Yashica Mat focus problem

Yashica-Mat focus

I recently acquired an early Yashica-Mat with Lumaxar lenses. I have never had a Yashica with these lenses I discovered that the ground glass image is not agreeing with the film plane At infinity the image is soft and sharpens up on the ground glass at the 60 feet mark As the bulb setting isn’t working it makes checking the image at the film plane dicey at best. But the last few rolls I shot agree with this .I have the distinct impression that the ground glass is not installed correctly. Before I remove the hood which I have done before on other Yashicas has anyone had any experience with these lenses?

To change the focusing of the viewing lens, you will need to remove the leatherette on the lens panel. Good luck with this- I don't know what Yashica used on these older 'Mats but it is either dried out or was melted into place in the first case. It is going to crack and flake off and take some chiseling in places.

After exposing the five screws that hold on the lens shroud (one at the bottom center), you'll also need to expose the four screws that holds the side cover panel in place. There are 3 sets of screws on the lens panel, and you want to LEAVE the 4 largest screws (slotted) in place as these hold the actual lens in place. They also have shims behind the for lens alignment.

If you want to hold the lens open for focus checking, remove the front lens element (by hand- don't take a spanner to the inner retaining ring, that is for the front element only), unscrew the notched ring, take off the main cam piece, put the lens element back, and hold the shutter release down.

The set screw for the viewing lens is accessible through an opening on the upper right of the lens board. Small slot, often difficult to break loose. Then the whole lens screws in and out- fine threading.

The Lumaxar is the same as the Yashinon lens. Well, some say it came from Germany, some say the name was changed because of a trademark issue. If you have done work with Yashinons, including maybe everything I wrote above, the Lumaxars and their mounting are the same. Also, if you have worked on 'Yashinon' Yashica-Mats, you have worked on the Lumaxar Yashica-Mats. Same body, parts, etc., just different lens (name?). Well, I do think that the Lumaxar versions are a bit heavier than Yashinon 'Mats, so maybe more steel?