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Continuous Focus and Locked Exposure


Starkman

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Hey all.

 

Still getting familiar with my X-T10. The issue now is when I try to use continuous Focus mode (pressing and holding the shutter button half way), I can't do so without locking in the exposure, which isn't something I want; the exposure, obviously can change as the subject moves.

 

Not sure if this can be gotten around.

 

Thanks.

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Depending on what where you are shooting, I can't imagine exposure changes that much.

 

However I've just tested.

 

With the focus switch set to AFC, half button pressed, changing Aperture/Shutter speed adjusts the exposure accordingly (I didn't expect it not to, but i've never tried before)

Edited by Tikcus
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That's a reason back-button focus is so popular. Use the back button to operate autofocus, and the shutter half-press for AE-lock.

 

I have to say, though, that (in my opinion) using AF-C on an X-T10 is a bit masochistic. The X-T10 just isn't built for subjects that move -- the AF-C, burst buffer, and video capabilities are noticeably weak. The X-T20 made huge strides in those areas. The X-T20 also has an option called Shutter AE that allows you to disengage AE-lock from shutter half-press.

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Thanks guys.

 

Well, as to the use of AF-C with the X-T10 being masochistic, hek, I've only sliced both wrists twice and attempted to hang myself once. Not bad, considering!

 

As expected, using just the shutter button locks in the exposure (on AF-C); hence, as you said, Doug, back-button focusing is better here. My problem was that even using back-button focus I couldn't get the AF-C to work but only once in a while. And then I figured out why.

 

I wasn't just trying to track things, I was also trying to move the camera from it's initial focused area to another area to see how the focusing would react. The camera wouldn't respond most of the time, which, okay, I get it: "Hey, give me something to track or shoot in single focus, idiot!" Got it.

 

But even when I try tracking, it's a bit of a task (part of that masochistic stuff you mentioned, Doug). It works, but it is definitely limited: single-point focus, for instance, seems much more comfortable either tracking object that are coming somewhat more so in or away from my direction, or objects moving fairly slowly.

 

Understanding this now, I can see what I'm in for, and that's fine. I'll deal with it: I'll buy an X-T20 and then carry the X-T10 along just so it gets more and more jealous as time goes on. Let's get sadistic!

 

Hey, thanks again, all. I appreciate the input. This camera is a bit of a change from my Nikon D3200, but it's a cool little camera.

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You might be interested in this treatise I wrote over at DPReview:

Phase Detect AF in the X-T10 - experimental results

Read the comments on that thread, too.

 

Fujifilm doesn't make it easy. Rico Pfirstinger recommends using Wide/Tracking mode, because that lets you set a starting point so the camera knows what you want to track, and the camera tracks across almost the entire screen. However, Wide/Tracking is contrast-detect only. Unless, that is, you're using CH with AF-C, in which case it switches to using only the PDAF area of the sensor, and using only PDAF unless your aperture is set to f/9 or higher, in which case it sticks with contrast-detect.

 

Zone mode seems to be what Fujifilm expects you to use for 3D tracking. Alas, in Zone mode there's no way to tell the camera what it is that you want to track. When you half-press to start tracking, the camera will just pick something inside the zone and track that. So a small zone gives you better control over what gets tracked, but limits the area of the screen that it'll get tracked across.

 

Bear in mind that DSLRs use dedicated AF sensors which provide a constant stream of data, often to a dedicated AF chip. Mirrorless cameras, including Fujifilm, use the main sensor which, on a good day, might provide new data 20 times a second or so. And that data is provided to the same processor that's handling all of the other functionality. You can see, hear, and feel each focus update when using AF-C on the Fuji. (I wonder if the Sony A9, with its much faster sensor readout, is better in that regard.)

 

Added: Regarding, "I wasn't just trying to track things, I was also trying to move the camera from it's initial focused area to another area to see how the focusing would react," I've heard it said that Fuji's 3D tracking does expect the background to be relatively still. I have no idea if that's just legend or if there's something to it. I pass it along simply as rumor.

Edited by Doug Pardee
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Oddly enough, Doug, most of the reviews I've read on the X-T10 weren't to thrilled about wide tracking; that and the subpar video. But I guess you do what you have to do.

 

As to zone for tracking, yeah, I saw that problem right away. I stay away from zone for the most part anyway, unless everything I want in focus in the zone is at the same focal distance from the camera. Otherwise it's a crap shot.

 

And good article, too. I don't know that I'll be able to remember the wide-tracking use of CDAF / PDAF since I will seldom use wide tracking. I am, however, going to give wide tracking a try. It definitely sounds useful in that you can choose the focus point. That's a plus, for sure.

 

Take care.

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Wide/Tracking in Wide mode (AF-S) is pretty reasonable for scenes like landscapes where pretty much any point could be used for focusing. Also, because Fuji's contrast-detect AF prefers closer subjects, if you take a picture of, say, a person in front of a backdrop, it'll tend to focus on the person, which is usually what you want. Still, it's necessarily sloppy about exactly what it's going to focus on, so you wouldn't want to use it with a narrow depth of field. And, since it's contrast-detect AF, it can take a second or two to focus.

 

Wide/Tracking in Tracking mode (AF-C) is a somewhat different critter, because you specify which AF point to (initially) focus on, so there's little of the uncertainty that Wide mode has. The thing is, because it's contrast-detect (except in CH continuous drive mode), the lens is continually pumping in and out as the camera checks for changes in subject distance. That's ugly and annoying. Worse, because the camera can't release the shutter mid-pump, it can upset the timing of the capture.

 

Tracking mode (AF-C) with CH drive mode limits the tracking area to the PDAF sensors, which on the X-T10 is a much smaller part of the scene. If your aperture is f/8 or wider, it uses PDAF exclusively, which is a whole lot nicer, although the limited tracking zone is a nuisance. But if you stop down to f/9 or beyond, you'll be back to contrast-detect AF and still have the limited tracking zone.

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Been out practicing wide tracking at the park. In that I missed what you said about wide-tracking AF-C --that it allows you to "initially" set the focus point -- I was back in masochistic mode until I reread the post.

 

Yeah, Doug, I can certainly see how getting a feel for wide tracking will have it's benefits. I'll be practicing that a bit more as I go along.

 

Too, the info you've given me here, and in your DPReview article has really helped (that is, when I've paid attention!). Thanks for taking the time to post here as intricately as you have. As I remember it, there wasn't near the learning curve with my D3200 as there has been with this mirrorless, but it's well worth it.

 

For Post, I used to use Lightroom, but I'm not spending $120 a year for it, so I bought PSE 15...another learning curve! But this x-T10 is definitely fun and great for street photography, which is my passion.

 

We'll, thanks again.

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