Olympus settings for BIF.

 

There has been intense discussion on the right setting for BIF wrt Olympus system. I think this depends partly on the shooting style as well as subject. Looking at the test results, I think actually 2 customs modes need to be dedicate for BIF. The AF system performs differently in different situations and customs settings for each need to be slightly different.

 

One setting would be for birds which have clear background, large in frame (20-30% at least) , good light and flying essentially slowly and perpendicular to the lens axis. The reason for this is that in the course of much testing, it seems to validate the theory put forth by certain people that the system uses the earlier frame to determine focus of the next frame. Generally the first 2-3 frames are out of focus and things improve after that.

 

When I started out for the testing, there were a few parameters which was of especial interest. 1) how many focus points to use, 2) sensitivity settings, 3) influence or impact of IS on BIF. 4) usefulness of bird ai.

 

The other factors which were of interest were 1) angle of attack i.e. whats the angle at which the bird is approaching or leaving and its effect on BIF accuracy, 2) contrast levels in the target itself, 3) background, i.e is it cluttered or clean, this pertains to camera being able to follow the focus even against cluttered background without losing track.

 

I live on the 17^th floor and since there is a lockdown currently in India, its not possible to go out anywhere. That means I could only do the testing on the birds that would fly outside my balcony. In this I had a fortunate selection. Pigeons fly erratically and very fast and are very small in frame, crows are slightly bigger and slower but with no contrast within the bird, 3) black kites that are quite large in frame and move in circular patterns so if you are lucky, you can test coming and going away patterns also. Sometimes they have a good background if they are flying eye level or just below and sometimes they are silhouettes so although large in frame, offer no details in the subject itself.

 

 

The basic settings were as below. All testing was done with em1x and 300/4.

1/2500s. : I started with 1/1250 and all the way upto 1/4000 but found 1/2500 to be best

AF canner mode 3

9 points or 25 points: I prefer 9 points

Electronic Shutter at 18fps

 

 

About the only things I consistently changed are sensitivity, toggling between -2, 0, +1, +2 and sometimes the af scanner mode 2 or 3 and some experiments with IS On or Off. I also did some experiments with bird AI in various situations.

 

Set 1: Sensitivity +1, IS: Off

I checked lower sensitivity to see if the focus hold better. Keeper rate is still in the 70-80%. I did get a chance to photograph a kite which was approaching very fast and very close. The camera did a good job and the frames were in pretty good focus.

 

Set 2: Sensitivity +1, IS: On

 

I was able to do a long sequence with a black kite at almost eye level. The bird was large in frame and I got all the aspects i.e. head on, approaching, parallel, busy background, clean (by clean I mean background which affords a good color separation or contrast to the subject).

 

 

Please keep in mind that though there were 67 frames more or less, the entire sequence was only 4 seconds long. The first 2 frames were out of focus as expected. The next few were dead on.

As soon as it entered the area with the white building with the blue top in the background, Focus was soft.

It was regained as soon as it left the white building behind. Next few frames were fine but then it started turning.

Focus was lost and reacquired in 4-5 frames. Remember, when its this close and flapping its wings (as opposed to merely gliding), the bird is actually going quite fast. The focus was excellent against the white shed where contrast was optimal. It held focus well even when it left the white shade and went to a darker background (although the background was dark, it wasn’t “busy”) . My analysis of this set is as follows: At the start, the first couple of frames go in acquiring focus. Once focus is acquired, and as long as the path is steady, its able to follow reasonably well. If it enters an area where the background has better or higher contrast, then the camera may try to refocus. It is here that I feel focus limiter might make some sense as it should be able to prevent the camera from focusing on a more contrasty background. Once the kite started turning, focus was lost. I think there is some truth to the concept that the camera uses the earlier frame to “predict” the next focus point. When the kite started turning, I think the camera still expected it to be on the original path and predicted a focus point where the bird wasn’t but should have been, leading to mis-focus. It caught on within 4-5 frames. In fact I have observed this phenomena amongst circling birds a number of times. It gets worse with +2 sensitivity. If you are photographing circling birds like eagles or vultures etc, I think you should let go and refocus at the time of turn. As long as the path is quite regular, and the background isn’t too contrasty, the focus hold quite well, even if there’s an obstruction in the frame like in the last few frames. Give it a good clean background, and the AF performance should be stellar. I also think the contrast in the subject itself is of great importance. Very silhouetted birds which appeared quite dark, fared quite poorly in AF tracking.

