Leica Apo-Summicron-M 2/50 APSH

[01af]

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Measurements may be slightly off since I have done it all by hand.

"Slightly off"? LOL

[thighslapper]

The diameter of the focus ring also has an rather large impact on this.

 

yes...... which is why the noctilux 0.95 is by far the easiest lens to focus of the whole lot.....

[Michael Geschlecht]

Hello Again Everybody,

 

I'm sorry I'm having so much trouble making myself understood. I will try again.

 

Whatever minimum focus a lens might have has no bearing on this discussion.

 

This is a discussion about whether a lens has a sufficient ammount of focus throw to make accurate focussing on a specific subject at a SPECIFIC distance reasonably easy.

 

NOT a discussion about whether there is a sufficient ammount of focus throw to make MINIMUM distance focussing reasonably easy. Minimum focussing distances vary (Sometimes among lenses of the same focal length.) & they mean different things for different focal lengths.

 

I chose one (1) meter to represent a subject at a standardized distance from the photographer because all of the lenses under consideration focus to that distance.

 

That is why I asked for the degrees of rotation of the focussing barrel when the lens is focussed at one (1) meter.

 

With a standardized reference point for infinity.

 

Focussing cams move differentially on an "M" camera. Except for 50mm lenses.

 

When a 50mm lens on an "M" is focussed so that the lens elements move 1 mm away from the film/sensor plane then the cam on the lens barrel allows the roller in the camera body to come forward 1 mm.

 

When a shorter than 50mm lens is focussed so that the lens elements move 1 mm away from the film/sensor plane then the differential cam allows the roller to move MORE than 1 mm forward with the actual ammount dependent on the specific focal length.

 

When a longer than 50mm lens is focussed so that the lens elements move 1 mm away from the film/sensor plane then the differential cam allows the roller to come forward LESS than 1 mm with the actual ammount dependent on the specific focal length.

 

Enough for now.

 

Best Regards,

 

Michael

[lct]

...I chose one (1) meter to represent a subject at a standardized distance from the photographer because all of the lenses under consideration focus to that distance. That is why I asked for the degrees of rotation of the focussing barrel when the lens is focussed at one (1) meter...

Yes you made it perfectly clear Michael. Should be interesting for photogs using many lenses with 1m minimum focus distance i guess. A computer is not necessary for that. Others may prefer having an idea on the focus throw of the Summicron 50/2 apo compared to similar lenses with minimum focus distance of 0.7m. Horses for courses as usual.

[Michael Geschlecht]

Hello lct,

 

I'm not saying anyone should OR should not use 1 meter or .7 meters or 1.5 meters as a standard.

 

The only thing I was saying was that the chart should have a level playing field instead of comparing apples to bathtubs.

 

You need to have a point of reference that is common to all participants.

 

On your original chart the closest focussing distance that was shared by all lenses was one (1) meter.

 

Varying the goal posts for each lens individually: Some at 1 meter, some at .7, or .65, does not give a meaningful reference since they are not equivalent either distances or image magnifications.

 

A standard that varies because of parameters not related to what it is measuring is not a standard.

 

Best Regards,

 

Michael

[lct]

Haha! glad to see that i'm good at "comparing apples to bathtubs" thank you but why don't you try to do a better comparo?

[pgk]

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.... but why don't you try to do a better comparo?

Actually it needn't be in graphical form - a simple note of lens and measured angle from infinity to 1m would be an equally useful comparison. This way we might build up a full set if owners of various lenses could provide this data (all it needs is a protractor - I must have one somewhere myself...).

[Erik Gunst Lund]

...Varying the goal posts for each lens individually: Some at 1 meter, some at .7, or .65, does not give a meaningful reference since they are not equivalent either distances or image magnifications. ...

 

This thread is about 50mm Summicron APO so comparing it to 50mm Summicron regarding the focus throw is comparing apples to apples IMHO.

 

Start another thread on focus throw if you think it is needed

[pgk]

This thread is about 50mm Summicron APO.....

Start another thread on focus throw if you think it is needed

See post 2 in which it was stated to have too short a focus throw to support fast focusing.

[Erik Gunst Lund]

That was why I compared the focus throw to 50mm Summicron latest version which has a focus throw of 120 deg; 0.65 cm to infinity same diameter, focal length aperture...

