Jump to content

Zone focusing with 50 lux asph


tosean69
 Share

Recommended Posts

Advertisement (gone after registration)

hi everybody,

 

I have a question and would seek for a better solution on this.

 

I have recently bought a new 50 lux asph and learn about the zone focusing for street photography...

 

but compare to my old 35 summicron IV, the scale of the 50 lux asph seems narrower than the 35 summicron. which means even when my aperture has stepped down to 16, the in focus depth is within 0.5m ( e.g. 1m - 1.5m)

 

Is this lens actually not suitable for zone focusing? or my concept is just wrong

 

THanks very much again:D

Link to post
Share on other sites

A 50 mm will always have a more narrow scale than a 35. Zone focussing can be practical, maybe even inevitable, but why did you buy a rangefinder camera ? To focus with that rangefinder...

In general, especially with a very sharp lens like the Summilux asph, there is only one place sharp in your image - and that is the plane of focus. An image will only improve with the focus spot-on.

Link to post
Share on other sites

Guys, this is basic photographic theory The longer the focal length the narrower the zone of acceptable focus.

 

It is but if you've come from years of shooting with lenses using auto focus or that don't have the DoF scale, or you just weren't using the DoF scale how the scale looks on different lenses is news to a lot of converts.

 

I started with film and a b&w darkroom and was also taught that the longer the focal length of the lens the narrower the focus but there are endless debates that this isn't "true" because you have to compare the shot framed the same way and so be further away from the subject for the longer focal length thereby increasing the DoF with the longer distance to the subject. It's amazing how basic concepts of photography are being manipulated on the internet. There are a very small number of photographers that have ever used and understand a DoF scale today. I agree with you completely that it's basic photographic theory but it's not understood by a lot of "photographers."

Edited by 1JB
Link to post
Share on other sites

Yes - but the scale is inaccurate anyway - and DOF has nothing to do with autofocus. Nor is it true that there is a block of sharpness between these marks - it is a gradient where unsharpness may be acceptable depending on the subject and magnification.

Link to post
Share on other sites

Advertisement (gone after registration)

I get it Jaap. My point with autofocus was that if all one has ever done is autofocus and set the aperture to address DoF they've never zone focused using the DoF scale and so aren't familiar with what the scale looks like on different lenses. That's probably the vast majority of photographers today.

Link to post
Share on other sites

But those don't shoot Leica M

Anyway, I feel it is a bit of a pity to buy a miracle lens like the Summilux 50 asph and throw away the potential by turning it to f 16 for max DOF and minimum sharpness and make out-of-focus images.
Link to post
Share on other sites

Tosean69 – to employ a useful over-simplification, depth of field decreases (1) with the size of the aperture opening, and (

with increasing size of the object on the sensor/film. Faster lenses use wider apertures, hence produce smaller d.o.f. when wide open, and longer lenses reproduce subjects larger on the sensor (given equal distance of course) so a 50mm Summilux at 1.4 produces a more shallow d.o.f. than a 24mm lens stopped down to 5.6.

 

Now Jaap is right: Given a correctly adjusted lens/camera combo, maximum sharpness is always in the plane of that detail you focused on – like your girlfriend's right eye. Fore and aft of that plane, sharpness (or definition, or resolution, or micro-contrast, or however you choose to define it) falls off gradually until you find the resulting drawing unsharp.

 

How fast that happens depends a lot on how large you print or display the image. In the old days we got away with a lot in a 6x9cm contact print from roll film that would look awfully fuzzy already in a 13x18cm print. The d.o.f. scale on the lens is founded on an assumption from the late 1920's (!) about how much you would enlarge a Leica negative – and that was "not much". Savvy photographers today read the scale two f-stops off, i.e. when setting the lens aperture to actual f:8, they read the scale at the f:4 markings. That is a lot more realistic.

 

So I would say that if you think that the main subject of your picture should be at least largely sharp (with max sharpness on at least part of it) then zone focusing is a viable proposition with 35mm and shorter lenses. That takes about f:8 with 35mm and 5.6 with 24 or 21mm. I point-focus my 50mm Summilux even when stopped down.

