Dof in the M9?

[Fotomiguel]

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Is depth of field in the M9 the same that we would use in a film camera?

With the m8 we had to calculate about one and half f-stop less to use the depth of field marks that are in the lens. Now with the M9 are the marks on the lens real or because of using digital sensor we have give at least half f-stop less?

Thanks

[noah_addis]

I'm sure the optics experts will chime in, but I think for a given print size the DOF will be the same.

 

However, since we can print quite large with the M9 (or pixel-peep, if you're into that) then you may find you need to stop down more than the DOF marks indicate.

[carstenw]

It is an interesting question. On the one hand, yes of course. Same crop factor, same magnification. On the other hand, no, the CoC for digital is much smaller, especially for sensors of this high a resolution. You will need to stop down more to get acceptable sharpness. The best would be to make prints for both in the kind of situation you shoot in and compare.

[luigi bertolotti]

Many views about... but give a look to www.dofmaster.com : the central question of CoC is clearly managed when you switch from film to digital... M9 isn't yet between the listed cameras, but of course you can take a FF DSLR with similar Mpixels to make some simulations. I do not say that the above site is the Bible of DOF (nor have the authority to assess if it is) but I think is a good reference.

[SJP]

The rule of thumb/consensus for the M8 appears to be 2 stops correction, 1 stop for the crop factor and 1 because we have become pixel peepers. The latter is the "digital" factor mentioned before.

 

On the M9 it would then be 1 stop as the crop thing disappears and we are still fixated on 1000% crops.

 

If you were to print the M9 files on regular photo size paper (8x12 cm or 10x15 cm if you want to go to town) then the barrel markings should be just fine.

 

This is presumably exactly the same as in the film era where photo's intended for enlargement needed more careful focussing and a smaller aperture than the snapshots for the album.

[Fotomiguel]

Many views about... but give a look to www.dofmaster.com : the central question of CoC is clearly managed when you switch from film to digital... M9 isn't yet between the listed cameras, but of course you can take a FF DSLR with similar Mpixels to make some simulations. I do not say that the above site is the Bible of DOF (nor have the authority to assess if it is) but I think is a good reference.

Very nice app for the iphone.

Thank you very much.

[Fotomiguel]

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One f-stop down. Ok

Thank you very much. I hope my m9 will arrive soon. I want to try everything.

[lars_bergquist]

There are two kinds or aspects of d.o.f.: On the film/sensor, and in the print.

 

The d.o.f. behaviour on the sensor is solely a function of aperture (f-stop) and reproduction ratio, i.e. how much smaller an object is on the sensor, compared to real life. This in turn depends partly on the focal length used, but also of course on subject distance: This is why d.o.f. shrinks, the closer you get.

 

So sensor d.o.f. is completely independent of the absolute size of the sensor, as long as you do not change any of the other parameters, e.g. by moving closer, thus changing the repro ratio. Reproduce an object on the sensor at 1:100 at f:5.6 and the d.o.f. will *always* be the same, no matter if the sensor is a 18x27mm chip or a 4x5" piece of cut film!

 

Then, apparent d.o.f. on paper. This, ceteris paribus as above, depends on enlargement. Let us say that a line in the subject is reproduced by the lens as a 0.01mm fuzz on the sensor. Enlarge this by five times, and the fuzz is 0.05mm, and you will see this as sharp. Period. Up the enlargement to 10x, and the fuzz is 0.1mm, which is perceptibly less sharp in a direct comparison, but you may well accept it as reasonably sharp. Increase further than that, and the fuzz will be -- fuzz.

 

Let us say that you photograph the same subject, a cardboard box for instance, with a M8 and a M9, same lens. You do not change your position, so the reproduction ratio *on the sensor* is still the same (though the larger sensor of the M9 takes in more real estate of course). The image of the box that the lens projects on the sensor will be of equal size in both cases. Same f-stop, too. In this experiment, on-sensor d.o.f. will be *exactly the same* with both cameras, because neither f-stop nor reproduction ratio have changed. (But more 'real estate' in the M9 ...)

