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Manual versus autofocus


fsprow

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Being somewhat immobilized with a broken foot, I’ve taken the opportunity to look over several thousand images from a variety of cameras and draw a probably not too unexpected conclusion concerning the use of manual versus auto focus.

 

Cameras included a wide variety of Leica M’s, both film and digital, Hasselblads (film and digital), many Nikon SLR’s and the Leica SL. I examined, qualitatively, both large prints and on screen images.

 

My conclusion is that when using lenses which have very little depth of field, manual focus provided substantially better images overall. This includes a number of images taken with long lenses in Africa where I was certain that the auto focus images would be better, but they were not. Many of these included images from the same lens used in both manual and auto focus modes

 

On the other hand, pretty much all images including stopping motion were substantially better in auto focus mode - moving children, basketball games etc. Despite having used manual focus for many many years, auto focus produced a better result. Obviously, the aperture selected and the lens’s depth of field make a difference here.

 

Probably nothing much novel in this result but it beats watching television. Also it convinces me that the M-series cameras using manual focus lenses in one form or another have a healthy future ahead.

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An EVF can provide much better accuracy

EVFs provide great accuracy, for a single point in the image at a time, with a stationary subject.

 

I came to the same conclusion as fsprow many years ago. My wife and I were reviewing vacation pictures (25 or 30 rolls), and there were only two mis-focused images in the lot. AF would have been worse; it will usually get "something" in focus, but it can't know which plane of focus works best.

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AF is not the problem ...... it's the fact that it makes the chump behind the viewfinder lazy and careless about checking whether correct focus is achieved or not.

 

AF is not 100% accurate and anyone that uses it should be well aware of the conditions under which it is unreliable. 

 

I use AF ..... but always pause before taking a shot to ensure what I intend is in focus ...... and manually adjust or re-focus if needed...... the SL's EVF is more than good enough to make this obvious.

 

If you are taking rapid shots and relying 100% on AF then you will get some failures ..... but much less than if you were doing the same manually at the same speed.

 

My OOF rate with the SL is miniscule. 

Edited by thighslapper
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If you use single point autofocus so you know what you are focusing on, autofocus can be extremely good with stationary subjects.  If you use multipoint of any kind you are letting somebody else decide, and my experience is reults suffer.   Of course, in action stopping situations, multipoint continuous AF works extremely well.  It is just a matter of using your tools properly.

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Single point AF on the SL still seems to look at a fairly large area for a high contrast target. I find I need to manually adjust fairly frequently.

 

I am hoping for more and smaller AF points and PDAF/CDAF in the next iteration. The goal would be better precision and accuracy under a number of scenarios. Eye AF on par with Sony would help with shallow DOF portraits as well.

Edited by LD_50
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The single point AF and face recognition AF is accurate for non motion subjects.

 

The AF tracking on AFC will tend to provide a 50% -70% hit rate and improves with better lighting on subject and best to avoid strong back light as the contrast detect is at its weakest then. On the contrary, the AF works from corner to corner consistently unlike phase detect sensors. More importantly is to select the right AF setting for the required situation. More frequent practice reduces human error.

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Face AF is not the same as Eye AF. Sony’s Eye AF is very impressive and I think with the right processing power and code the SL (or its successor if processing power is limiting) could be the same.

 

The AF system on the SL is not competitive with the best AF systems and it should be given the design and marketing of the camera and native lenses. Practice doesn’t change the inherent limitations of the system relative to the competition. I say this after years of using the best Nikon PDAF systems.

 

I’m confident it will get better over time, and already has with FW updates. The next big leap will be with faster sensor readout, faster EVF refresh, and hopefully cross type on sensor PDAF. On sensor PDAF can cover corner to corner and doesn’t share the limitations of DSLR PDAF systems in terms of coverage.

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I think I can say that I have never known the SL's face recognition miss focus on the eye itself, if it has properly locked on. I suspect it is effectively eye focus.

 

It's surprising how far marketing can push a suitable brand name: Apple's Retina screen branding continued to be trumpeted way after the time when competitors had better screens. Sony's Eye AF is good, but given that, in my experience, the SL's face recognition already goes for the eye, I'm not convinced the difference is significant once you forget the branding.

 

I agree that the next SL should have better tracking and AFc, perhaps more focus points and (it can never be good enough) faster and better low light focusing.

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I'm happiest with the results I get focusing manually, regardless of SL, M, or any other camera. 

Many times I don't have to focus at all, per se: I just set a distance on the scale and my results are right on the money. 

 

Such it is. 

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I think I can say that I have never known the SL's face recognition miss focus on the eye itself, if it has properly locked on. I suspect it is effectively eye focus.

 

It's surprising how far marketing can push a suitable brand name: Apple's Retina screen branding continued to be trumpeted way after the time when competitors had better screens. Sony's Eye AF is good, but given that, in my experience, the SL's face recognition already goes for the eye, I'm not convinced the difference is significant once you forget the branding.

 

I agree that the next SL should have better tracking and AFc, perhaps more focus points and (it can never be good enough) faster and better low light focusing.

 

 

My experience is similar. No issues with face recognition on getting sharply focused eye on the face. 

 

I also agree that focus tracking could be improved, but there are always limitations from the best system and how much selection choice one has as you can never complete predict the next situation will turn out to be. I would rather learn and get the best out of the current SL system than to always bitch and compare.

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