R-D 1 does a studio session (long)

[Ed Schwartzreic]

I'd like to clarify what Sean is saying, so if he thinks this is not correct, he should definitely respond.

Any 50mm lens, for whatever format, will behave similarly with respect to DOF and what Sean calls "drawing." Therefore a 50/4 Distagon for Hasselblad and a 50/2.8 for a Pentax 110 have similar characteristics in this regard, despite their major differences in image circle / coverage. The 80/2.8 Planar on my Rolleiflex and my 75/1.4 Summilux will likewise be similar.

Ed

 

[jlw]

You know, one thing that's interesting about that is that a 50 on the R-D1 is still a 50. People sometimes think of it as a 75 but it's really a cropped 50 and I make that distinction because a 75 has a different kind of spatial compression, a different abrubtness of transition from sharp areas to OOF areas, etc.. So the frame edges come in closer, of course, but the "drawing" is a 50mm kind of drawing, not a 75mm kind of drawing. I need to remember to talk about this in the fast lenses article.

True, although to be pettifoggingly academic, the spatial effects of perspective depend on the relationship between the lens' viewing angle of the scene and the eye's viewing angle of the reproduction.

There's a longish but very clear explanation in one of Kingslake's books: Imagine that you're viewing a scene with your naked eye, which by definition produces "normal" perspective. Now hold up an 8x10-inch sheet of glass at normal reading distance, and use a grease pencil to trace the outlines of objects in the scene.

This tracing will reproduce the spatial relationships of objects in the scene, and consequently also will have "normal" perspective -- as long as you continue to view the sheet of glass at the same distance.

If you hold the glass at a shorter or longer distance, the outlines will have a different spatial relationship to the scene, and an "unnatural" perspective. This represents what happens when you use a wide or long lens instead of a "normal" lens.

Note, however, that if you re-traced the scene with the glass held at a shorter or longer distance, the perspective would still appear "natural" when the glass was viewed at that distance. This corresponds to the fact that the spatial relationships of a picture taken with a super-wide-angle lens appears natural if you view the print from a very close distance, and the spatial relationships of a super-tele picture appear natural if you view it from a very long distance.

In other words: As long as the angle subtended by the eye when viewing an object in the reproduction is the same as the angle subtended by the eye when viewing the object in its original scene, the spatial relationships will appear "natural."

This concept also can be used to illustrate Sean's point -- that using a 50mm lens on a small-sensor digital camera doesn't change the spatial relationships compared to using the same lens on a 35mm camera.

To follow Kingslake's analogy, you're still making the sketch while holding the glass at the same distance; the only difference is that you're sketching on a smaller piece of glass.

Does that make sense to anyone besides me?

 

[Sean Reid]

Well...to clarify further (and this all is good practice for writing a final version on this topic in the fast lenses review). A given 50mm lens will produce the same optical image no matter what camera it is mounted on. I do mean image, not picture, although the former term is often (mistakenly, I think) used as a synonym for the latter. DOF is a measurement that can only be expressed in relation to a given print size with defined circle of confusion limits. An 8" x 12" print from the R-D1 involves greater magnification than the same size print from a frame of 35mm film. As such, in theory, the CoC requirements are more stringent for a given area to be defined as "in focus". For that reason, the effective DOF of a given 50mm lens (mathematically) decreases as the size of the capture medium decreases and/or as the size of the final print increases. The smaller the capture medium (or the larger the final print), the greater the magnification and thus the greater the demands placed on focus. So DOF isn't an independent property of the lens itself and, by definition, can't be. In fact, perceived DOF can also be affected by the way in which the digital file is sharpened in post-processing. It's a muddy business. <G>

The way in which a given lens "draws", that is to say the way it converts a three-dimensional world into a two-dimensional projected image, varies from lens to lens and sometimes even among examples of a given lens. The ways in which lenses can vary in their drawing is almost infinite which is why MTF numbers, etc. can't even begin to describe a lens accurately (any more than one could describe the taste of a specific wine using the number "seven"). But...a 50mm lens (as a category) has a specific way in which it portrays objects in relation to each other in space. It's somewhere between the expanded sense of depth created by a wide angle lens and the compressed sense of space created by telephoto lenses. To my eye, the longer the focal length, the more the drawing of the lens starts to approximate a collage.

jlw wrote:

"To follow Kingslake's analogy, you're still making the sketch while holding the glass at the same distance; the only difference is that you're sketching on a smaller piece of glass."

Exactly, beautifully said. That is exactly true. And yes, of course, your post makes sense.

The practical relevance of this, methinks, is that those of us who like the way a certain focal length (say 50mm) draws objects in space, may still prefer to use that lens on the R-D1 even though it now has a 75mm FOV. The borders of the picture may match those made with a 75 but the content inside those borders is still pure 50mm drawing.

