Interval timer STRANGENESS

[BackdoorArts]

The problem is the first image. Even with -2/3 EV compensation, the shutter speed is simply unimaginable for ISO 100 f/16 in bright sun.

So the problem is NOT so much that the later exposures improve (1/1600 sec SHOULD BE UNDEREXPOSED), but is that the first one is so bad.

I'm with Wayne here. If Sunny 16 is to be believed (and I haven't read many people going out of their way to refute it) then it's definitely the first image that's at issue.

 

[MattB]

Yeah, I had also thought sunny 16, but my test came out way overexposed. That and the fact that I just did another interval test with a 50mm/1.4 and it came out exactly as it should, leads me to believe there's something very weird going on with the lens.

So, mystery half solved, and I'll be dropping off the lens for servicing soon.

 

[BackdoorArts]

Then the odd thing is that your test came out overexposed, but it likely would have been OK with the Sunny 16 exposure once the camera "settled in" - or so it would seem.

If a test with the 50mm came out fine then it definitely points to something with the camera and lens not metering correctly - but then somehow correcting over time. It's very odd, and I suspect that you'll need to drop both the lens and camera off if the results can't be replicated on a second body.

 

[MattB]

Yup, a second body test would be a good idea. Anyone have a D600 they want to lend me?

 

[Dave_W]

Ahhhh, I think I might know that the problem is but have no clue how or why it's doing this - the ISO is getting stuck at a much higher level than it's indicating.....or not I messed up ISO "regulator" (if you will) would produce something similar to this. What we need is a series of just snaps at several different ISO's, all taken at the same sitting. Some in sun at different ISO's and some in shade at different ISO's and it might shed some light on this.....or not

 

[Blade Canyon]

I agree that the darker shots look correct for the chosen exposure/ISO. Could it be that the aperture blades on your lens are not closing properly for the initial shots, but then come unstuck or something in the later shots?

In other words, it appears the lens is wide open on the early shots, but then closes down to f16 for the later shots. The EXIF might still show f16, because that's what the camera's trying to do, but in reality the aperture did not close.

Have you tried this with a different lens?

Also, does a variation in EV make any difference if you're shooting manual mode?

 

[MattB]

When I'm shooting manual with that lens, it does expose strangely, but it seems consistently strange, not getting darker from shot to shot. I can't imagine why this would be the case specifically with interval shooting.

And yeah, I've tried another interval shooting with a 50mm/1.4, and it worked just fine. So it's definitely the lens, or a lens/camera combo.

I'll do some more conscious tests and come back with a few shots...

 

[WayneF]

It sounds like a mechanical problem. My bet is that it is related to the little lever sticking out on the back of the lens. This lever is how the camera stops down the aperture. You can move it with your finger and see the lens stop down. The camera body has another lever (camera right side of lens opening) which interfaces to move that lens lever. These levers get bent and damaged, causing this kind on inoperative problem. Or it could be the aperture blades are dirty and binding? The drift with time seems new however.

If some lenses work, it must not be the camera. Compare that lens lever to a working lens.