 

Now I know that Saint Henri Cartier-Bresson zone-focused his 50mm Summicron. But a look at his pictures reveals that lots of them, and especially those clearly 'shot from the hip', are not terribly sharp. HCB did not make a fetish of sharpness. What made his pictures was content. Saint Ansel (Adams) on the other hand made his pictures as tack sharp as the technology available to him could make them, but the Half Dome Rock in Yosemite has not moved around much in the last few thousands of years. So he could fiddle with the image on his focusing screen, black cloth over his head, until it was down to a 't'.

 

LB

Link to post
Share on other sites

I was also somewhat surprised by the question but can understand the dilemma facing a photographer whose mind is set on automation. I would like to ask the OP, why did you invest in a rangefinder camera? Surely not simply for street photography?

 

Zone focusing only really works with wide angle lenses because they have more generous zones of acceptably sharp focus. I urge you to recognize the lens classic you now have and practice manual focusing on a range of different subjects, just to acquire fluency in this technique.

 

I rarely use zone focusing; but when I do, I set the focus at the approximate shooting range. Then I shoot and then fine-tune the focusing if time permits a second shot.

 

Once again, I urge you to discover the huge potential of this lens, at wide aperture settings. You will be amazed how it can transform your vision and results.

Link to post
Share on other sites

The 50 Summilux ASPH is an absolutely wonderful lens, but is unforgiving for newcomers using it for street photography. A 28 or 35 set to zone or hyperfocal will give you much greater DOF at the same aperture and as long as your shutter speed isn't too slow your hit rate of successful (ie not blurry) images should improve.

 

I don't zone focus my 50 Summilux ASPH when using it for street, but instead rely on muscle memory to set focus as the camera is coming up to my eye. My first shot is taken this way, then if there is time I check focus with the rangefinder and continue shooting. Practice, practice, practice...

Link to post
Share on other sites

Focussing using the hyper focal setting has never worked for me - the pictures simply lack clarity.

 

Similarly zone focussing, unless I'm using wides. I see little point in using such fantastic glass as the 50 Summilux and zone focussing. Much like David above, I might preset the focus to what I think it will roughly be as I bring the camera up to my eye, but I almost always want that last bit of fine adjustment.

 

I might fire off a couple of quick shots if timing is critical. I just missed a very fine shot at a wedding on Saturday. I got the bride and her son in perfect timing, but she was just out of focus (Summicron 75). With a bit of processing, it didn't turn out too bad, but it was disappointing.

 

The scale on the barrel of the lens is very useful, but no substitute for actually using the viewfinder. That just takes practice. One thing which helped me was the focus peaking on the NEX-5n. With that, you can see the zone of acceptable focus move backwards and forwards, which has helped me with learning the fine adjustment of the focussing ring.

 

Cheers

John

Link to post
Share on other sites

Yes - but the scale is inaccurate anyway - and DOF has nothing to do with autofocus. Nor is it true that there is a block of sharpness between these marks - it is a gradient where unsharpness may be acceptable depending on the subject and magnification.

 

Among other factors (Focal length, Distance,Aperture), DOF is a function of your tolerance for 'unsharpness' and the related concept of degree of enlargement.

 

The scales are meaningless in a digital world because 'pixel peeping' is the equivalent of radical enlargement in the good old days.

 

H

Link to post
Share on other sites

Among other factors (Focal length, Distance,Aperture), DOF is a function of your tolerance for 'unsharpness' and the related concept of degree of enlargement.

 

The scales are meaningless in a digital world because 'pixel peeping' is the equivalent of radical enlargement in the good old days.

 

H

 

Well THAT was an oversimplification! The scale is not meaningless. You have to interpret it and use it in a knowledgeable way. If you can't, or won't, well then it is indeed meaningless – to you.

 

You can do the darnedest things with photographs, including peeping at pixels. In film days, we could use a microscope to peer at grain structure. But if we assume that we want to look at a picture as a picture, i.e. as a whole, then your statement is untrue. Do you have an assortment of pixels hanging on your walls? I don't.

