Recently there are a few threads about technique in focusing Leica camera, such as focus at hyperfocal point etc.

Let me introduce Harold Merklinger's method of focusing.

In his opionion, the common practice of focusing at hyperfocal point is actually not as good as simply set the lens at infinity.

He wrote a lengthy technical book "The INs and OUTs of FOCUS" about his technique.

Harold Merkinger used Leica M3 with 50mm dual range Summicron for many of the illustrations in the book

For an introduction to his focusing method, see Harold Merklinger Focusing Method

For scenic photos, I usually set my Leica/Rollei/Minox camera to infinity and shoot.

-- martin tai (martin.tai@capcanada.com), January 18, 2001

Answers

I do mostly scenics and landscapes with Hasselblad, Leica R and M. When the subject foreground and background are both at infinity, I set the lens at infinity. When attempting to show acceptible sharpness in foreground detail as well as at infinity, focusing at infinity will work only if the lens/aperture chosen is such that the "near end" of the DOF scale for that aperture encompases the nearest point you want to appear acceptibly sharp. That would, depending on focal length, closeness of foreground objects and film speed, require increasingly small apertures and longer shutter times, opening the door to diffraction degradation and image blur from subject motion (i.e. things blowing in the breeze). Although technically, you achieve true sharpness at infinity *only* if focused on infinity (that goes for any subject at any distance), hyperfocal is the only way to get *acceptible* sharpness over a range of distances from near to infinity. Anyone who does a lot of that type of shooting eventually recognizes the advantage of using equipment that makes use of the Scheimpflug Principle as well, eg. large- format, the Hassy flex- or arc-body or the Canon or Nikon Tilt/Shift lenses.

-- Jay (infinitydt@aol.com), January 18, 2001.

It seems that H.M. may have shown that focusing on infinity can be adequate in some cases, but I don't think he said anything that argues in favor of this practice over hyperfocal distance focusing. I don't usually settle for adequate; I usually want the best I can get. Let's remember that D.O.F. is really just a euphemism for acceptable unsharpness. In my view no unsharpness is acceptable unless it's the best I can get.

-- Bob Fleischman (RFXMAIL@prodigy.net), January 18, 2001.

Apprently, HM's method is seldom practiced here. Harold Merklinger's book is written with a lot of mathematics, not every one can follow his reasoning. But instead of simply dismiss it, I urge all of you take one or two rolls of film and set it at infinity, and set the distance to one third of the focal length of you lens and shoot, you will be surprized at the result you get, and learn a valuable technique.

For example if you use a 50mm Summicron, set apertue at 50/3 ~ f16, if you use a 35mm Summilux, set aperture at 35/3 or about f11 etc.

Merklinger's method is based on DISK OF CONFUSION of the OBJECT FIELD, instead of circle of confusion in film plane. When a lens is focus at infinity, the DISK OF CONFUSION is exactly equals to the lens open, for example if you set 50mm lens at f12, the diameter of the opening is about 4 mm, and the DISK OF CONFUISON is 4 mm. What does it means ? It means, ANYTTHING which is greater or equals to 4mm diamter will be RESOLVED. This cannot be said with hyperfocal distance focusing. When you focus a lens a hyperfocal , at 2x hyperfocal, the DISK OF CONFUSION = lens opening, but beyond 2x hyperfocal, the DISK OF CONFUSION increases without bound ! You must try it to believe it.

-- martin tai (martin.tai@capcanada.com), January 19, 2001.

Harold Merklinger is a master is the theory of depth of field. This is not only manifested in his theory of Object field dof theory, but also in hia masterful book on DOF theory for the view camera : Focusing the View Camera. Scheimpflug principle is well know to LF photographers, but less the 0.1% of LF practisionner knows that Scheimflug principle is NOT ENOUGH, a long forgotten Second Scheimpflug principle-- the HINGE rule is necessary to determine the focus of LF camera.

Further, really only a handful of LF users know that the DOF in LF is RATICALLY different then that in 35mm camera. in that the plane of near limit, exact focus and far limit are not parallel as in 35mm camera, but are three planes intersecting on the HINGE LINE, with the plane of exact focus at center, the far limit and near limit plane on both sides foring a wedge shape zone of aceptable sharpness extends to infintiy.

For LF, only ths simplest case of low flowers on the foreground then mountain at distance is easy to encompass with lens tilt/back tilt. If you have a daisy in foreground, a cherry three at 10 meters, followed by a barn at 50 meters, then these three objects are not in a plane, then the handling of DOF is quite complicated. HM is the only author I know of completely solved this problem with a set of tables in FOCUSING THE VIEW CAMERA. Any LF users will also benifit greatly from his books.

-- martin tai (martin.tai@capcanada.com), January 19, 2001.

The failure of conventional hyperfocusing method was masterfully demonstrated by Merlinger with as set of 5 photographs on page 23 of The INs and OUTs of FOCUS: He photographed his niece June with a 50mm/F2 dual range Summcron at F8, focusing on hyerfocal distance 9.1m; June was standing at 3m, 4.6m, 9.1m, 18.3m and 49m, at corresponding distance, holding one card bearing 3, 4.6, etc at corresponding distance to show at what distance the picture was taken. Among the five pictures, only the ones at 3m, 4.6m 9.1m and 18.3 m were sharp, while the June the persona the the card at 49m was COMPLETELY BLURRED. The traditional hyperfocusng method can only deliver depth of field up to 18.3 m, it failed completely at 49m.

