L-Fn Button (Focus Stop)

[Gwyver]

Each of the m43 Pro lenses has a control button labelled "L-Fn" whose default function is to 'Stop Autofocus' whilst the button is pressed.

Apologies in advance if the following questions seem stupid, but...

1. Does anyone use this button for (temporarily) stopping AF?
2. If so, under what practical circumstances do you find it useful?
3. Do you use it as an alternative to the AFL/AEL button?

Any advice on exploiting the L-Fn feature would be appreciated (the Oly camera and lens user manuals are - as usual - very laconic on this subject).

I would find it more useful if the L-Fn button could provide a AF limiter function for the existing Pro lenses - particularly the 40-150.
It should be possible to do the following:-

• Press once to limit focus to close distance (e.g. 0 - 4m)
• Press again to limit focus to far distance (e.g. 4m - inf).
• Press again to disable focus limit (i.e resume 0 - inf range for AF).

This action, combined with a simple symbol in the EVF (or on the LCD in Live View) when focus limiting was active ought to be very useful.
Any views?

[Graham_of_Rainham]

Re: L-Fn Button (Focus Stop)

So many buttons, so many functions...

Focus stop seems a bit redundant as the focus clutch does that.

I keep trying different things, but the L-Fn tends to get forgotten about as it's only on two lenses I have.

I think I'll try switching off auto focus assist and assigning Magnify to it.

[timboo]

Re: L-Fn Button (Focus Stop)

So many buttons, so many functions...

Focus stop seems a bit redundant as the focus clutch does that.

I keep trying different things, but the L-Fn tends to get forgotten about as it's only on two lenses I have.

I think I'll try switching off auto focus assist and assigning Magnify to it.

Great minds think alike mine used to be used for magnify, agree re the collar though I cant think of any reason to even have the option of manual focus.

[PeterBirder]

Re: L-Fn Button (Focus Stop)

IIRC when the 12-50mm EZ lens (the only one I have with a L-Fn button) came as the "kit lens" with my E-M5 it was stated that it was assigned to "AF Stop" for video shooting using C-AF. The intention was to enable you to temporarily stop the auto focus when you were panning on a moving subject that was likely to disappear briefly, eg a person who was about to walk behind a closer object. This would enable you to maintain the focus distance of the wanted subject, continue panning and re-aquire it without the camera doing a re-focus search when clear of the closer object. In this mode the "AF Stop" only operates as long as you hold down the L-Fn button.

If (like me ) you don't "do" video then either ignore it or if you have need of "another button" re-assign it.

Regards.

ps. The focus limit idea sounds good, just have to persuade Olympus.

[Gwyver]

Re: L-Fn Button (Focus Stop)

IIRC when the 12-50mm EZ lens (the only one I have with a L-Fn button) came as the "kit lens" with my E-M5 it was stated that it was assigned to "AF Stop" for video shooting using C-AF. The intention was to enable you to temporarily stop the auto focus when you were panning on a moving subject that was likely to disappear briefly, eg a person who was about to walk behind a closer object. This would enable you to maintain the focus distance of the wanted subject, continue panning and re-aquire it without the camera doing a re-focus search when clear of the closer object. In this mode the "AF Stop" only operates as long as you hold down the L-Fn button.

Thanks for this. Your recollection is good - though there's nothing in the E-M5 manual and next to nothing in the 12-50mm EZ user sheet. The most "comprehensive" description I can find is on the 12-50mm EZ web page

http://www.olympus.co.uk/site/en/c/lenses/om_d_pen_lenses/m_zuiko/m_zuiko_digital_ed_12_50mm_13563ez/index.html

ps. The focus limit idea sounds good, just have to persuade Olympus.

I'll email a more detailed description of the proposal to Olympus. It would be good if they acted on it.

[maccabeej]

L-Fn Button (Focus Stop)

I have it set to dof preview. The only use I could find for it.
Tried three times to overcome spell checker on iPhone. Dog preview did sound useful for pet portraits

[Gwyver]

Re: L-Fn Button (Focus Stop)

So far nobody has owned up to using the L-Fn button for it's default function - i.e. Focus Stop.
I guess this demonstrates that very few e-Group members do video (at least not using Olympus kit). All the more reason to have a more useful function such as Focus Limit associated with this button.

[drmarkf]

Re: L-Fn Button (Focus Stop)

Yes, I've thought about it for a while, but can't come up with anything really useful. I have magnify and peaking assigned to the two right hand front buttons so don't need them there as well. I suppose DoF preview might be occasionally of use.

I like your focus limiting idea, but to be perfectly honest I find the 40-150 pro focuses so fast that I haven't missed it, I have the Panny 12-35 rather than the 12-40, and I use the 7-14 almost only for tripod-based landscape work so auto focusing is not much of an issue.