35mm 2.8 goggled summaron - screw mount?

[Jul]

Interesting. So neither the focus scale or the rangefinder allow proper focus?

No, you didn't get it. Focus scale allows proper focus estimation. Erik said that if you try to focus with the rangefinder (which is wrong without the goggles as it lacks the proper correction), the focus scale would show another distance (which is to be expected).

 

[Jul]

As I said...not really usable. 😀

You are spoiled by modernity… 😉
What if you wake up tomorrow morning in 1931?
Do you adapt and use the available tools or do have a photography break till 1932?

 

[WJJ3]

No, you didn't get it. Focus scale allows proper focus estimation. Erik said that if you try to focus with the rangefinder (which is wrong without the goggles as it lacks the proper correction), the focus scale would show another distance (which is to be expected).

He said he focused on an object 90cm away and the focus scale was at 65cm. That’s not allowing proper scale focus.

90cm away can easily be measured with a yardstick or tape measure, so the rest should be simple. It sounds to me like unscrewing the lens from the bayonet makes the flange distance too short.

 

[Jul]

He said he focused on an object 90cm away and the focus scale was at 65cm. That’s not allowing proper scale focus.

With the focus cam such as the one of a goggled lens for the M3, the rangefinder need the goggles' correction to be effective. Trying to focus with a rangefinder without this correction will be wrong as expected. It does not mean anything regarding the actual resulting plane of focus or the focus scale accuracy which is unchanged by the presence or absence of rangefinder focus correction.

Except for the focus cam and the shortest written distance on the focus scale, the lens unscrewed from the M2 or from the M3 version are the same.

Let's change perspective. First focus with the M2 version and the rangefinder at whatever distance. Note what the focus scale shows. Remove the lens, mount the M3 version without the goggles or just its unscrewed part into the adapter from the M2 version. Dial in the same distance on the focus scale, now look in the rangefinder, as expected the focus seems way off but only in the finder. Both pictures result in the same plane of focus, not the ~1/3 distance difference.

 

[WJJ3]

With the focus cam such as the one of a goggled lens for the M3, the rangefinder need the goggles' correction to be effective. Trying to focus with a rangefinder without this correction will be wrong as expected. It does not mean anything regarding the actual resulting plane of focus or the focus scale accuracy which is unchanged by the presence or absence of rangefinder focus correction.

Except for the focus cam and the shortest written distance on the focus scale, the lens unscrewed from the M2 or from the M3 version are the same.

Let's change perspective. First focus with the M2 version and the rangefinder at whatever distance. Note what the focus scale shows. Remove the lens, mount the M3 version without the goggles or just its unscrewed part into the adapter from the M2 version. Dial in the same distance on the focus scale, now look in the rangefinder, as expected the focus seems way off but only in the finder. Both pictures result in the same plane of focus, not the ~1/3 distance difference.

So the scale is accurate? This is good news, and now I really want one of these. I have a Leica 1f and enjoy scale focus shooting with the 35mm FL...

 

[WJJ3]

Could someone with one of these post a photo of where the grub screw is please?

 

[analoged]

 

[WJJ3]

[............]

Thank you!

 

[Jul]

I have a Leica 1f and enjoy scale focus shooting with the 35mm FL...

The longer the focus throw, the easier to set precisely and accurately it will be (5° "error" would result in less focus distance offset). Some older 35mm have 180° from 1m to infinity so they fit even better the scale focus use case. Some of the first Elmar even have almost 360°.

 

[Erik van Straten]

It sounds to me like unscrewing the lens from the bayonet makes the flange distance too short.

No, on infinity there is no difference between the two, but the closer you get, de bigger the difference is.

So on infinity the lenses with a curve cut for the goggles and the lenses with a "normal" curve are equal.

Erik.

 

[WJJ3]

No, on infinity there is no difference between the two, but the closer you get, de bigger the difference is.

So on infinity the lenses with a curve cut for the goggles and the lenses with a "normal" curve are equal.

Erik.

So the flange distance is correct. That is good to know. I thought your report of how the lens was behaving on the screw mount body meant the rangefinder coupling and the focus scale were off. If infinity is correct then flange distance is correct and the scale should be correct as well.

 

[Dralowid]

Removing the M mount by undoing the screw wasn't really supposed to be a 'user' practice. Be careful, some mounts are glued on too.

 

[WJJ3]

The longer the focus throw, the easier to set precisely and accurately it will be (5° "error" would result in less focus distance offset). Some older 35mm have 180° from 1m to infinity so they fit even better the scale focus use case. Some of the first Elmar even have almost 360°.

It’s a good point. Longer focus throw is nice for scale focus shooting. The W-NIKKOR 3.5cm I often use on my 1f has 180° throw, and is a good match for this compact body.

 

[yossarian123]

I'm pretty comfortable with scale focus, that shouldn't be a problem.

Since I rarely use my Barnack, I'm kind of thinking that maybe I could remove the googles, convert to LTM mount, then add an LTM-M adapter and voila - a scale focusing M summaron. For street it would be perfect.