Sensitivity of focus peaking

[Sandokan]

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Hi, This has bothered me for many years and that is what does the "sensitvity" mean when selecting focus peaking? 

It is not just a question for M users but also SL. 

My confusion is which has the narrower of tolerances for what is and is not in focus; "Low" or "High" sensitvity? 

I like to setup for B&W with red peaking. Even with an f1 lens, the peaking occurs over a range of focus. I know on the M11P, if I turn on magnification and peaking, it is most accurate, but generally for street shooting, I do not have time to magnify so I just want it to show peaking when i am focused on my subject. 

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[pop]

I presume that the sensitivity setting controls the depth of the range that's marked as sharp. You can easily visualize the effect when pointing at a gravel path or some similar structure at an angle,with the sensitivity set to different values. Depending on that setting, focus peaking might highlight just a thin line or a larger area of the gravel.

When in a hurry, you can move the focus so that the subject of interest stands in the middle of the highlighted area.

[frame-it]

16 minutes ago, Sandokan said:

Hi, This has bothered me for many years and that is what does the "sensitvity" mean when selecting focus peaking? 

It is not just a question for M users but also SL. 

My confusion is which has the narrower of tolerances for what is and is not in focus; "Low" or "High" sensitvity? 

I like to setup for B&W with red peaking. Even with an f1 lens, the peaking occurs over a range of focus. I know on the M11P, if I turn on magnification and peaking, it is most accurate, but generally for street shooting, I do not have time to magnify so I just want it to show peaking when i am focused on my subject. 

low = ballpark range [not accurate], high = finer detail [vaguely accurate but difficult to see unless zoomed in]

on the SL2S/GFX/XH1[all with manual focus lenses] - i keep the screen on mono and use peaking RED-Low, then zoom in with BBZ to check, adjust and shoot.

[frame-it]

13 minutes ago, pop said:

subject of interest stands in the middle of the highlighted area.

that's the area of real focus 99% of the time

[lct]

3 hours ago, Sandokan said:

I know on the M11P, if I turn on magnification and peaking, it is most accurate, but generally for street shooting, I do not have time to magnify so I just want it to show peaking when i am focused on my subject. 

You may wish to try auto zoom. Menu page 4, Capture Assistants > Focus Aid : Automatic.

[Sandokan]

Thanks all for the tips. 

The problem with focus peaking is it peaks at a certain place in the photo and stays lit up as you focus by more than ten degrees, even at f1.2 (yesterday lens), which is clearly not focused anymore. 

I have one profile setup with autozoom, but as turning the ring requires a large movement before autozoom kicks in,  I have the top plate button set for this which is faster. 

I wanted a view of the full screen without autozoom and focus peaking on (red colour with jpeg set to B&W) and to know which is the more accurate indicator of plane of focus setting; High or Low sensitivity. Both seem to have a similar latitude to the plane of focus. There is nothing in the manuals of the M11, M10 or SL about the difference between the two. I want to rely on this when trying street photography as it is faster than zooming in. I was hoping this would be as fast but more accurate than optical rangefinder focusing. My eyes are not as good as they once were. 

I will just stick to using the rangefinder for this style of photography. I guess the distance and under estimate the distance. My instinct is to turn the lens clockwise which brings the subject into focus. Slightly reversed when using a Nikon RF where the lenses focus the other way round, so I overestimate the distance. 

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30 minutes ago, Sandokan said:

I was hoping this would be as fast but more accurate than optical rangefinder focusing. My eyes are not as good as they once were.

I don't think FP will ever be as fast and accurate as the RF, even with poor eyesight. With a good rangefinder I have been able to focus accurately even with my reading glasses on. It's not only the coincidence of contours, but also that the image suddenly becomes very crisp. My eyesight has never been very good, as I have a somewhat pronounced coma.

[lct]

I like much RF as my favorite focus aid in the film days but how i feel it, focus peaking is faster when i count the time spent by doing focus / recompose in RF mode. There is a bit of learning curve though.

[pop]

This is what the CL does. First image is with high sensitivity, second image with low sensitivity. Your camera might do it the other way 'round for all I know.

As I don't have much gravel on my desk, I used a structured mat. You can clearly see that the 'high sensitivity' lowers the threshold for the contrast detection. Usually, I set the sensitivity to 'low' unless I use a lens or a subject with a smallish contrast.

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[davidmknoble]

Focus peaking is from the sensor and uses contrast.  So, high contrast items can sometimes appear to be in focus using focus peaking, but not in reality (as you mentioned with f/1.2). Lower contrast items sometimes have a little trouble with focus peaking because of the lack of contrast.

So, here are the rules of thumb I follow:

1. If I am shooting with a higher f/stop and larger depth of field, I use simple focus peaking and get pretty much what I want all the time.

2. If I am shooting with a narrow depth of field (50 noctilux at 0.95 - 1.4, APO 90 at 2.0-4.0) I use the zoom function and focus until the EVF shows the crisp detail I want, ignoring the focus peaking at full size.

Clearly, if I am focusing on moving subjects with narrow depth of field, it isn’t so easy, but then I typically switch to a native SL or autofocus lens (if on the SL) or use the rangefinder (if on the M).

[jaapv]

It wasn’t Leica but Sony using a high-contrast Apo Telyt 180 to photograph a herd of Zebra with focus peaking resulted in a complete red-out of the viewfinder, lending credence to the colloquial “a Dazzle of Zebras 😉”. I regard peaking as a practical aid as long as one walks the focus to find the middle of the DOF field but never as a precision technique. Combined with magnification it is better. I usually set it to white to create shimmering edges. 

[Sandokan]

11 hours ago, pop said:

This is what the CL does. First image is with high sensitivity, second image with low sensitivity. Your camera might do it the other way 'round for all I know.

As I don't have much gravel on my desk, I used a structured mat. You can clearly see that the 'high sensitivity' lowers the threshold for the contrast detection. Usually, I set the sensitivity to 'low' unless I use a lens or a subject with a smallish contrast.

 

Thanks Philipp, that is what I thought; LOW = lower sensitivity (less likely to shimmer until focus is reached). I shall play over the weekend with it. 

[Sandokan]

Thanks to Frame-It:-

https://blog.kasson.com/the-last-word/manually-focusing-the-fujifilm-gfx-50s/

this is a pretty good explanation and tutorial. My expectations will not be met by focus peaking alone, I will need the magnified view. 

[Al Brown]

Once people realize focus peaking is just an APPROXIMATE contrast based aid that has a similar function to "find edges" in Photoshop they stop relying on it for critical focus. And properly so. The rule of thumb should always be: for FAST lenses, find pseudo sharp area with focus peaking and then zoom in for critical focus.

Edited March 26, 2024 by Al Brown

[davidmknoble]

On 3/25/2024 at 9:21 AM, jaapv said:

 Combined with magnification it is better. I usually set it to white to create shimmering edges. 

+1

 

Edited March 28, 2024 by davidmknoble