Hyperfocal Distance & Manual Focus

[diogenis]

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I found a published matrix showing hyperfocal settings for a 24mm lens on an APS C format ... and used those figures after 'rounding' them.

 

You can also use the tech. manuals from the 35mm summarit lens here: Leica Camera AG - Photography - LEICA SUMMARIT-M 35 mm f/2.5

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[dkCambridgeshire]

But the problem is, that the X1 does not retain its distance on the lens. Meaning, if you say place the lens manually to hyperfocal dist, it will move past this setting, even if in manual. Otherwise you would be using an aperture of 8-16: anything after 2m comes in focus. But can you maintain 2m in your lens?

 

 

But, if the scale's 'click settings' are calibrated to actual distances then at least focus settings which approximate to the hyperfocal distances would be possible ... and any preset distance could be maintained for up to ten minutes if the 'power off' is set to ten minutes.

 

dunk

[dkCambridgeshire]

You can also use the tech. manuals from the 35mm summarit lens here: Leica Camera AG - Photography - LEICA SUMMARIT-M 35 mm f/2.5

 

Those DOF matrices are for FF format not APS ... and the lenses are different focal lengths.

 

dunk

[damnsharp]

Hm, dunk, when I use the formula (Hyperfocal distance - Wikipedia, the free encyclopedia) I get some other results then what you wrote on your nice card on the SBLOO. Maybe I am making a mistake...

[diogenis]

Yes Dunk, but your lens is not 35mm/2.8 it is 24mm/2.8.

The one I told you about is 35mm. It is the same as if you used your lens on APS-c sensor:

1.5 x 24= 35

[dkCambridgeshire]

Yes Dunk, but your lens is not 35mm/2.8 it is 24mm/2.8.

The one I told you about is 35mm. It is the same as if you used your lens on APS-c sensor:

1.5 x 24= 35

 

Apologies ... I thought that even though the lenses have the same angle of view , the APS format had larger DOF but I'm incorrect as the DOF should be the same.

 

Cheers

 

dunk

[dkCambridgeshire]

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Hm, dunk, when I use the formula (Hyperfocal distance - Wikipedia, the free encyclopedia) I get some other results then what you wrote on your nice card on the SBLOO. Maybe I am making a mistake...

 

I used the matrices from this link

 

http://www.nikonians.org/html/resources/guides/dof/wide_angle_tables.pdf

 

... which are specifically for APS C size sensor hyperfocal distances. But my hyperfocal figures on the SBLOO are rounded to nearest 0.5 meter ... however, the minimum to infinity figures in the third column on my SBLOO are not rounded.

 

Cheers

 

dunk

[dkCambridgeshire]

Apologies ... I thought that even though the lenses have the same angle of view , the APS format had larger DOF but I'm incorrect as the DOF should be the same.

 

Cheers

 

dunk

 

 

But AFAIAA , DOF is only the same for the same circle of confusion ... and different formats eg FF and APS C use different circles of confusion in the calculations.

 

This is a more complex subject than originally thought

 

dunk

[diogenis]

Damiaan, while waiting for that X1 to arrive, take a look here for dof: Depth of field - Wikipedia, the free encyclopedia

then, go and download specs of say, an M lens like here: Leica Camera AG - Photography - LEICA SUMMARIT-M 35 mm f/2.5.

The thing is, that on an M camera, you get the whole DoF as a bonus while looking at the lens, it is there! Check the lens photo, and you will see the markings on the barrel of the lens. It is the same as the zones you get from those lens specs. Check it it's fun!

You can see there, that when you choose a higher f/stop (larger number= close the lens more), dof gets larger as well.

[damnsharp]

Thanks diogenis, I will look into this! I know some about DoF but the more the better

[lars_bergquist]

I am very sorry to appear at the party like the Grim Reaper. But the circle of confusion is not based on any kind of natural law, but on convention, and do never believe those d.o.f. scales on the lenses (or Leica's tables, for that matter). I'll explain why.

 

It was generally felt during the 1920's that a PRINT with a minimum (in focus) c.o.c. of 1/10th of a mm would be acceptably sharp. This may be true, though this does not mean that we can't see the difference with one with a c.o.c. of 1/15th or 1/20th. But OK, let's accept that basic premise.

