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Focus peaking & contrast


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Being into a first R lens search. I tested a lot of lenses. And I did notice something. 
 

The best way to manual focus is not wide open ! Especially with focus peaking. But it is also kinda true with magnification, but to a lesser extend. 
 

Some old lenses have quite low contrast/acutance wide open. You can check beforehand this with MTF charts. Look at 5 & 10 lp/mm lines. 

Stopping down a bit, the acutance will increase. Hence improving focus peaking accuracy.
However if you stop down to much, everything will turn red, due to larger depth of field. 
 

I also found that the longer the lens, the more accurate focus peaking be. 
Wide angle shows everything in a unsavoury red lines across the image. For those lenses I prefer to rely on hyperfocal when stop down and to magnification for focus confirmation when wide open. 
 

With newer M lenses, it is not necessarily true. Because they usually offer high to very high contrast wide open. 
 

So did you notice something similar ? 
 

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This is perfectly normal. Focus peaking detects the areas of maximum contrast. However, stopping down may well increase the contrast, making peaking more visible, but it will also increase DOF, making it (even) more imprecise. Obviously narrow-DOF lenses like long lenses and macro will make peaking more precise. In fact, those are the only situations I will use it for. One trick is to "walk" the peaking through the image and put focus in the middle of the peaking.

I found that using a high-contrast lens on a herd of Zebra makes peaking unusable, creating a complete red-out in the EVF.

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Focus magnification works fine with any lens for me. I use peaking for good enough focusing only when the subject matter is not too contrasty. Same with legacy lenses (Elmar 35/3.5 from 1948 on CL here) so the age of the lens doesn't change anything for me. YMMV.  

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Oh yes that’s all the problem Jaap : enough contrast, without too much depth of field. 

Good old rangefinder are much faster. But it’s also far from perfect. 
 

Another issue with long lenses when used handheld : shaky live view. Making them harder to focus. 
SL2’s IBIS is quite magical for those lenses. With stable viewing and large high pixel counts EVF. It makes such telephoto way easier to focus. 

That makes me think, that CL is maybe only for not too long AF lenses. And SL2 will be way more suitable for long manual lenses handheld. 😩 I have almost convinced myself not to buy the SL2. And now this R lenses itch may drove me into its hands. 

Edited by nicci78
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FYI. I started to test those R lenses at the SL2 pre-announcement workshops. Lots of lenses were available. Among them a bunch of R lenses of all kind. I found them so nice to use with the SL2. That I start to research about them for my CL. But now I am quite disappointed. CL is not the SL2. Neither is the SL for that matter. IBIS change everything. Really. 

I also discovered that R lenses are not necessary better on the CL than on the SL2. On one hand you cut out the worst part of the lens : the external third. But in the other hand you also magnified lens defects : CA mostly and/or lack of resolution. 
So in both case you really need excellent lenses. Otherwise the result will not be on par with more recent Leica lenses. 


Another problem. I only bought the R-Adapter-M. It was a bargain, but R-Adapter-L is so much better.
M version Included accessories are very poor no cap and no case at all. How am I supposed to carry it ? Tripod adapter lacks the fast nice finger screw of L version. Relying on 2 hex screws instead. 😩 
M version also lacks the ROM. It is not a problem except for the zooms. CL or SL2 really need the zoom real focal length to apply the adequate software correction, EXIF data and IBIS and/or auto ISO settings. 
Real aperture value transmission is also needed to avoid relying on SL2 external sensor to guessestimate the chosen diaphragm.


To sum up. The ultimate way to enjoy R lenses. Is to use an SL2 coupled with R-Adapter-L and the latest ROM R lenses. Quite far from my CL + R-Adapter-M stacked with M-Adapter-L + non ROM R lens. 😅

 

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Besides adapter issues i was not aware about i wonder why i would need any software correction or guestimated aperture on my R lenses, especially on a crop camera like the digital CL. IS? Why not but i did w/o that feature for many years so as long as i keep steady hands i don't see this as a problem either. Now i don't use much my R lenses on the CL to be honest but my only reasons for that are the larger size of R lenses together with adapter(s) and the satisfaction i got with M lenses on a compact body like that. FWIW.

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Peaking, or edge contrast detection, was designed originally for use with motion capture where precise focus is much less important than keeping the important areas of the subject in approximate focus as the subject/scene moves. When used in still cameras, it's best seen as a way to quickly 'rough in' the correct focus zone. It depends upon the lens having good contrast at the specific aperture being used, of course. 

Magnification is great for dialing in critical focus at any aperture and with any lens. It is, of course, easier to use magnification with short lenses or image stabilization, lest camera movement cause the EVF display to jitter too much for focus evaluation. 

I can't imagine why I'd look at MTF curves to determine whether my lens has good contrast wide open if I already have the lens in my hand. Much easier to just look through the viewfinder...

