Using C-AF with moving subjects

[Gwyver]

Re: Using C-AF with moving subjects

I do indeed have "Release Priority C" set to On but that is deliberate and, I believe, the default when the camera is delivered.I have never found "Release Priority C" Off to be a very usable experience! The new pdaf routine (firmare 3 hack!) only kicks in when the burst has started shooting. If the burst pauses due to not being focused, it doesn't seem to be able to get back in focus.

I haven't tried this for quite a while. Do you think it would work better?

Tony,
I thought the defaults for Release Priority are:-
S = On. (So that you can override the AF lock)
C = Off. (To minimise OOF images)
I have yet to decide which setting works best for me in C-AF.

There is a discussion of this subject on p321-323 of Darrell Young's eBook "Mastering the Olympus OM-D E-M1".

Seems to me that Olympus could do a lot to demystify this topic by publishing some more comprehensive documentation or tutorial on action photography with the E-M1. I'm not holding my breath for this

[birdboy]

Re: Using C-AF with moving subjects

If action photography is your thing I would advise folk to study the Clarkvision articles because mirrorless bodies cannot do true predictive focusing which is what you need for BIF. Camera choice however is a compromise, the best CAF body out there is the 7DmkII I am told, but to make use of predictive CAF you need fast glass circa f 2.8 and that comes with a weight and cost penalty. I am coming to the conclusion that I will be better off using MF and seq high and developing my skills to get the one sharp pictures out of a burst.

[Olybirder]

Re: Using C-AF with moving subjects

I thought the defaults for Release Priority are:-
S = On. (So that you can override the AF lock)
C = Off. (To minimise OOF images

According to page 149 of the manual they are the other way round: S – Off, C – On. I have both mine set to On as I found it very annoying when the camera wouldn't allow me to press the shutter button when I wanted to. I think I should have the option to take OOF shots if I want to.

Ron

[Olybirder]

Re: Using C-AF with moving subjects

On the subject of default settings, I can't find the confusing 'IS with sequential shooting' setting in my menus now. I know they reworded it to make it less ambiguous at one point but have they removed it altogether now? If so, what is the default setting?

Ron

[Bikie John]

Re: Using C-AF with moving subjects

Seems to me that Olympus could do a lot to demystify this topic by publishing some more comprehensive documentation or tutorial on action photography with the E-M1. I'm not holding my breath for this

Hear hear! If we had some clues about how the system actually worked and what it looked for, we could tune our technique a lot more constructively that the current shooting in the dark. But my breath, like yours, is distinctly unheld.

John

[Gwyver]

Re: Using C-AF with moving subjects

According to page 149 of the manual they are the other way round: . I have both mine set to On as I found it very annoying when the camera wouldn't allow me to press the shutter button when I wanted to. I think I should have the option to take OOF shots if I want to.

Ron

Ron,
You're right. Apologies to all for causing more confusion on this topic.

[Gwyver]

Re: Using C-AF with moving subjects

On the subject of default settings, I can't find the confusing 'IS with sequential shooting' setting in my menus now. I know they reworded it to make it less ambiguous at one point but have they removed it altogether now? If so, what is the default setting?

Ron

Ron,
It is now called "Image Stabilisation" and appears in Cog C (just after SeqH fps) and the default = Off.

[Olybirder]

Re: Using C-AF with moving subjects

Ron,
It is now called "Image Stabilisation" and appears in Cog C (just after SeqH fps) and the default = Off.

Thanks Chris. I seem to have a mental block with that setting. I think it is because the last item on the first window of Cog C is 'Image Stabilization'. If you go down, the first item of the next window is 'Image Stabilizer' with the sequential shooting icon before it. Too subtle for my ageing brain! I am pleased to see that I have it set to On anyway.

Ron

[TonyR]

Re: Using C-AF with moving subjects

Ron,
It is now called "Image Stabilisation" and appears in Cog C (just after SeqH fps) and the default = Off.