 

I have met several old roll film and plate cameras with d.o.f. scales based on a c.o.c. of 1/10th. Here, the idea was of course that the print would be a contact one, so that print and negative c.o.c. would be the same. But if we enlarge a neg, then we also enlarge the confused circles in proportion. So we have to divide the print c.o.c. (1/10th mm) by the ratio of linear enlargement to obtain the largest acceptable c.o.c. in the NEGATIVE -- or on the sensor.

 

As you have already grasped by now, the industry standard 35mm c.o.c. of 1/30 mm, introduced by Leitz in the late 1920's for the Leica camera, rests on the assumption that the negative would not be enlarged more than 3x, i.e. to a size of 7.2 x 10.8cm. This way, the Leica prints could compete with the amateur standard print of that time, which was a contact from a 6x9cm roll film. -- And you would think that Leica still believe that this is the maximum size print from a M9 image file! For they do still use that c.o.c. which was obsolete already before WWII.

 

If you reduce the acceptable c.o.c. to 1/60, you double the largest print size to a stately 14 x 22cm. And remember, an APC sensor image has to be enlarged even more to reach these 'immense' dimensions. Great. If this is not enough for you, forget about depth of field. Only superwide lenses have d.o.f. enough to work with. With all other lenses, focus to a point, and stop down a bit to get a bit of leeway. You will develop a feeling for how much you get, dependent on your print sizes, but exact computations, tables or scales are just self-deception.

 

Old man Nemo from the Depth of Field

[barjohn]

I'm not sure why Leica couldn't have done the following except that maybe they believed that Leica customers wanted a true manual camera in which they had to manually compute distance and f-stop before taking a picture. Note how the DOF scale (green) changes as the f-stop is changes and also as the distance is changed.

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[dkCambridgeshire]

That is a very useful Focus and DOF scale .

 

Thanks for posting.

 

dunk

[nhabedi]

I'm not sure why Leica couldn't have done the following

 

Ricoh often does clever things where one wonders why other camera makers don't adopt them or why it takes them such a long time. As far as user interface design for digital compacts is concerned, I think they're far ahead of the pack.

 

Unfortunately, the Ricoh I had had to be repaired twice in one year, so it's not all roses...

[diogenis]

As Lars already vividly explained, my guess is, that Leica wanted to keep things easy. Anyway it must not be that important for the camera to have a more detailed focus sale, as hyperfocal limit kicks in and you can take a reasonable pic. For all the other cases, you still have the AF.

[AlanJW]

I found this thread to be extremely informative. The manual focus difficulties explained (and the fact that any setting is lost after the camera goes to sleep) would impel me to forgo the $2000 investment. I had thought that perhaps an X1 could serve as a small but sophisticated backup for an M9. I don't think that is going to work, at least for me for now. I expect that the X1 can produce very nice images with its larger sensor, but seems to me it has been unduly burdened with firmware directed solely at a P&S audience. I hope Leica is working on something better (but my expectations are low).

[dkCambridgeshire]

More experiments with focusing modes show that when AF has been used on a subject, the focus setting is retained when the camera is switched to Manual Focus. This can be proved by experimenting with the 'Manual focus assist' facility which magnifies the central part of the image. Transferring the AF setting to the MF will facilitate accurate pre-focusing without having to consult the manual focusing scale and should thus enable confident use of the exterior finder. But the focus setting will be lost as soon as the camera powers down. Power down can be delayed for 2 minutes, 5 minutes or 10 minutes. Presumably with the monitor switched off ie 'external viewfinder ON' , battery drain should be minimal if the camera is left on ... but I have to try it to find out. With the monitor 'off', it will switch on again when the 'DELETE/FOCUS' button is pressed or when the 'INFO' button is pressed.

 

dunk

[SJP]

+1, this means that you do not need to fool around with LCD focussing things, just guesstimate the distance you want, focus on a suitably placed object (preferably not a cat) with AF, switch to MF and set the aperture. C'est tout.

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[barjohn]

SJP, pray tell how do you know what you focused on with the LCD turned off?

[lars_bergquist]

But AFAIAA , DOF is only the same for the same circle of confusion ... and different formats eg FF and APS C use different circles of confusion in the calculations.

 

This is a more complex subject than originally thought

 

dunk

Yes of course. The smaller a sensor is, the more you have to enlarge the file, and thus the fuzz, in order to obtain a same format print. So not only are the c.o.c. requirements far more stringent for a FF camera than Leitz thought they had to be in 1927, those of an APS-C sensor have to be *even more* stringent!

 

And please do remember that the c.o.c. is the fundamental parameter. Not the lens.

 

The old man from the Age of Tape Measure Focusing