Cheers,

Sean

 

[LCT]

Yes but perspective depends on the position of the lens w.r.t. the subject.
If i use a 50mm lens on the R-D1, i'll have the same FoV but also the same perspective as a 135 film user with a 75mm lens because both of us will shoot from the same place approximatively.
Then my pic taken with the R-D1 will not be a pure 50mm drawing but a drawing with 50mm DoF and 75mm FoV and perspective IMHO.
Best,
LCT

 

[Ed Schwartzreic]

Aren't we confusing two things here? A 50 on an R-D1 and a 75 on an M6, shot of the same subject at the same distance, and both enlarged full frame to an 8x12 size and viewed from the same distance should show the same perspective.

On the other hand, all 50mm lenses ought to behave more or less the same with regard to how they portray objects in relation to each other in space, and all 75mm lenses should more or less behave the same, but different from the 50's.

Ed

 

[Sean Reid]

"On the other hand, all 50mm lenses ought to behave more or less the same with regard to how they portray objects in relation to each other in space, and all 75mm lenses should more or less behave the same, but different from the 50's."

Agreed.

"Aren't we confusing two things here? A 50 on an R-D1 and a 75 on an M6, shot of the same subject at the same distance, and both enlarged full frame to an 8x12 size and viewed from the same distance should show the same perspective."

What do you mean by perspective? Field of view?

Sean

 

[Sean Reid]

Yes but perspective depends on the position of the lens w.r.t. the subject.
If i use a 50mm lens on the R-D1, i'll have the same FoV but also the same perspective as a 135 film user with a 75mm lens because both of us will shoot from the same place approximatively.
Then my pic taken with the R-D1 will not be a pure 50mm drawing but a drawing with 50mm DoF and 75mm FoV and perspective IMHO.
Best,
LCT

Hi LCT,

What do you mean by "perspective"? Are you using this in the traditional sense of vanishing points and the like?

Cheers,

Sean

 

[Ed Schwartzreic]

Yes, FOV and vanishing points, as well as DOF if the 75mm lens is closed down 50% relative to the 50.

 

[LCT]

Yes even the DoF won't be exactly a 50mm one due to the different circles of confusion.
It's rather a 50mm DoF at one f stop wider in practice.
For example the same 50mm lens gives approximately the same hyperfocal distance @ f/8 on the R-D1 as f/5.6 on a 35mm film camera.
Best,
LCT

 

[Sean Reid]

I talked about the DOF factor above. I wouldn't interchange the term "perspective", as its used in drawing for example, with the aspect we're discussing. One's vantage point and distance from the subjects might be the same with a 75mm and with a cropped 50mm but the compression of space each lens creates will not be the same. Of course we're not talking about space side to side in the frame or top to bottom, that's defined by the picture edges. That kind of space, field of view, will be the same between the 75 and the cropped 50.

The space that I'm talking about, and I think some may have misunderstood this, is the space across the depth of the picture from foreground objects to background objects. Wide angle lenses will make foreground and background objects seem further apart (they expand the drawing of the space), telephoto lenses make them seem closer together (they compress the space). This quality doesn't change when one crops the image circle in tighter (as the R-D1 does relative to a 35mm camera). One might well stand in the same place with an R-D1/50mm lens in one hand and an M6/75mm lens in the other. Both combinations would yield the same field of view and could have the same picture edges. But in pictures made with the latter combination, foreground and background objects will appear to be closer to each other. This isn't because of perspective, per se, it's because of the differences in the ways these two lenses draw space. It's an aspect of lenses I seldom see discussed.


The longer a lens is, the more its image appears to compress the picture space - the more the drawing of the lens begins to approximate a collage. That's not quite the same as perspective. One can crop the image from a 50mm lens to show the same picture edges as a 75mm lens (which is what's happening with the 1.5X sensor mag) but that doesn't mean the 50mm will compress the picture space in the same way as the 75.

I think it might be good to illustrate this point with pictures which I'll try to do as soon as time allows.

Cheers,

Sean

 

[Ed Schwartzreic]

Posting pictures will be really helpful, Sean. I'm torn on this subject between Kingslake's text, which supports exactly what you say, and the material in Scheerer's (?sp) and Makovitch's Leica book which shows a 21mm view of the Norwegian town of Alesund, with marked-off areas for 400mm, 200mm, 135mm, 90mm, and 50mm fields of view, then also the shots taken with these lenses. I'll try to post this picture. I think the problem may be that at infiinity this all works, but we are talking about images made of objects in space at various distances.

Ed

 

[Sean Reid]

"I think the problem may be that at infiinity this all works, but we are talking about images made of objects in space at various distances."

Exactly. I wish I could make illustrations for this today but I'm behind on several projects right now and never seem to be able to catch up fully. Does anyone else want to make some picture experiments and post them?