Thanks for reminding me about this. I carrently usually have IS switched on for sequential shooting but I have been trying with it off recently. I forgot about this setting so I have been using the switch on the 300mm to enable and disable IS. Setting IS Off for sequential would mean I didn't have to worry about this and half-press IS might still work.

Damn! Just checked it and the lens IS switch overrides any other settings so no good. I would like an option to override the lens IS switch .

[Bengeo]

Re: Using C-AF with moving subjects

You can see the relative position of the selected focus point using the (for PDAF) the second table in this post:

http://e-group.uk.net/forum/showthread.php?t=33943&highlight=focus+points

The % numbers show the position across from left/up from bottom on the image where the selected focus point occurs.
The other numbers in these tables show a position in a range 0-255 across/up - so these indicate the size & location of a rectangular region of the image where focus points are active.

Thanks for that - very useful and I hadn't seen it before.

In the example I posted the AFPointSelected changed from 67%,42% in the first and second shots to 67%,49% in the third shot of the sequence. Doesn't that show that the focus point moved?

Most of my shots seem to show the AF Area being the centre point (even when that hasn't been specifically chosen) (115,117)-(138,137) but one of a sequence I found did move to the one below that (115,137)-(138,156).

[Gwyver]

Re: Using C-AF with moving subjects

Andy

In the example I posted the AFPointSelected changed from 67%,42% in the first and second shots to 67%,49% in the third shot of the sequence. Doesn't that show that the focus point moved?

Yes it looks that way - though other posters seem to confirm my original observation.

Most of my shots seem to show the AF Area being the centre point (even when that hasn't been specifically chosen) (115,117)-(138,137) but one of a sequence I found did move to the one below that (115,137)-(138,156).

Maybe under some circumstances if the C-AF completely "loses the plot" during a sequence it restarts finding AF lock and hits on a different selection point?
As I said above, if Olympus provided it's customers with some more comprehensive documentation on features such as this, we would all be able to use their products in an optimum way and get better results.

[Walti]

Re: Using C-AF with moving subjects

Been having a play today, and am obviously doing something wrong, as I never get to see the PDAF focus box pattern, only ever the CDAF ones...

I have the 9*9 centre pattern selected, do I need to select something else?

[TonyR]

Re: Using C-AF with moving subjects

I have just discovered that my 300mm IS Pro back focuses!

In the week that I have had the lens, I have been very impressed with the quality of pictures takenn with S-AF but rather underwhelmed by those taken with C-AF. It occured to me today, while reading about focus errors on SLR's, that the (probably rather pure) pdaf routine that is used by Sequential-H might have a focus error.

A quick test with a sloping ruler and vertical target confirmed that the lens had back-focus. Only by 2 or 3 mm at nearest focus, but enbough to be significant. I set a ballpark adjustment of -4 using this test target and then cheked outside with a distant target. The target was a transmitter mast about 1km away. I compared a S-AF, single, electronic shutter shot with bursts in sequential-H and settled on an adjustment of -2.

The difference between the unadjusted and adjusted results was quite significant. Unadjusted, the mast was poorly focused. Adjusted, it equaled the S-AF shot.

More tests required but quite promising. I think I need to test on a test target at BIF sort of distance (30m) to eliminate atmospheric effects.

It might be worth checking your lenses in sequential-H.

[TonyR]

Re: Using C-AF with moving subjects

Been having a play today, and am obviously doing something wrong, as I never get to see the PDAF focus box pattern, only ever the CDAF ones...

I have the 9*9 centre pattern selected, do I need to select something else?

You only see the outline of the pdaf array between frames when shooting in Sequential-H with C-AF or C-AF+Tr.

[Miketoll]

Re: Using C-AF with moving subjects

Surprised by this as I always thought that it was only SLR's that suffered from back focus (or front focus) because of the use of a mirror for viewing requiring a separate focusing array and the different light path not quite matching the light path to sensor.
In other words I would appreciate an explanation of how the back focussing can arise seeing the PDAF sensors are actually on the sensor used for the image. Not that I am doubting you, I just don't understand unless there is an actual fault with the PDAF sensors themselves.