As a stark contrast, Harold Merklinger demostrated the powerful result of his INIFINITY focusing method. In a secons set of 5 photographs in page 30, Merkonger again photographed June, with same 50mm/F2 Summcron, at same F8, but this time, FOCUSED AT INFINITY. At 1m, 3m,25m 50m and 100m. The pictures at 3, 25m were sharp, at 50mm, the "50" on June's hand held card is clear, and even at 100m, the letters "100" on June's card were still decernable (albeit rather blurry, but still far better than the picture at 49m of previous tests when the lens was focused at hyperfocal distance 9.1m ) Conclusion: Summicron 50mm/F2 aperture F8 focused at hyperfocal distance 9.1m is really sharp from 3m to 18.3, beyond that it fails.

On the contrary, same Summicron, same F8, but FOCUSED at INFINITY: The pictures were sharp from 1m to 50m and beyond.

In other words. Merklinger's infinity focusing method actually delivers a much depth DOF then conventional method !

-- martin tai (martin.tai@capcanada.com), January 19, 2001.

I strongly recommend BUY the book The INs and OUTs of FOCUS. A great deal of material, including the two sets of tests, Hyperfocusing vs Infinity focusing pictures of June were not posted on his website.

This book is a must have for any Leica camera user. What is the point of possesing the best lenses in the world, but fail to use it to maximum power ?

This book is far more important then buying another expensive Leica lens to your holdings.

Harold Merklinger provides a road map for Leica lens users how to get the best out of their lenses !

Of course his method is equally applicable to other brands of lenses.

-- martin tai (martin.tai@capcanada.com), January 19, 2001.

Harold Merlinger, as a LF user, loves landscape photography. He was disappointed with the traditional focus at hyerfocal distance mehod, and tried different methods, including smaller apertures, but still not satisfacotry. He then took on himself to seriously investigate the matter, he searched literature on DOF theories as far back as 1933 article on depth of field by Vith in Leica Handbook, Rudolf Kingslake :The Complete Photographer 1942, and G. H Cook (of Taylor Taylor and Hobson ) 1950 Leica Photography articles, followed up with intensive experimetation and mathematical deductions. He finally worked out a completely new theory of DOF.

He wrote: Since working out these details, I find I do a lot of photography with the lens simply focused at infinity.

-- martin tai (martin.tai@capcanada.com), January 19, 2001.

Leicaphile Merklinger's method is really SIMPLE:

1) Focus at infinity

2) How to select aperture ? Ask yourself, what is the smallest object you want it to be resolved ? the look at your lens, turn the aperture ring, close down the aperture to THAT size. That is it.

-- martin tai (martin.tai@capcanada.com), January 19, 2001.

Dr. Merklinger is also a camera collector, he had written articles on camera and lens on Shutterbug. I remember one of his camera collector corner article was about dual range Summicron lens

-- martin tai (martin.tai@capcanada.com), January 19, 2001.

Is there something wrong with focusing on the subject of the picture? When people start discussing various shortcuts to use to turn multi- thousand dollar instruments into $10 plastic throw-away type cameras I cringe.

-- Michael Darnton (mdarnton@hotmail.com), January 19, 2001.

I tend to agree with Darnton. Too much hyperfocal distance setting is bad for sharpness! For slides that are to be projected you really notice the difference between objects that have been deliberatley focussed on and those that are just within the depth of focus. When viewing slides I think that hyperfocal distance methods are not so effective. For prints this is often not the case. However, I still, even in 6 x 6, try and ensure that I focus on the main point of interest and try and get the DOF to include the other items I feel need to be sharp rather than adjust the focus so that the DOF could be adjusted to get all the objects "in focus" which thereby sacrifices critical focus on the main object of interest.

-- Robin Smith (smith_robin@hotmail.com), January 19, 2001.

See paragraph "depth of field problem"

http://www.geocities.com/Athens/Atlantis/4628/sharpness.html

-- martin tai (martin.tai@capcanada.com), January 19, 2001.

Discussions at LUG

-- martin tai (martin.tai@capcanada.com), January 19, 2001.

I definitely see the difference between zone focused snaps and spot on focusing - especially with the new asphs. These lenses engrave the in-focus contours so sharply into the emulsion that anything else is just not as good. The beauty of the M is that focus is so positive. Maybe no quicker, depending on your skill level, but you really _know_ when something is in focus. That's why I continually refocus like an obsessive.

Rob.

-- Robert Appleby (laintal@tin.it), January 19, 2001.

RE snap on focus

Absolutely, when you are photography a person's face, or a painting on a wall, you must focus on the spot.

But where do you focus your Leica such as

-- martin tai (martin.tai@capcanada.com), January 20, 2001.

I must say that this has been an illuminating discussion for me. I've been dutifully using my DOF scales and wondering why focus at infinity was so bad in my landscapes. Now I know. Thanks for sharing this, Martin.

