Possible Underexposure Causes

[ORBITALBOX]

Hi Everyone.

I was reading the threads regarding underexpsoure issues because I was experiencing 1 to 1.3 underexpsoure on my r-d1. Shooting with a Skopar 25/4, the UE occurs even in day light. Disappointed, but I'll just have to learn to compensate for it.

Recently I bought a Nokton 40/1.4. Love it! Surprisingly, no more underexposure. The histogram looks perfect and so are the pictures, even in indoor. The third lens I bought is the Heliar 15/4.5, and there it is again- underexposure.

So that got me thinking- could wide angle lenses from Skopar and Heliar be the culprit? Or, that's just normal on RF w/ interchangeable lenses, which means there is nothing wrong w/ my r-d1?

What do you think?

 

[Kim Coxon]

I am not a digital expert but I understand extremme wides do cause a problem because of the way the light strikes the sensor at an angle.

Kim

 

[rogue_designer]

could be the meter is picking up more of the sky due to the wide angles, and thus compensating for the brightness there?

Always a problem with center weighted meters.

 

[Terao]

Cameraquest states the following:


Yep, the 12, 15 and 25 are quite usable on the M6, M5, CLE, CL WITH TTL metering!! Some users report adjusting the ASA due to the metering pattern, so check this out before you do critical shots.

So I guess there could be an issue. I find my 12mm underexposes slightly on my Bessa T, its less of an issue on the R-D1 though

 

[furcafe]

I agree w/rogue. It's my understanding that the R-D1's meter is actually "bottom-weighted" (though still centered horizontally) to partially compensate for this (personally I find it annoying because I don't do much landscape shooting & prefer Leica's semi-spot). Even so, a wide would still capture more of the sky & possibly skew the metering.

could be the meter is picking up more of the sky due to the wide angles, and thus compensating for the brightness there?

Always a problem with center weighted meters.

 

[iml]

I noticed on a first outing with my VC 21 last weekend the metering seemed a bit odd. Now I know why, useful info.

Ian

 

[ORBITALBOX]

Thanks for all the responses!

I wonder if the little rectangle focus frame in the viewfinder (not the frameline) is where the r-d1 gets its meter reading? If so, a user might be totally off on the metering when composing with an attached viewfinder??

 

[rogue_designer]

I would have assumed that the RD1 would meter the same way the CV cameras do - which is to take a reading off the outer shutter curtain...

but then, I don't know why I assume that.

 

[Terao]

Takes a meter reading off the gray outer shutter curtain, and its biased to the lower half of the frame I believe...

 

[pfogle]

I would have assumed that the RD1 would meter the same way the CV cameras do - which is to take a reading off the outer shutter curtain...

but then, I don't know why I assume that.

Inside the box, you can see the cell top left, as you look into the lens mount. It does point at the curtain, and I guess it's designed to use the lighter, center blade as a crude center weighting. To my eye, it would seem to pick up more from the lower part of the image, which would imply it gets rather more from the sky than it should. If I get time, I'll test this at the weekend...

 

[ORBITALBOX]

Takes a meter reading off the gray outer shutter curtain, and its biased to the lower half of the frame I believe...

I am learning all these new things about r-d1... OK, so the camera gets the reading off the curtain? Light comes into the box, hits the gray curtain, and a cell somewhere located inside the box detects the curtain surface?