PME45 and VFC6 Finder reading differences

[William D. Lester]

<p>About 25 years ago I purchased a VFC metered finder and eventually sent it to Hasselblad service where it was adjusted to read correctly with an Acute Mat 42165 screen in my 500CM. The finder has a small label indicating such. I also have a 503CX with the same screen installed. Some time back I purchased a PME45 finder. The PME45 finder consistently indicates 1EV value number higher than the VFC finder. Is it possible that the newer PME45 finder is programed to read through a newer screen which might account for the different readings? Also my Pentax spot meter typically agrees with the VFC finder when pointed at a uniformly illuminated surface. None of this is anything I can't correct for or work around, I just wondered if there is some reason that I'm not aware of.</p>

<p>

 

</p>

[q.g._de_bakker]

What type of screen, Bill?<br><br>Generally, the answer to the first question is: no. There are no other screens that are significantly brighter the PME45 would be calibrated to work with. It and the (recalibrated) VFC6 should produce (virtually) the same readings.<br>What can happen is that when used in spot metering mode, the PME45 is fooled by a focussing aid (like a split image rangefinder) on the screen.<br>And, of course, you must make sure you have the lens aperture and film speed set correctly (or at least the same) on both meters.<br>Other than that, they really should give the same results.<br><br>The PME45 also offers an incident metering mode. How does what it says then compare to another incident light meter? If the same difference, the meter in teh PME45 needs seeing to.

[William D. Lester]

<p>The screens in both cameras are Acute Mat 42165 which I believe are the original versions of the Acute Mat screens. I purchased at least one directly from Hasselblad, the other may have been in the 503CX when I purchased it new as well. In any event, the screens are identical. When checking the readings, I set both cameras on a tripod side by each facing the same blank wall in my basement. I use an 80mm lens on both and the meters are set with the same max aperture and film speed settings - the PME45 on avg mode which I think approximates the metering pattern of the VFC. The incident meter is overly affected by the overhead lights so I have discounted that reading. </p>

[q.g._de_bakker]

Sounds... well... not good.<br>To be certain, best to swap the meter prism and use just one camera, screen and lens with both prisms.<br>If then still that different, one of the meters is in need of attention.<br><br>You say the VFC6 compares well against another meter, which would imply the PME45 is the one that would be at fault. To be sure, and to rule out the screen and lens, check it in incident mode. That should, of course, be done comparing it to another incident light meter, reading the same light.

[William D. Lester]

<p>Q.G. The answer lies in the manual. The finder is optimized for the newer Acute Mat D screens. The older Acute Mat 42165 that I have requires a compensation of plus 1/3 to 2/3 of an EV number which can be programmed into the finder. It works and the readings from both meter prisms now match.</p>

[q.g._de_bakker]

Great that it worked out, Bill.<br>But mind that the compensation differs with lens speed, and is not needed in spot metering mode.<br>Needing a full EV compensation still sounds not right though.

[William D. Lester]

<p>Q.G. - I didn't make the distinction between the 2 metering modes until I re-read the manual. Presumably then, the correct long term solution would be to change the screen to a D type. Which then poses another question. Which one? The manual suggest that a 42204 is standard and then suggests a 42207 for use with the PME45 finder. Can you expain the differences?</p>

[q.g._de_bakker]

The 42207 shows the spot circle, the 42204 does not. So yes, the 42207 would be preferable with either PME45 or PME90 prism.