Focusing Leica: Merklinger Method

All Merklinger said was focus at infinity bring out the supreme power

of a lens, at its best on main object at infinity <p> With some sacrifice resolution a near zone ( As indicated by my table at

beginning of thread <p>

<p>In the above picture, the buildings at far zone is my main object

of interest. Those far zone object occupied the almost 95 % of all

the film area. Rendering those 95% area as sharp as possible

enhance greatly the overall sharpness of the picture, because 95% is

at sharpest coc, not 0.02, not 0.01, but around 0.004 mm. (estimate )

<p> At hyperfocal point there is some dirt, I don't want to render

dirt or stone as sharp as possible, and degrade 95% of my picture to

only 0.01 mm coc. Bill you may chose to do so, that is your artistic

decision.

<p> As for the often quoted Merkling canon picture, he stated, he

main theme of his picture was the small village build on a sand bar,

he want that village to be sharpest, at the maxium resolution of lens

permited, the canon is not that important. That was his choice.

When there are substantial object of interest in foreground, focus

at infinity method can not be applied. Traditional DOF method is

best suited for such situation <p>

As described in my article about where to focus at at slanted

field of tulips with SLR.

<a href="http://www.accessv.com/~martntai/public_html/manual/hyperf.html">Hyperfocusing a Field of Tulip Flowers </a>

Martin, I agree that to photograph a subject at infinity the lens should be focused at infinity. It would make no sense, for example, to set the lens to a hyperfocal distance to photograph the moon.

However, photographs of landscapes often include middle- and foreground objects, as well as distant scenery, all of which should be acceptably sharp in the image if possible. To focus on infinity for such a shot is to reduce the zone of acceptable sharpness unnecessarily. So, in such cases, it makes much more sense to focus at a point closer than infinity (the hyperfocal length), so as to maintain acceptable sharpness for as much of the the foreground and middle-ground as possible, but not so close as to render the distant scenery visibly unsharp.

Exactly what the hyperfocal length should be depends, of course, on the lens's focal length, its aperture and the size of CoC that is required, be that .03mm or smaller. The smaller the required CoC, the more distant must be the point of focus in order still to have the distant scenery rendered acceptably sharp.

Of course, with a very small CoC the hyperfocal length would be so great that it couldn't be measured using the distance scale inscribed on the lens barrel and neither could the camera's rangefinder be used effectively. If that were the case, then I agree that there would be no point in trying to focus closer than infinity.

I challange Bill, Robert, Ray Moth to show me a 200x enlargement of

detail using Mike's method.

Martin, it seems you have become so defensive, that most or your arguments are no longer making sense. But to give you the benefit of doubt, I will respond to your issues, even though they have been addressed prior.

You wrote��Impractical with 35mm camera. Bill, tell you how do you focus a Leica M or R at 30M ?

I am sure this is a loaded question, and I do not use these cameras. But the point is, you focus at the distance required to meet your DOF requirments. If the camera does not have focus ranges, than use Mikes Broomstick method and mark the lens yourself. If your using a camera that can not be focussed than it should not apply to this discussion.

You wrote�. More fundamentally, the question boils down to where do you want your sharpest place to be ? As shown in the diagram, there is only ONE sharpest razor edge.

Yes, we all know Martin the point of exact focus will be the sharpest. So?

You wrote�.When main object of interest is at infinty, the only way to allocate the sharpest point on that object is to focus at infinty not a stone or nothing in between,

Yes, you are stating the obvious. In Mikes method if there is nothing worthwhile in the scene, except infinity, then we all would focus at infinity. But that is not what this is about.

You wrote�.

After all his labour, his smaller coc is still > 0.02mm 50 lpmm. not good at all. 5) Leica lens is much sharper then 50 lpmm. Summilux 50 can resolve up to 95 lpmm on developed film. You need at least 0.005 mm coc to achieve sharpest far zone object. That can only be achieved by focus at infinity.