My  R Adapter M includes both front and rear caps, a leatherett/microfibre cloth pouch, the tripod foot, and the appropriate hex key for the foot. 

The APS--C frame of the CL automatically eliminates much of the typical problem areas at the corners and edges of the frame that the lens profiles are intended to affect, and it's also true  that R lenses, in general, benefit less from the lens profiles' correction than M lenses do because of the optical designs required for the greater mount register and reflex mirror. However, having tested my entire range of lenses on the CL for critical rendering both with and without the lens profile enabled, some lenses benefit noticeably from having the lens profile enabled. 

It's important to remember also: The purpose of the Leica lens profiles isn't to correct all their lenses to perfect technical qualities. The purpose of the lens profiles used with M and R lenses on digital M and L-mount Leicas is to allow these lenses to render with high fidelity the way they were designed to on whatever Leica digital camera they are now being used on. This is where you can see the differences between lenses used with and without lens profile: put your Leica R lens on a Leica R body, record a series of exposures on film, and then do the same thing with an SL or CL using lens profiles enabled and disabled. When you look at the lens rendering qualities in this sort of test, it's pretty obvious that the lenses render with improved fidelity to their original intent with the lens profile enabled. 

G

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Problem is M and L lens profiles are not made for R lenses so i wonder what intent they could improve fidelity to. A good test could consist in removing the opcodes of DNG files when coding R lenses and compare to the same files with opcodes on. I did this with some VM lenses already and results can be surprising when profiles do not match the design of the lens. 

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You're supposed to use the lens profiles for the R lenses with R lenses, not M or L lens profiles. I don't know what problem you're referring to.

R lens codes are ONLY available when you trigger the camera to present them using an R Adapter M on the M Adapter L, or an R Adapter L, another good reason to use the Leica mount adapter vs third party adapters on Leica bodies. :)

G

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10 hours ago, nicci78 said:

Oh yes that’s all the problem Jaap : enough contrast, without too much depth of field. 

Good old rangefinder are much faster. But it’s also far from perfect. 
 

Another issue with long lenses when used handheld : shaky live view. Making them harder to focus. 
SL2’s IBIS is quite magical for those lenses. With stable viewing and large high pixel counts EVF. It makes such telephoto way easier to focus. 

That makes me think, that CL is maybe only for not too long AF lenses. And SL2 will be way more suitable for long manual lenses handheld. 😩 I have almost convinced myself not to buy the SL2. And now this R lenses itch may drove me into its hands. 

I've been shooting long and heavy lenses since the 1980ies, using all kinds of cameras. M-with Visoflexes, both the EVF variety and the optical ones, R cameras, Canon DSLRs, with and without O.I.S medium format, MFT with amazing dual I.S., you name it. Each had its own difficulties to overcome. I guess it has made me gear-insensitive and I concentrate on shooting and focusing technique.

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The magnified view is excellent, and I can easily see what is in- and out-of-focus, but when I review the images on a monitor, most of them are off. This is usually when shooting people, so maybe there is a little movement that I don't notice? I do much, much better with a rangefinder, though, which surprises me. 

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It is always possible that you make a slight movement between focusing and releasing, especially if you flick back to full view for framing. The most secure technique is to frame, focus (magnified), release.
Basically an EVF is WYSIWYG, so it is hard to imagine a technical reason for your problem.

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Agree. I DO go back to full view to frame before hitting the shutter - it feels strange not to. I probably need to play with it - the full frame view is not enough for me to focus without magnification. I've heard that some people do that on the SL though. 

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It's difficult not to go back to a full frame view since the viewfinder reverts to the "preview" setting when half pressed. 

Examine your frames for why they seem unsharp closely. Is it motion blur or focus? I find, in my use, I'm much more likely to get a little motion blur if I'm at the lower end of the available shutter time range. A way to check whether you're moving the camera or not focusing accurately is to put the camera on a sturdy tripod, focus, and make the same exposure you would hand-held that has proven to be slightly unsharp. Also: check that the viewfinder diopter is properly adjusted to match your vision. It's impossible to critically focus an image if the viewfinder diopter adjustment is slightly off for your eyes. 

I'm pretty good at getting the focus spot on without peaking or magnification as long as I'm working with a lens that's sharp and contrasty at the aperture setting I'm using and presuming that the focal length is around 43mm or greater. Shorter lenses I usually need to flip on magnification to be sure I'm critically focused. 

G

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I must just need more practice. It's not motion blur, as some things are in focus - usually a little behind the intended subject. This is using mostly the 35/1.4 distagon but also a 50/2 and a 28/1.4. I can nail it with all of them using an M, even if my eyes are no longer young - and my rangefinder is vertically out of alignment (again!).

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