-- Ed Buffaloe (edb@unblinkingeye.com), January 20, 2001.

re: snap on focus: On the sign, the only area of sensible data in the brightest spot on the photo, to which the eye is ultimately drawn. If you don't have some sort of center of interest in a photo, you're better off not pushing the button.

-- Michael Darnton (mdarnton@hotmail.com), January 20, 2001.

Ed A few years ago, in rec.photo.medium+format news group, a photographer complained that he used his MF camera using according to the DOF rules for his landscape pictures, but when enlarged the distant objects were quite unsharp. Then I pointed to him Merklinger's book

a few weeks later he posted another message, saying his results were greatly improved.

IMO, this book is one of the best technical book about how to get sharp pictures with great depth of field.

-- martin tai (martin.tai@capcanada.com), January 21, 2001.

Martin,

Thanks for all the info. It's really very inteteresting and helpful. Some personal observations about my own results:

I hardly ever use my Leica equipment for the type of photography requiring infinity focus, such as the typical landscape image. Most of my Leica images are made at intimate distances at large apertures, where precise focussing on a particular element is necessary, and the maximum DOF is either not possible or not important. So I never bothered too much with hyperfocal settings, and when I did I was only concerned with the sharpness in the middle distances or at the focussed point, not at infinity.

However, for a long time I was using the hyperfocal method of focussing for landscape type images with my 38mm Zeiss Biogon, a lens that I often used on a tripod at minimum apertures for maximum DOF and sharpness. I was using the traditional hyperfocal settings when stopping down to f/16 or f/22, hoping to get everything in sharp focus from the immediate foreground to infinity.

I often found that the distant subjects at infinity were not critically sharp, and unless I used an aperture one or two stops smaller than my hyperfocal setting I would usually see a softness in the distant backgrounds. Then I started focussing at infinity, even when stopping down to f/16 or f/22, and was amazed at the incredible difference in sharpness at infinity. And the foregrounds and middle grounds were just as sharp as before, when I used the hyperfocal settings.

Take care, Sergio.

-- Sergio Ortega (s.ortega@worldnet.att.net), January 24, 2001.

It looks like there's som empirical evidence out there to support this idea. It is difficult to understand why infinity should not be included within the zone of acceptably (un)sharp focus, equally as well as all other distances within that zone. The observation, which seems pretty well true, that DOF extends about twice as far behind the plane of focus as before it, suggests that the best point of focus when DOF is desired, is at a distance relatively closer to the camera than the midpoint bewteen the lens and the farthest subject of interest. Ansel Adams wrote someplace that he thought it usually best to focus on the nearer of two objects.

Nevertheless, the only scientific thing to do is to give it a try, which I will do. I do agree that focusing on the subject of main interest is a good idea, which has something to do with why that rangefinder is provided!

-- Bob Fleischman (RFXMAIL@prodigy.net), January 25, 2001.

I have found Merklinger's articles in the net a couple of years ago. All the math is absolutely correct. During this years I used sometimes his approach (and use it now when needed) and I confirm it works fine. (Even though I don't have Leica; I hope the community forgives me my SLR).

The important point is to undestand, that focusing on the infinity does NOT give you "sharp" foreground (as sharp as it could be if you focus on this foreground), but allows you easily evaluate the unsharpness level and decide if this unsharpness is acceptable for your purposes. But Martin has already pointed it out above.

Merklinger's method makes it also possible evaluate DOF when the focus in not in the infinity. I do it also, it works great. The unexpected problem was the relationship between the quantity (the size to be resolved) and the quantity (what a given quantitative unsharpness looks like). The articles give some examples, but practice is necessary.

Merklinger's method makes possible to easily solve an opposite task: make something intentionally blurred. We so often try to get maximum sharpness and so often forget about the artistic effect of unsharpness...

I have no Merklinger's book; in my opinion his articles in internet contain all the neccessary information (even more detailed than needed to comprehend the idea and to follow the math).

I want also attract attention to his article about bokeh ("Thechnical view on bokeh"). As far as I know it is the first attempt of a rational attack on this "mysterious" property.

Thanks and sorry for my bad English.

-- Andrey Vorobyov (AndreyVorobyov@mail.ru), January 25, 2001.

Sorry, a misspell: it should be ...between the quantity (the size to be resolved) and the QUALITY (what a given quantitative unsharpness looks like). ...

-- Andrey Vorobyov (AndreyVorobyov@mail.ru), January 25, 2001.

Martin, thanks for very useful info. To demonstrate partly the difference between Merklinger’s and hyperfocal method of focusing I take the SLR camera (Nikon F, 1.4/50) and focus the lens on hyperfocal distance 5m at f/16 stop. Then look at any subject at infinity and stop down the aperture to f/16 with pre-set knob. It’s very noticeable that the subject stays OUT of focus yet, but when turning the lens ring to infinity mark, the subject becomes as sharp as possible. You could also watch how the sharpness of images (from 1m to 50m and beyond) is changing when changing f/stop.

Regards

Victor

-- Victor Randin (www.ved@enran.com.ua), January 26, 2001.