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Thread: Help me understand focusing on rangefinder camera

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    Help me understand focusing on rangefinder camera

    My experience has been limited to dSLR's (oh, and the Oly E-P1) but I have never used a manual focus viewfinder camera. My last manual focus camera was the Canon FT-QL! But at least it was through-the-lens focusing.

    I don't understand how one focuses a viewfinder camera's lens. How do you know when you have accurate focus? What do you see inside the viewfinder (I know you see an outline of the frame)? Small errors at wide aperture can create a disaster so there must be a way to get it right.

    A corollary question: can one focus quickly? I can't imagine that it's anywhere near the speed of autofocus on a dSLR.

    Also, is the M9 introducing a new technology to assist focusing?
    Last edited by tom in mpls; 9th September 2009 at 10:46.

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    Re: Help me understand focusing on viewfinder camera

    Do you mean rangefinder camera?

    If you go to the DPreview preview on the M9 he actually has some nice examples showing how the rangefinder system works.

    Unfortunately I have an eye condition that apart from not allowing me to manual focus, specifically stops me from rangefinder focusing period, the images will never line up for me. Shame really...
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    Re: Help me understand focusing on viewfinder camera

    D'oh, yeah, I mean rangefinder. See how little I know?

    MODERATOR NOTE: I edited the subject, to make the thread more self-explanatory
    Last edited by Mike Hatam; 6th December 2009 at 08:58.

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    Re: Help me understand focusing on viewfinder camera

    Here is a very good example of what you see in the viewfinder when focusing the M9

    http://m.leica-camera.com/messsucher_en.html

    Look at the thumbnail on the far right.

    You focus with the patch which is inside the frame lines

    As for quick when street shooting you learn to use hyperfocus.

    As for helping with focus you can add viewfinder magnifyers.

    "The market wants a Leica to be a Leica: the inheritor of tradition, the subject of lore, and indisputably a mark of status to own."
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    Re: Help me understand focusing on viewfinder camera

    Quote Originally Posted by tom in mpls View Post

    A corollary question: can one focus quickly? I can't imagine that it's anywhere near the speed of autofocus on a dSLR.
    I think if you use hyperfocus (as in setting to a pre-determined distance and then adjusting to an aperture that will allow for some leeway) you can be pretty fast. And as one gets more accustomed to focussing with a rangefinder, it does get faster. But I don't think it will ever be able to compare to the speed of a decent, modern SLR with autofocus. To some, that's part of the appeal.

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    Re: Help me understand focusing on viewfinder camera

    Focusing a rangefinder takes some getting used to, but once mastered is very accurate and can be quite quick ... especially in low light where a DSLR AF may hunt and miss-focus.

    There is a rangefinder patch in the viewfinder and you simply bring the double image together inside that patch ... best done using an edge or highlight.

    I've used a rangefinder for well over 30 years ... and one trick I learned for speed is to return the lens focusing ring to infinity after each round of shots so you know which way to turn the lens every time ... then it'll become habit. Focusing from infinity usually requires very little movement of the focusing ring, so it's a very fast technique.

    Hope this helps,

    -Marc

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    Re: Help me understand focusing on viewfinder camera

    And to build upon Marc's suggestion, if scene it tricky with lots of busy items - like tree leaves, I'll prefocus using the distance scale. And I'll do the same for low-light indoor shooting. What I've learned from this is that I'm horrible at guessing at the difference between 4 feet vs 5 feet Seriously though, pre-focusing can really work, especially if you're waiting for a particular moment and you know the subject will be at the point / distance (like a bride & groom coming down the stairs as they leave the church).

    The weak side of range finder focusing is when the subject is to the left or right of center. At that point it's a focus / recompose gamble. In those I know to add a touch of front focus. How much front focus? That's the Vegas part If off-center compositions are your norm, a rangefinder might not be the best camera. It's certainly do-able, but you really have to know the camera and lenses.

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    Re: Help me understand focusing on viewfinder camera

    I think with ome training you can focus pretty fast. Faster as a bad AF but not as fast as a very goood AF.
    very accurate for wide and normal lenses, more difficult for 90 and 135mm if you shoot wide open.

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    Re: Help me understand focusing on viewfinder camera

    Now I understand.

    What I've learned so far:

    Focusing is done much like a split screen in a manual focus SLR.

    It's a risk if you focus and recompose. However, that's a frequent problem with dSLR also as I generally prefer to use a single center focus point.

    And all the issues that I had manually focusing my old SLR are still there with a rangefinder.

    Your help has been much appreciated.

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    Re: Help me understand focusing on viewfinder camera

    Tom, one other big difference between rangefinder and dSLR manual focusing is that the rangefinder image size is the same magnification for all lenses. A rangefinder viewfinder is not magnified to correspond to the lens used as it is in through the lens viewfinders in dSLRs. For some reason which I do not completely understand, I feel much more "connected" with the process of making images when using a rangefinder. It is simply a different process than taking photographs with a dSLR.

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    Re: Help me understand focusing on viewfinder camera

    ––I am resurrecting my thread to ask another related question.––

    When shooting my autofocus lenses at very wide apertures (Canon in the past, and now Sony as I changed systems recently) accurate focusing is very difficult due to the very thin DOF. Using single focus point and placing it on an eye of the subject would be my approach and I could get a high percentage of keepers.

    Isn't it even more difficult to get spot on focus when shooting a rangefinder at, say, 85mm at f/1.4? or even f/2?

