back button focus purpose

[Olyjohn]

If you are using any of the lenses with the lens function switch and MF clutch, you can get the same or similar) effect by just using SAF on the desired point, and then press the lens function switch to either stop AF, or change to MF. For me,this has the benefit of keeping the focus point in the viewfinder, whereas if you have to switch to MF initially that is lost. Or have I missed something?

Regards, John

 

[Anders W]

If you are using any of the lenses with the lens function switch and MF clutch, you can get the same or similar) effect by just using SAF on the desired point, and then press the lens function switch to either stop AF, or change to MF. For me,this has the benefit of keeping the focus point in the viewfinder, whereas if you have to switch to MF initially that is lost. Or have I missed something?

Regards, John

With my E-M1.2, I can retain the focus frame in the viewfinder in MF mode by setting AEL/AFL to do AF in that mode and setting AF Area Pointer to On2. The focus frame remains visible as long as I keep AEL/AFL pressed even after the AF cycle has finished.

Another alternative is to switch to Zoom Frame AF. In that case, the frame remains visible all the time even in MF mode and it works even on bodies that don't have the special On2 setting for AF Area Pointer

 

[vigna]

To make it more fun, for birders you can assign custom buttons to help the camera to focus either near or far this is to snap BIF from busy background and a bird hidden behind bushes

 

[Steve Rushing]

[No message]

 

[Olyjohn]

Thanks for that info, my em1's mk1 don't appear to have those options.I would like the improved autofocus on the mk2, but at the age of 88 I don't think it is worth upgrading, especially as they are both immaculate. I'm not as fit and active as I used to be, so most of my photography now is more everyday stuff. I still want it to be as good as possible though, and i would love the 40-150 f4 if it ever appears. Still, it's a hobby that helps to keep the brain working.

 

[bs1946]

All of the Fuji, Olympus, and Panasonic mirrorless cameras I have owned have Back-Button-Focus. Some have separate AF and AE buttons but most have a single combined AE/AF button. Then in the menu you select the parameters; AE only, AF only, or both. You can also select if the focus is locked while you hold the button or if the button acts as a toggle switch; press to lock and press again to release. Back Button Focus is very handy if you are going to take multiple photos without changing the focus point, especially on a tripod, which is where I use it most.

 

[Anders W]

Thanks for that info, my em1's mk1 don't appear to have those options.I would like the improved autofocus on the mk2, but at the age of 88 I don't think it is worth upgrading, especially as they are both immaculate. I'm not as fit and active as I used to be, so most of my photography now is more everyday stuff. I still want it to be as good as possible though, and i would love the 40-150 f4 if it ever appears. Still, it's a hobby that helps to keep the brain working.

The E-M1.1 remains a fine camera. I didn't replace mine with the mark II until this spring.

I don't think you have the On2 setting for AF Area Pointer on your EM-1.1. But you certainly have "Zoom Frame AF", where you can always see the AF frame even in MF mode. I find "Zoom Frame AF" very useful in general so on all the Oly bodies I have owned (previously E-M5.1 and E-M1.1, now PEN-F and E-M1.2) I have one button assigned as "Multi-Function Button" and "Zoom Frame AF" then chosen as the function I actually use with that button. A short press on the button takes you into zoom-frame mode and a long press takes you back. When in zoom-frame mode, a short press on the button moves you into magnified view and another short press moves you back to normal view.

The magnified view is useful when you want to make sure that AF actually nails focus where you want it nailed. Of course, it's also useful for MF. And AF in zoom-frame mode with the smallest frame is about the same as using the smallest frame outside zoom-frame mode, so there's no real disadvantage being in zoom-frame mode most of the time if, like me, you usually use the smallest AF frame.

Check this out if you haven't already.

 

[Olyjohn]

Thanks again for that info. I have saved the instruction part as a Word document to refer to and try later.

John

 

[Chris Noble]

What are the advantages of using back button focus?

Hard to hold focus for a long time with a half-press of the shutter.

 

[magnesus3]

Since backbutton focus doesn't force a refocus before taking a picture, you can choose whether to refocus or not for each picture. With the normal half-press on a shutter button method, there is no choice. Choice is always better. Once accustomed to BBF, there is no loss of speed even with subjects like birds in flight.

I use backbutton for birds in foliage and in failing light where I can predict the bird will be. Traditional AF may hunt at the wrong time, leading to a missed picture.

It's also very important for legacy lenses that are slow to focus. I use the 50-200 legacy in MF but use the button to prefocus. That way I can take a series of pictures without waiting for the autofocus to refocus again. (I do that on Pen F which has no PDAF, the 50-200 is very slow to AF on it.)

 

[ttbirds]

With my Oly EM5 Mk 3 and Pan G9, I have set it up so I just need to tap the BBF assigned button to refocus. When I release the button, the focal distance remains the same until I tap again to refocus.

Another benefit is you can have AFS of AFC enabled. If AFC, then it functions as AFS due to the tap/release which keeps focal distance constant. If AFC is actually needed then tap and hold and regular AFC occurs.

 

[Bobapingu]

In short, not good for moving subjects. For still subjects, back button focus on what must be in focus (eyes), spot meter by half press on what needs to be correctly exposed (skin), recompose and shoot.

 

[prairiedog]

Versatility.

Can be in MF but can still hit back button for focus.

Can be in AFC and touch back button for single focus or hold back button for continuous focus.

Can focus when I want and fire shutter when I want. So in situations where you don't want to miss a shot because it tries to focus again before you press the shutter and gets it wrong.

Least useful for landscapes etc but then again it doesn't get in the way.

Most useful for wildlife or moving subjects. e.g. an animal that jumps about with pauses in between.

But it's personal choice. I switched to it not because it was a fad (it's been a fad on and off for two decades) but because I was missing some wildlife shots and found BBF helped me.

 

[TorsteinH]

What are the advantages of using back button focus?

One advantage, focus and recompose without need to move focuspoint. Often faster and more efficient.

 

[DwrCymru]

However, with my EM5II, the button is just a bit further away, so I don't have BBF set up.

I found the location of the fN1 very awkward using my E-M5 II so I re-assigned the BBF to the Preview button on the front of the camera which happens to fall under my ring finger when my index finger is perched on the shutter button. It took me a while to get used to it but it has now become second nature. I now have FBF