Multi-focal glasses and focusing

[Firsty]

I have just picked up my first TLR, a Mamiya C220
and before I head out tomorrow for my first try at getting an image or two I have a question about focusing normally and with the magnifier
I have multi-focal glasses where as the name suggests the focal length changes from long distance at the top to reading at the bottom
I want to make sure that the changes in my glasses lens won't affect my focusing.
So am I right in moving my head/glasses so that the circular fresnel lines in the screen are sharp and then focusing the image to the camera screen will get me the focus I wanted and do I use the same method when using the magnifier.
By using this method do I negate the need to use any sort of diopter adjustment.
Am I on the right track or have I got it all wrong

 

[Lukino]

the entire focus assembly is placed before the ground glass, so if you see a sharp image in the finder, it will be sharp in the picture. The ground glass act as a projector screen: the image there is flat, has no depth, so you can't be wrong.
Think of it as the final image: if something is out of focus on a print, no lens can make it sharp. Focus screen acts in the same way.

 

[rxmd]

I have just picked up my first TLR, a Mamiya C220
and before I head out tomorrow for my first try at getting an image or two I have a question about focusing normally and with the magnifier
I have multi-focal glasses where as the name suggests the focal length changes from long distance at the top to reading at the bottom
I want to make sure that the changes in my glasses lens won't affect my focusing.
So am I right in moving my head/glasses so that the circular fresnel lines in the screen are sharp and then focusing the image to the camera screen will get me the focus I wanted and do I use the same method when using the magnifier.
By using this method do I negate the need to use any sort of diopter adjustment.
Am I on the right track or have I got it all wrong

With a TLR you are focusing on the ground glass. The ground glass is matte, meaning that the image projected there directly represents the sharpness of the final image (assuming that it's properly adjusted and everything).

In other words, if you can look at the ground glass and see the fresnel lines there sharp, it will be fine. This will usually be at a similar distance from your eyes as when reading a book.

This is different from focusing through a prism viewfinder, or through a rangefinder. In the prism viewfinder of an SLR, for example, you also have a ground glass, but the viewfinder contains extra optics that make this ground glass appear further away than the 5-10 cm of light path between it and your eye. (Otherwise your eye would have a hard time focusing on it.) Also, the position of your eye with respect to the prism is relatively fixed - you can't adjust a lot by moving closer or further away, or by tilting your head with multifocal glasses (as you could with a TLR, or a view camera). That's why with a prism viewfinder you'd need diopter adjustment lenses, to adjust the viewfinder's optical system to the diopter adjustment needed by your eye.

 

[robert blu]

Since I use multi-focal glasses focusing my TLR has become much easier: just look at the glass and focus 'till it is ok.
robert

 

[sepiareverb]

I can't focus my Rollei without my reading glasses anymore, unless I use the magnifier, when I must take the glasses off...

 

[Ronald M]

I the grid lines look sharp and the image looks sharp, the pic will be sharp unless the camera is defective.

 

[newspaperguy]

That's the joy of the TLR... and the waist level viewing of a medium format SLR, too: What you see is what you get... and you can compose to your hearts content.

It's that one degree of separation from the prism view of most slrs and the direct view of the rf.

 

[robklurfield]

I think Keith's question is more about his glasses than it is about his camera.

you need to tilt your head in the same way you would if you were reading so that you're using the correct part of your prescription. if you're holding your TLR at waist level, that's probably either your close or middle distance prescription. if you're holding the camera closer, it's certainly going to be your close prescription. if you can't see that edges of the viewfinder or some other part of the camera on roughly the same plane as your focusing screen in focus, you should tip your head before trying to focus. otherwise, everything will look fuzzy even if the camera is focused because your glasses will be out of focus.

only someone else familiar with trifocals or progressive lenses would even get this. I wear progressives myself. focus your eyes, then worry about focusing your camera. simple enough.

 

[robklurfield]

lol. me too. a pain in the neck.

I can't focus my Rollei without my reading glasses anymore, unless I use the magnifier, when I must take the glasses off...

 

[Firsty]

thanks for all the replies I went out yesterday and I think I have got the focus right... but I won't know till I get the film developed 🙂

I'll share a few on the forum, if any work

thanks again