reason I got quite a few under and overexposed captures during the shoot. For example, two captures taken a second apart: the first was at 1/250 (a touch under exposed) and the second at 1/30 (blown out so bad it can't be salvaged). I'm trying to get a handle on what happened as the amount of ambient light stayed fairly steady for the entirety of the shoot and there were no drastic changes that would've required slowing the shutter that much.

For those of you that use Aperture Priority, has it worked pretty reliably for you? Any thoughts on what caused the over and under exposed captures I got? Does anyone know if the calculation for shutter speed is based off ambient light in frame or just the brightness of the focus point?

Here's the setup I had:

K-1 on firmware v1.50
DA* 200mm at F2.8 and ISO 100
Spot focus
Single frame shooting

05-27-2019, 03:36 PM   #2
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Were you also using spot metering? This could be the issue. Center weighted or matrix is generally a safer go-to.

Could you post the pics with exif intact?

Adam
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05-27-2019, 03:37 PM   #3
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Hi Corey

Can you post some photos with the EXIF data intact? I can't say that I have had any issues using Av mode.

Kind regards,
Mark
05-27-2019, 06:18 PM - 1 Like   #4
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QuoteOriginally posted by CoreyC Quote
Hi All,
I used aperture priority (Av mode) for the first time yesterday in the hopes of getting some reasonably consistent exposures while there were some spotty rain showers in the area. The model and I found a nice shaded area to shoot in with the hopes that'd further stabilize the ambient light, but for some reason I got quite a few under and overexposed captures during the shoot. For example, two captures taken a second apart: the first was at 1/250 (a touch under exposed) and the second at 1/30 (blown out so bad it can't be salvaged). I'm trying to get a handle on what happened as the amount of ambient light stayed fairly steady for the entirety of the shoot and there were no drastic changes that would've required slowing the shutter that much.

For those of you that use Aperture Priority, has it worked pretty reliably for you? Any thoughts on what caused the over and under exposed captures I got? Does anyone know if the calculation for shutter speed is based off ambient light in frame or just the brightness of the focus point?

Here's the setup I had:

K-1 on firmware v1.50
DA* 200mm at F2.8 and ISO 100
Spot focus
Single frame shooting
Hi Corey
One simple thing to eliminate -- was the eyepiece of the camera covered while you took the shots?. Light gets in an uncovered eyepiece and mucks up metering.

05-27-2019, 07:12 PM   #5
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Make sure AE-L was not engaged and camera was using A & S for current scene. I have pressed AE-L by mistake. Another wild possibility is enabling bracketing.
05-27-2019, 07:33 PM   #6
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I looked it up in the manual just to confirm, but I did have it in Spot Metering mode as suspected and that is backed up by the EXIF data too. I'm going to bet that is what was causing the issue.

Even though I'm fairly confident the spot metering is the issue, I am attaching the two images I referenced in the original post with intact EXIF info. The images themselves are not great visually, but they illustrate the issue nicely, so don't judge me too harshly.
Attached Images
View Picture EXIF
PENTAX K-1  Photo 
View Picture EXIF
PENTAX K-1  Photo 
05-27-2019, 07:59 PM   #7
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Ok seeing it is overexposure then it is not light getting in the eyepiece and looking at these shots I suspect you didn't use a tripod which is when you need to be careful. Presumably your spot reading was in the V area - the sudden transition from light to black there would easily cause the difference, with black doing the overexposure.
PS- cool photos
05-27-2019, 09:19 PM   #8
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Two exposures at the extremes. One at 1/30 secs and one at 1/250 secs. That's the risk when you use spot metering without due care.

05-28-2019, 04:54 AM   #9
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QuoteOriginally posted by beachboy2 Quote
Two exposures at the extremes. One at 1/30 secs and one at 1/250 secs. That's the risk when you use spot metering without due care.
In this case, it was more a lack of not knowing the camera well enough and not having things set appropriately for what I wanted it to do. Thanks everyone for helping to point out my failures! Seriously though, this is how we improve and get better.
05-28-2019, 08:50 AM - 1 Like   #10
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Yes the light meter use is incorrect.

All said and done, readers on the forum (Pentax or non-Pentax) suddenly feel alarmed about the quality of the equipment when posts like these pop up on the front page. I am sure they are more than willing to help and steer to the correct solution but I would like to see a title that is more palatable as in "What am I doing wrong..." vs "Inconsistent exposures in Aperture Priority with K-1...". The title is so technical that the reader almost thinks there is an issue with the camera and not the setting.
05-28-2019, 10:21 AM   #11
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QuoteOriginally posted by shardulm Quote
Yes the light meter use is incorrect.

All said and done, readers on the forum (Pentax or non-Pentax) suddenly feel alarmed about the quality of the equipment when posts like these pop up on the front page. I am sure they are more than willing to help and steer to the correct solution but I would like to see a title that is more palatable as in "What am I doing wrong..." vs "Inconsistent exposures in Aperture Priority with K-1...". The title is so technical that the reader almost thinks there is an issue with the camera and not the setting.
That's a good point. Thanks for mentioning it to the OP.
05-29-2019, 01:48 PM   #12
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Corey,

Actually, I prefer spot or center weighted exposure and use back button activation. Pick your focus and exposure area, get your values then re-compose and shoot. You can do this by using the shutter release button also by half depressing and holding to recompose and then shoot. I started with film in 1977 and this fits my paradigm. The matrix exposure will work well, but often I am shooting with too many opportunities for incorrect settings to be chosen. Also, observe the readings and understand that something is out of functional range, f2.8 and 1/30 shutterspeed in daytime should send a redflag.

Read about exposure, shutter speed, ISO, and time of day, light angles, etc. There are articles here and elsewhere. there are folks that can help you with each "style" of managing your input. Remember you are capturing the light as it interacts with your subject.

I shoot manual a lot with older lenses and, AV, and TAV with modern lenses.I would rather be underexposed and work in post processing to recover from darker areas, than try to recover over exposed or blown out.

JB
05-29-2019, 05:48 PM   #13
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QuoteOriginally posted by Take-5-JB Quote
Actually, I prefer spot or center weighted exposure and use back button activation. Pick your focus and exposure area, get your values then re-compose and shoot. You can do this by using the shutter release button also by half depressing and holding to recompose and then shoot
That will not lock your exposure in any of the auto exposure modes unless you either:

press AE-L to lock the exposure

Change the default menu setting to have the exposure lock when focus lock is obtained.
05-30-2019, 09:21 AM   #14
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Pschlute,

That is why I use the back button setting including AE-L. I didn't state that well about using the shutter release, as I don't use the shutter release depression method. I should have referred to the manual section covering that. Thanks for clarifying.

JB
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