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View Full Version : ARTHUR MORRIS ON USING AI SERVO AND C.FN-04 ( * FOCUS LOCK)


slejhamer
26th of March 2004 (Fri), 09:26
There have been several recent threads relating to custom EOS functions, in particular C.Fn-04 and its use in certain types of photography.

I had bookmarked an old article (circa 2000) by famed bird photographer Arthur Morris in which he explains why he uses C.Fn-04 in conjunction with AI Servo mode. Unfortunately the link no longer works, but I was able to use the cache component of a Google search to resurrect the article sans pictures. Since I can't link you to the original (on NaturePhotographers.net) I will quote the article here, with added bolding where I think the comments are particularly informative.

Note that this is NOT intented to be the ONLY reason to use C.Fn-04, nor the only type of photography for which C.Fn-04 is useful. It is simply to show how and why one person gets good use from the custom function and to hopefully shed some light on a somewhat confusing topic. YMMV.

Enjoy.


Teaching on Old Dog New tricks
Text Copyright and Photography Copyright Arthur Morris


On a crisp fall afternoon, dozens of Sanderlings scurried frenetically in search of sand fleas and other tasty invertebrates that live in the wet sand along the deserted beach at the very edge of the Atlantic Ocean at Stone Harbor Point, New Jersey. Occasionally, they would stop for a few seconds to preen or simply to stare at the crashing waves.

I was seated (with a wet butt) behind my Gitzo 1548 Carbon Fiber tripod, working with the Canon EF 600mm f/4.0L super-telephoto lens and a Canon EOS 3 camera body. The EF 1.4X teleconverter yielded the 840mm-f/5.6 combination that is my everyday bird photography rig. Before I came to realize the many benefits of Custom Function 4 (CF4), available on all mid-range and high-end Canon EOS camera bodies, I would have faced the following dilemma: Should I work in AI Servo mode so that I could easily track the moving birds, or switch to One-Shot mode so that I could focus on a momentarily still Sanderling, recompose, and make the image?

By opting to utilize Custom Function 4, I had the best of both worlds. When activated, CF 4 transfers autofocus operation from the shutter button to the exposure lock button, the left of the two small buttons on the top right of the camera back. With autofocus set to AI Servo mode (for moving subjects), I simply activated autofocus with my right thumb to track a running or a foraging bird, or tapped the button once to focus on the eye of a stationary bird. In the latter instance, I would quickly recompose and make the image by fully depressing the shutter button. I was able to enjoy the benefits of both AI Servo AF and One-Shot AF without having to toggle back and forth (by pressing the AF button and turning the main dial). In addition, when photographing static subjects, I did not have to keep the shutter button depressed halfway as is customary when working in One-Shot AF mode.

When a Royal Tern flew by, it was a simple matter to frame the shot and activate AI Servo autofocus with my right thumb. To boot, I was able to pre-focus manually before engaging AF. This allows the photographer to drastically reduce the time of initial focus acquisition, and is especially helpful when attempting to do flight photography with the 600mm-lens/2X teleconverter combination. (Focus manually until the bird is relatively sharp, then engage AF by depressing the exposure lock button; thus, the system does not have to struggle to "see" the subject.)

Referring to the use of Custom Function 4 in "The Art of Bird Photography; The Complete Guide to Professional Field Techniques," I wrote, " Many photographers rave about this function, but I do not." And in public lectures and seminars I expressed disdain for CF 4 by stating that those attempting to use it would surely wind up on a psychiatrist’s couch. (I felt that they would become extremely confused when attempting to activate AF--is it the shutter button, or is it the exposure lock button? Is it the index finger, or is it the thumb?) But oh, how wrong I was. Today, when photographing perched birds or those on the ground, I activate CF-4 so that I am always ready to make either static portraits or images of the birds in motion.

For in-flight only photography situations, such as those that often arise at Bosque Del Apache NWR, Socorro, NM, or at the Venice Rookery, South Venice, FL, I find it easiest to set CF 4 to the default setting (0) so that autofocus is activated in the traditional manner, by depressing the shutter button halfway. Additionally, I am often afield with a big telephoto lens and one of Canon’s lightweight, hand-holdable flight lenses, either the EF 300mm f/4 L IS, the EF 100-400mm f/4.5-5.6L IS, or the "toy lens,” the EF 400mm f/5.6L. (FYI, the latter is still the world’s best for photographing birds in flight.) When I carry one of these lenses on a shoulder strap, mounted on a lightweight EOS A2 camera body, I always set CF 4 to the default setting, as these lenses are used almost exclusively to photograph birds in flight or in action. Thus, I simply depress the shutter button to activate AF. The body on my big tripod mounted super-telephoto is, however, set with CF-4 activated, as this lens is used primarily to make portraits of birds at rest. In reality, I do not have any problem switching between shutter button AF activation and exposure lock button AF activation as the shooting situation demands. And, I have not, as I once predicted--needed to undergo psychotherapy.

Though the owners of the newest Canon Super Telephoto Image Stabilizer Lenses have full time manual focus available, (hey--the folks at Canon Japan sometimes do read my product critiques!), they will still benefit from activating CF 4 when photographing perched or standing birds. They will then--as described previously--have the option of working in either AI Servo AF, or, effectively, in One-Shot AF, without having to keep the shutter button depressed halfway. To attain One-shot AF while utilizing CF 4, simply tap the exposure lock button to focus on the bird’s eye, then release the button, recompose, and shoot. As I said, the best of both worlds.