[lct]

I still bet for the same focus throw as the tabbed 50/2 v4 or very close.

[hhanebeck]

All,

 

If I may throw in a purely subjective note here, I put the APO on an M7 today just to see how it performs on film (in a couple of weeks, of course) and found that it is "subjectively" harder to focus than any of the other lenses. I am not a technical expert, but I have shot enough to know the difference.

 

In a way this was a good field test, since I tend to be much more careful with film than digital. It is comparable to the 75 Cron and maybe a little more difficult. This is not to say that it's impossible. Just that I am anticipating it will take a bit of time before I can handle it with confidence. The good news here is that when you master the APO, your ability to focus should improve for all lenses. : )

 

Cheers, Chris

[01af]

... and found that it is "subjectively" harder to focus than any of the other lenses.

That's what I'm talking about.

 

And yes, accurate focusing sure isn't impossible. But it's significantly harder than it could be, for the sole reason of someone at Leica Camera having made a foolish decision.

[Bundestrainer]

I'm going to sell my copy of the lens because I just keep the Summilux. In case someone is interested in purchasing my lens, please send me a personal message.

[Michael Geschlecht]

Hello Everybody,

 

Well, I think I might stop trying to find equivalent parameters for now.

 

Sometimes when you tell a person they are driving a car with different sized wheels at the end of each axle they don't hear you. Or don't want to hear you.

 

Another thought:

 

Another thing people are not mentioning in terms of focussing problems with this lens is that the 50mm Summicron V is a lens with floating elements.

 

A designer may use floating elements to improve image quality on the plane of exact focus.

 

But:

 

Lenses with floating elements have a shallower depth of focus at any given aperture than lenses of the same focal length in which all of the elements move together at the same rate during focussing.

 

Less depth of field = Easier to miss focus within acceptable boundaries.

 

Someone might check to see if the lenses they are having trouble focussing are ALSO floating element designs.

 

Note:

 

Hello 01af,

 

Be careful about what you were about to say in your Post # 93 just above. This can be a touchy Thread when someone brings up the issue of focus throw.

 

Some people become defensive when you try to help them out of a box.

 

Best Regards All

 

Michael

[Michael Geschlecht]

Hello Everybody,

 

Please note:

 

If you look at the depth of field engravings on a 50mm Summicron IV you will see that when the lens is focussed at infinity the depth of field indicated at F16 is slightly MORE than 5 meters.

 

When you set the focus of a 50mm Summicron V to infinity the depth of field indicated at F16 is slightly LESS than 5 meters.

 

One additional note: When a lens has floating elements not only is the depth of focus less than with non-floating element lens designs but the correction of the out of focus image on either side of the plane of focus is sometimes not as good.

 

Best Regards,

 

Michael

[johnbuckley]

The bad points of this lens are the focusing throw (which is way too short to support quick and accurate focusing) and the stupid built-in hood (which is nicely executed but way too short to be useful).

 

Optical performance, of course, is just excellent ... provided you get it focused at where you intended to.

 

I think this statement about the deficiencies of the APO's focusing throw has sent us all on a long, confusing, and wild goose chase. I mentioned this in a separate thread, but having used the APO, where I found the focusing both quick and accurate, I can attest that the statement above, stated so assuredly and then repeated over and over, in this thread and others, is not borne out by actual use. YMMV, but I find the APO every bit as easy to focus as the Summilux and the Noctilux 0.95. And it is so easy to focus, and with an f/2 focal plane slightly more forgiving, even as the Bokeh is pleasing, I can see this becoming a go-to portrait lens, and even a lens you would use on the street.

[johnbuckley]

Example, this took about 2 seconds to focus on. Focus is on the eyes. May not come across via downrezzed LUF posting, but it is sharp. For those who don't want to keep their APO because there isn't a sufficient difference between it and the Summilux -- I actually think there is, as I am now seeing that it is far sharper, and has nice Bokeh -- I completely understand. It's ridiculously expensive. But: this discussion on focus throw, which I have read thinking it's progenitor likely knew what he was talking about, had proved to me in actual use to be a load of hooey.

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[johnbuckley]

Again, way downrezzed crop. Photo taken from 40 feet away. Elapsed focusing time: uh, negligible.

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Hallo,

Look here: Leica M

[lct]

Would you say that the focus throw of the 50/2 apo is significantly shorter than that of the 50/1.4 asph?