Dan Daniel
Well-known
This is an attempt to show a variety of focus screen options for TLRs. All images were shot at the same exposure and processed exactly the same. EXCEPT the Maxwell screen is installed in a Rolleiflex 2.8C with a f/2.8 viewing lens, so I reduced its exposure by 1/3 EV. All other screen shots were with a Rolleicord or Minolta Autocord with a f/3.2 viewing lens (YashicaMat sample is from a YashicaMat that I recently acquired, so it had not been cleaned or had a new mirror installed; its viewing lens is f/2.8).
I did a similar test a while back. It is here:
http://www.rangefinderforum.com/forums/showthread.php?t=142212
This new test was at night because I was going to be swapping out screens and I knew it would take time. I didn't want the light to change. I tried my best to re-locate cameras in the same place, but there is some variance. I also tried to keep the framing the same. The camera used for the shots was a Sony RX-100. Set at 0.5 seconds, f/8, ISO 400.
Some observations: In 'real life,' all of these screens (except one, the Rollei ground glass) give a viewable image and can be focused (and yep, some will be happiest with the Rollei ground glass, I know). Camera shots like these don't accurately show the brain's ability to adapt and adjust, even when changing attention from the center to the edge of a small screen.
* Look at both the center of the shot and at the edges, specially the lamp on the left side. You can see both brightness and evenness of distribution.
* The Maxwell screen is clearly the brightest and has the best distribution.
* The Brightscreen's 13mm central microprism spot is great for me. The size of the prism grid (meaning the small triangles/prisms that go in and out of focus, not the overall circle that contains these small prisms) is much larger than the Mamiya small triangles/prisms (which is only about 5mm in diameter, the rest of the center spot being clear). I am going to put one in a TLR and field-test it as soon as possible.
* Plain, microprism, or split image? I think this is strictly a personal decision. I could say the advantages and disadvantages I see with each, but I won't bore you.
The Maxwell screens run over $200 USD (Bill Maxwell also sells a screen with a split image and microprism center but I didn't have one for this test). Email or phone is the best way to contact.
https://www.facebook.com/pages/Maxwell-Precision-Optics/200647716643807
Rick Oleson sells the Brightscreen microprism for $80, I believe is his current price.
http://rick_oleson.tripod.com/index-175.html
You can get Mamiya sceens for $40-60 on Ebay but stock is limited and they need to be cut down. I will sell Mamiya screens for $90, and will install them on cameras I refurbish for sale or for repair, but there aren't enough around to make a real go of them.
NOTE: If you have been around camera repairs and around this whole site, you have probably run into Rick Oleson's post and maybe his web site. I find Rick to be one of those helpful types, someone always willing to answer a question or provide information. And Bill Maxwell is also a helpful guy. If you are thinking of getting a new screen, I'd encourage people to focus on those two offerings. If the screen will work for you, you'll be giving your money to the right people.
If anyone wants the original file at full size (~6000x8000 pixels), drop me a note. It can also be seen here and might enlarge depending on your screen and such:
http://dandaniel.zenfolio.com/p1062669410/h737b3f51#h737b3f51
I did a similar test a while back. It is here:
http://www.rangefinderforum.com/forums/showthread.php?t=142212
This new test was at night because I was going to be swapping out screens and I knew it would take time. I didn't want the light to change. I tried my best to re-locate cameras in the same place, but there is some variance. I also tried to keep the framing the same. The camera used for the shots was a Sony RX-100. Set at 0.5 seconds, f/8, ISO 400.
Some observations: In 'real life,' all of these screens (except one, the Rollei ground glass) give a viewable image and can be focused (and yep, some will be happiest with the Rollei ground glass, I know). Camera shots like these don't accurately show the brain's ability to adapt and adjust, even when changing attention from the center to the edge of a small screen.
* Look at both the center of the shot and at the edges, specially the lamp on the left side. You can see both brightness and evenness of distribution.
* The Maxwell screen is clearly the brightest and has the best distribution.
* The Brightscreen's 13mm central microprism spot is great for me. The size of the prism grid (meaning the small triangles/prisms that go in and out of focus, not the overall circle that contains these small prisms) is much larger than the Mamiya small triangles/prisms (which is only about 5mm in diameter, the rest of the center spot being clear). I am going to put one in a TLR and field-test it as soon as possible.
* Plain, microprism, or split image? I think this is strictly a personal decision. I could say the advantages and disadvantages I see with each, but I won't bore you.
The Maxwell screens run over $200 USD (Bill Maxwell also sells a screen with a split image and microprism center but I didn't have one for this test). Email or phone is the best way to contact.
https://www.facebook.com/pages/Maxwell-Precision-Optics/200647716643807
Rick Oleson sells the Brightscreen microprism for $80, I believe is his current price.
http://rick_oleson.tripod.com/index-175.html
You can get Mamiya sceens for $40-60 on Ebay but stock is limited and they need to be cut down. I will sell Mamiya screens for $90, and will install them on cameras I refurbish for sale or for repair, but there aren't enough around to make a real go of them.
NOTE: If you have been around camera repairs and around this whole site, you have probably run into Rick Oleson's post and maybe his web site. I find Rick to be one of those helpful types, someone always willing to answer a question or provide information. And Bill Maxwell is also a helpful guy. If you are thinking of getting a new screen, I'd encourage people to focus on those two offerings. If the screen will work for you, you'll be giving your money to the right people.
If anyone wants the original file at full size (~6000x8000 pixels), drop me a note. It can also be seen here and might enlarge depending on your screen and such:
http://dandaniel.zenfolio.com/p1062669410/h737b3f51#h737b3f51
