closer focusing distance ...

[haagen_dazs]

hi peoples!
it seems that the CV 35mm classic skopar doesnt seem to have very near focusing distance (0.7m).
i say this in relationship to slr cameras where for 28mm or 35mm lenses, one is able to focus ono an object at 0.25 or 0.3m.

1)
does the focusing distance have to do with an RF lens design ? (maybe lens build is too small or something?)

2)
what are some LTM lenses that have very near focusing distance?

3)
could someone explain to me why an RF has problems focusing very near?
(i understand the part about RF's not being able to focus far because of the base line distance. with a smaller baseline distance and long far away subject distance, the angle change is smaller)

 

[VinceC]

I don't quite understand it myself, but there must be a technical reason having to do with the RF coupling. Zeiss Ikon was initially announced with a close-focus of .5 meters / approx. 18 inches. That extra .2 meter had me seriously thinking about selling all my Nikons. Then, when the camera came out, it's close focus was .7 meter like the other Leica Ms. The Zeiss Ikon wide-angle lenses focus down to .5 feet, but with no RF coupling.

Over the years, I have compensated by doing very tight framing with a 35mm lens for situations where I might have used a 28 or 24mm very close on an SLR. But it's not quite the same, and it requires carrying two lenses where, on an SLR, one would suffice.

 

[VinceC]

It doesn't have anything to do with the lens design itself. The 1950s Nikkor 50mm lens focused, uncoupled, down to about 18 inches. This took advantage of the lens's repuation for being optimized for close up and wide open.

 

[haagen_dazs]

2)
what are some LTM lenses that have very near focusing distance?

3)
could someone explain to me why an RF has problems focusing very near?
(i understand the part about RF's not being able to focus far because of the base line distance. with a smaller baseline distance and long far away subject distance, the angle change is smaller)

bump...
any more LTM lenses ? anyone could explain question 3 pls?

 

[VinceC]

I believe that, because of the very limited depth of field at close focus, that the mechanical linkage of a rangefinder mechanism isn't accurate at wide-open f/stops at distances closer than about 2.5 feet.

 

[Doug]

I suggest it's a matter of parallax. The lens and viewfinder are separated by a couple of inches, so they have slightly different viewpoints on the subject. The closer the subject, the more significant the parallax error becomes. At, say, 10 inches distance to the subject, the difference in viewpoint is fully 1/5th of that. The viewfinder would have to be able to look down and to the right at a fairly steep angle to center the subject the lens sees. Because it's looking in from high to the left, the viewfinder sees more of the left side and top of the subject than the lens, so the view isn't the same. Further, this close subject's relationship to its background is significantly different through the viewfinder than through the lens due to the different angle at which its seen.

An RF camera's viewfinder framelines move down and to the right as you focus closer, to help get the subject centered, but there's a limit to far the frame can move. And this is not truly "correcting" parallax since the framing is accurate only for the distance you're focused to. The relationship of the subject to objects that are nearer or farther is different through the viewfinder than through the lens.

Larger cameras, such as medium format and 4x5 press cameras have their viewfinders much farther from the lens than a Leica, for instance, so the parallax error is much greater with these, and the practical close-focus distance is therefore longer. Bottom line... if you want to get closer to your subject than a meter or so, you're better off with an SLR where there is no parallax issue at all.

 

[VinceC]

Doug's explanation sounds reasonable.

 

[haagen_dazs]

An RF camera's viewfinder framelines move down and to the right as you focus closer, to help get the subject centered, but there's a limit to far the frame can move.

thank you Doug for the explaination.
i completely understand now.
no wonder there is no marco photography for RF cameras


when i focus closer, i dont see my Bessa R framelines moving.
there are all fixed in place... 😕 😕 😕

 

[laptoprob]

My Steinheil Quinon has a focusing cam that reaches down to about 60cm. I adapted my IIf to give the rangefinder cam more room to move outwards. I know this is beyond the range it was designed for but the first tests (on SLR focusing screen, not on film yet) look promising. The framing accuracy and parralax error is about as great as at a meter distance: too big.
I should be able to use an accessory finder with the parralax indicator quite well.
That is about the same distance as the Summicron DR with goggles. Great that the Quinon does that without goggles! First film is in the IIf now for a 35mm test. I will include a close focus test on that first roll.

 

[Nikon Bob]

You can do Macro with an M if you use http://www.leica-camera.com/produkte/msystem/objektive/makro/index_e.html. A little rich for my blood though.

Nikon Bob

 

[rool]

If you want to make the focussing distance a little shorter, you can also unscrew your lens (works only with LTM obviously) one or two turns when needed.
The lens is then a little further from the film plane, thus reducing the focussing distance.... No super accurate but it's always good to know the trick.

 

[haagen_dazs]

If you want to make the focussing distance a little shorter, you can also unscrew your lens (works only with LTM obviously) one or two turns when needed.
The lens is then a little further from the film plane, thus reducing the focussing distance.... No super accurate but it's always good to know the trick.

cool
thanks for the tip!
=)

 

[enochRoot]

you can also stop down and use the depth of field to allow you to "focus" closer (ie: focus as close as it will go, and then just move the camera toward the subject). you lose the whole "out of focus" thing though, which is often the point of doing macro...but it's another option. it has worked well for me.

 

[VinceC]

>>Why do 90mm lenses or even better 135mm
not go deeper than the typical 1m or .9m ? That should be less of a problem
for the parallax, no ?<<

The telephotos have an even worse parallax problem up close. With a 35mm lens, you're maybe shifting the field of view 6 or 8 percent of the image. With a 135mm lens, you're shifting it's field of view something like 50 percent between infinity and 5 feet.

 

[Nikon Bob]

If you have an LTM camera and a 50mm (Summitar I think) you can use a NOOKY-HESUM, fitted between lens and body, to focus closer. It will work only with certain 50s and there are several versions. It compensates for parallax at shorter distances and moves the lens away from the body.

Nikon Bob