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What Focus Screen do I have?
- Thread starter HasselRob
- Start date
polypal
Active Member
Good job!
Welcome here Rob and thank you for your first post.
The screen you show is from the first generation.
Centre section has an enlargement lens in the center.
This screen carries Hasselblad partnumber 42250.
Later AM versions with grid do not have the enlargement section but have a split instead.
Early Acute Matte with grid and split is 42170.
The last generation Acute Matte with split and grid has part number 42270.
These AM screens are the most wanted ones.
Acute Matte screens are about one stop brighter than the first generation screens which
makes focusing easier especially with slower lenses and low light levels.
Paul
Welcome here Rob and thank you for your first post.
The screen you show is from the first generation.
Centre section has an enlargement lens in the center.
This screen carries Hasselblad partnumber 42250.
Later AM versions with grid do not have the enlargement section but have a split instead.
Early Acute Matte with grid and split is 42170.
The last generation Acute Matte with split and grid has part number 42270.
These AM screens are the most wanted ones.
Acute Matte screens are about one stop brighter than the first generation screens which
makes focusing easier especially with slower lenses and low light levels.
Paul
So this is isn't an AM screen?
This is strange because my PME was metering about a stop too fast. I knew the reading were off so I tested it against a hand held meter. I found if I set the max aperture to 2 when using a 2.8 lens I got a better reading.
When I read some forum posts I assumed I had a brighter screen causing false meter readings. If this is not the case then is my PME off I wonder?
This is strange because my PME was metering about a stop too fast. I knew the reading were off so I tested it against a hand held meter. I found if I set the max aperture to 2 when using a 2.8 lens I got a better reading.
When I read some forum posts I assumed I had a brighter screen causing false meter readings. If this is not the case then is my PME off I wonder?
polypal
Active Member
Your 42250 screen is not of AM design.
This is a confusing matter because early PME finders left the factory calibrated for first generation focusing screens.
At some point these prisms could have been recalibrated to suit the brighter AM screens.
If this job was done at a Hasselblad service center you will find a small sticker under the eyepiece that states the modification for AM screens.
If your prism is calibrated for AM screens and you use a first generation screen the reading will be one stop too low i.e. the reading is EV 12 when the light level is EV 13.
You can compensate this by setting the largest aperture value at the finder one stop smaller: use F4 for a 2.8 lens.
It looks like your PME is not correctly calibrated.
This is a confusing matter because early PME finders left the factory calibrated for first generation focusing screens.
At some point these prisms could have been recalibrated to suit the brighter AM screens.
If this job was done at a Hasselblad service center you will find a small sticker under the eyepiece that states the modification for AM screens.
If your prism is calibrated for AM screens and you use a first generation screen the reading will be one stop too low i.e. the reading is EV 12 when the light level is EV 13.
You can compensate this by setting the largest aperture value at the finder one stop smaller: use F4 for a 2.8 lens.
It looks like your PME is not correctly calibrated.
I am having the opposite problem. The prism is measuring too much light and the actual light is less. To get a correct reading I need to set the prism to a wider aperture setting than I am actually using.
There are no stickers or marking suggesting that the PME has been re-calibrated.
Is it possible that my screen is non Hasselblad? An aftermarket that is brighter than the first generation screens?
My symptoms are that of an old style PME with a brighter screen.
Another possibility is that the PME is totally out of calibration. Is that a possibility, does it happen?
There are no stickers or marking suggesting that the PME has been re-calibrated.
Is it possible that my screen is non Hasselblad? An aftermarket that is brighter than the first generation screens?
My symptoms are that of an old style PME with a brighter screen.
Another possibility is that the PME is totally out of calibration. Is that a possibility, does it happen?
polypal
Active Member
As far as I know there is no identical screen from another manufacturer.
It would be interesting to know what the reading is with a standard first generation screen with cross hairs.
The center enlargement section of your current screen could have some influence on the accuracy of the reading.
I suspect the PME needs to be calibrated.
To avoid extra cost it is good practice to adjust the PME for use with an AM screen.
Good chance that you will decide to upgrade to an AM screen soon.
It would be interesting to know what the reading is with a standard first generation screen with cross hairs.
The center enlargement section of your current screen could have some influence on the accuracy of the reading.
I suspect the PME needs to be calibrated.
To avoid extra cost it is good practice to adjust the PME for use with an AM screen.
Good chance that you will decide to upgrade to an AM screen soon.