Any guesses what happened here? - DPChallenge Forums

08/19/2010 01:24:49 AM · #1

So these two images were taken 1/8 of a second after each other, under identical lighting, and with identical exif. So any guesses why the exposure is different? These are straight from camera RAW save for web. Photos were taken using aperture priority.

I've never noticed anything like this before, and it struck me as more than a bit odd.

ETA: They were shot using AWB, but according to the files, the same AWB setting was used for both photos during capture by the camera.

Message edited by author 2010-08-19 01:31:45.

fotomann_forever

08/19/2010 01:28:51 AM · #2

The camera simply chose different shutter speeds, about 1/2 stop as far as I can tell. Nothing odd about that. The slight shift in composition likely changed what the camera was metering.

08/19/2010 01:32:24 AM · #3

Originally posted by fotomann_forever:

The camera simply chose different shutter speeds, about 1/2 stop as far as I can tell. Nothing odd about that. The slight shift in composition likely changed what the camera was metering.

Shutter speed is identical. Aperture is identical. Exif is identical across the board.

MelonMusketeer

Nikon D7000

Nikon MF 50mm f/1.4

08/19/2010 01:37:30 AM · #4

The mother ship crossed between your subject and the sun just as you were shooting the second one. The numbers for shutter, ap, and iso are the same, but may be rounded off a bit. One other possibility is that the aperture didn't close all the way down to the set point in the first one but it did in the second. Use your fingertip to work the aperture lever that sticks out the back of that lens, and see if it is getting sluggish feeling. The lever is on the lower right side of the back of the mount, looking at the lens from the camera end. You might also try setting the aperture at f16 and work the stop down (DOF Preview) button on the camera while watching the aperture from the front of the lens, to see if it closes to the same size each time.

Message edited by author 2010-08-19 01:37:59.

08/19/2010 01:46:51 AM · #5

Originally posted by MelonMusketeer:

I'll check this out tomorrow when I'm not at work, with the lens. As far as rounding values, I checked the detailed exif and the values were identical (IE, shutter= 8965784/1000000
The lens explanation makes sense to me though.

fotomann_forever

08/19/2010 01:58:58 AM · #6

Originally posted by spiritualspatula:

Originally posted by fotomann_forever:
The camera simply chose different shutter speeds, about 1/2 stop as far as I can tell. Nothing odd about that. The slight shift in composition likely changed what the camera was metering.

Shutter speed is identical. Aperture is identical. Exif is identical across the board.

And Iso? Not in Auto ISO is it?

Leica 35mm f/1.4 Summilux M Aspherical MF - Black

08/19/2010 02:27:53 AM · #7

Originally posted by fotomann_forever:

Originally posted by spiritualspatula:

Originally posted by fotomann_forever:
The camera simply chose different shutter speeds, about 1/2 stop as far as I can tell. Nothing odd about that. The slight shift in composition likely changed what the camera was metering.

Shutter speed is identical. Aperture is identical. Exif is identical across the board.

And Iso? Not in Auto ISO is it?

Nope. Exif identical across the board. Strange, eh?

scarbrd

Leica M10

08/19/2010 03:07:27 AM · #8

Are the profiles (sRGB) the same in your editing software?

Sigma 12-24mm f/4.5-5.6 EX Aspherical DG HSM for Nikon

08/19/2010 04:33:45 AM · #9

Originally posted by scarbrd:

Are the profiles (sRGB) the same in your editing software?

Yeah. The actual raw NEF files look different like that. I opened them with ACR one after the other consecutively and saved for web to display them here.

Message edited by author 2010-08-19 04:34:30.

bohemka

Nikon D700

08/19/2010 05:54:04 AM · #10

Odd. Did you have a loose polarizer flopping around?

Nikon AF-S DX Zoom-Nikkor 18-55mm f/3.5-5.6 ED

08/19/2010 06:58:11 AM · #11

Originally posted by bohemka:

Odd. Did you have a loose polarizer flopping around?

Nope, no use of polarizer. I'm glad that this is perplexing to others beside myself, as I was pretty confused and did a double take when I first noticed it.

Apple iPhone 5

08/19/2010 07:01:33 AM · #12

I bet it's an AWB thing. Either the camera made a slight WB adjustment between shots, or the RAW processor applied it's own WB rules differently between the shots.

