Focus with Shutter or * [AF ON] button? -READ ME-

Maderito,

I understand what you are saying, and I agree with a lot of your points.. but I have to disagree with one aspect of your point.

That being your assertion that the use of CF#4 is "overrated"

I disagree because the importance of this set up is clearly highly subjective. For me I can not stress how invaluable this has been to my photography. If you read over some of the other posts here,. you will see many say the same.

As to your question
Q:

A: Because there are times that a photographer may not want the point of exposure to be the same as the point of focus and there are times when splitting these functions from one button to two will in fact make gaining focus and exposure from two seperate parts of the composition much faster.


To me this added control is not over rated at all.
I feel there are some additional points that should be made.

1. The degree to which this method effects your photography will vary considerably based on what and how you shoot.

2. No matter how used to doing things one way or the other, it is allways a good idea to try something that may in fact help to improve your photography and give more control to the photographer and less to the camera.

3. For some reason this debate is reminding a lot of "RAW Vs. jpeg"

In my mind, in both cases.. there is ONE method that clearly offers more control and flexibility which can only benifit the final product. In each case there is however some obvious adjustment that is required on the part of the photographer to allow themselves to take full advantage of the additional control. With RAW Vs. jpeg however, it is also clear that to take advantage of RAW a lot of adjustments must be made,. storage size, post processing time, etc.. all adds up to some solid reasons why somone would not wish to try or switch to RAW.

With CF # 4-1.. all it takes is a a month or less time with your camera set up in a new way.

I want to make sure I understand this, this function has no use if your shooting in full manual mode, correct?

I want to chime in here and add the the CF-4 is one of the primary reasons I sold my DRebel and got a 10D.

I was shooting a lot of dance with the DRebel and found that I really needed AF-Servo to follow the dancers. When I could trick the camera into going into AF-Servo mode (by doing the half-press, move the focus ring trick), it was a chore to keep it in AF-Servo. And when I could keep it there (after a shot only letting up on the shutter release to the half-pressed point, not all the way), I constantly ran into the buffer full, and it would take forever to flush. I had to relase the shutter all the way (loosing AF-Servo lock), allow the buffer to clear (30 seconds or so), then start the whole thing over again.

With the CF-4 function, it's a non-issue. Even though you can set the 10D into AF-Servo mode, without CF-4 the only way to track the subect is with a half pressed shutter. It's under the same limitations as the DRebel.

maderito wrote:
Let me go out on a small limb here and say that CF 4-1 (or CF 4-3) is highly overrated. Why split AF/AE between two buttons when it is so easily and intuitively accomplished with one?

This is a setting primarily for sportshooters and action (e.g. wildlife) photography. As best I can tell (and I've tried it), it is most useful when you have the camera in AI Servo mode. Then you can press and hold the * button to use AI Servo continuous focus _OR_ you can press and release * to focus/recompose as if you were in One Shot mode. So you get finer control over how you engage and lock focusing.

The other advantage is that you can lock exposure with the shutter button (CF4-1), since normally exposure is continuously adjusted until the shutter is fully depressed (which is what happens with the CF4-3 setting).

It's not particularly hard to adapt to using CF4-1 or CF4-3. I just don't see the point except under situations when want to switch (in effect) between AI Servo and AI Focus easily.

My other major complaint is that since I shoot with my left eye and with glasses, my thumb doesn't quite find the * button target easily and comfortably. But I'd live with that if I felt that adapting to CF4 shooting was a significant advantage.

I'm still open more arguments in favor of CF4 -- but I've read quite a few.

Even with single shot mode when you release * it keeps the focus even if you raise your finger completely from shutter release. Easier than toggling lens M switch on and off.

Only instance where shutter release focus is better is when you must shoot on one hand (e.g. above crowd -shots) because holding down camera with one hand and thumb on * is not well balanced.

And separating controls for exposure and focus is IMHO very important in daily photography.

This is exactly how I set up on my 1D for all my shootings.

One thing though I'm not very clear of, it is said to release * button then press shutter, but when shooting moving object coming towards you, do you just let go of focusing? Or do you keep focusing while pressing shutter? burst mode, that is.

It doesn't make sense when you stop focusing while object is still moving, does it

CDS,

Points taken and accepted.

I tried hard to convince myself that that CF4-1 would help me with shooting action. It really didn't take long to get used to. But I did keep switching back to standard shooting modes for everything else. In the end, I just couldn't convince myself that CF4 worked better for me in the sports arena. If I shot action every day, especially for a living, I'd probably use it for the small increase in flexibility.

For wildlife photography (which I don't do) - CF4-1or3 makes a lot more sense to me since you would want the ability to switch between between One Shot and AI Servo effortlessly and on-the-fly (which is what you effectively get with CF4-1,3 when in AI Servo mode). Maybe if I took more shoots of stationery, screaming sports fans and coaches, I'd give the * focus technique another try.

The usual CF4 explanation given by sportshooters is that while in AI Servo mode, they activate focusing with the * button and then snap off shots when desired with the shutter button. I do the same in the standard way: activate focusing with a half-shutter depress, and then fire shots with a full depress.