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    Re: Help me understand focusing on viewfinder camera

    Tom,

    A few thoughts, starting with your comment on post #9 that all the issues with manually focusing a SLR are still there with a rangefinder...

    The process is actually quite different on a rangefinder, and quite a bit easier than manually focusing on an SLR. For example, you don't have to open up the lens to focus on a rangefinder, since your view is not TTL (through the lens). It tends to be a faster and more accurate process on the rangefinder.

    As for your last question, regarding DOF...

    Just like an SLR, accurate focus is more critical when shooting a long lens and/or wide aperture.

    If the subject is fairly still, it's not a problem on a rangefinder, as you can put the "patch" directly over the important part (i.e. eyes of the subject), and then precisely focus the lens.

    The of the rangefinder "patch" as the equivalent of the single center AF point, but with the ability to be actually more precise than an a typical AF system.

    I have a lot of trouble focusing a 50/1.4, 75/2, 75/1.4, 90/2 at wide open apertures if the subject is moving around quickly. In those cases, a good AF system (i.e. Canon 1-series) is far superior to get a high percentage of keepers.

    That's one reason why I still keep a DSLR, even though the M9 is my main system. When I'm going to shoot sports, kids playing the surf, birds flying, etc., I grab my 7D with a telephoto lens, and rely on the AF system.

    For everything else, I far prefer the M9.

    Rangefinder-coupled lenses are well designed for manually focusing. They have a nice amount of "throw" (amount of rotation of the focus ring from near focus to infinity) that allows you to quickly cover the entire range, while also making very accurate small increments when you are fine-tuning your focus. They work quite differently this way than a typical SLR AF lens.

    If you decide to try a rangefinder camera, you might start with an M8 and just an inexpensive lens or two, to see how you like it. Give yourself some time to get used to it. You won't be effective with the camera in the first day or two, so don't make a premature conclusion. Allow yourself a few weeks with the camera in non-critical shooting situations to develop a feel for how they work, and how to quickly achieve accurate focus. Then try it out in more demanding situations, and then you can decide if the system works for you.

    Be sure to keep a DSLR system around too, as you'll definitely need it for certain situations.

    Hope this helps,
    Mike
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    Re: Help me understand focusing on rangefinder camera

    another little trick, on leica lenses with a tab, when the tab is at 6 o'clock the lens is focused at 4.5 feet. This is true for all leica lenses with tabs. Helps you preset the focus without looking at the lens scale.

    You can practice then presetting the focus for different distances so that you know mostly by feel where the lens is focused. This speeds up focus because if you are preset, when you get the camera to your eye the object you are attending to is nearly lined up in the rangefinder patch, a little tweak can get you all the way, instead of racking the focus back and forth. And often it really won't matter if you are only a bit off, you could bring the camera to your eye and shoot immediately and tweak as you go. In this way the rangefinder is as fast as autofocus.

    makes a good game to guess distances, preset the lens and then see how far off you are. Eventually you will be more accurate.

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    Re: Help me understand focusing on rangefinder camera

    In my experience the errors introduced by focus-and-recompose on rangefinders are usually not a problem. Mostly due to the relatively long minimum focus distance on most rangefinder lenses, which ensures a reasonable DOF most of the time. There's a big difference in DOF with a 50/1.4 wide open at .7m and .4m.

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    Re: Help me understand focusing on rangefinder camera

    Thanks, Mike. I had wondered if the eye can achieve accurate focus as well as AF when the DOF is so very thin, and by your report it is not an issue. And, yes, I was referring to a stationary subject with a lens in the 50-135mm range.

    I would find it hard to get an M8 and some "inexpensive" lenses--I always veer for the high end. Which has lead to some very expensive short trials with some cameras and lenses, but that's me. I can hear the siren call of the M9...

    Actually I feel that I'm getting some sense of the rangefinder experience with my new GF1; I'm using the 20mm lens and a Voigtlander 40mm viewfinder. It is a different experience, for sure. I also like the prime lens, as I am not thinking about "zoom in–zoom out"; instead my though is "composition!" Still, though, I'm not getting the MF lens experience. Which still instills fear in me!

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    Re: Help me understand focusing on rangefinder camera

    Next focusing quetion: Since longer lenses have a narrower DOF at similar apertures, is it not hard to get accurate focus on a longer lens; I'm thinking of the 75 or 90. Since these are commonly used focal lengths with the M's, it must be possible, but how does it compare versus shorter lenses?

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    Re: Help me understand focusing on rangefinder camera

    A rangefinder is more accurate than an SLR at all focal lengths up to 135 mm. Depending on geometry the point where the two are equally exact is somewhere between 90 and 135 mm. Accuracy for both systems is expressed in the effective measuring base. Comparing a Leica R camera to a .72 magnification rangefinder we get, for instance (RF first value, SLR second value)
    21 mm 49.9 mm -- 1.63 mm
    35 mm 49.9 mm -- 4.43 mm
    50 mm 49.9 mm --9.82 mm
    90 mm 49.9 mm -29.90 mm
    135 mm 49.9 mm --65.70 mm

    (source: Gunther Osterloh, Leica M- Advanced Photo School)

    So you see that an RF system is dramatically more exact at the focal lengths at which most photographs are taken.
    And speed of focussing can indeed be a problem for novices. However, with training it is quite possible to outperform most AF systems. I prefer manual focussing for instance for shots of flying birds. Only that way can I be sure that the eye or the beak is in focus. It needs a very sophisticated AF system to achieve anything comparable.
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