Why Minolta / Leitz CL not good with fast lenses

[dryice66]

I guess I said it in the title... anyway, would like to ask why a Minolta or Leica CL would not be good with a fast lense like a voightlander 40 / F1.4 or indeed low light conditions?

I believe it's something to do with focussing accuracy - but I don't really understand why! Anyone care to explain?

I like the look of the CL as a second body and I do like to shoot in low light with fast lenses f2 and above / (below)!

cheers

 

[sebastel]

short rangefinder base leads to bad distance measurement accuracy - just not accurate enough to reliably focus with faster lenses.

 

[HansDerHase]

short rangefinder base leads to bad distance measurement accuracy - just not accurate enough to reliably focus with faster lenses.

Yup. But that doesn't really explain why.

Should add that in low light and with a fast lens (large opening) you are likely to open the aperture as far as it gets. The trade-off is: The bigger the aperture the less depth-of-field you get. What means the less tolerance there is at what distance objects seem to be in focus. (That's why fast (large aperture opening) lenses are not only good in low light but also in situations where you want everything which is not your subject to be thrown out of focus.) What means the bigger the aperture opening the more focus accuracy is needed. And this is where the rangefinder base (plus viewfinder-magnification plus rangefinder adjustment) kicks in. As rangefinders work by triangulation: the longer the base the more acurrate you can measure a.k.a focus (all other factors constant).

Hmm. Maybe this doesn't really explain it as well 🙂

 

[clintock]

In terms of what you see in the viewfinder as you turn the lens to focus, the image in the RF patch of the CL does not move as much for a given turn of the lens as a body with a longer RF baseline.
Put the same lens on a M3, and turn the lens focus ring a quarter turn, you'll see the image in the rf patch move a much larger distance sideways in relation to the rest of the VF image than you would on the CL. Errors in focus are much more apparent in the finder of the M3. On either camera it's possible to get the focus exactly right, it's just harder to tell quickly if it's really right on the CL with the smaller RF image displacement.
The CL is not to be dismissed though, with the great 400 speed films available now.

I like to use my CV 1.9/28 on mine, using the whole finder beyond the framelines for the view.

 

[Andy Aitken]

The above answers explain the situation very well. I'd just add that in my experience you can use lenses a stop faster than normally recommended on the CL without much problem.

In other words IHMO a 90mm f2.8 or a 40mm f1.4 can be focussed wide open and close up fine on the CL. Pushing it any further (90mm f2, 50mm f1.4) might be asking for trouble though.

Having said that it all depends how good your eyesight is and assumes that your rangefinder is bang on.

 

[Andy Aitken]

I should also mention that the CL only meters down to EV5 which makes it of limited use in very low light anyway.