40mm manual focus and speed

Hi all,

I had the pleasure of trying out the 40mm pancake on my 5D2 yesterday in a shop. Usually I shoot with the 35mmL, so Im trying to figure out if the pancake would be a good stand-in for more casual photography.

Optically, from the tests, if definitely seems to. But I really missed the distance indicator, and had the feeling the focus was a bit slow. The 35mmL is a huge piece of glass, so I was a bit surprised the 40mm seemed slower. I was inside, in artificial light. Did unfortunately not do a direct comparison.

Also, since there are no distance indicator - and I sometimes prefocus - I was thinking of marking a few points e.g 1m, 3m, infinity on the protruding lens element

1. How would you rank the focus speed of the 40mm ?

2. Would there anything technically hindering marking a few point myself - would they be good for absolute reference or is there some kind of hysteresis in the focus mechanism?

Thanks!

BlueInTheShadow said:

1. How would you rank the focus speed of the 40mm ?

Click to expand...

It may take a while to get replies here because not a lot of people have the lens yet. I've got one on order, and will post some thoughts when I get it but...

BlueInTheShadow said:

2. Would there anything technically hindering marking a few point myself - would they be good for absolute reference or is there some kind of hysteresis in the focus mechanism?

Click to expand...

From what I understand of focus-by-wire systems, marking the lens for distance indicators will do absolutely nothing. Since the focus ring can spin freely while the lens is turned off, and since the actual moving parts of the focusing element is controlled by an electric motor, even in MF mode, the focusing element won't move while you spin the ring with the camera powered off, thus disaligning your marks immediately.

Again, I don't own the lens, but all the reviews say this, and from the focus-by-wire lenses for NEX that I've owned, that's how I've learned that these types of lenses work.

cedrec wrote:
Thanks a lot for your input!

cedrec said:

BlueInTheShadow said:

1. How would you rank the focus speed of the 40mm ?

Click to expand...

It may take a while to get replies here because not a lot of people have the lens yet. I've got one on order, and will post some thoughts when I get it but...

Click to expand...

I know But if there is a place for early adopters, this will be it. I also does not seem to recall it mentioned in great detail in the reviews yet, so any other impressions would be good.

cedrec said:

cedrec said:

2. Would there anything technically hindering marking a few point myself - would they be good for absolute reference or is there some kind of hysteresis in the focus mechanism?

Click to expand...

From what I understand of focus-by-wire systems, marking the lens for distance indicators will do absolutely nothing. Since the focus ring can spin freely while the > lens is turned off, and since the actual moving parts of the focusing element is controlled by an electric motor, even in MF mode, the focusing element won't move > while you spin the ring with the camera powered off, thus disaligning your marks immediately.

Again, I don't own the lens, but all the reviews say this, and from the focus-by-wire lenses for NEX that I've owned, that's how I've learned that these types of lenses work.

Click to expand...

Thanks - Yes, I can confirm that the front manual focus ring can be turned freely without any impact on the focus, as long as the shutter is not half pressed. It is interesting what you write about the lens elements; my idea was to mark distances on the protruding part of the lens, using how far it extends as a gauge (making a line for each distance I wanted). Of course, if this extension is not a monotonous movement, due to some internal movements of the elements as well, then that idea does not work.

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Compared to my 50L the focus speed of the 40mm seems about the same. But compared to my 28/1.8 and 50/1.8II the focussing of the 40mm is defintely slower (but not annoyingly so).

At around 3m focusing the internal barrel barely sticks out (i.e. all your points would be from MFD to 3m). And since you have to half press the shutter in order to pre-focus anyway, I wouldn't bother with the pre-marking idea. Mayeb think about the voigtlander instead if distance markings are more important than AF.

BlueInTheShadow said:

Hi all,
1. How would you rank the focus speed of the 40mm ?

2. Would there anything technically hindering marking a few point myself - would they be good for absolute reference or is there some kind of hysteresis in the focus mechanism?

Thanks!

--

Click to expand...

BlueInTheShadow said:

BlueInTheShadow said:

BlueInTheShadow said:

1. How would you rank the focus speed of the 40mm ?

Click to expand...

It may take a while to get replies here because not a lot of people have the lens yet. I've got one on order, and will post some thoughts when I get it but...

Click to expand...