 

We can see a picture as a picture as long as the eye's image angle does not exceed c. 53°. This means that the viewing distance is equal to the picture diagonal. At a comfortable close viewing distance and corrresponding picture diagonal of abt. 30cm (12 in.) the eye resolves one minute of angle, or appr. 0.08mm. Pixels are way smaller than that, and hence irrelevant.

 

Now structures even smaller than 0.08mm may well be resolved in the picture – but that is pointless because we can't see the difference between say 0.05mm and 0.08mm. It's all sharp. We do in fact accept an image as sharp if it resolves 0.1mm. And d.o.f. scales are computed upon that fact. The scale on your lens is computed for a circle of confusion in the neg of 0.033mm, giving 0.1mm with an enlargement of 3x. By using the 'two stops off' reading I mentioned, the maximum accepted c.o.c. on the sensor is reduced by half, to 0.016mm and your 30cm diagonal print is saved. If you print larger, you look at it from a larger distance in order to keep it within those 53°, so it's still sharp.

 

And if you insist on going at your 2x3 meter print with a magnifier, then you are not a photographer but a pixler. And that may be a valid hobby, but it's not mine.

 

LB

Link to post
Share on other sites

Now you are oversimplifying , Lars, by applying a purely mathematical interpretation to a biological/psychological phenomena. You are leaving out the impact of subject matter. The less contrast, the more apparent sharpness. The simpler and larger the forms, the more apparent sharpness. In other words a highv frequency image will require a more narrow interpretation of the DOF scale than a low frequency image. And suddenly we are back to the concept of minimum acceptable sharpness and Harold's remark.

Edited by jaapv
Link to post
Share on other sites

Let's get practical.

 

A small aperture (f8-ish) will provide you with a workable zone of focus on a 50mm lens for street shooting where sharpness is not your primary goal. I do a lot of "street" with my 5cm Elmar on my II and set it to f9(!) and 10ft. That enables me to be reasonably reactive when "snapping what I see" without focussing further then taking shots 2, 3 or more while tailoring focus and, if time permits, exposure.

 

Zone focussing is usable, but you have to have a good "sense" of distance and be able to fine tune. Relying on zone focussing alone is simply not going to get you anything worthwhile.

 

Regards,

 

Bill

Link to post
Share on other sites

From the November 2011 issue of LFI magazine:

 

"Hyperfocal focusing is often considered the all around solution for any kind of focusing issues, as it maximizes any aperture setting's depth of field up to infinity. However, this method merely creates a very basic level of sharpness across the entire image, making no more than an emergency solution, rather than a replacement for the proper approach of precise focusing on the main subject. "

Seems to go along with my experience... But I see the value in it.

Link to post
Share on other sites

Now you are oversimplifying , Lars, by applying a purely mathematical interpretation to a biological/psychological phenomena. You are leaving out the impact of subject matter. The less contrast, the more apparent sharpness. The simpler and larger the forms, the more apparent sharpness. In other words a highv frequency image will require a more narrow interpretation of the DOF scale than a low frequency image. And suddenly we are back to the concept of minimum acceptable sharpness and Harold's remark.

 

Jaap, surely you can't expect manufacturers to supply lenses with different (interchangeable?) d.o.f. scales for different kinds of subjects. Certain assumptions have to be made, and they will be expressed in units of meters and millimeters (and fractions of millimeters).

 

Maybe we should abolish the d.o.f. scales. S2 lenses do not have them. But I suspect that this is because the camera will be used tethered to a computer, with the monitor watched by a bleary-eyed art director, barking commands at the poor camera carrier. (Yes, sweeping generalisations are bad, but admit that they are fun. Especially when the subjects are well paid for being pelted with raw eggs.)

 

LB

Link to post
Share on other sites

Here I have to remind you of the forum mantra that automation, scales and such are no replacement for the photographer's brain.

i'm not sure abolishing the scale is a good idea, as they provide a reference point, depending on focus throw etc. Butit might be a good idea to leave out the apertures, as they convey a false sense of precision. Just numbering as some kind of ruler scale might be better.
Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
×
  • Create New...