PDA

View Full Version : E-M1 low light - yeah! & C-AF tracking low level - ouch!


catkins
20th November 2013, 03:59 PM
The good the bad and the ugly:
How do I describe my first week with the E-M1? Overall, an excellent week of photo opportunities ranging from

an artist's studio in lowish light with the Sigma 70-200mm f2.8 EXII APO attached! An unusual choice of lens for studio work but I was diverted enroute to somewhere else and needed a good location to test the new camera's capabilities - conclusion; excellent in low light, with few focus issues, and IS very good :)
an Abbey with the 12-40mm f2.8 Pro lens. Very low light but again very good results at high ISO and focusing spot on :)
Durham Lumiere in the dark with varied lit installations. Very good, at 3200 ISO, low shutter speeds etc., but no obvious issues to worry me. EVF viewfinder great to show me how the scene would come out. *chr
A few outdoor locations with the 12-40mm lens again. Excellent in all lighting conditions, very limited focus issues with certain objects but not enough to worry me and otherwise very good. Colour rendition seems excellent though I await a RAW update for my ACDsee Pro 7 software so that I can develop RAW more effectively :)
Low-mid Level military aviation with the Sigma 70-200mm f2.8 EXII APO. Ooh heck, did I have a few problems for this, with C-AF & Tracking almost being comical if it weren't for my photo opportunity swiftly moving past. It occasionally would lock on, sometimes not, and if it locked on to the target after a few seconds the lit square would get bored and wander off aimlessly around the screen! :mad: Other times I had a good sequence of images while on C-AF and then as the target got close enough for the 'ideal shot', oops, the focus would lose lock and the lens would go a-hunting! :mad: So back to S-AF but focus hunting was not ideal so back to C-AF and short bursts of shots which was better unless the camera again lost lock and would then hunt. :mad: But when it did work properly, some lovely shots were caught. But again, the loss of focus lock at critical times, the wandering C-AF Tracking point, meant that my fears about the low level AIF (Aviation in flight!) abilities of the E-M1 were founded. I need to be able to track an aircraft for some distance so I can judge its flight pattern, and then as it gets closer or makes some evasive manoeuvres I then need to be able to rely on the constant and quick reactions of a focus lock on - this just wasn't happening reliably. The freezing micro-seconds of the EVF while in a 'motordrive' sequence was unnerving but I seemed to cope, but I did wish it just gave me the constant view. :mad:
The biggest But though is the operator . . . it is back to the manual and check the settings just to see if it is I who was at fault rather than the camera! Low level aviation fears were factored into my purchase decision and I'm sure that I can extract more from the camera yet. But if anyone has some hard gained facts, ideas or settings that I should check out, then let me know - thanks

Despite the low level aviation C-AF issue, I'm very pleased with my decision, but for sports, aviation, etc., there will need to be some improvements, as most of these shots were fairly standard and were a contrast of darkish aircraft and lovely blue sky. I will post the better shots later in Foto Fair.

Regards
Chris

David Morison
20th November 2013, 04:17 PM
I may be wrong but I thought that CAF Tr is more for focusing and then re composing and it works well for this. I'm not sure it is meant for fast moving objects.

David

Imageryone
20th November 2013, 04:18 PM
If you follow the BiF threads for the EM-1, Chris, seems a lot of testing and experimentation on your problem, and some observations and conclusions that may help :)

Ian
20th November 2013, 05:51 PM
I may be wrong but I thought that CAF Tr is more for focusing and then re composing and it works well for this. I'm not sure it is meant for fast moving objects.

David

Absolutely - just use C-AF (not C-AF+TR) and no more than a group of AF points (rather than all AF-points).

Ian

birdboy
20th November 2013, 06:21 PM
Absolutely - just use C-AF (not C-AF+TR) and no more than a group of AF points (rather than all AF-points).

Ian

I must admit to being puzzled by when to use this setting. By fast do you mean relative to the background? What sort of action shots is it suited?

I have tried C-AF +TR with planes (not at an air show but stacking planes for Heathrow which seem to gather over my area). They are some distance off set against a blue sky and yet this setting seems completely unable to track the plane wandering off into a corner.

Does it only work for a lady on a horse splashing through a pond:D

photo_owl
20th November 2013, 06:40 PM
Low-mid Level military aviation with the Sigma 70-200mm f2.8 EXII APO. Ooh heck, did I have a few problems for this, with C-AF & Tracking almost being comical if it weren't for my photo opportunity swiftly moving past. It occasionally would lock on, sometimes not, and if it locked on to the target after a few seconds the lit square would get bored and wander off aimlessly around the screen! :mad: Other times I had a good sequence of images while on C-AF and then as the target got close enough for the 'ideal shot', oops, the focus would lose lock and the lens would go a-hunting! :mad: So back to S-AF but focus hunting was not ideal so back to C-AF and short bursts of shots which was better unless the camera again lost lock and would then hunt. :mad: But when it did work properly, some lovely shots were caught. But again, the loss of focus lock at critical times, the wandering C-AF Tracking point, meant that my fears about the low level AIF (Aviation in flight!) abilities of the E-M1 were founded. I need to be able to track an aircraft for some distance so I can judge its flight pattern, and then as it gets closer or makes some evasive manoeuvres I then need to be able to rely on the constant and quick reactions of a focus lock on - this just wasn't happening reliably. The freezing micro-seconds of the EVF while in a 'motordrive' sequence was unnerving but I seemed to cope, but I did wish it just gave me the constant view. :mad:


the EVF in H sequential is a little iritating but in the L seq you would have been using, and with the fast shutter speeds necessary without IS, I have to say I don't really notice it anymore.

C-AF+tracking isn't really going to work for what you indicate without an m43 MSC lens. the tollerance indicated in the manual (for the AF point leaving the selected target) doesn't seem to be exagerated to me ie you really need to keep the AF point tight to the target and are as well off (better off) using more points rather than tracking. definitely the weakest area relative to the later E's (30 & 5) with 43 glass IMO.

catkins
20th November 2013, 11:00 PM
Thanks for all the comments which I will follow up. The C-AF+TR was a bit of a red herring - it was so plainly not working, as I had assumed it should from its title, that I quickly stuck with trying C-AF and S-AF.
With both the issue was similar, sometimes locking focus as expected but occasionally suddenly losing a locked focus point and then by the time it refound the target, it was too late - these low flying assets don't hang around for too long unfortunately!!
With one series of helicopter flying towards me, focus locked well and I got a good sequence of photos only to then lose focus lock at the ideal point. I got my photos but was surprised with loss of focus when it happened - is there some software that shows where your focus point was, as per the info view on the camera?
With distant aircraft, again trying to get initial focus lock was sometimes difficult although I tried different options. I also nearly tried manual focus but I had magnify on and that wasn't ideal for making judgements about composition, so gave up on that very quickly.
I also stuck with single focus point for most shots as the aircraft is usual kept central to the frame.
Regards
Chris

brian1208
20th November 2013, 11:08 PM
Have you tried changing the focus lock setting Chris, I find that setting it to Normal seems to give me the best hold when locked on focus, even to the extent that is will hold a bird flying behind or in front of tree branches (mind you that is with m4/3rds lenses but I think it should have the same effect with 4/3rds as they are both using PDAF as all or part of the focusing system)