Focus techniques

[dwind]

I learned a lot from the exposure thread.
What techniques do people use for focus?
I know their are a lot of different focus depending on the scene.
What are some techniques and tricks used to get the correct focus you are looking for.
Thanks
Dennis

[Sandokan]

One helpful hint from another member here was:
Always leave the lens to infinity so you will always focus in one direction and wont hunt the wrong way (speeds you up).

One thing I learnt recently was to set up a focus test rig for your lens and camera. With digital the feedback is instant but it is well worth wasting a roll of film too. I found my M8 was focuing behind the subject so many shots I thought were user error were actually mechanical and could have been fixed a long time ago.

Ravi

[gfspencer]

Originally Posted by bindrar

One helpful hint from another member here was:
Always leave the lens to infinity so you will always focus in one direction and wont hunt the wrong way (speeds you up). Ravi

Dang. I wish I had thought of that. I'm going to do that from now on. Thanks.

I always try to find and focus on straight line somewhere in my picture. It doesn't always work but sometimes it does.

[Nicoleica]

I've mentioned this before, but at the risk of sounding like a scratched record, I'll plonk it into this thread too.

In awkward situations where there may not be any distinct straight lines to help, or in low-ish contrast scenes, I find it can help if you angle the camera at about 45 degrees when focusing.

[jaapv]

<enters stage left. Makes not unexpected entrance and plunks down soapbox. Climbs it laboriously and with creaking knees. Holds forth:>

Before you start thinking about focussing you must make sure that the rangefinder is correct for your eyes. You must be able to see the framelines and rangefinderpatch sharply without effort. Do not worry about the sharpness of the image itself.
If not you must find out about the strength of your eyes by either going to the optician and inserting his tryout lenses between your eye and the ocular, or use the primitive method by using throw-away reading glasses at the chemists for the same purpose and order the appropriate diopter correction glass with your dealer.

There are two basic techniques to focus.
1. Split focussing: find a straight line and make sure it runs unbrokenly through your RF patch.
2. Coincidence focussing. Make sure structures coincide in your RF patch.

The tip to turn the focussing ring one way and to "hunt" as little as possible is very valid at this stage.

Once you have achieved approximate focus using one -or both- of the methods above you should fine-tune it to perfection by contrast focussing, i.e. making a minimal adjustment which will produce a sudden " jump" in contrast in the RF patch. When that happens you are spot-on.

<falls off soapbox and limps off - exits stage right>

[russell c. greenberg]

Originally Posted by jaapv

<enters stage left. Makes not unexpected entrance and plunks down soapbox. Climbs it laboriously and with creaking knees. Holds forth:>

Before you start thinking about focussing you must make sure that the rangefinder is correct for your eyes. You must be able to see the framelines and rangefinderpatch sharply without effort. Do not worry about the sharpness of the image itself.
If not you must find out about the strength of your eyes by either going to the optician and inserting his tryout lenses between your eye and the ocular, or use the primitive method by using throw-away reading glasses at the chemists for the same purpose and order the appropriate diopter correction glass with your dealer.

There are two basic techniques to focus.
1. Split focussing: find a straight line and make sure it runs unbrokenly through your RF patch.
2. Coincidence focussing. Make sure structures coincide in your RF patch.

The tip to turn the focussing ring one way and to "hunt" as little as possible is very valid at this stage.

Once you have achieved approximate focus using one -or both- of the methods above you should fine-tune it to perfection by contrast focussing, i.e. making a minimal adjustment which will produce a sudden " jump" in contrast in the RF patch. When that happens you are spot-on.

<falls off soapbox and limps off - exits stage right>

Jaap, you are right about the 2 techniques to focus. Please, when you climb on the soapbox, don't be holding one of your M8's, you don't need any more costly repairs or any more bad luck. Russell P.S. did you you go to the 2009 IDS show in Cologne?, if yes, send me a PM with your thoughts.

[jaapv]

No, I didn't go there, Russel And I am trying to keep my gear in one piece, honest

[sfokevin]

Also make sure you understand the depth of field of your focus in conjunction with your aperture setting... All those numbers and lines on the lens mean something

Bing "zone focusing"

[PavelDerka]

Very nice points to remember Jaapv. I'm one who sure does need a I trip to check my eyesight.

[el.nino]

Outlined in this informative video are 4 different techniques for accurate focus as well as a discussion on DOF (depth of field) as it relates to each method. Additional information is provided on off-center focus using a rangefinder camera such as a Leica M. Video length: 12 minutes 11 seconds.

Focus and Depth of Field The Figital Revolution

[dwind]

Thanks for all the focusing information.
Not quite as simple as autofocus. I never knew so much went into it.
Dennis

[lars_bergquist]

Originally Posted by dwind

Thanks for all the focusing information.
Not quite as simple as autofocus. I never knew so much went into it.
Dennis

It's simpler, because it will rapidly become a subconscious, reflexive thing: See the picture. See where you want maximum focus. Raise the camera to your eye and focus on that point.

