OMD-EM1 Back Button Focus

I don't have the camera in front of me, but if you go to the settings menus, then the button/dial/lever assignment menu, one of the options for the ael/afl assignment is s-af (single auto focus). Then the half press of the shutter is set to exposure and the full press is set to take the picture.


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It is in the menu where you configure the AEL button behavior. Basically, you change the AEL button to do AF instead of AEL.

Go to "Menu / Gear/ A / AEL-AFL /S-AF" and select mode 3, which means:

Shutter half press: AEL (exposure lock)
AEL button press: S-AF (AF lock)

 

If you search this forum, Ned has posted a detailed step-by-step to set this up on Olympus cameras. In addition to changing S-AF (and/or C-AF) to mode 3 you need to assign AF lock to a different button, which is done in the Gear-B menu "Button"

 

Have a look at this (page 5) if it is any help for you: http://www.clintsteed.com/photography/Setting up the EM-1.pdf

 

Page 98 in the manual- set the AEL/AFL mode to 3 or 4

 

Chekout this:

http://robknightphotography.com/back-button-focus-on-the-olympus-om-d-e-m5/

The function to assign to the button is AEL/AFL. Then for each focus mode (AF, CF, ecc.) you customize the behaviour of the shutter button full-press, half-press and the AEL/AEF function at the same time.
The mode 3 means: locks the exposure on shutter button half-press, take the shot on full-press, and invoke AF-S when the AEL/AFL function is activated.

 

Are these three individual functions discretely separated, sequential and each essential to completion of the exposure sequence? Not only does the menu set up process for this action seem more complicated than, say, with most later Nikon DSLRs (or, for that matter, the Panasonic GF1 and GX1 that I've used), the execution itself, as explained above, actually appears to add an additional activity to a Nikon's (and I suspect a Canon's) execution of back button focusing. For example, with the Nikon, having selected the "AF-on" function in the menus and assigned it to the AEL/AFL button, the photographer 1) selects a focus point in the frame, 2) presses and holds or presses and releases the AEL/AFL button (dependiing on whether the subject of focus is still or moving), and squeezes the shutter release button at that magic moment when the shot, if it's ever going to be right, it's right then, and releases the shutter. In other words, in this procedure there is no half press--the camera is simply adjustng its exposure to the lighting, the subject, etc, on the fly, so to speak, and there's a bit of a risk of altered exposure to the extent that the photographer moves the focus point for the actual execution of the shot. If the camera is matrix or centerweight focusing it will be adjusting to the extent it needs to very close to the instant of exposure and, for spot metering, the spot that is metered should be the spot of focus. Of course, it's easy enough to assign AEL to one of the function buttons before the actual exposure.

 

It may sound complicated, but once set up the E-M1 functions exactly the same as my D7000: select the focus point(s), press the AEL/AFL button and release, press the shutter button.

 

bassman,

So no half-press of the shutter button is needed; i.e., I could squeeze (smoothly, of course) on through to shutter execution without a pause for AE reading or capture by the EM-1? And, could I, like the newer Nikons, select (probably with Olympus' unique menu names) a focus/exposure process(s) like either, with a Nikon DSLR, AF-S or AF-C?

 

Yes. Although there are performance differences between the two cameras, the user operation can be essentially the same. On the E-M1 you can select S-AF or C-AF. You can select back button or shutter button focus separately for each. You can have a button to switch to MF, to magnify the image when you use MF, and/or turn on blinkies as a focusing aid. You can have the camera dynamically switch to MF whenever you grab the focus ring, but use AF when you press the button (like Nikon's AF-S lenses). You can choose the direction that the focus ring turns to get closer. It's quite flexible.

On the exposure front, remember that you're seeing a reasonable approximation of the actual exposure when you look at the EVF or LCD. So you have early warning if it's not correct.

 

Bassman,

Am I correct in assuming by "performance" differences you're discussing things like speed of AF, differences in effect at the same (high, presumably) ISO levels, etc, rather than the straightforward mechanical functions of the two camera systems as they pertain to the differences in menu labeling, or the basic photographer's physical technique in executing back button focus. For me, as an old film shooter, SLR and "real" rangefinder (Leica, Retina, Vitessa, etc), it's been 1) achieve focus, 2) squeeze shutter at the correct time to get the shot. This style broken down to its two simple elements and kept simple is easily carried out with a Nikon (at least one of the newer models) and at least the GF1 and GX1, the only M43 bodies I've used. If I can simply and completely duplicate the mechanical ergonomics of my current non-Olympus equipment on an E-M1, then I think the E-M1 may edge ahead of the GX7 for my purchase. Of course, focus peaking, etc are a real bonus.

I'm not sure what trm I'm seeking here but it seems that it might be a sort of operational ergonomics having nothing to do with the grip of the body on the hand but rather with the physical ease of operation (for me) being transparently functionally identical with my current practice.

 

Mohun, you don't have to pause at half-press of the shutter button to take an exposure reading - with live preview the camera is constantly metering the exposure (as indicated by the histogram or highlight/shadows "blinkies" display options which change as you wave the camera around). Holding the shutter half-pressed would just lock the current exposure for situations where you want to spot meter and then recompose, etc. If you have assigned AF to a back button, then your sequence would be as you described - 1) AF on the desired point, then 2a) optionally recompose and 2b) squeeze the shutter to lock exposure on the way to image capture.

You can also save an entire collection of configuration options as a "MySet" or something similar, for example I have one set with back-button focus and another set with more of a point-and-shoot setup for times when I have to hand my camera off to a family member, and a third with some settings that pertain to using manual focus lenses (quicker access to focus peaking and magnification).

 

Let's review this again for a moment. How, exactly, does your Nikon know to simply adjust its exposure? It is the same process as used by the E-M1. Under normal shooting settings, the meter is activated by a touch of the shutter, and then locked at the half-press, just like the Olympus. There are no extra steps. Information provided in previous posts just elaborated on the steps in more detail than your description of how the Nikon accomplished the same task. The ergonomics of the buttons may vary, but the processes are nearly identical.

Good luck in your decision,

--Ken

 

Based on what you describe here, it looks like you may be looking for the "AF stop" function that can be assigned to a button, and is assigned by default to the lens function key (l-fn) for the lenses that have it, namely the 12-40 and 12-50. I.e. you run C-AF and it runs continuously until you press the AF stop button at which point it fixes on the point it was at at the time.

Edit: right, I can't read - you said as long as, I understood until. I'm afraid you can't do that exactly but the AF stop gets you the same effect... just that you have to keep holding AF stop.