This discussion has only resolved around DOF. Of course we all know there is a max. amount of resolution any film / lens combination can record. This is established by the formula, 1/R = 1/R1 + 1/R2 + 1/R3, etc.. Where R is the total resolution to film, and R1 through Rx represents the max. possible resolving power of all the cameras components such as lens, film, filters, etc. Velvia is the sharpest color film made today, and even with the sharpest lenses, approx. 55 lpmm is the highest resolvable lpmm to film. (and only at the point of exact focus) With Tech Pan, it is possible to get up to 95 lpmm to film. So one uses this as their max. on film resolution, assuming they want to achieve resolution this high. It�s the photographers option to pick the highest on film resolution or trade some of this resolution for increased DOF. It�s all about tradeoffs. However, what ever lpmm, or cc Mike chooses, this will be the lowest resolving portion of his image, and that is the goal, and the DOF formula will advise you exactly where to focus to achieve this. For some reason, I do not think you are grasping this point.

You wrote.. 6) Minox COMPLAN has even higher resolution, it resolves over 170 lpmm on developed film. I need to get 350 lpmm that is 0.0029 mm coc at that object. That can be easily achieved with Minox camera focus at infinity.Bill, can you show me how, with your Mike's method achieve such size coc ? Give us an example.

First off, I don�t know any film made today that can resolve 170 lpmm to film. I believe you are mistaken there. However, it is a mute point. Once again, enter your desired cc into the DOF formula, enter near and far, and you will get the focus distance required. And in the case of Minox, which was designed to photograph flat documents, well it�s a no brainer, focus on the document!

You wrote..No matter what small coc you chose, the sharpest point of lens for object at infinity is always at infinity, don't waste the sharpest lens on a piece of stone or gravel on something in between.

If that is the case, then Mike would focus at infinity also, it is only when he desires something in the foreground to meet a min. acceptable resolution will he enter the near distance in the formula, but if a scene is entirely at infinity, well, it�s a no brainer again! I can tell you are missing this portion of Mikes argument.

You wrote..Within the circled area, there is a street sign. Enlarge a small part of that sign 200x The " one " still can be resolved.

Not sure what you are tyring to prove here.. I can resolve a pole 400x too? I can still see it�s a straight structure, does that mean I resolved it to some standard? Or does it mean I can identify it is a vertical object. This discussion revolves around resolving to a known standard.

Such kind of highest resolution result for far object can only be achieved by focus at infinty.

Yes, no one will disagree with you. If your subject is at infinity, then focus at infinity, no argument, that will provide you with the PSF at infinity, the sharpest part of the scene. But what if you have something equally important closer than infinity, that is the point Mike was making! Do you get this Martin, I keep repeating it, and so does everyone else in this thread

?

You wrote..Bill, show me a picture of yours, using Mike's method, enlarge a small segment 200x, will you ?

It makes no sense what you are demonstrating. Your defensiness has taken your arguments to a new level.

All Merklinger said was focus at infinity bring out the supreme power of a lens, at its best on main object at infinity With some sacrifice resolution a near zone ( As indicated by my table at beginning of thread

Why are we still arguing this.. the sacrifice is exactly what Mike discussed. His point was, let the photographer pick the importance of each subject and how much is willing to be sacrificed.

You wrote..In the above picture, the buildings at far zone is my main object of interest. Those far zone object occupied the almost 95 % of all the film area. Rendering those 95% area as sharp as possible enhance greatly the overall sharpness of the picture, because 95% is at sharpest coc, not 0.02, not 0.01, but around 0.004 mm. (estimate )

I am willing to bet Mike, and others following this thread would all agree, under that circumstance, we would all focus at infinity. But it was our decision that 95% of the scene is most important, so we focus at infinity. Very simple!

You wrote..At hyperfocal point there is some dirt, I don't want to render dirt or stone as sharp as possible, and degrade 95% of my picture to only 0.01 mm coc. Bill you may chose to do so, that is your artistic decision.

Yes, this is very correct, and this is what we have been trying to convince you of, let the photographer decide, not Merklinger.

You wrote..As for the often quoted Merkling canon picture, he stated, he main theme of his picture was the small village build on a sand bar, he want that village to be sharpest, at the maxium resolution of lens permited, the canon is not that important. That was his choice.

Wonderful, and using the standard DOF he can make that his choice also and enter such in the formula and it will advise him to focus at infinity.

