Focus by wire - WHY???

TassieFig · Dec 4, 2014

I hate it

I know roughly what it is but I don't know if it is necessary. Is it necessary for AF? Are there any technical or economic reasons why there aren't any (?) AF lenses with direct focus?

If there are compelling reasons to keep focus by wire, is it possible to make it more like direct focus?
For example, I know there some lenses with hard stops. Why don't we see this in ALL lenses?
Also, I hate it when you trying to focus and you gone just past and then you have to make large adjustments to go back again. Can this be improved or is it part of the deal?

Is it just a lack of demand and manufactors just keep churning out them because they think we all love it?

Rudy · Dec 4, 2014

There are both economic and technical reasons for this.
Autofocus requires motors to move some lens elements around.
On some lenses it can mean moving different elements at different rates.
Being able to also do this mechanically would require a clutch or several and a precise mechanical helicoid or gearing system.
This would also add weight as the mechanically actuated parts would require much more strength to take the abuse of someone turning them by hand.
It would also likely make the moving parts heavier slowing down autofocus performance.
I think the best bet would be to improve focus by wire by increasing the ring sensor resolution and improving the software in to translate the rotation into focus motor movements.
This is probably not high on the lens / camera maker's list, since few people use manual focus.
Rudy
p.s. manual focus works like a charm on legacy manual lenses

usayit · Dec 4, 2014

Design wise a proper lens designed for direct focus contradicts what makes a good AF lens.

Think about it....

A very important aspect of a manual focus lens is that the focus ring is damped properly with the proper amount of resistance. This same damping works against an AF motor which has to work harder (more wear) or a larger motor that can provide more torque. There are some ways to compromise.... In the case of the Olympus 12mm f/2, the designed a clutch system that disengages the damping mechanism when the lens is in AF mode. Unfortunately, the 12 f/2 is expensive in part because of that mechanism. Or like some EF canon lenses, they design in a lighter amount of damping into the focus action with a proper sized AF motor.

There are other aspects as well. Fast AF likes smaller lighter weight moving parts. I've also noticed that they also prefer short focus throws while many manual lenses are designed for long focus throws. Notice how many manual focus lenses are built around magnesium, aluminum, or brass construction while many of the AF lenses comprise of composites and plastics.

In the end, anything is possible but I don't think this feature will be highly demanded by a system that goes to primarily shooters interested in AF capabilities..... and not especially interested in the associated cost. Besides... you like manual focus? there are many options out there already.

usayit · Dec 4, 2014

Oh one thing I would love to have....

A hyperfocal at a single push. The camera knows the attached lens focal length.. it should be able to calculate hyperfocal and position the lens groups accordingly. Missing range markings on the lenses AND focus by wire make it near impossible to find hyperfocal any other way.

OzRay · Dec 4, 2014

One of the benefits of focus by wire is that you can vary the 'speed' of focus. Turn the ring fast and the focus will move greater distance quickly, turn it slowly and the movement is less and more precise. This can be very handy with long focal length lenses when you want to focus from a close object to a distance object, or vice versa.

Also, don't forget the other advantages such as being able to focus remotely with tethered shooting and the like.

The 4/3 14-35mm lens has a manual focus design incorporated with the AF motor, so that you can choose how to focus, but it doesn't enable you the feature I mentioned in my first para.

TassieFig · Dec 4, 2014

Ok, but how much heavier? 10g? 100g? 500g? Similar arguments have been made about IBIS vs Iens IS. But how much difference does it really make? I'd say not that much.

On low end lenses, ok maybe not much demand but I hear a lot of talk about manual focusing. Maybe they are just the minority nerds? If manual focusing was to be taken away on lenses in the future, I'm sure there would be lots of protesting, no?

And I don't even use it that much but that is partly because of these issues
Am I the only one who want a better manual focus experience? Surely not.

yes, of course manual lenses have great manual focus. But I want both AF and MF!

Edit: wow, didn't see all those new replies. Thanks everyone for clarifying this. I accept there are some (ok, maybe many) advantages with focus by wire. I still hope they can improve the experience with some big leaps.

usayit · Dec 4, 2014

TassieFig said:
Ok, but how much heavier? 10g? 100g? 500g? Similar arguments have been made about IBIS vs Iens IS. But how much difference does it really make? I'd say not that much.

Compare a proper manual focus lens (Voigtlander) to similar sized native AF lenses. Native lenses are not going to see 100g or 500g difference.... most of our lenses don't even weight that much in the entirety.

On low end lenses, ok maybe not much demand but I hear a lot of talk about manual focusing. Maybe they are just the minority nerds? If manual focusing was to be taken away on lenses in the future, I'm sure there would be lots of protesting, no?

And I don't even use it that much but that is partly because of these issues
Am I the only one who want a better manual focus experience? Surely not.

yes, of course manual lenses have great manual focus. But I want both AF and MF!

Yes.. you and most here are the minority. Rarely do the forums represent the larger segment of the consumer base.... Its almost impossible for any modern manufacturer of cameras targeted for the vast consumer base to use manual focus as a key selling point/feature.