With EOS A2, Elan II, and 1N bodies, activate Custom Function 4 by toggling from CF 4-0 to CF 4-1. EOS 3 users may wish to note that there are two ways to activate CF-4, either by choosing CF 4-1, or CF 4-3. The former locks the exposure when the shutter button is depressed halfway after focus has been set, the latter yields real time exposure. I almost always choose the latter so that I need not keep the shutter button depressed to hold the exposure when photographing static subjects.

To Chuck Westfall, Canon technical representative, who has suggested for years that I give CF 4 a try, I say, "You were right. I was wrong, big time wrong. I wish I that I had listened to you sooner." I guess that you can teach an old dog new tricks.

garethhhhh
26th of March 2004 (Fri), 10:23
Thanks for that Slej, :D

Perhaps you should also post this in the "top tips" sticky?

Ferdinand
26th of March 2004 (Fri), 11:09
Thanks Mitch this is awesome.

Regards,
Ferdinand

slejhamer
26th of March 2004 (Fri), 12:35
Perhaps you should also post this in the "top tips" sticky?

Good idea. I just did.
8)

Ferdinand
26th of March 2004 (Fri), 12:36
Thanks Mitch :)

Ferdinand.

IanD
26th of March 2004 (Fri), 13:54
Just what I was looking for. Thanks!

CyberDyneSystems
26th of March 2004 (Fri), 18:04
I had a go at using the * to focus some time back,. and I was just too used to it being included in the shutter.. but coincedently I just tried it again.. and now I am warming up to it.. (I guess this time I just felt more familiar with everything else on the 10D)

In Conjunction with AIservo is the way to do it though,. that was my other mistake the last time I tried it.

If you are just starting out with a DSLR,. you may want to try this now rather than later.. so you don't get too used to doing it the other way around.

FYI, I think the "thumb button" is the default on Nikon bodies?
If not,. then it is a coincedence that every AF Nikon I have ever used was allready set this way by the owners.

LazyPhotographer
26th of March 2004 (Fri), 21:46
This guy is amazing.. I have one of his books and it's loaded with fantastic information. It's very motivating & encouraing too - you can't help but learn and want to do better after seeing his pics and reading how & why he got the image.

Here's his link: http://www.birdsasart.com/index.html

CyberDyneSystems
26th of March 2004 (Fri), 21:49
Yes,. I have had his site bookmarked for some time,. he is a remarkable wildlife photographer.

ClydeD
13th of September 2007 (Thu), 15:04
Thanks for posting the quote, Slejhamer, and thanks to other posterrs. Several questions I had on the use of the AF-ON button have been answered.

joayne
16th of September 2007 (Sun), 19:39
*Note to self... keep reading this thread......

yb98
27th of January 2009 (Tue), 06:58
Is there any advantage to use CF4-1 rather than CF4-3 ? Any concret example ? Thanks.

bohdank
27th of January 2009 (Tue), 07:20
I don't like to switch back and forth. I find it much better (no brainer) to leave it at one setting. I had focus on the AF-ON button but recently moved it to the * button because of the grip I use now. That I am still not used to, instinctively pushing the AF-ON button on the camera body when in landscape mode unless I think about it.

I can imagine switching it between the shutter and back button all the time. Not for me. I want to concentrate on taking the shot and not having to remember where I moved the focusing.

Same for AI Servo... I rarley use it and when I do I am not switching lenses. Again, possibility for momentary confusion depending if you are using a lens with IS or without. The tap and release method isn't going to work if you need the IS on. I usually forget to keep hoding down the focus button, as it is, when I swith to an IS lens after shooting for awhile with a non IS.

Sean
27th of January 2009 (Tue), 07:30
Nice find. Thanks. Borrowed and saved.

This is the primary reason I moved my AF to the AF-ON button, and off the shutter. I had read similar (not as concise) where putting the AF to the AF-ON would allow for this function, among others.

Cheers,

donaldjl
27th of January 2009 (Tue), 13:21
Great post, and a truly worthwhile read.

I tried this a while back and found that it was easier to use only one of the C.Fn4 modes or the other. Switching between -1 and -3 had me all mixed up.

The only time I turn C.Fn4 off now is on a tripod while using a remote trigger or on a couple of rare occasions that I had to one-hand the camera.

sacral
28th of January 2009 (Wed), 12:40
Just switched over on my 30D - HOLY CARP!!! Love it.

bob-e
28th of January 2009 (Wed), 13:41
* focus ftw. First thing I did when I got my 50D. Focussing with the shutter button feels like I'm shooting a P&S now.

Ren Damkot
28th of January 2009 (Wed), 16:00
Is there any advantage to use CF4-1 rather than CF4-3 ? Any concret example ? Thanks.

CFn 4-1 does lock AE with half press of the shutter, CFn 4-3 doesn't.

I use 4-3 on my 1D and 1D2.

CFn 4-1 was the only option on my Eos 1n, and I found it caused me to "mash" the shutter, since I did *not* want to lock AE when using Av mode. (Very, very bad technique ;))

The 1D series (and all other camera's except the 10D and some newer models (after 30D I think) will still lock AE when AF is locked, whatever the CFn says, when using Av, Evaluative and One Shot AF, for as long as the * button is pressed.

AiServo, or any other metering mode then Evaluative doesn't exhibit this inconsistency.