When there are substantial object of interest in foreground, focus at infinity method can not be applied. Traditional DOF method is best suited for such situation

So now you confess that focussing at infinity is not always best, even if infinity is part of the scene? If so, this thread was a waste. We all know if the scene is at infinity, focus at infinity, the discussion was about if there was subjects not at infinty that were equally important.

I challange Bill, Robert, Ray Moth to show me a 200x enlargement of detail using Mike's method.

If we all focus at the same point, use the same camera, lens and film, we should all get the same result, right? If you challenge Mike to get infinity at 200x then he can just as easily challenge you to get something less than infinity at 200x. But you are getting way to carried away, nothing is getting resolved at 200x anyway. But if you selected a more reasonable number, my argument still stands, i.e. wherever the point of exact focus is, we both will get the same on film resolution! Does this make sense to you?

Ray, thank you for clarifying these points to Martin. I think this thread is getting a bit rediculous.

Bill

Did I stated very clearly it is a matter of personal choice in the message with Peggy's Cove picture:

"The above Peggy's Cove pictures was taken with a Minox 35ML at infinity setting

In the foreground, there is a rope. Why should I chose to make the rope as sharp as possible and make the fishing hut fuzzy ? I prefer the far zone very sharp I just don't care the rope shows every strain of fibre

It is a matter of choice"

Bill wrote: "First off, I don�t know any film made today that can resolve 170 lpmm to film. I believe you are mistaken there. "

<p> FYI. Agfa Copex Rapid 600 lpmm, Fuji Super HR 850 lpmm

The critically important Mike's premise is accepting an anticipated enlargement factor and viewing distance. It is his key point. If one does accept this premise he MUST admit that there is a REDUNDANT sharpness at plane of sharp focus, and finally he will inevitably admit that Mike's method gives the optimal result. If one does NOT accept this premise he'd better to describe WHY, i.e. to describe a situation when it is better to refuse the Mike's premise to get an optimal result (and what 'optimal' means in this case).

Any further debates without explicitly clarifying one's choice relating to this premise are absolutely meaningless.

And after the choice is made there is no more room for personal preferences.

Any theory can only benefit from finding its own intrinsic limits. Martin, I regret that you sink down to such level of arguing. In truth, a clever criticism is much more health-giving for a method than a fanatical defense. Sorry to say that.

"The critically important Mike's premise is accepting an anticipated enlargement factor and viewing distance. It is his key point."

<p> From the start, it is his weakest and flawed premise. <p>

Why restricted oneself to "anticipated enlargment " ? Why restrict

on self to certain "viewing distance" ?

<p> I may want my Leica negative enlarge to 4x6", or 8x10", or 20x 30" or mural. No restriction.

<p> How do you limit viewer to certain "viewing" distance ? You hang

a picture on a wall, people like to take a closer look. How can you

limit people's view. What about some one take out a magnifier

and examine the detail .....

<p> Different premise and restriction yield different result

<p> Merklinger's method is not based on the limitation of naked human eye, which has very low resolution capability.

but based on what is really resolved.

<p> Apparent "sharpness" to the eye is not the same thing as resolved

<p> One picture may look pretty sharp. But when it may not stand

scrutiny under high power loupe or microscope. Where passed for :"sharp" by the eyes may turn out to be unrecongizable.

<p> On the other hand, resolved does not necessarily mean sharp to

the eye. It is two difference criteria.

<p> Merklinger's focus at infinity method, packs the maxium information content in to negative. <p>

<p> Suppose there are one thousand sign posts with letters along

a road, two meter apart, from 1 meter to 2000 meter. <p> With Merklinger's focus at infinity, as long as I choose the aperture

opening smaller than the width of the letter on sign post, all

the sign post letter will be resolved, from 1 meter to 2000 meter.

<p> Merklinger method is the method of maxium information content.

The sign post at 1 meter will be fuzzy, but from information stand point, the letters will be recongized by human or OCR.

<P> Focus at hyperfocal distance will not provide maximum information

content. It over resolve 1 meter cannot resolve far region.

<p> Classical DOF is only a method of fooling the naked eyes.

Ok, Martin, great! We've finally got a real progress! No mocking!

We could save a lot of efforts and not torment each other if we at the very start clearly stated that the real difference is here, in accepting or refusing this premise.