I considered the possibility that pressing the * button allows predictive focusing to work before, during and after you fire shots so that you're focus is more likely "spot on" when you fire the first shot(s) AND the next shot or burst. I concluded that it doesn't matter whether you use the * button or the half-depress shutter method. In AI Servo mode, predictive focus is always working between shots as long as the shutter is depressed - fully or partially.

You're right - overrated may be the wrong word. Perhaps better said: CF4-0 is underrated - the standard half-depress to focus and full depress to complete autoexposure and image caputre method. It's one of those not-so-small camera design things that somebody got right quite a while ago.

I don't have my camera with me to check this. (And I don't do a lot of burst shooting.) On the 10D, the buffer won't clear with the shutter half depressed in AI servo mode? And it does clear when CF4-1 is set and the * button depressed during shooting?

As you know, the Rebel doesn't have selectable AI Servo - only AI Focus which becomes AI Servo when the subject starts moving. That's the reason I thought people concerned with flexible focusing modes chose the 10D over the Rebel.

dtrayers,

Just confirmed your statement. Without the CF4-1 setting, you do have to release the shutter button fully to get the buffer to clear while burst shooting in AI servo mode. (I checked on my 20D). After torturing my camera, I did get an Err 99 - but not the dreaded lockup. Everything went smoothly using CF4-1 instead.

Now I have to rethink (and retest) this CF4 thing all over again.

Thanks.

Once you go back you'll never go back.

It takes a lot of getting used to. Yes, there are times it is quicker to use the standard set up. But, you will find that by seperating these two it increases speed under certain conditions.

Sports photogs and wildlife photogs not using it, are depriving themselves of a key functoin available to them.

Notably, with a large Canon prime with AF-stop buttons, you can set the AF-stop buttons to activate AF like the back button. CF-19 on 1 series bodies.

I cannot stress enough, that this is a function that takes time to master, but you will not regret it.

Tried it, don't like it, did nothing for me. Sorry disciples of the CF 4 :P

I used to use the "*" button for focusing all the time when I first got my 10D a year and a half ago. But after a couple of month of suffering from a soar thumb (CTD?) I gave up on it. It was just putting too much strain on my thumb.

The occassional "push the button to focus" was fine but it was those "keep pressing the button while tracking" that was killing me, even though I didn't do those too often. And, of course, the repeated thumb movement of pressing the button didn't make things any better. Maybe I just need to work out my right thumb a little bit more to strengthen it becaues I did like using the "*" for focusing while I was using it.

I started assigning AF to the * button a long time ago when I was shooting film with an EOS 3. I still use it with my digital Canon. I use this setting mostly for wildlife photos where it is too easy for autofocus to zero in on some twig or blade of grass instead of the eye of an animal or bird. With the * button you can get focus very close, then touch up with the focus ring. You don't have to worry about keeping the shutter button partially pressed after manually focusing. This only applies if you use good Canon or Sigma lenses that have full time manual focus override. It wouldn't be worthwhile using a lens that does not allow manual focus when set to AF.

I also keep the AF set on the AI-Servo mode. If the animal starts moving I can keep the * button depressed and focus will track it.

On the other hand, for many other types of photography I return autofocus to the shutter button. Who wants to fool with the * button when trying to photograph a fast moving skier while wearing gloves?

The CF 4-1 or CF 4-3 setting is a tool that should be used when it assists you. If it doesn't help, switch CF 4 back to 0. It only takes a few seconds to make the switch and you usually only have to do that once on any given shoot.

Nobody ever said you had to choose one or the other forever. Like any tool, use it when it is appropriate for the job at hand.

I do not know if I am missing something here, but isn't the focus/exposure already separated (if required) with CF4 set at 0. You can use the * button to set the exposure and then use the shutter button as normal for focussing. I tried this on my 10D and as long as you keep the * button depressed the camera only refocuses and does not reset the exposure.

Mark.

This has been one of the most informative threads in a long time. I intend to give the CF4-1 and 3 settings a try and see how it goes. It seems to me that it won't be much different than using my old Canon T90 manual focus except that I press a button instead of turning a ring AND I don't have to rely on my eyesight.

I was first aware of this feature when I viewed Jack Reznicki's video highlighting the MarkII's features shortly after it came out. Looking back at that video, I see that the CF4 options are the very first feature that he discusses. He says that most pros, having been accustomed to years of manual focusing, switch to the button focus.

http://www.photoworksh​op.com/canon/markII/ma​inpage.html#

Jim

Correct - that's what most people do to separately control focusing and exposure. Indeed, that's why there is the * button, the focus exposure lock button.

The issue in this thread is not how to control exposure lock but rather how to control focus behavior (acquiring focus, tracking, and locking). If you experiment with your camera, you'll see that you get additional flexibility via CF4-1,3 which quite frankly is hard to define precisely. Among other things, CF4-1,3 gives you the ability to rapidly switch between One Shot and AI Servo focus modes using the * button. The alternative is to change focus modes by pressing the drive mode selection button and then rotating the main dial - clearly not easy under dynamic shooting conditions. CF4-1,3 creates additional flexibility in managing focusing behavior. As noted in earlier posts, it has its advantages under certain shooting conditions.