A piece of serious advice: Forget about depth-of-field or 'zone focusing'. The numbers on your lens are nonsense, because they are holdovers from the 1920's, founded on notions of 'acceptable unsharpness' that are obsolete because, believe it or not, they were based on the assumption that a Leica 24x36mm neg would not be enlarged more than three times, i.e. to 7.2 to 10.8mm! Except in the cases of very short wide angle lenses, depth of field simply isn't there. So:

Find the point to focus on, and point-focus on it!

The old man from the Age of Scale-focusing

[Fotomiguel]

For me the focus tecnique depens on which lens I'm using, how much light, how quick I have to focus , how far is the subject, which f-stop I want to use or I can and finally if the subject is moving or not. The focus tecniques is one of the most important points in a M camera and is always posible to improve and learn a new trick. For me is very important to know the lens, to learnt to meter distances ( as a golf player do) and be able to prefocus quick in close distances. The daily practice will give you the control of the focus, being able to focus much better than a autofocus. If you don't touch your camera for two weeks, don't expect to be very quick.

[akiralx]

Originally Posted by Nicoleica

I've mentioned this before, but at the risk of sounding like a scratched record, I'll plonk it into this thread too.

In awkward situations where there may not be any distinct straight lines to help, or in low-ish contrast scenes, I find it can help if you angle the camera at about 45 degrees when focusing.

I don't understand what you mean.

[Nicoleica]

Originally Posted by akiralx

I don't understand what you mean.

Hi,

If you tilt the camera at an angle to the horizontal, then the rangefinder patch image will seem to come from either above or below and to the side instead of just from the side. This can help in finding the best focus on difficult subjects. Also, you might find a suitable 'straight' line if you angle the camera that isn't available if the camera is horizontal.

It's easier to see what I mean by trying it than it is to explain it.

[yanidel]

Focus technique depends a lot on what you are shooting, the rendering you want and the speed of the scenes.

Most important is the pre-focus. Usually, I have my 35mm lens set on 3 meters and F2.8.
As I am positionning myself for the shot, I pre-adjust distance or aperture depending on whether I feel I will have time or not to align the patch when I bring the camera to my eyes:

No time to adjust : close aperture.
Time to adjust or want to gamble : open aperture.

Practicing to estimate distances is a good excercice. Look at an object, estimate distance then check if you were correct by focusing the patch and look at distance on lens.

[lars_bergquist]

Everyone finds a way of working that feels right. Still, I want to endorse the 'start always from infinity' method, because it is quicker than pre-focusing, i.e. fiddling in various directions with the focusing ring. And I have done quite a bit of street photography, from demonstrators to buskers, with various kinds of equipment. No comparison, the M is best -- as long as your technique is instinctive.

The old man from the Age of You-Know-Who

[dwind]

The book I'm reading talks a lot about hyperfocal distance.
Hyperfocal Distance
This goes against what Lars mentioned, I think.

[wizard]

Well, Hyperfocal Distance is just another term for what is meant by zone focusing. In essence, you are still focusing on one point in your image, but take advantage of the fact that there will be acceptably sharp areas in front of and behind that point, the more so as you stop down the aperture. I only use zone focusing in rare instances. The rule should be to focus exactly on your point of interest in the image. And I second the "always put your lens on infinity" rule.

Andy

[lars_bergquist]

Note the words "acceptable sharpness". What's acceptable to you? How much fuzz can you stand?

Formerly, pros who understood the issue used to estimate their depth of field "one stop down": If the lens was set to f:8, then read the d.o.f. at 5.6. Even that was optimistic. I found that with that technique, I could get away with a 10x15cm (4x6") print. But with the increased enlargement necessary from the 18x27mm sensor of the M8, and with the increased discrimination between 'sharp' and 'pretty sharp' that digital makes possible, I found that I had to read at least two stops down: If f:8, read at 4.

That is equivalent to working with a maximum circle of confusion of 1/60th of a mm, as compared to the official c. 1927 industry standard of 1/30th (introduced by Max Berek, of Leitz). But even so, I could see even on my laptop monitor the difference between the plane of best focus and 'maximum acceptable unsharpness'. And if Leica switched their standard from 1/30th to 1/60th or even 1/50th, then the numbers on a 90mm or even 50mm lens barrel would be too close to be engraved. So I told myself to forget about depth of field. Even a picture with great depth should have a point of maximum sharpness--focus on that. In front of or behind that plane, well, that's like shooting a shotgun: You rely on instinct.

Sharpness in itself does not make an image. As I have said before, sharpness is the fetish of boring photographers. An interesting picture must have several qualities to it, and Weston and Adams and Cartier-Bresson and Capa did not shoot resolution charts. But sharpness is one important part of our toolkit, and where we put it is one of our most important image-making techniques. So you might even say that unsharpness is an important imageing technique--as long as there is sharpness as a contrast to it.

The old man from Radio and Roll Film Days