Rant about Pentax's One Legged AF and a weird quirk that I wish would go away

*Wheatfield* · 08-22-2009, 10:26 PM

So I went out and shot a wedding today.
As a bit of history, my wedding photography career mostly ended prior to my buying a DSLR, and I only once used an AF film camera at a wedding.
I've shot perhaps 4 weddings since I went digital.
Most of my photography is done in good light these days.
I use an old school Metz 60 flash. It isn't fancy, but it has balls and I'm quite fond of it.
My intention was to use the K-7 as my main camera and the K20 primarily as a back up.
Unfortunately, the plate that holds it to the camera is a bit too big to allow comfortable access to the vertical release when mounted to allow the vertical release button to be up, and I find the camera to be virtually unusable with the button down.
No worries, I decided to use the K20 as the main camera and the K-7 as the available light camera. This is better anyway, since the K-7 behaves better than the K20 in this sort of situation.
The situation being a pretty brightly lit hall, but lit with 8' yucky green coloured tubes.
The auto white balance did quite well.
Everything was going swimmingly until the processional. I got the shots of the bridesmaids without much difficulty, though there was slight AF locking, but when it was time for the bride's dad to the hand off to the groom the camera decided that it didn't want to take a picture. The damned AF indicator was lit, but the camera refused to fire.
I missed the hand off, one of the "important" pictures.
The lens in use was the 31/1.8.
So, I decided at the reception and dinner to suck it up and put the k20 away and use the K-7, even though it isn't as comfortable with the Metz.

I missed the toast to the bride because the K-7 did exactly the same thing to me.
This was with the DA* 55/1.4.

Annoying as hell.

And as an aside, why, when the shutter speed is set to x, is the green button enabled?

rawr · 08-22-2009, 10:58 PM

I've had the same thing happen with my K200D. But not at any such critical junctures as the ones you describe. Annoying as all hell.

Using AF-C mode though will mean the camera will let you release the shutter even if the subject is not in focus, unlike AF-S mode, which might help.

Manual focus ftw.

PDL · 08-23-2009, 12:05 AM

So each time you pushed the shutter button the camera tries to focus? On the "hand off" just why not focus on the groom and blast away -- after de-coupling AF from the shutter button.

With de-coupling -- you decide when the camera will focus - not the other way around. With Pentax lenses you can use manual focus function and just blast away.

AF-C will not allow the camera to shoot without shutter button (or AF button) confirmation. However, once I let got of the AF button (OK button on the *istDs) and I push the shutter - the camera captures an image. I decide when the camera shoots - not the AF function.

Do those people really move that much that the system would have to refocus the entire image? What if the camera wants to focus on the bald guy in the second row? Who controls what you are doing - the camera's computer or your brain?

The Elitist - formerly known as PDL

Rico · 08-23-2009, 12:05 AM

Wheatfield how do you have the AF set up i.e. a half press of the shutter button plus the AF button or just one or the other. I don't use autofocus that often. I recently changed the autofocus to just the AF button.

My K20D seems to function better this way.

octavmandru · 08-23-2009, 12:07 AM

I understand the pain. It's a shame such happens.
The problem with AF-C is that it will fire even when not in focus. And this is a wedding.

kittykat46 · 08-23-2009, 01:08 AM

Originally Posted by Wheatfield

.......... but when it was time for the bride's dad to the hand off to the groom the camera decided that it didn't want to take a picture. The damned AF indicator was lit, but the camera refused to fire.
.......

I think there is something else other than AF at work here, if the Red AF indicator had come on.
The K-7 has no shutter lag worth talking about, once the AF has locked in.
Imaging Resources put the K-7's in-focus shutter lag (from half-press shutter to action) at 0.074 seconds.

I assume you had flash "On". Did you have Red-Eye reduction turned ON ? The shutter will not be released until the Red-Eye function has completed its double-pre-flash cycle.
The P-TTL pre-flash itself introduces a slight delay, but hardly noticeable. If Zero-Pre-Flash delay is very important, I just shoot in Auto Flash mode.

Eruditass · 08-23-2009, 01:18 AM

When in AF-S mode and it doesn't fire even with the indicator blinking or even lit solid, I just switch the body over to MF mode with my left hand and fire, hoping it is close enough. Or I do slight adjustments.

Digitalis · 08-23-2009, 01:31 AM

I feel your pain, during my brothers wedding I had the same lens the 31mm f/1.8 limited, and I had to deal with the same problems. but I would quickly switch to MF when the green AF lock indicator lit up in the viewfinder and trip the shutter manually the focus was usually spot on. I later switched to the 50mm f/1.2 It's manual focus only lens, but you can fire away at 3FPS with bounced flash..that helps you bracket the focus. but the K10D can be a tightly wound pain in the arse when it comes to AF. I later switched to my 1Ds MKIII with a 35mm f/1.4 unsurprisingly, my keeper rate was significantly higher.

Russell-Evans · 08-23-2009, 02:27 AM

Originally Posted by Eruditass

When in AF-S mode and it doesn't fire even with the indicator blinking or even lit solid, I just switch the body over to MF mode with my left hand and fire, hoping it is close enough. Or I do slight adjustments.

AF button set to disable AF, and hitting it, would accomplish the same. I find the AF button is much easy to work than the focus selector switch.

Thank you
Russell

Russell-Evans · 08-23-2009, 02:29 AM

Originally Posted by kittykat46

I assume you had flash "On". Did you have Red-Eye reduction turned ON ? The shutter will not be released until the Red-Eye function has completed its double-pre-flash cycle.
The P-TTL pre-flash itself introduces a slight delay, but hardly noticeable. If Zero-Pre-Flash delay is very important, I just shoot in Auto Flash mode.

I believe the Metz he is shooting with, is not a P-TTL flash.

Thank you
Russell

StigVidar · 08-23-2009, 02:35 AM

On K-7, custom function 14 set to off is the most important setting in my opinion. It let you focus when you want with the AF button and it let you take pictures at exactly the right moment.

So you prefocus a few seconds before taking pictures and are ready for that special moment.

impact · 08-23-2009, 03:03 AM

Still, if the camera indicated good focus (green hexagon lit up), it should let you take a picture. Unless of course it was waiting for the flash to recharge or something.

Big G · 08-23-2009, 06:57 AM

I've only done one wedding for a practice, I shot the entire thing usual manual focus.

*Ash* · 08-23-2009, 07:10 AM

Sorry for that experience Wheatfield.
I just don't get why the cams didn't fire seeing as though AF locked on.
Flash wasn't P-TTL and so won't stop camera from firing if not ready to discharge.
Care to shed some light on the possiblities there?

*Clem Nichols* · 08-23-2009, 07:12 AM

With the K10D at least, with "AF with shutter button half-pressed" turned off in the custom setup menu the shutter will open in AF-S whether in focus or not. My only wish is that depressing the AF button would wake the camera out of sleep mode instead of having to press the shutter button to do so.

CN