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Question about AF-ON button Anonymous
I've never used anything better than a 400D and I'm confused as to what the AF-ON button does after reading the following on DPR.

>> A welcome addition and a carry-over from the EOS-1D cameras is the dedicated AF-ON button on the rear of the camera to the left of the AE lock button (just 'under your thumb'). This button becomes particularly useful in a continuous focus situation where you want focus to follow the subject while being able to trigger the shutter release independently.

>> The AF-ON button allows you to trigger auto focus independently of the shutter release 'half-press'.

With the 400D, if you're in continuous focus, you're half pressing the shutter button and the camera will track whatever you're pointing it at and you can fully press the shutter to take pictures.

Why would you want to have the focus and shutter release in 2 different buttons?

Is it because you can keep the AF locked to your subject and trigger the shutter with the other button and once the picture is taken, you're still focused on the subject?

I never really tried it on my 400D but I guess you lose the focus tracking after you have clicked the shutter?
>> ac !!VPzQAxYPAMA
You know, I actually don't know.

I have mine set up to trigger AF in live view, and that's all I use it for.
>> Anonymous
I use it when I know the camera and subject won't be moving. Instead of turning off AF on the lens I simply don't press the AF button on the camera when I know I have the focus I want. It's also great for focus-and-recompose shooting. I can aim the center point at what I want in focus, press the AF button then recompose and shoot away without the camera trying to re-focus. It's more of a shooting style preference thing and some people just don't need it for their style.
>> heavyweather !4AIf7oXcbA
AF-on's cool. It took some getting used to, but I like having AF separate from the shutter release. I like it better than focus-recompose while half-depressed. Shit's too complicated.
>> Anonymous
I use mine for AF+exposure lock. Though I really should switch it to AF-lock and exposure lock should be on shutter half press.
>> Butterfly !xlgRMYva6s
>Is it because you can keep the AF locked to your subject and trigger the shutter with the other button and once the picture is taken, you're still focused on the subject?

This would be awesome, but iirc the AF mech requires the mirror to be down, so wouldnt be able to track during exposure. Would be neat for sport bodies though.
>> Anonymous
Hm, could see a good use for that (if I'm reading the use right) for focus-recompose on a tripod. Right now I'm stuck focusing and flipping off the AF switch on the lens to get it right.
>> Anonymous
>>245121
You DEFINITELY need to get focus set to that. I set it to focus that way on both my 40D and my XT (well, * for the rebel) about a month ago, and it's very easy to pick up.
It allows east focus/recompose and metering somewhere other than the focus point. I love it.
Set it to the back right away!!
>> Sicko !L3HRY/miC.
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>>245121

Snap, although on my Pentax body it's in a pretty handy position.
>> Anonymous
Why do you want AF and shutter to be in 2 different buttons?

I don't see the point, someone explain.
>> Anonymous
>>245289
Read the thread, asshole.
>> Anonymous
>>245289
if you have auto focus as the same button as shutter speed you have to go through some sort of menu. would you rather flip a switch or sort through a menu?

trolled
>> Anonymous
>>245290

So what, it's only to trigger the shutter without making the camera refocus?
>> Anonymous
>>245121

NEVER USE FOCUS-RECOMPOSE TECHNIQUES.

BAD HABIT

BAD BAD BAD BAD BAD BAD BAD BAD BAD BAD
>> Einta !!MWv3ICYobCM
>>245350
It is often the only reasonable technique. It's fast, and good enough when not using particularly fast apertures.

Would you simply have everybody either
1) focus manually, or
2) change their focusing point (quickly enough?)?
>> Anonymous
>>245350
Do you have any actual reason, or do you just lack the neurophysical coordination to think, focus, recompose, and shoot in a reasonably quick manner?
>> Anonymous
>>245350
is correct.....however, if your shooting at say 18mm f8 its going to make 1/64th of fuck all difference

If your shooting f1.4 at 85mm its the difference between tack sharp and slightly soft.

forgive my laymans terms bullshit, but the lens expects that the corners of the frame are further away than the center ( eg if your taking a picture of a wall, and you are square on )

use trig, etc
>> Anonymous
Focus and recompose can lead to ruined shots where the point of focus or the focal plane is shifted. You should really use the other autofocus points when you can. There are some situations where it does not matter, but all too often it does and people use this bad habit for portraits with shallow DOF and end up with many misses and ruined shots.
>> Anonymous
i focus and recompose at f/32 at 12mm

take that bitches
>> ac !!VPzQAxYPAMA
>>245368
One of the main reasons I decided to upgrade to the 40D. The little joystick lets me choose my focus point directly so I don't have to do that.

But it's not a bad technique if used at reasonable apertures, and I certainly wouldn't call it a bad habit.
>> Anonymous
>>245365
>>245368
Two people who understand neither trig nor basic spatial orientation as it applies to focus and recompose.
>> eku !8cibvLQ11s
>>245470

I bought battery grip, and now I had to change to the default way of choosing focus point. It's not that bad actually, because there's like two or three points I mainly use, and they all are next to each other. :(

But battery grip is sweet for 30D. I went almost two months without charging my batteries. Well, I didn't take much photos either, but still.

But I would so love to have separate focus button. Just like 1D have.
>> Anonymous
>>245483

one person who does not understand basic photography
>> Anonymous
>>245491I bought battery grip, and now I had to change to the default way of choosing focus point.

why
>> Anonymous
I liked the addition of the AF-ON button. I've used * for focusing for ages now. It just feels more natural. Hate to lose the ae-l though.

The 40D actually has a minor flaw. The BG-E2N grip doesnt have a AF-ON button, so you actually have to use a custom function to transfer AF-ON and * buttons between eachother. It works just fine like this while shooting, but when reviewing images the buttons have changed too.

Takes a while to get used to press AF-ON button to zoom out :)

40D has other minor flaws like this too.
>> Anonymous
what does the wireless grip do

automatically transfer your files by wi-fi to your computer or server?
>> Anonymous
>>245607

Yep
>> Anonymous
>>245631

pretty useless lol ¯\(°_o)/¯
>> Anonymous
>>245494
grip does not have AF-ON button.

Anyway, AF-ON button is very relevant when you have a lens with AF-STOP