Q3 43 - Focus Recompose, your results?

[darlesch]

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I'm venturing into Q territory after I bought the Q3 43 to add to my M. I'm used to focusing and recomposing using centre target.

On the Q3 AF I use the following settings:
- AF-S
- Spot focus/field, shot wide open f/2.0

Observations:

- Centre focus results in tack sharpness. But when I focus on a target in the centre and recompose, the focus is quite noticeably behind the target. When I now move the focus point using touch AF/directional pad to the off-centre target, it is tack sharp as expected. 

Questions:

- Is anyone else experiencing this? 

- Did this occur on Q3 28? I've never owned one.

- Best way to adapt to the limitation of the lens, if it is the lens? Eye tracking doesn't seem great and multi field focusing is like playing the lottery.

Another reputable user confirmed the same experience using Q3 43 AF-S, he said using Manual Focus then recomposing seems to improve focus acquisition off-centre suggesting it might be an AF-S problem when recomposing.

Thoughts?

 

Edited September 30, 2024 by darlesch

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[SrMi]

Focus-recompose technique is prone to focus errors with any camera. The issue has been published on the web.

[Sandokan]

As above. 

Did you try AF-c and recompose ... just guessing it might work, but I doubt it. 

Use either zone field (my setting) or point focus; compose; focus on the object you want and shoot. 

Alternatively use iAF and let camera find the subject - you did not say what type of photography you do

[JNK100]

Focussing on one object and then recomposing will never very be as sharp as focussing on the subject you want in focus.

[LocalHero1953]

This is not a fault or limitation - it's basic geometry, and what you expect with focus and recompose. It was always something to keep in mind when I had a M.

Edited September 30, 2024 by LocalHero1953

[Le Chef]

Surely it’s just easier to manually focus?

[JNK100]

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Yes, or use AF with a manually-selected point

 

[LanceR]

When you recompose, you are changing the plane of focus.  Think of a sphere around you at 6ft.  When you focus on a spot and then move the camera, the distance to your subject is no longer at a point on the sphere.  That is, the distance to the subject has changed.

At any given aperture and distance to subject, 28mm will give you greater depth of field with acceptable sharpness compared to 43mm.  At 28mm f/2 with a subject 6ft away, you have acceptable sharpness that ranges from 5.43ft to 6.71ft.  Simply changing to a 43mm focal length, changes the acceptable sharpness range from 5.74ft to 6.28ft, which is less than half.

Acceptable focus is not critical focus.  So while the subject may still be within acceptable focus, it will likely not remain as sharp as you want, unless you are shooting at at higher aperture or there is more distance to the subject.

Aperture, distance to subject, and focal length all combine to affect depth of field and the range of acceptable focus.

As mentioned, there is an abundance of photography materials covering these topics in detail.

[darlesch]

Thanks for all your responses. I'm going to be utilizing the different focus modes more and moving the focus point to the target if I'm using spot. 

[matt736]

Just be careful what focus option you leave it on . I left my Q3 on animal eye by mistake after photographing our pet cat and it was not until I was on the streets of Malaga checking my pictures that I spotted they were not well focused had I realised what I had done.

[haelio]

You can use the same technique you have now, just use tracking AF. That way after you position the camera for framing, the focus box will automatically move to remain atop the point you engaged focus on.

[darlesch]

5 minutes ago, haelio said:

You can use the same technique you have now, just use tracking AF. That way after you position the camera for framing, the focus box will automatically move to remain atop the point you engaged focus on.

Yes thanks just discovered that recently. I’m also having a good time with manual focus and that seems pretty quick even compared to M.

[LanceR]

1 hour ago, haelio said:

You can use the same technique you have now, just use tracking AF. That way after you position the camera for framing, the focus box will automatically move to remain atop the point you engaged focus on.

I have had limited success with the Tracking AF with the Q3 43 so far.  For me, it does not really seem to hold what I have selected.  Has it worked well for you?

On the SL3 it seems to work better, but uses a significant amount of battery.

I manually move the focus on both the Q3 and SL3.

[haelio]

I must admit I don't use that too often.

I've improved my success rate with using field and moving the focus point around with my thumb on the touchscreen while looking through the viewfinder. The implementation of this is far behind that of others such as Sony who allow for only the top right quarter of the LCD to be used for this -- so your nose doesn't move focus point around and you don't need to swipe all the way down to the bottom left to move the focus point to the bottom left of the view (you'd only move it to the centre of the screen).

For people I rely on the People/Eye detect mode, but when there is more than one face in the scene the system really goes haywire and can't be told to prioritise a certtain face or region like all the other brands do. This was highlighted in the DPReview review as well as a con.

[darlesch]

Yes thanks for bringing up the touch screen. I did the same thing by putting the camera to my face and used my right thumb to move the focus point around. I’m going to experiment to see which is faster, joystick or touch. That’s pretty smart to limit the right upper corner for moving the focus point. I hope that can be added to firmware.

[SrMi]

34 minutes ago, darlesch said:

Yes thanks for bringing up the touch screen. I did the same thing by putting the camera to my face and used my right thumb to move the focus point around. I’m going to experiment to see which is faster, joystick or touch. That’s pretty smart to limit the right upper corner for moving the focus point. I hope that can be added to firmware.

I am OK with both methods but use the rear LCD to move the focus point only when the joystick is unavailable.

Edited October 1, 2024 by SrMi