OzRay · Dec 4, 2014

You do have manual focus available, it's just not a mechanical process. I would also suggest that people in general prefer autofocus and wish camera manufacturers to keep improving this and offering better capability all the time. I can see the day when the EVF can read what you're eye is looking at and instantly focus on that and stay focussed exactly on that spot, or wherever your eye moves. That technology is already partly available for some applications.

usayit · Dec 4, 2014

OzRay said:
I can see the day when the EVF can read what you're eye is looking at and instantly focus on that and stay focussed exactly on that spot, or wherever your eye moves. That technology is already partly available for some applications.

Had that feature in my Canon Elan more than a decade ago.... I like it.. thought it was neat and fast. Of course I only had 3 AF points... lol The biggest complaint which eventual lead to its demise was 1) a large number reported the mechanism wasn't reliable (was for me) 2) if you wore glasses it could detect your eyes (I shoot without glasses).

Thinking back...

For the life of me, why do cameras these days don't use multi-point spot metering? My Canon 1v had it.....

TassieFig · Dec 4, 2014

Gee, I can't keep up here lol

I hear you. I'm already convinced that it's a good thing now. And I will always use AF most of the time BUT I just hope there will be improvements in manual focus too. Hard stops (yes I mean ring stops at far and near focus). More precise so you don't have to adjust back and forth so much. Simple :wink:

Oh, and that hyperfocal button sounds great to me.

OzRay · Dec 4, 2014

usayit said:
Had that feature in my Canon Elan more than a decade ago.... I like it.. thought it was neat and fast. Of course I only had 3 AF points... lol The biggest complaint which eventual lead to its demise was 1) a large number reported the mechanism wasn't reliable (was for me) 2) if you wore glasses it could detect your eyes (I shoot without glasses).

Thinking back...

For the life of me, why do cameras these days don't use multi-point spot metering? My Canon 1v had it.....

Perhaps we might start seeing development in these sorts of areas, now that the technology is becoming more sophisticated. We're already hearing of sensors where pixels can selectively switch off once the ideal exposure has been reached, while other pixels remain on. Olympus is rumoured to be developing a multi-exposure sensor that will increase the effective pixel count dramatically: http://www.43rumors.com/ft5-e-m5-successor-has-sensor-shift-to-create-up-to-40-megapixel-images-on-the-fly/. Anything seems possible.

usayit · Dec 4, 2014

TassieFig said:
Yes, but is it so much more expensive compared to other lenses of similar standard (eg 75mm)? Is that the reason for it's price? Maybe they can make it cheaper in the future as with all technology.

Does it "work" as expected? Do people like this feature?

I might have to try it out in the shop just to see how it feels...

What about the oly 17mm. It has hard stops doesn't it? That can't be too hard to do?

Only two lenses have the snapshot focus mechanisms; 17mm f/1.8 and 12mm f/2 olympus. Both of which are priced slightly premium. Nothing is for free...

And no... its not a popular feature. People are not clamoring over those lenses because of the focus mechanism but because they are good optics.

If by hard stop meaning the ring stops at far and near focus... yes.

If by hard stops you are referring to the indented focus action at certain increments.. no. Historically wide lenses intended for zone focusing had those... one modern example is the Voigtlander 12mm Heliar.

I shoot with the 12mm f/2. My primary system is completely manual. On MFT with the 12mm f/2, I rarely use it with direct manual focus.

HarryS · Dec 4, 2014

My Olynpus 17mm f1.8 goes into manual focus mode pretty well. It has less than 100 degrees between near focus and infinity. There are a few others in the lineup that are comparable. So they can do it and get you a faster action, but it's still focus by wire. Probably not cheap to do either. The 17mm isn't cheap.

I'm thinking the motors in some of these lenses don't even look like conventional motors which to me is a can with a gear, Here's what the SWD motor looks like in some of the Olypus 4/3 lenses.

RnR · Dec 4, 2014

Manual focusing? Pffft... it will never catch on... :tongue:

humzai · Dec 4, 2014

Yeah harrys is correct. The 12mm, 17 mm and the 12-40mm and 40-150mm pro have the mf clutch. They are as he stated still focus by wire.

The 12mm lens apparently vs isn't very granular and therefore not that great. The 17mm, and the two pro lenses are improved over the 12mm and work very well. You have hard stops and a nice smooth focus range. I believe all of olympus' premium lenses going forward will have the mf clutch. Its very useful, it even works well for birds in flight.

I haven't extensively tested it yet, Bu so far its very effective and it might make up for the caf performance.

OzRay · Dec 4, 2014

I've said many times, and even written to Olympus, that one feature that would make the focus mechanism infinitely better is if the focus limits (near and far focus settings) could be user specified in-camera. Many of the longer focal length lenses have pre-set limits, but these invariably are not suitable for many applications. It would make focussing faster, consistent and more accurate in many applications, so I can't see why such feature couldn't be implemented.

bassman · Dec 4, 2014

In software, it would be pretty easy to implement:

- set to closest focus point at current zoom setting
- set to infinity
- set to hyper-focal distance at the current Fstop
- after focusing on two points successively, set the fstop and focal point to include both within DoF

All the information needed is already known to the camera, except perhaps for a DoF table.

Focus by wire - WHY???

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