[pure-silver] Re: Metering 135 vs 120

Mark, Thanks for taking the time to answer. I will try the two meters, testing one against the other. I don't know why I didn't think of that. I did have the shutter tested on both my Zeiss lenses and they're fine. Thanks again. 

Janet


On Aug 26, 2008, at 10:48 PM, Mark Blackwell wrote:
I use a Minolta IVF I believe and it has an adjustment buried in the back so a tech could make the adjustments IIRC.
Mine can be either a reflective or incident light meter, but to be a reflective meter it requires an additional attachment. Unless you are using the extra attachment that makes it a spot meter, then its a incident meter and that introduces a number of issues.
Let me suggest a couple of tests. Richard please chime in here if you see some things that would help.
First is if you can do it on a bright sunny day it would be best. Why? With that bright sunny day you have the sunny 16 rule to keep you close. If you have a big difference between the meters, on a bright sunny day the most likely one to be reading properly is the one closest to the sunny 16. Without that all you have is two different meter readings.
Second compare the readings with the in external meter and the reading of the in camera with the camera pointed at a gray card with the full frame covered by the card. If the meters readings are close, it likely isn't the meters unless there is a drastic difference between what they read and the sunny 16. If you find a problem, Id probably just take them both to the shop. At that point the tech can tell you not only that they are off and by how much. If they can't correct the problem with an in camera adjustment, you can compensate for the difference yourself.
I ran into this a few years ago and found another way to foul up. I had been doing a lot of 35 mm with in camera metering, then moved to one that had an external meter. I stuck a filter on the lens and forgot to compensate for the filter factor. Then it took me a while to figure out why I had thin negatives. Very very unlikely in your particular situation, but something to check if others happen to run into this type of thing somewhere down the line.
One other possibility is that the problem isn't in the metering, but in the shutter. A slow shutter is more common, in that time and use tends to make springs less effective and junk ect and all sorts of things that happen via normal use can slow the shutter down, particularly at slow shutter speeds. I have heard of a shutter getting hung up at a higher speed than the dial would show. It would let you move the dial to 1/125th of a second, but the mechanics were stuck on 1/250th. If the shutter is electronic it would be highly unlikely. I guess it might still drag, but the electronics eliminate a lot of mechanical things that can go wrong.
My old 4x5 shutter is about a stop slow at slower speeds. As the speed increase the drag drops off so there really isn't much of an effect the way I play with the camera. To fix it would cost way more than the camera is worth. I just adapt.
Now if you find that all that checks out, then Id use what ever processing you need to get what you are looking for in a negative. 

--- On Tue, 8/26/08, Richard Knoppow <dickburk@xxxxxxxxxxxxx> wrote:


From: Richard Knoppow <dickburk@xxxxxxxxxxxxx>
Subject: [pure-silver] Re: Metering 135 vs 120
To: pure-silver@xxxxxxxxxxxxx
Date: Tuesday, August 26, 2008, 5:34 PM
----- Original Message -----
From: <eroustom@xxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Tuesday, August 26, 2008 3:14 PM
Subject: [pure-silver] Metering 135 vs 120



There is for me.  I'm assuming it's a

difference in

metering.  My 35s
have built in meters while I use a Minolta IVF for

the

mf.  The
exposures seem to be very different so I always

have to

add
developing time for my 120 film.  I shoot TMax

(finishing

off some
old film) and TriX.


That's an interesting problem. Why not chase down

the

metering issue, and leave a variable out of

processing?


Your minolta is an ambient light meter (I think), and

your

camera's TTL meter is an incident meter?

I've noticed some situations that have given me

readings

two stops off from each other when using my handheld

meter

against the TTL in my Canon bodies. But I assume

it's how

I'm using the meter(s), so I work to find the same



reading, or try to reason out why that's

happening.

Sometimes the lens (I use a 24, a 35, a 50, or 100)

brings

in less or more light to the TTL meter at the back -

or so

it seems - or they average differently, whereas the
handheld meter has no lens in front of it.

But an exposure value for Zone V, or 18% gray, for a a



given ISO should be the same from meter to meter, no?

Can anyone more experienced chime in on this?

Elias



    Some meters seem to be calibrated for 12% mid gray. In
general, however, a reflected light meter should read the
same from an evenly illuminated 18% gray card that fills
its
field of view as an incident light meter reading the
illumination. There are some variations on this, for
instance, my ancient Weston Master II does not agree with
either my Luna Pro or with a Sekonic Studio Deluxe (Norwood

pattern) meter. This is with the correct equivalent Weston
speed set. I've come to the conclusion that either
Weston
included a fudge factor in its speeds or that the
calculator
is set up for some other reflectance for the pointer value
than 18%. In any case, I get the identical readings when
the
Weston speed is set for about half of the speed translated
from ISO speeds. I have a second Weston meter of a
different
type which shares this characteristic. My old GE meter
agrees with the two more modern meters. To be clear, the
Luna Pro and Sekonic agree exactly for both incident and
reflected light.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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