Roger Hicks report of 50mm Nokton & R4

[gb hill]

On my other thread I asked about the 50mmf1.5 Nokton and small reference to a future purchase of the new R4 Bessa. Ironically I picked up the Jan07 Shutterbug last night and Roger Hicks,who wrote a good report on rangefinders @Photokina. I was a bit taken back on his view on the 50mm Nokton and the R4a. He said that the small viewfinder magnification, about 0.52x, gives a correspondingly short effective rangefinder base, under 20mm. And it"s not really adequate to focus the 50mm f1.5 at full apature or at short distances, that the 50mm f2.5 would be better. But overall he gave a good report on the camera. I'm not really sure what he means by all this so maybe some of you can explain.

thanks
Greg

 

[varjag]

Precision of optical rangefinder determined by its effective base, i.e. distance between rf windows multiplied by magnification of viewfinder. Since R4 is designed for wide angle lenses, magnification is by necessity small (to "fit" the actual wide view), while physical base remains the same as in R2/R3. Hence it is not surprising it can't focus 50/1.5 with required degree of precision.

This is not what camera is intended for however. R4 designed for wide and super wide angle lenses, where requirement for focusing precision at same apertures is dramatically lower.

 

[Graham Line]

On my other thread I asked about the 50mmf1.5 Nokton and small reference to a future purchase of the new R4 Bessa. Ironically I picked up the Jan07 Shutterbug last night and Roger Hicks,who wrote a good report on rangefinders @Photokina. I was a bit taken back on his view on the 50mm Nokton and the R4a. He said that the small viewfinder magnification, about 0.52x, gives a correspondingly short effective rangefinder base, under 20mm. And it"s not really adequate to focus the 50mm f1.5 at full apature or at short distances, that the 50mm f2.5 would be better. But overall he gave a good report on the camera. I'm not really sure what he means by all this so maybe some of you can explain.

thanks
Greg

A short-base rangefinder is going to be equally good or bad with any lens . . . the catch is that longer lenses, or faster lenses used wide open, will make the errors more visible.
Using a wider angle lens, or a smaller f/stop, your zone of apparent sharpness is deeper, so it's harder to see when you have misfocused.
All talk aside of wide angles and depth of field, what you're trying to achieve is finding the exact plane of focus. The.52 finder and 20 mm effective base length make that job a little more critical.

My Minolta CLE has a .58 viewfinder, an effective base length of 27.8 mm and can produce razor-sharp pictures with a 90/4 lens, so it's obviously possible.

http://www.rangefinderforum.com/photopost/showphoto.php?photo=37105&ppuser=1085

http://www.rangefinderforum.com/photopost/showphoto.php?photo=37104&ppuser=1085

 

[dazedgonebye]

I've wondered about this myself.
I've been thinking that, if April comes along and I've moved along with rangefinders well enough, that I'd treat myself to a R4A. Problem is, if I can't afford to have 2 bodies, or don't want to carry them both, I wonder how well I'll do with 50mm and 75mm with the R3A.
I think the answer is, it depends on what aperture I want to use those lenses at.
A 2 camera kit, R4A w/21mm, 25mm, 35mm plus a R3A with a 50mm and 75mm (the 15mm can ride either camera because focusing is pretty much N/A with that lens)....might work, but sounds complicated.

Lots to think about.

 

[gb hill]

I'm asumming that the short rangefinder base difference being refered to, is the distance from the film plane to rear of the lens at wide open aperatures. So then if the R4a is primarially for wide angle lenses then would the Bessa R be better suited for me to use for all around, plus low light situations, being I already have an L?

 

[dazedgonebye]

The rangefinder base is the distance between the beamsplitter and the mirror in the illustration you'll find on this page.
http://www.camerapedia.org/wiki/Rangefinder_(device)

Effective rangefinder base is that distance multiplied by the viewfinder magnification.

 

[Graham Line]

I'm assuming that the short rangefinder base difference being referred to, is the distance from the film plane to rear of the lens at wide open apertures. So then if the R4a is primarily for wide angle lenses then would the Bessa R be better suited for me to use for all around, plus low light situations, being I already have an L?

No and yes.

The rangefinder effective base length is the distance from the center of the big finder window on the right (looking at the front of the body) to the center of the little rf window on the left, multiplied by the magnification of the finder.

You're focusing with a triangle -- the EBL is the short side and lines from the two windows, converging at your subject, are the very much longer sides. Basically, when you get the two images in your viewfinder window to coincide, you're bringing those two lines together at the point of focus. The longer the EBL, the easier it is to triangulate the distance correctly.

The R has a longer EBL because it has a larger finder magnification. With the 50/1.5, yes, it will be a little easier to get accurate focus. But it is possible with both bodies.

 

[gb hill]

Thanks Joe and Steve for the lessons. Now I have a better understanding of whats going on inside my cameras. These are wonderfully complex devices aren't they?🙂


Thanks
Greg