D300 + Sig 150-500 OS on v OS off

Pierro

Pierro

Senior Member
Dont know if i'm just being dumb here, but check the EXIF on both photos, and the shutter speed changed just because i switched OS on. Is this normal ?

Both photos were shot within seconds of each other, the only time taken was switching on OS on the lens.

Both handheld

ISO 1600 on both

A/P f7.1 on both

Photo 1 S/S was 1/500th
Photo 2 S/S was 1/250th

Absolutely NO processing at all, other than resizing

Obviously with the slower S/S of shot 2, the photo is brighter. But why the S/S change ?

3cgc3q0zud.jpg


nuz30gu1wh.jpg


I'm not sure why the camera changed the shutter speed, as the light didnt change within the 2 seconds that passed between the 2 shots
 
bluenoser

bluenoser

Banned
My first guess would be that in the 12 seconds (according the EXIF) between shots, you may have ever so slightly moved the camera so that the spot metering mode you were using focused on a slightly darker area in the second shot require a longer exposure. You were at over 500mm (35mm equivalent) so it wouldn't take much to shift that focus spot (in spot metering especially) enough to change things.
 
W

westmill

Banned
The two shots are slightly different. Its poss the light meter could have read from a different spot.
A full stop seems a tad extreme though, but should be ruled out first.
Maybe you could do the same test mounted on a tripod or some thing just to be sure.
It does seem odd though.
 
Pierro

Pierro

Senior Member
Ok - time to tell !

James - westmill, please check the EXIF carefully, just like I didnt. I later spotted that i had exposure bias set to -1 in photo one, and somehow without knowing i'd done it, i must of accidently had my shutter finger brush the EV comp button and my thumb must have moved the rear dial. I didnt realise i had done anything like that. ! It seems I reset the EV to zero in shot 2. Earlier i had been messing with EV bias, and obviously had left it on -1 ( thats in the EXIF of photo 1 )

Ooops

Must pay attention :uncomfortableness:
 
W

westmill

Banned
I must admit to not looking at the Exiff lol. I took your word nothing had changed :)
A good ending though :D Its nice when a problem gets resolved with total certainty.
I guess there was a clue, in the fact it was exactly one stop too lol
 
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