 

Now comes the enlargement bit. Suppose that we do an A4 or a 16x24cm or 8x10" print from each of the two image files, full frame. Then, clearly, the M9 file has to be enlarged less, so the fuzz too will be enlarged less, and apparent d.o.f. will be greater in the M9 picture! But -- the box will be printed smaller. If on the other hand you print so that the box is of the same size in both prints, then you will see that ...

 

... the depth of field is exactly the same in both cases!

 

So at the end of the day, it is all a matter of the size difference between the real box, and the box in the photograph, and the aperture. And that is not decided by the camera BUT BY YOU, MISTER.

 

The old man from the Age of the Dark Darkroom

[GMB]

There are two kinds or aspects of d.o.f.: On the film/sensor, and in the print.

 

The d.o.f. behaviour on the sensor is solely a function of aperture (f-stop) and reproduction ratio, i.e. how much smaller an object is on the sensor, compared to real life. This in turn depends partly on the focal length used, but also of course on subject distance: This is why d.o.f. shrinks, the closer you get.

 

So sensor d.o.f. is completely independent of the absolute size of the sensor, as long as you do not change any of the other parameters, e.g. by moving closer, thus changing the repro ratio. Reproduce an object on the sensor at 1:100 at f:5.6 and the d.o.f. will *always* be the same, no matter if the sensor is a 18x27mm chip or a 4x5" piece of cut film!

 

Then, apparent d.o.f. on paper. This, ceteris paribus as above, depends on enlargement. Let us say that a line in the subject is reproduced by the lens as a 0.01mm fuzz on the sensor. Enlarge this by five times, and the fuzz is 0.05mm, and you will see this as sharp. Period. Up the enlargement to 10x, and the fuzz is 0.1mm, which is perceptibly less sharp in a direct comparison, but you may well accept it as reasonably sharp. Increase further than that, and the fuzz will be -- fuzz.

 

Let us say that you photograph the same subject, a cardboard box for instance, with a M8 and a M9, same lens. You do not change your position, so the reproduction ratio *on the sensor* is still the same (though the larger sensor of the M9 takes in more real estate of course). The image of the box that the lens projects on the sensor will be of equal size in both cases. Same f-stop, too. In this experiment, on-sensor d.o.f. will be *exactly the same* with both cameras, because neither f-stop nor reproduction ratio have changed. (But more 'real estate' in the M9 ...)

 

Now comes the enlargement bit. Suppose that we do an A4 or a 16x24cm or 8x10" print from each of the two image files, full frame. Then, clearly, the M9 file has to be enlarged less, so the fuzz too will be enlarged less, and apparent d.o.f. will be greater in the M9 picture! But -- the box will be printed smaller. If on the other hand you print so that the box is of the same size in both prints, then you will see that ...

 

... the depth of field is exactly the same in both cases!

 

So at the end of the day, it is all a matter of the size difference between the real box, and the box in the photograph, and the aperture. And that is not decided by the camera BUT BY YOU, MISTER.

 

The old man from the Age of the Dark Darkroom

 

Lars, You should publish a collection of these submissions to the forum. They are a joy to read because they are spot on and very well written. Your recent post in another thread on the philosophy of rangefinder photography was one of the best -- correction: the best -- I have read in this forum since I became a member about three years ago.

 

Georg

[Steve Ash]

Lars,

you very well explained an often confused matter. It is not too difficult, isn't it?

 

Regards

Steve

 

...

 

So at the end of the day, it is all a matter of the size difference between the real box, and the box in the photograph, and the aperture. And that is not decided by the camera BUT BY YOU, MISTER.

 

The old man from the Age of the Dark Darkroom

[luigi bertolotti]

Lars, You should publish a collection of these submissions to the forum. They are a joy to read because they are spot on and very well written. Your recent post in another thread on the philosophy of rangefinder photography was one of the best -- correction: the best -- I have read in this forum since I became a member about three years ago.

 

Georg

 

+1 for the Old Man...

