AF on wide pirmes

[fran__ois_p._weill]

<p>Illka,</p>

<p><em>I would put it this way: "The subject can be near to the camera which creates a dynamic perspective and the viewer gets a sense of being involved in the activity, instead of being a faraway observer." :-)</em></p>

<p>As a heavily myopic person, I can indeed feel just as if I were the witness of the situation you describe, with the main subject in focus and everything beyond blurred... I just need not to wear my glasses. :) ...</p>

<p>On a more serious mood, I think the value of the result with such kind of pictures is something very subjective. May be because of my myopia, I tend to hate unsharpness when it doesn't fully transform the background into a totally abstract background. I fully admit it is subjective.</p>

<p>Oskar and Ken, the problem of the DOF is much more complicated than you seem to figure. The notion of circle of confusion is partly subjective and the seriously designed scales are made in reference to existing tables based on a commonly accepted value of this circle on the light sensitive medium (once a film, now a sensor) and a typical final enlargement. The final enlargement value is the most subjective part of this problem as it is assumed beyond a certain enlargment value people see the picture from a longer distance so the need for a smaller circle of confusion is obviated. If we had an infinite definition on the sensor and our eyes were perfect, then there will be no DOF at all - whatever the lens.</p>

<p>Ken, you example is somewhat atypical and simply show that then, (when the picture was taken) you were not aware of a well known fact, you expressed nowadays in a very precise and scientific terms speaking about magnification but which is clearly explained and can plainly be seen just looking at a lens with a DOF scale : on a given lens the nearer you focus, the less you get DOF for a given aperture. So it was obvious trying to frame the same subject with the same degree of magnification with a shorter focal length you won't be able to get more DOF. the only thing which is modified in such case is the perspective.</p>

<p>>> <em>I'm not knocking anyone who prefers the scales at all, I'm just saying that many people are now using a different method and the demand for lens scales seems to be greatly reduced.</em> <<</p>

<p>You don't seem to understand the other methods you refer to are either even more subjective than a good DOF scale ("seeing" the DOF through a darkened small finder by closing the aperture to the effective one) or slow (shooting a test pic and examining it on the screen of a DSLR, which is simply what I did in studio photography with my Hasselblad and a Polaroid back) and none of them allows for a distance pre-set.</p>

<p>Of course the latter method is far more precise but it implies your subject, like the deer skull you present here, won't move. The former is extremely imprecise and need to be used only under a fair amount of subject lighting.</p>

<p>>><em> If there was a demand for the scales, they would be there</em> <<</p>

<p>There are far more reasons than the alleged lack of demand for them to have disappeared :</p>

 

<ol>

<li>Ring actuated zooms precludes their existence unless you introduce a very complicated mechanical link between the focus ring and the aperture ring and a lot of other problems (entry of dust, lack of capability to hold the chosen focal length when moving the camera upward or downward) being generated by push-pull zooms lead to their abandonment which in turn precluded the presence of engraved DOF abaques on the barrel.</li>

<li>The first generations of zooms were mainly in the tele and then the medium focal length ranges where a precise focusing on the main subject is far more important in the average than DOF control.</li>

<li>AF added the necessity to have the smaller possible angular movement of the focusing ring to allow the fastest possible operation with the samllest possible inertia. On original Nikon AF lenses the focusing ring was even freewheeling ! Even today, DOF scales on AF lenses, when they exist at all, are cropped to the two or three smaller aperture value. This has no particular inconveniency with longer lens, but on a very wide one, where values like f/4 give you a fair amount of DOF this is a liability. To proceed otherwise seem to be considered a costly and perhaps impractical solution by all the manufacturers ! ... Finally the reduced angular movement of the ring between minimum focus distance and infinity leads to a less precise manual positionning of the ring.</li>

</ol>

<p>After more or less two decades of all AF and zoom supremacy (the latter first in the amateur world which is where the sales volume is) it is obvious few people ask for manual lenses and complete DOF scales ! But originally this was imposed by the manufacturers for technical and financial reasons, not by the lack of demand (at least on the professional level).</p>

<p>I just thought the appearance of manual third party high quality primes and the fact a lot of pro photographers find a place for them in their bag will trigger a renewed interest by mainstream manufacturers for these lens, at elast where they are the more practically useful : very wides and macro lenses...</p>

<p>FPW</p>

<p> </p>

[ilkka_nissila]

<p><em>I think the value of the result with such kind of pictures is something very subjective. May be because of my myopia, I tend to hate unsharpness when it doesn't fully transform the background into a totally abstract background.</em></p>

<p>Well, although it would be nice to be able to freely control who is in focus and who is not, this often isn't possible in indoor available light photography. I take the position that if the photo is about interaction between people, it's best to have one person truly sharp and then if the other one is a bit blurry, then so be it. I have one picture of a couple on the altar kissing, and the priest is smiling at them in the background. The priest is not in focus, but you can tell that he's smiling happily. It would of course have been possible to adjust the focus to be more in balance, or even have it on the priest, but the kissing part took the priority in my mind at that time, and in any case things happen so quickly that it's hard to make a decision to go with DOF scales in such a case. Maybe a more confident photographer would have tried a compromise. Anyway, the couple thought it was perfect and used it even in their thank you card to the guests. I have another shot in which I and a friend of mine are subjects, it was taken by another person in the table with my camera. The focus on us is perfect (the 28mm was used at f/2) yet you can see the bride looking towards us and smiling in the background. She is a bit out of focus but still ... a nice detail. Perhaps it'd be better if the DOF had been greater, in some ways, but it just wasn't possible.</p>

[fran__ois_p._weill]

<p>(...) <em>this often isn't possible in indoor available light photography</em></p>

<p>Hello Illka,</p>

<p>I'm sure some situations lead to the impossibility you refer to. In such case it is more than often "get what you can"... But take into consideration the fact most of the time a wide to ultra-wide cans be safely used with a very reduced shutter speed when compared to what is necessary even with a standard lens. I bet f/4 (so one shutter speed slower) might have been possible and with the distance between the priest and the couple being relatively small and your 28 pre-set to cover both the couple and the priest into the lens D.O.F. I think you should have been ready well in advance to have the required picture... In the past, when AF was inexistent, such pictures were as current as they are now and a lot of them were taken with this technique successfully. My guess is you are so used to focus directly on the subject (despite the fact you also use manual lenses), a classic AF technique, you even didn't think about this distance pre-set option.</p>

<p><em>I take the position that if the photo is about interaction between people, it's best to have one person truly sharp and then if the other one is a bit blurry, then so be it.</em></p>

<p>Looks for me like a version of a very current movie technique : two people have a conversation, when one speaks the movie camera is in focus on him and when the other answers the focus is shifted to him. Unless you really can't do otherwise, I don't think this technique leads to the better result in photography (obviously because you can't shift focus on a single image).</p>

<p><em>The focus on us is perfect (the 28mm was used at f/2) yet you can see the bride looking towards us and smiling in the background. She is a bit out of focus but still ... a nice detail. Perhaps it'd be better if the DOF had been greater, in some ways, but it just wasn't possible.</em></p>

<p>The most frequent occurrence for such a situation is when the subject is really moving as the subject's movements cannot be "slowed" enough as are the operator movements effect by the wide angle... And with f/2 a mandatory aperture, I admit AF can be of a great help.</p>

<p>I received a mail through photo.net you will soon receive my mail address.</p>

<p>Best regards</p>

<p>François P. WEILL</p>