I know But if there is a place for early adopters, this will be it. I also does not seem to recall it mentioned in great detail in the reviews yet, so any other impressions would be good.

Click to expand...

OK, I just got mine. Autofocus speed is pretty average. It takes a bit longer than I'd expect to travel all the way from 0.3 m to infinity. However, normal travel time from middle distances to other middle distances is perfectly acceptable, fairly instantaneous.

One oddity I noticed is that the manual focus speed is slower than the autofocus speed. No matter how fast you turn the ring, full travel from 0.3 m to infinity takes about 50% longer time. Not to mention that the lens goes to "sleep" after only 5 seconds, which is downright bizarre, considering that other focus-by-wire systems never put their lenses to sleep. So if you're manually focusing, you have to take into account that you must half-press the shutter before you can focus anything.

BlueInTheShadow said:

BlueInTheShadow said:

BlueInTheShadow said:

2. Would there anything technically hindering marking a few point myself - would they be good for absolute reference or is there some kind of hysteresis in the focus mechanism?

Click to expand...

From what I understand of focus-by-wire systems, marking the lens for distance indicators will do absolutely nothing. Since the focus ring can spin freely while the > lens is turned off, and since the actual moving parts of the focusing element is controlled by an electric motor, even in MF mode, the focusing element won't move > while you spin the ring with the camera powered off, thus disaligning your marks immediately.

Again, I don't own the lens, but all the reviews say this, and from the focus-by-wire lenses for NEX that I've owned, that's how I've learned that these types of lenses work.

Click to expand...

Thanks - Yes, I can confirm that the front manual focus ring can be turned freely without any impact on the focus, as long as the shutter is not half pressed. It is interesting what you write about the lens elements; my idea was to mark distances on the protruding part of the lens, using how far it extends as a gauge (making a line for each distance I wanted). Of course, if this extension is not a monotonous movement, due to some internal movements of the elements as well, then that idea does not work.

Click to expand...

Oh, then I think that could work if you have a fine enough pen to write with, or if you use an exacto knife or something to score the paint on the barrel very precisely.

Chev Chelios said:

Compared to my 50L the focus speed of the 40mm seems about the same. But compared to my 28/1.8 and 50/1.8II the focussing of the 40mm is defintely slower (but not annoyingly so).

At around 3m focusing the internal barrel barely sticks out (i.e. all your points would be from MFD to 3m). And since you have to half press the shutter in order to pre-focus anyway, I wouldn't bother with the pre-marking idea. Mayeb think about the voigtlander instead if distance markings are more important than AF.

Click to expand...

Thanks, Chev Chelios

It sounds a bit slow, but definitely doable, thanks for the direct comparisons. Its is indeed a fair point you make about those distance marking.. Its just sometimes, for the really quick shots, I use zonefocus leaving the lens f8 at 1m. Noting to special, and not to often.

Thanks a lot, Cedrec!

cedrec said:

OK, I just got mine. Autofocus speed is pretty average. It takes a bit longer than > I'd > expect to travel all the way from 0.3 m to infinity. However, normal travel time > from > middle distances to other middle distances is perfectly acceptable, fairly > instantaneous.

Click to expand...

Thanks, thinking about it, this does sound a bit like what I experienced in-store. But really good to hear it from general use too.

cedrec said:

One oddity I noticed is that the manual focus speed is slower than the autofocus > speed. No matter how fast you turn the ring, full travel from 0.3 m to infinity takes > about 50% longer time. Not to mention that the lens goes to "sleep" after only 5 > seconds, which is downright bizarre, considering that other focus-by-wire systems > never put their lenses to sleep. So if you're manually focusing, you have to take into account that you must half-press the shutter before you can focus anything.

Click to expand...

Yes, I think I can work that routine in. Its only for a few shots, where I like to prefocus to 1m or 3m with a large aperture f8 or so. So I could imagine prefocusing, and then just leaving it on manual and not touching the focus for those.

cedrec said:

Oh, then I think that could work if you have a fine enough pen to write with, or if > you use an exacto knife or something to score the paint on the barrel very precisely.

Click to expand...

Exactly what I was imagining. Will test this when I get one, and let you all know ;-)

Does this lens focus at infinity where it stops turning? The old 28mm f/2.8 and 50mm f/1.8 mk I do this and it is very convenient at night. If it goes beyond infinity we will have to pre-autofocus then set to MF.

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