[jonoslack]

Lars, You should publish a collection of these submissions to the forum. They are a joy to read because they are spot on and very well written. Your recent post in another thread on the philosophy of rangefinder photography was one of the best -- correction: the best -- I have read in this forum since I became a member about three years ago.

 

Georg

 

Yes Georg

I completely agree - Lars that was a joy to read (not less because I agree). Now I want to read the rangefinder philosophy post (where is it please Georg?)

[GMB]

Yes Georg

I completely agree - Lars that was a joy to read (not less because I agree). Now I want to read the rangefinder philosophy post (where is it please Georg?)

 

Jono, This is the post I was referring too.

 

The most important difference as against a SLR is what happens BEFORE you ever raise the camera. It is a different mindset.

 

Let us say you are bringing your Leica M to a garden party. You have decided to put a 35mm lens on it, because it is quick and easy to use, and takes in a lot of human interaction at close range -- which is just what a Leica is famous for. Being an experienced M user (which you will be very soon) you have already put your '35mm eyes' on, so you know how much of the action the lens will take in. You have also already selected a likely working aperture, 4.0 or 5.6 maybe so you get a bit of depth of field.

 

In front of you is a piece of human interaction you want to record. You are spontaneously pre-visualizing the picture (see above about 'eyes'). You understand without thinking about it that you want to have the focus on Aunt Emma to the right. You raise the camera to your eye. And there it is -- the piece of reality you saw, and part of it framed inside a bright line. You put the rangefinder patch on Auntie's spectacle frame. Because you are carrying the camera with the lens set to infinity (important) it's just a quick, short twist of the focusing tab, and the specs snap in. Recompose the picture and press the shutter release. Click.

 

No searching for the subject at the end of a dark viewfinder tunnel. No pumping your trombone of a zoom to find a suitable field of view. No fiddling with cryptic buttons strewn all over the camera body. No wrestling with obstreperous electronic imps. No giving up and permitting them to decide focus for you.

 

Flying the M is like riding a bicycle. It is very straightforward, and mostly unconscious. But in order to ride a bicycle, you must learn how to make your arse do the job. To use a M, you have to be a photographer. You must know about apertures and shutter speeds, and what they do. The camera will do what you tell it to do, without any ifs and buts, but you must decide. You learn the way you learn to ride a bike. You try it out, and you extract yourself from various hedges and brambles, but you learn the knack. With a digital M, the process is fast, because of the quick feedback. All it takes is the basic knowledge, and some determination. And learning it is fun, too.

 

And when you have learned to ride the bicycle, or fly the M, you are a different person.

 

The old man from the Age Before the M

[lars_bergquist]

Well, I blush. When I started out in photography (and learned to soup 35mm film in the darkroom of a Royal Swedish Air Force base) there was a plethora of books available that you could learn the basics from. Even the very basic basics that pertain only to the operation of a camera, not what happens later. There is very little of this now. Where does a novice learn about shutter speeds, f-stops and depth of field?

 

A Leica M is eminently a camera where the pilot has to know about shutter speeds and the rest, because he is in the pilot's seat with his hands on the controls, and it is up to him to control the craft. This is the kind of photography I grew up with. When I started my pilot training (in civvies, not in the RSAF!) my very first plane flight was with me at the controls -- and I was alone in the plane. This is true: In those brutal days, they put you in a glider that looked like a modern ultralight minus the engine and even the suspicion of flight instruments, gave you some summary instructions as to the controls, and then they injected you into the airspace with a few tips on how to bring the craft back in one piece, and hopefully yourself too. It worked, but for many years I disliked commercial aircraft because I could'nt look over the shoulder of the pilot. But I have always remained a stick shift man; and with an un-synched gearbox too, if necessary.

 

So I think fledgling Leica users should have some of the same hands-on knowledge, because without it they will never develop in a useful and consistent way. I think the only modern book that does to some extent fill the bill is Günther Osterloh, Leica M, Hohe Schule der Kleinbildfotografie, Umschau Verlag 2002. But Herr Osterloh is maybe not the most systematic of writers, and being professionally involved with the camera makes it difficult to get a newbie's perspective on it, I presume.

 

The garrulous old man from the Age of Gab