PDA

View Full Version : Odd problem


KeithL
26th September 2017, 10:00 AM
Folks
We had a long weekend away last weekend, and after much agonizing, I decided to take my PL7 but dropped my two long lenses in the bag (40-150 and 75-300); I didn't once use the pancake! Watching archery, I tried the PL7's performance at multishot; and I was disappointed. It has an odd problem.

Initially, I used the 75-300, keeping my distance, and I did get some good long shots. But when I tried multishot, irrespective of whether fast or slow setting, it focused correctly on the first frame, then for every following frame found a different target - something static.

I'm wondering if anyone else has met this issue? I haven't had this experience with the M5 photographing fast moving aeroplanes.

http://e-group.uk.net/gallery/data/500/P9241104_fast.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/95432)

Initially, I focused on the lady. But as you can see from this shot, after the first shot it found the grass behind the scene, and focused on that! I thought at first that it was camera shake, but it can't be, can it? Otherwise it would all be fuzzy.

Incidentally, I also took quite a few shots of the nighttime entertainment; again using the 75-300 (ambitious, given the light!) It didn't meter correctly, and I had to underexpose by a stop. Not that it was a big issue. One thing i did find was that the performers bodies were perfectly sharp, but they were moving their heads in time with the music, so their heads, at shutter speeds of around 20-50, were blurred. Not easy to do, getting good shots of such subjects.

Back to the archery. I next tried the 40-150, and got the same result, but not quite so bad. I'll post the best shots later, so you can see that it would get very sharp shots, on single frame.

Any ideas? Has anyone met this problem? Your thoughts would be very welcome; thanks!

GyRob
26th September 2017, 12:24 PM
Not camera shake ,I guess you were using more than 1 focus point if so it's simply that the camera went for the higher contrast in the BG.
Rob.

KeithL
26th September 2017, 12:48 PM
Not camera shake ,I guess you were using more than 1 focus point if so it's simply that the camera went for the higher contrast in the BG.
Rob.

No, Rob, I always use a single central point. Once it has locked on to a point, and the focus is held, surely it should stay on that point for the total number of frames in a burst, shouldn't it? The M5 certainly did that when I used it in burst mode, but the PL7 doesn't seem to.

Ian
26th September 2017, 01:22 PM
I have moved this from the Lounge (off-photography topic) to the E-PL7 board.

Ian

GyRob
26th September 2017, 02:04 PM
Well yes I think it should, many people use focus recompose I cant think why it would do this as the focus should be locked.
Rob.

AMc
27th September 2017, 09:41 AM
I presume there was no movement in the camera that caused the centre of the frame to move around?
It does seem weird. I'm wondering did your focus point actually capture the bright arrow against the dark tree and when that moved from the focus point the camera grabbed something else high contrast?
Can you replicate it by trying some tripod held bursts with static subjects?

KeithL
27th September 2017, 12:21 PM
I presume there was no movement in the camera that caused the centre of the frame to move around?
It does seem weird. I'm wondering did your focus point actually capture the bright arrow against the dark tree and when that moved from the focus point the camera grabbed something else high contrast?
Can you replicate it by trying some tripod held bursts with static subjects?

The first frame was sharp! I focused on the bow just above the arrow, then recomposed and held the release at half cock - as usual - and of course held it down for the burst. The only thing I can think of is that the camera tried to refocus between shots; with no viewfinder to talk to, maybe there would be time? I don't know, but wouldn't have expected there to be. It did the same on low speed burst too, so maybe it does that. If so, you'd have to move the focus point with the touch screen to the place you want, and not move the camera at all during the burst. Not very practical, unless using a tripod (which I wasn't).

I had a similar problem once with a Lumix G2. However much you shrank the focus area size, the moment you pressed the shutter, it momentarily went to nearly full screen! The result was a heron standing by a muddy bank, perfect focus on its neck, take shot; in the image the heron was blurred, mudbank behind it was sharp. It took quite a while before I discovered the cause of that one. I'm wondering if Oly did something similar with the PL7...

AMc
29th September 2017, 03:23 PM
From your description of focus, recompose then a burst I suspect the camera used your original focus distance from the half press and refocused for each shot of the burst back on the centre point.
On my EM10 & E-PL5 when reviewing images you can press the "info" button to cycle through to a mode the shows the green box around the chosen focus area.
IIRC "Sequential L" refocuses from shot to shot, "Sequential H" uses the same focus as the first shot but I'd need to check a manual to be sure.

FWIW I use the touchscreen or arrows to set the focus point rather than focus recompose which may be why I've never seen this issue.

pdk42
29th September 2017, 04:51 PM
From your description of focus, recompose then a burst I suspect the camera used your original focus distance from the half press and refocused for each shot of the burst back on the centre point.
.

Yes, I agree that this sounds like the problem. Back button focus fixes this sort of behaviour.

KeithL
29th September 2017, 07:28 PM
From your description of focus, recompose then a burst I suspect the camera used your original focus distance from the half press and refocused for each shot of the burst back on the centre point.
On my EM10 & E-PL5 when reviewing images you can press the "info" button to cycle through to a mode the shows the green box around the chosen focus area.
IIRC "Sequential L" refocuses from shot to shot, "Sequential H" uses the same focus as the first shot but I'd need to check a manual to be sure.

FWIW I use the touchscreen or arrows to set the focus point rather than focus recompose which may be why I've never seen this issue.

You are right about the first shot being the focus point. I checked in the PL7 manual - it's the same as the M5. I reckon it must have refocused each shot, even though it shouldn't. Can't think of any other logical explanation!