 

Set 3: Sensitivity -2, IS off

I took many shots with this combination and I think its not recommended at all for BIF. It may be ok for slow moving birds like kites but I don’t really see any point to it. It did quite badly with fast movers like pigeons, getting on 30-40% frames in focus. It didn’t help much in tracking the bird against a busy background vs sensitivity +1. So I didn’t find it to be sticky wrt busy background. However, it held focus better for circling birds and had less mis-focus at the time of turn.

 

So I think bird motion and background considerations are two separate issues which need to be approached differenty. Whereas sensitivity might influence stickiness wrt bird motion, I think we may have to consider focus limiter to reduce background issues.

 

Set 4: sensitivity -2, IS On

There has been some discussion about IS ON or OFF. In my testing I didn’t really find any influence as far as focus acquisition and maintenance are concerned. But I think there are other considerations. 1) with IS engaged, you are actually giving the processor more work to do. I have read that there’s a seperate chip for IS but I don’t know whether it will influence or tax the processor sufficiently for it to interfere in AF. 2) The camera may not sense the motion correctly and might shift the image in a direction that is detrimental to image sharpness. In many thousands of images, I haven’t found conclusive evidence either way. But at 1/2500s, IS shouldn’t matter and it just makes more sense to me to not tax the processor more and leave its power for the job at hand which is AF. So I generally leave IS off for BIF.

 

Set 5: sensitivity +2, AF Scanner Mode 2

 

One idea I had was that maybe the camera was doing too much and Af scanner should be mode 2. Mode 2 means the camera will try to acquire focus once if it doesn’t find something in focus, mode 3 means the camera keeps trying to find things in focus.

 

Although the camera was able to focus on slow flying large in frame objects, it didn’t do very well against fast movers or in birds with a busy backgrouns. I would not recommend scanner mode 2 for BIF.

 

cropped

 

Set 6: sensitivity +1 and scanner mode 3.

 

By now I was coming to the conclusion that this is the better setting to have. In my tests with sensitivity +2, I sometimes found that the camera was trying to do too much. There were more instances of mis-focus. Also it tended to shift to a busy background more. So I decided to test this setting i.e. sensitivity +1 and Af scanner mode 3 a bit more rigorously.

 

One problem with doing AF studies on BIF is that the situations are never repeatable. So its actually very hard to compare and you have to use best guesses.

 

 

The fastest bird we have, where I stay,  are pigeons. They can go from this

 

To this

 

 

In just 2 seconds. So this was the ideal bird to check if the +1 sensitivity was fast enough. The Af speed was more than capable of keeping up with the pigeons.

 

I also checked for slow movers against busy backgrounds. I had no problems

Low subject contrast and approaching dead on…. No problem.

 

So this is the mode I finally settled on. I know many photographers advocate sensitivity of +2. But I feel for my style of shooting, the camera tries to do too much and chance of misfocus increases. +1 I feel gives just enough stickiness whilst still focusing very quickly.

 

So As of right now, my settings for Bird in Flight photography are

1/2500s

AF scanner: mode 3

AF sensitivity: +1

C-AF centre start: ON

C-AF center priority: OFF

 

AF area pointer: I feel it didn’t contribute much so decided to keep it mode 1.

 

 

Some additional comments:

AF sensitivity: while I could get away with AF sensitivity of +1 for bare lens i.e. 300/4, I got better results using +2 when I put on the TC. I think putting on the TC slows down the process enough that the extra sensitivity from +2 is tamped down. In fact +1 is just a tad slow. I think its very difficult to remember to change the sensitivity if you put on or remove the tc so keeping AF sensitivity to +2 might make some sense.

 

AF focus limiter: I found focus limiter to be quite useful in a narrow range. So if you are sure of the range, its better to keep the background out of the range so the camera doesn’t get distracted. I think ranges of 4-300m for example are plain silly. You aren’t achieving anything. In my situation, most of the bird were in the 5-150m range and the background buildings were 200m or more. So within this narrow range, things worked well. At a practical level though, its pretty much impossible to gauge distance accurately. I have lost opportunities when the birds were just out of range say 180m. So unless you know exactly what the range is, I would keep this off. A wide range of 4-300m or something just makes no sense to me. There is another school of thought which says that given the focal length of 840mm (300+1.4x tc), whats the size of bird you will get at more than 150-200m? It will be very small in frame. So its better to keep a cap of 150-200m and ignore anything beyond that as being too far away.

