Focusing Accuracy - which is better?

Krosya

Krosya

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I was reading something online and came across conflicting statements - some say RF is more accurate and others say SLRs. So which is it? I know, for RF there are limitations with longer lenses. But lets take most used FLs - 50mm and 35mm. WHich would be more accurate? Using best RF vs best SLR (whichever those may be).
 
I find I can focus more quickly and accurately with a good SLR provided it has a decent viewfinder (bright) like my OM and I'm using a fast lens ... f2 or better. To me the advantage of a rangefinder is definitely not in it's focusing ability because it lacks versatility IMO in that focusing on an object at the edge of the frame can't be done without moving the camera around!
 
My personal preference is SLRs incorporating a central split-image rangefinder screen with a matte screen for the rest of the view. A lot quicker and more certain than RFs, IMO.
 
with shorter lenses, at least, the RF is more accurate assuming that the RF is in proper alignment. When shooting slr exclusively I had a high percentage of soft fotos. With my Leicas the soft fotos were dramatically reduced. Big difference.
 
The focusing accuracy of a rangefinder depends on the base length between the window multiplied by the magnification or demagnification of the optics. With an SLR it's pretty much the same thing, but the base length is essentialy the diameter of the lens. With a 50mm f/2 lens you're stuck with a 25mm base length at best, and most SLR's demagnify the image.

Split image rangerfinders in SLR's Make things worse. The prisms angled so they look bright with usually something like an f/4 aperture. Stop the lens down below that point and one side or the other will start to black out as you move your eye around. What's really happening is that your effective base length for the split image rangefinder is never greater than you could get with the diameter of an f/4 lens. Opening up will give you a brighter image but no additional accuracy. So called microprism spots in the center of the ground glass work the same way, lots of little prisms angled for a particular f/stop. Opening up the lens past this point gives no more accuracy.
 
Perhaps nothing is the best for everyone. One of my Canon SLRs had a microprism screen, and I did well with it. The other had a split image screen and I could never come to terms with it. The person who bought the two bodies has opposite preferences.

[edit] I could focus a 135 quite comfortably on my M3. Now I find it a bit tricky to focus a 90 on my M2. I am older, of course -- but Al has explained the principle.
 
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When I got back into photography, I was using a camera with a microprism spot. I was also doing a lot of party photography. It forced me to learn how to use the whole screen, and move back into and out of focus. Much like modern AF. I have always since thought that was the best way to focus. For that reason I often prefer SLRs. But really I use whatever tool I have. RF Camera, split image in SLRs, whatever.

I am surprised at the number who say they prefer SLR. If the focus overall is better, I think there is a perception the photo is better focused. SLRs allow that, because you can see what you are going to get, and you can inspect the overall image that will be recorded. Perhaps that is why?
 
best for focusing is the active double infrared autofocus of the hexar af 😛

Between rf and slr, i prefer focusing a rf. The oof background blur of the slr screen gives me the false idea of a sharp,well focused subject while the low mag of the screen is often cheating, and later if i magnify the image i realize the focus is a bit off. This is especially true with screens that have no focusing aid like all AF SLR screens.
This is also a problem a bit with the rolleiflex screens I have, but if time permits i can use the magnifier there.
 
Al Kaplan said:
Stop the lens down below that point and one side or the other will start to black out as you move your eye around. What's really happening is that your effective base length for the split image rangefinder is never greater than you could get with the diameter of an f/4 lens. Opening up will give you a brighter image but no additional accuracy.
Click to expand...

Al, sorry to be a smartass here, but most if not all SLRs made since the seventies do not stop the lens down before you press the shutter release button... 🙂
 
For 50mm and shorter, I can focus an RF (S2, SP, ZI) more accurately than an SLR (FM3A, F3HP), but I find SLR more accurate for 85mm and longer. As for focusing speed, well its no contest there! SLR.
 
oftheherd said:
I am surprised at the number who say they prefer SLR. If the focus overall is better, I think there is a perception the photo is better focused. SLRs allow that, because you can see what you are going to get, and you can inspect the overall image that will be recorded. Perhaps that is why?
Click to expand...

I can think of one clear example. When I want a non-central subject in sharpest focus, I prefer my SLR since focus-and-recompose with an RF' increases the potential for error. (I use plain or grid screens in my SLRs.) Think of very shallow DOF portrait shots where you want the eyes completely sharp and the subject is well off-center. Tough to do with an RF shooting a fast, long lens wide open.

Generally though, modern SLR auto AF systems with multiple, selectable focus points are so flexible and accurate that comparisons aren't fair. I prefer using an RF for the kinds of shooting where extremely accurate AF isn't needed anyway.
 
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I have to agree with Dexdog about the SLR arrangement. As a new M3 user I never found a problem with film loading that appeared to be a concern with some. Maybe it was because I had used film for thirty years but I was dissapointed with the focus arrangements. It does strike me as a very small area within the viewfinder that you have to rely on. I presently use a 40 Nockton and also find that the tab arrangement less than ideal too.
I now zone focus. That is when the camera really hits its stride and you begin to appreciate the advantages of the RF design.Anything else seems clumsy in comparison
 
I find my rangefinders to be more accurate in low light and that I can use them without my glasses or diopter correction, which is something I wasn't able to do with my SLRS.
 
In general a SLR it's easier and faster to focus than a RF. On wide angles the RF "feels " better because one is using the Viewfinder, which is much better than the split screen with 21 mm lens, but not more accurate.
 
I don't know, the last time I checked almost every photojournalist, event photographer, wedding photographer, war photographer was using a SLR...

Maybe, just maybe there is something with SLRs which make them the first choice of serious photographers, one of these could be their superior focusing, but I could be wrong because that understanding has not reached this forum yet. 😛
 
well this is just situational for you. I know of 10 personal friends who happen to cover the gamut of your list that all shoot RF's (more specifically leicas) People use SLR's today for the same reason people use RF's and any other medium... because it works for them, neither is better or worse, it's just what works.

In any regard...if the camera and lens are built to spec and within tolerances then both systems should focus just fine...better or worse is just splitting pointless hairs that are only meaningful on paper and theory.

Nh3 said:
I don't know, the last time I checked almost every photojournalist, event photographer, wedding photographer, war photographer was using a SLR...

Maybe, just maybe there is something with SLRs which make them the first choice of serious photographers, one of these could be their superior focusing, but I could be wrong because that understanding has not reached this forum yet. 😛
Click to expand...
 
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