M8 and rangefinder accuracy

[mohir_ali]

The common knowledge is that the film cameras with 0.72 finders was just barely

sufficient to focus the Noct and 75 lux. When mounted on the M8, these lenses

become 66/1 and 100/1.4, respectively. Is the RF up to the task?

[mike dixon]

<i> When mounted on the M8, these lenses become 66/1 and 100/1.4, respectively.</i><P>

No, they don't. The 50mm will have the same angle of view as a 66mm would have on a film Leica, and the 75 will have the angle of view of a 100, but they do not become longer focal length lenses (with the commensurate effect on DOF). The DOF will, however, decrease somewhat because of the greater degree of enlargement needed from the smaller sensor.

[aaron_benner]

To be exact the DOF decreases by the crop factor, 1.33 in this case, when using the

same lens at the same aperture and focal distance, moving from a larger to a smaller

sensor.

[roland_r]

That the Noctilux his hard to focus on a .72 finder is myth, in particular with its 1m minimum focus distance. For instance, a Bessa R2 will do fine with it. The 75mm Summilux is a completely different beast at .7m minimum focus with added focal length.

 

I recommend to play with http://www.dofmaster.com/dofjs.html.

Also, have a look at the attached chart.

 

Best,

 

Roland.

[jerry_lehrer1]

Aaron,

 

May I ask where you and Mohair got your optical information?

 

Jerry

[kelly_flanigan1]

A cropped sensor or piece of film may or may not have a tighter circle of confusion; it depends on the operator and what his/her goals are.

[mohir_ali]

It's quite clear from Roland's linked chart that the M8 is less 'adequate' than the other Ms, the diference in crop is reflected in the COC. There IS a difference.

[furcafe]

I've never had problems focusing the Noctilux or 75 'lux on my 0.72 M7. However, I occasionally have difficulty focusing those lenses accurately in low light on lower-mag. bodies like the Hexar RF & M8; it's not a problem when shooting in daylight. Since I use the M8 mostly for "available darkness" shots of bands, etc., I've been using 1 of the HK-made 1.25x VF magnifiers as extra insurance.

[seth_honeyman]

Jerry

 

Depth of field does change with crop (think magnification) factor. Check the charts at http://www.dofmaster.com/dofjs.html

 

Seth

[jerry_lehrer1]

Seth,

 

With thr so called "crop factor" the frame size is smaller, but the image size is the same. There is just less of it on the usable focal plane.

 

Once you arbitrarily change your definition of circle of confusion, you then change your acceptable depth of field..

 

Look-- a 50mm lens will project the same size image no matter how much of it you crop. But when you start enlarging thr image, the acceptable COF does change. However your range finder does not know any of this.

 

Jerry

[neilambrose]

<p><strong>Is the RF up to the task?</strong></p>

 

<p>Yes - just take a walk through Flickr. There's a vast amount of photographs showing that

the RF is sufficient to focus those lenses just fine. But whether any particular photographer

can focus those lenses is another question, and is mostly dependent on their eyesight.</p>

[michael_matsil]

Mohir.... the answer is, some can focus the nocti and some can't. Not the rangefinder, but

the photographer! And yes, degree of enlargement, aperture, etc. are always mitigating

factors in the so called depth of field of any lens.