"How do you limit viewer to certain "viewing" distance ? You hang a picture on a wall, people like to take a closer look. How can you limit people's view. What about some one take out a magnifier and examine the detail ....."

Ok, I also wrote about. My point is IF we accept Mike's restriction then the Mike's method is optimal. IF we DO NOT accept it, it can be NOT optimal.

Mike's premise is in my opinion a very realistic restriction. And having agreed to obey this restriction he takes 100% control of the sharpness. I'd call it a 100% success.

Have we always to accept this premise? --- No. I already showed the example with a detective where Merklinger's method is 100% optimal and Mike's is not. All depends on HOW we intend to use the photo, will we come closer and closer, probably with loupe (again no mocking) or just view it from a reasonable distance. I also have a questionable habit of inspecting my prints with my nose close to the print surface, but I won't affirm it is a 'normal' behavior. I also appreciate the fun when the print reveals more and more details at infinity when I come closer and closer to the print (for sake of this fun I can also ignore the fact that near details reveal more and more unsharpness). --- But it is not an argument in the polemic above. I'm absolutely sure Mike will never claim that his method is able to provide me such a fun, --- it is against his premise!

One may or may not accept the restrictions imposed by naked human eye, indeed THIS is matter of personal choice (or matter of intended usage of the photo) but it should be explicitly stated, and such a statement puts a stop to the mess.

"Classical DOF is only a method of fooling the naked eyes."

Exactly! But many viewers are absolutely happy when their eyes are fooled in appropriate way. Mike doesn't promise anything more.

Well, happy end?

That's the best line in this entire thread! LOL!!

:-)

Mike

<i>Classical DOF is only a method of fooling the naked eyes.</i>

I guess Robert and I are the only ones here without bionic eyes.

Martin, I give up on the DOF issue. Either you have set up a mental block in your head to not accept what we are explaining or you have too much pride to acknowledge some of what you (and Mr. Merklinger) beleived is a flawed. At least give us credit for trying. But we can only repeat the same thing so many times.

Martin wrote....

FYI. Agfa Copex Rapid 600 lpmm, Fuji Super HR 850 lpmm

I am shocked any film can resolve this high, but even so, after you run it through the 1/R formula for total camera system resolving capability, 850 = R1 and 190 lpmm lens = R2, you are still reduced to max. resolution of 155 lpmm to film. So I hope you are not fooling yourself thinking you can get 850 lpmm to film? For futher information, read the Fuji Film handbook. I don't want this to turn into another massive thread.

Bill wrote:

"I am shocked any film can resolve this high, but even so, after you run it through the 1/R formula for total camera system resolving capability, 850 = R1 and 190 lpmm lens = R2, "<p>

FYI, Minox COMPLAN R2 = 330 lpmm, wiht FUJI SUPER HR R1= 850 combined R = 237 lpmm on film.

Total system resolution need to include the resolution of enlarging lens.<p>

<a href="http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=003HG0">Minox enlargement</a> In which I tablulated the combined resolution of camera lens + film + enlarging lens <p>

Regardless, to get the maximum resolution from Minox lens, I must

use a coc of 1/330mm as a starting point.

There is another high resolution photographic film <p>

<a href="http://www.gigabitfilm.com">www.gigabitfilm.com</a><p>

A sample picture of violist Vanessa Mae by Raphael Stoetzel with

Gigabitfilm

<p>

<a href="http://www.gigabitfilm.com/images/stoetzel1_large.jpg">Violinist Vanessa Mae</a>

<p>

Resolution of gigiabitfilm 720 -900 lpmm

Another reasonable perspective on focusing at Infinity:

Quoting Igor Yefremov:

---

Focusing at infinity should be preferred to focusing at the hyperfocal distance, only if all of the following conditions are observed:

1. There are no important objects closer than the hyperfocal distance.

2. The negatives are going to be enlarged significantly (larger than 8� x 12�).

3. The camera is installed on a tripod, and a fine-grain film is used.

If at least one of the above conditions is not observed, it is worth focusing the lens at the hyperfocal distance.

---

Reference - Search for this string:

Focusing at infinity vs. focusing at the hyperfocal distance

after linking to this page:

http://hobbymaker.narod.ru/English/Articles/sharpness_eng.htm

Mike Davis