Cheers,

Sean

 

[pfogle]

Maybe a silly question, but we never had all this concern when moving between medium format and 35mm, which presents exactly the same issues; we just know that the lenses give different results. Seems to me the same thing applies here. Without specifying the degree of enlargement, the arguments about DOF etc are purely academic.

Also, perspective is a function of the point of view only; none of the other factors (focal length, format etc) have any effect.

just my 2c worth, sorry to interrupt! 😉

Phil

 

[Ed Schwartzreic]

Here is the 21mm Sheerer picture with the FoV of several lenses marked out upon it. Here also are the 200mm and 135mm segments, taken with their respective lenses.

Edhttp://www.rangefinderforum.com/forums/attachment.php?attachmentid=5037&stc=1
sheerer1.jpg

 

[LCT]

Maybe a silly question, but we never had all this concern when moving between medium format and 35mm, which presents exactly the same issues...

Right but we can hardly view the results of a Leica lens on a MF camera can't we ;-)
To some Leica users at least the R-D1 has become a digital back for M lenses sort of and it is interesting to check if the qualities, flaws and 'signature' of such lenses are maintained in the digital field.
Hence those comparisons i guess.
Should the 'cron 50mm be treated as a 75mm lens for example or would it be usefull to purchase the new 'cron 75mm for R-D1 users?
Would the 'cron 28mm give the same results on a R-D1 as a 'cron-C 40mm on a Leica M?
... and so on.
Best,
LCT

 

[pfogle]

good point LCT 🙂

 

[Sean Reid]

Those of using the R-D1 and eager to share information about it are a very small group. But I'd venture a guess that among that group are many people who are very aware of (and who care about) the way various lenses render the world. Some of us are professional photographers and some aren't but most of us seem to be quite thoughtful and intentional in our photography. That being the case, it's important to know that a 28 on the R-D1 definitely does not draw like a 40 on a Leica M. They'll show about the same FOV but are distinctly different animals. I think this in part explains why people seem to like the 50 on the R-D1 even though they didn't work much at the 75-80mm range before with film. The 50 is cropped but its still rendering like a 50, not like a 75. In fact, I think the juxtaposition is really interesting. For a given FOV, what we now have, with these APS-C sensor cameras, are lenses that show more effective DOF and less spatial compression. For example, if someone is using a 35 on the R-D1 in lieu of a 50 on a Leica M he or she now has the combination of 35mm (focal length) drawing and most of the 35mm DOF potential with the FOV of about a 50. It's a fascinating kind of combination and I expect that, over time, very good photographers will make use of it just as Cartier-Bresson made use of the space compressed/space non-compressed middle ground of the 50mm lens.

The point made about medium format vs. small format film is true but kind of a horse of a different color. One generally used a given lens on either an MF or an SF camera, not both usually. If one got a feel for a certain 80mm MF lens, that feel probably came from using it on an MF body. One would be unlikely to mount it on a 35mm body (even if that were possible).

But it's different with these digital bodies that take 135mm format lenses. Most of us have been at this for awhile and have, consciously or unconsciously, come to know the drawing of various 135mm format lenses, whether they're from Leica, CV, Canon, Nikon, etc.. I have a friend, for example, who does much of his professional work with the 50 Noctilux. He really knows that lens and is very familiar with the way it translates the world. When he puts that lens on an R-D1 (as he is doing right now, in fact) the edges of the picture are all going to move in a bit but the lens will still behave like itself.

So, since we are now using lenses, that we know from 35mm film use, on the R-D1 it really is useful to know that a 28 doesn't really become a 42, etc.. The image is just being cropped.

Cheers,

Sean

 

[LCT]

... For a given FOV, what we now have, with these APS-C sensor cameras, are lenses that show ... less spatial compression ...

Interesting indeed Sean.
I've never heard of such spatial compression effect until now.
Is there some litterature on the subject?
Best,
LCT

 

[Sean Reid]

Hi LCT,

I'll look but you've no doubt experienced this effect without calling it by that name. If I come across a good link on this I'll post it. It's one reason that you're able to recognize a telephoto picture as such even without knowing how close the person was to the subject. It's such a familiar effect that many of us, I think, never think about it.

Cheers,

Sean

 

[Sean Reid]

LCT,

Erwin Puts starts to talk about this in his review of the R-D1 at: http://www.imx.nl/photosite/japan/epsonrd1/epsonrd1.html

One quote from that article which is relevant: "You may thus conclude that the correction factor of 1.53 gives you the same magnification of the subject as the original 50mm lens, but it will simply show less image area. When you say that that the original 50mm lens will become a 75mm lens, this is only true for the scene framing, not for the focal length. There is no magnification of the scene as will happen when you replace the 50mm lens by a 75mm lens."

It's that magnification that creates the compression of space and it also goes hand in hand with decreasing depth of field.

Cheers,

Sean