Losing bokeh or quality when raising or lowering the aperture on P4P?

[Dingoz]

I wasn’t having a shot at you specifically, I was sharing my general observation. I have performed similar tests to what you have done here with many lenses and for a time fell into the trap of letting the technical considerations take priority. Now- if I want to shoot at f1.2 for extremely shallow focus I will, even though I know a couple of stops closed down on the aperture will give a significantly sharper image viewed at 100%, I will also stop down to where I know I will see the effects of diffraction on a 100% view, the reality is there is two stops or greater latitude to where this will be perceptible to most people in a print viewed at a reasonable distance. It would be interesting to see how your test shots compare when all viewed full screen uncropped.

Fair enough... I must have been overdue for a coffee. I do agree with that and also do not have as strict boundaries with my DSLR gear - although with that gear provided the subject is in focus the quality is so good that diffraction is irrelevant in normal viewing almost throughout the whole aperture range (you really do need to pixel peep to see flaws in excellent gear).

On the other hand this little lens is far from great and on a 4K TV video and images are almost close to 1:1 and being viewed at 100% where flaws do poke out more. Naturally - out of focus is out of focus - and the previous focus test viewed uncropped looks bad when focus is even slightly off the small 10m-infinity window as the focus roll off is rapid with this lens leaving less room for give or take leeway or much trust in the auto focus system. Unless trying to capture a 1m-5m selfie there really is only 3 focus settings for everything else (infinity to 2 markers off infinity and it is splitting hairs in this small range so basically manually focus once and then forget about focusing for each scene as such... its fairly useless for the most part).

I will test again the aperture and curious to see the results cropped and uncropped too.

 

[Dingoz]

Well the repeat series of tests with some extras was interesting... note all the group shot examples were raw without any lens corrections but with +25 noise reduction/sharpening and +.5 exposure and +50 shadows (sun is not in ideal direction so to lift the brightness for comparing equal adjustments across all images/groups so it is easy to see in the shadows and without some of the noise distraction). Image is at full size so click to see 100%.

Also note there is some wind so in shots where aperture changes the shutter is being changed also from in the 2000's to min of 120. Therefore comparing the moving treeline is not so great (better to look at the static items in the distance such as the tree trunk in the water on the far side).

This first test is a manual focus test at the infinity end all at f3.2:

My take away is as follow:

- At f3.2 (or near) max infinity today is the sharpest across the range from 10m (number plate) to 85m/100m tree trunk in water on far. The 10m object does not get sharper by focusing closer in from infinity.

- The other day the same test revealed 1 marker off infinity to be the sharpest (some wiggle inaccuracy in the lens movement perhaps). In any event 1 marker off infinity is very close regardless and at web size barely noticeable.

- At any size 2 markers off infinity is obvious to me for both near and far objects.

In summary, at this aperture or near enough to focus at infinity to 1 marker off.

 

[Dingoz]

This test is with focus at 1 marker off infinity (infinity basically) and through the aperture range.

- Today this test revealed little variance from f2.8-f5.6 approx. If I had to pick which one is sharpest (which is hard to do) perhaps f4.0 or f4.5.

- Diffraction quality loss is obvious towards the end and seems to roll off from f6.3 onward. If viewing at 100% I still see less quality at f5.6 vs f4.0 but splitting hairs again.

- Raising the aperture while focused at infinity does not make any objects sharper (with the exception of maybe f2.8 in this example). Better off taking advantage of higher shutter speeds with the lower apertures to minimise camera shake for sharpest images.

Summary, when focused at infinity using f2.8-f5.6 is very similar. For small images or video up to f7.1 is unlikely to affect perception much.

 

[Dingoz]

And lastly these 2 tests show again the aperture range with focus set at macro and then in the middle of the focus range.

- When focusing close up increasing aperture will bring more into focus from 10m to infinity.

- When focusing at 1m-5m some decent background blur or bokeh range is possible using low f stops (by decent I mean relative for this lens/sensor combo - not relative DSLR quality.

- None of these image are better in the 10m to 100m range vs just focusing at infinity and using f2.8-f5.6 like in the first aperture test.

In summary, keep it simple and use manual infinity focus at low f stops up to f5.6 - If you insist on taking selfies try auto focus and hope for the best along with choosing an aperture for either maximum background blur or maximum chance of getting your mug in focus.

 

[Dingoz]

And for the self obsessed test or for those that like to film dangerously here is a donkey at 1.5m from camera tested at every manual focus setting with both f2.8 and f8.0. TBH I do not know what to make of this one and do not care much either Sorry for the poor image quality... bad light but enough to get an idea.

- Perhaps I am left wondering why in the f2.8 series almost 50% of the manual focus range is for objects closer than 1.5m.

- Or why the best image at f2.8 is at the 5th focus mark and the best image at f8.0 is at the 3rd focus mark (although TBF there is not much in some of them).

- Or why focus is not consistent on the subject between apertures while increasing depth of field (normally as aperture increases you would expect a little more in front to be in focus and a lot more in the distant to be in focus. It is but it also seems to change the focus on the subject somewhat. IDK its just odd in the 1m-5m range.

 

[With The Birds]

And for the self obsessed test or for those that like to film dangerously here is a donkey at 1.5m from camera tested at every manual focus setting with both f2.8 and f8.0. TBH I do not know what to make of this one and do not care much either Sorry for the poor image quality... bad light but enough to get an idea.

- Perhaps I am left wondering why in the f2.8 series almost 50% of the manual focus range is for objects closer than 1.5m.

- Or why the best image at f2.8 is at the 5th focus mark and the best image at f8.0 is at the 3rd focus mark (although TBF there is not much in some of them).

- Or why focus is not consistent on the subject between apertures while increasing depth of field (normally as aperture increases you would expect a little more in front to be in focus and a lot more in the distant to be in focus. It is but it also seems to change the focus on the subject somewhat. IDK its just odd in the 1m-5m range.

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Most lenses show increasing sharpness across the whole frame (including an increase in DOF) when closed a few stops so that part makes sense. I suspect a few high end mobile phones would outperform this imaging system- they cant fly though.

I’m looking at the I2 with an X7 seriously. It’s hard to get great performance out of a lightweight system it seems.

 

[Dingoz]

Most lenses show increasing sharpness across the whole frame (including an increase in DOF) when closed a few stops so that part makes sense. I suspect a few high end mobile phones would outperform this imaging system- they cant fly though.

I’m looking at the I2 with an X7 seriously. It’s hard to get great performance out of a lightweight system it seems.

Looking at the full frames vignetting does improve marginally but sharpness does not due to diffraction taking over before sharpness gets a chance.