Canon EF 100-400mm f/4.5-5.6L IS

08/19/2010 07:21:08 AM · #13

Originally posted by JH:

I bet it's an AWB thing. Either the camera made a slight WB adjustment between shots, or the RAW processor applied it's own WB rules differently between the shots.

WB in ACR was 7400, -9 tint for both, for "as shot." It also seems to be a difference of exposure between the two shots. I was thinking the same thing initially though.

Strikeslip

Canon EOS-5D

08/19/2010 08:54:40 AM · #14

Originally posted by MelonMusketeer:

The mother ship...

Bird's shadow flicked past your lens?

jim29028

Olympus E-5

Olympus 12-60mm f/2.8-4.0 Zuiko

08/19/2010 09:07:05 AM · #15

What metering mode were you using? Maybe the camera metered a tiny bit different between shots, not enough to change exposure but enough to change some of the raw data that was captured and therefore the end image.

Apple iPhone 5

Nikon AF-S DX Zoom-Nikkor 18-55mm f/3.5-5.6 ED

08/19/2010 09:20:55 AM · #16

Perhaps it's the mirror flip-up? - Since there was only 1/8s between shots, does the mirror have time to return to position and flip up again, or is it an electronic shutter for the second shot?

Bear_Music

Samsung Galaxy S24, S24+, S24 Ultra

Sony 24-70mm F4 Vario-Tessar T* FE OSS

08/19/2010 09:22:35 AM · #17

If you were in manual mode, i.e. with a fixed shutter speed and aperture both, EXIF would remain the same and this is a very slight change in lighting intensity, possibly another, very high cloud, invisible from the ground, slightly obscuring the sun and slightly dimming the lighting.

Ditto, possibly, if you were in burst mode and Av or Tv; I believe there are some burst modalities that don't change exposure between frames. I might be wrong about that, though.

Otherwise, my gut feeling is that the likeliest suggestion presented thus far is that the lens didn't stop down as far as it was told to for the brighter of the two shots. Or it could just be a wonky exposure meter that can't repeat its own results consistently, for what reason I do not know.

R.

Spork99

OM System OM-1

Canon EF 100mm f/2.8 USM Macro

08/19/2010 08:25:15 PM · #18

That wouldn't happen if you shot with Canon.

vawendy

Sony Alpha 1

Sony FE 200-600mm f/5.6-6.3 G OSS

08/19/2010 08:31:10 PM · #19

Originally posted by Spork99:

That wouldn't happen if you shot with Canon.

Naw. I've had it happen before with my Canon. But my camera actually changed the shutter speed, even though nothing changed in the shot (setup, inside, still life, no changes.) Happened about 3 times over the course of a year.

Message edited by author 2010-08-19 20:31:23.

Olympus 7-14mm f/4.0 Zuiko Digital Zoom

08/19/2010 08:34:50 PM · #20

Well, I checked out the lens today. Aperture seems to stop down fine, nice and smooth. It isn't really something that has me horribly worried since I've never seen it before, but it was peculiar. Despite seeming totally fine, I'm still thinking this is the best guess. Interesting though. I'll have to see if I can recreate it when firing at 8fps again.
I'd agree with the cloud theory but those were the only clouds and the exposure is changed universally over the photo, not just one part. Considering I was shooting with a 10-20mm lens, it seems pretty unlikely that such a huge swatch of sky would be covered that quickly.

It was spot metering, in aperture priority. But the metering doesn't seem to me like it would make a difference, as the metering just determines the other values, which were seen to be identical via exif data.
Mirror does flip up/down for all shots.

All the guesses are much appreciated.

one2one

Olympus E-5

08/19/2010 08:35:19 PM · #21

White balance. Was it on auto? It says the same WB but does it say it in degrees Kelvin and are the numbers exactly the same?

Message edited by author 2010-08-19 20:37:07.

vawendy

Sony Alpha 1

Sony FE 200-600mm f/5.6-6.3 G OSS

08/19/2010 08:38:33 PM · #22

ghosts? demons? trolls?

alohadave

Pentax K-5

Pentax DA 16-45mm f/4.0 ED AL AF

08/19/2010 09:31:24 PM · #23

Originally posted by JH:

Perhaps it's the mirror flip-up? - Since there was only 1/8s between shots, does the mirror have time to return to position and flip up again, or is it an electronic shutter for the second shot?

The mirror is far faster than 1/8 of a second.

This illustrates the sequencing of an exposure:

//www.youtube.com/watch?v=4cJyKKnR5b8

If your mirror is showing in the shot, then your camera is in need of repair.