 

Bird AI:

In December, Olympus released a firmware that incorporated bird recognition and you could tie it into AF+Tracking where the idea was that it would recognize the bird and focus on the eye. It works reasonably well in static birds although I wouldn’t recommend it for primary use. I was curious to see if it worked for BIF. As per one of the posts from Olympus, changing sensitivity has no effect on Bird AI. So the only option was to test it against different subjects and see what happens.

 

These were the circumstances I was able to test

Set 1

 

subject speed	fast
background clutter	cluttered
subject contrast	low
subject size in frame	15%
subject approach angle	90
keeper rate 10%	20%
subject movement	straight

 

Angle 90 means its almost approaching the camera head on. The Kite was flying very close to the ground and approaching almost head on

 

The Bird AI didn’t work at all in this situation. Definitely not recommended

Set 2

subject speed	fast
background clutter	clean
subject contrast	low
subject size in frame	10%%
subject approach angle	-20deg
keeper rate 10%	50%
subject movement	straight

 

These two pigeons were flying away from me very fast. It was a bit overcast so contrast wasn’t great.

I think the subjects were too small to really figure out AF accuracy which was about 50%

 

Set 3

 

subject speed	medium
background clutter	clean
subject contrast	medium
subject size in frame	25%%
subject approach angle	0
keeper rate 10%	70%
subject movement	straight

 

This crow was flying with nesting material with a clean background and quite slowly. Focus was good even though subject contrast was poor. I think keeper rate was around 60-70% or so.

 

Set 4

 

subject speed	slow
background clutter	cluttered
subject contrast	medium
subject size in frame	25%%
subject approach angle	variable
keeper rate 10%	70%
subject movement	circles

 

 

I got one set of this black kite at eye level in decent light and I tracked it all the way until it went beyond the building

 

Tracking was quite good even though I didn’t manage to keep the subject in the centre of the frame. I have noticed that things are better when the subject is close to the focus points and not all over the place.

Set 5

 

subject speed	high
background clutter	clean
subject contrast	high
subject size in frame	15%%
subject approach angle	90
keeper rate 10%	60%
subject movement	straight

This pigeon was coming straight at me and the focus was reasonably good. Not as good as C-AF

 

I think Bird Ai isn’t too bad for BIF. As long as the bird itself has sufficient details or contrast for the camera to latch on to and the background isn’t too bad and the bird is flying reasonably slow, it does a decent job. Especially if the bird is flying perpendicular to the lens.

Bird AI may be quite useful for large birds like cranes or flamingos. These birds are so large that many times the AF latches on to the wings and not the eyes. Its almost impossible to keep the focus point on the eye. In such situations, Bird AI might well be very useful and should at least be kept in mind as an option. I would not necessarily recommend it for fast flying birds although I did manage to get a swift a few times with bird ai but that’s probably more an exception than a rule.

 

 

So in summary, the Olympus AF system isn’t bad. As long as can create enough history to predict the next point of focus, it does quite well. I sometimes feel that AF sensitivity of +2 gets ahead of itself and would probably be happier with +1, except when I have the TC on. In good light, with good details in the subject and a decent background, I have no problems using it. It does less well in backlit situations where the subject is dark or when background is a bit challenging and subject to background contrast is low. In such cases, AF limiter might be useful. The Bird AI also works quite well but I wouldn’t total replace it with C-AF just yet until I do more testing.

 

Ultimately, there is no one size fits all and it comes down to individual preferences and handling.

These are the settings that are working for me

1/2500s

AF scanner: mode 3

AF sensitivity: +1

C-AF centre start: ON

C-AF center priority: OFF

Also check out these settings that have been developed by 3 photographers from India, Mital Patel, Rahul Chavan, Mahesh Kondwilkar. https://drive.google.com/file/d/17PER3eRmdw9O2xIeE4GeJoyAfErLJ8kQ/view

 

 

Happy Shooting

 

Girish Vaze

April 2021