Technical question about adjusting the Yashica RF

[Paolo Bonello]

Hi.

I have noticed on more than a few shots when shooting low available light from both my Yashica GSN and my GS when using wide open aperture i'm missing the focus on my subject by a few inches forward of where I thought it was to be in focus. I do understand that it is generally a bit of a softer look wide open but I definitely see more in-focus (in the resulting images) a few inches forward of the subject. The distance to subject is in that 1.5 to 2 and up to 2.5 meter zone. I usually use the persons face to focus on if the background is contrasty enough but have noticed for example that their leading shoulder was more in-focus than the face.

I do which the close focus (1m point) adjuster is and the infinity adjustment screw but am unsure on the effect of aperture on this focus point adjustment.

ie: If I adjust the 1m focus and the infinity focus using f4 for example, will my f1.7 aperture focussing be a lot different? So what Aperture do you normally adjust RF focussing at? Does it have any effect which aperture you use when making adjustments? Or are there standards that we should set adjustments to?

I got too many of these yashicas to learn the intrinsic differences between each camera and remember it each time I use one so I'm trying to get them all behaving very similarly.

If anyone can help it would be much appreciated.

 

[farlymac]

What aperture you use to set the rangefinder is irrelevant Paolo, since it is only a matter of aligning it with the infinity mark on the lens. Set the lens to infinity, and adjust the horizontal on the rangefinder while looking through the viewfinder to make sure the two images are correct (while looking at something more than 100ft/90m away).

Really fine adjustment entails holding the shutter open on Bulb, placing a piece of either ground glass, or plastic sheet roughed up with sandpaper to mimic ground glass (rough side toward camera front) in the film plane with the camera back open, and focusing the image on the glass/plastic. Compare this image (using a loupe) with the infinity setting on the lens, and adjust the rangefinder accordingly. Close focusing should fall in line after that. I don't think there is a 1 meter adjustment to make, but then I could be wrong.

PF

 

[Paolo Bonello]

Thanks I did everything but use a loupe. I guess I might have been fooled by the aperture thing. Wide open aperture obviously requires more accuracy due to the shallower depth of field so I'm starting to beleive my adjustments were not quite right to begin with although my GSN displayed the same problem without me ever adjusting it. I'll have to try again with a loupe, a more defined image subject to do my testing and a bit more patience.

BTW, the 1m adjustment is a small hexagonal head bolt just under the front window. Needs a very thin and small open ended spanner to adjust.

 

[farlymac]

Like they always say Paolo, 'If at first you don't succeed; try, try again'. Looks like I need to bone up on rangefinder adjustments on the G series😱

PF