Yashica Mat124G and infinity focus

[kmallick]

I have a Yashica Mat 124G and it focuses beyond infinity (whatever that means). In other words I have a crisp image in WLF when the focusing knob is not turned all the way out to infinity. Is it normal?

I am planning to install a Rick Oleson screen with a split image microprism to get a better focusing aid. Is it typically a drop in replacement for the stock screen or do I need to do some shimming for hitting the infinity focus accurately? What else to check to make sure that focusing is well tuned? Any advice will be highly appreciated.

 

[Dan Daniel]

It is common for the taking and viewing lenses on TLRs to go out of sync. The only way to be certain about what is going on is to test the focus of the taking lens first. You can put ground glass on the film plane, open the lens, and view a distant object. If the taking lens isn't focusing at infinity properly, the adjustment involves loosening the focus knob and resetting its position. Then you can adjust the viewing lens to match- there is a set screw on its mounting flange to the upper right side; all the lens shrouding needs to be removed to get to this.

Rick Oleson might be able to guide you through shimming the screen, ask him. But remember- the important thing is how the taking and viewing lenses are aligned, not what the viewing lens shows on the screen.

 

[kmallick]

It is common for the taking and viewing lenses on TLRs to go out of sync. The only way to be certain about what is going on is to test the focus of the taking lens first. You can put ground glass on the film plane, open the lens, and view a distant object. If the taking lens isn't focusing at infinity properly, the adjustment involves loosening the focus knob and resetting its position. Then you can adjust the viewing lens to match- there is a set screw on its mounting flange to the upper right side; all the lens shrouding needs to be removed to get to this.

Rick Oleson might be able to guide you through shimming the screen, ask him. But remember- the important thing is how the taking and viewing lenses are aligned, not what the viewing lens shows on the screen.

Thanks. Those are invaluable pieces of advice. I will try putting a ground glass on the film plane and follow your tip to check focus on the taking lens.
Rick does provide directions on shimming the focusing screen. However I do not feel comfortable taking the shroud off and adjusting the focusing of the viewing lens etc.