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Discussion on "3D effect"...with Lenses on images
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PostPosted: Sun Jun 17, 2007 2:14 am    Post subject: Discussion on "3D effect"...with Lenses on images Reply with quote

... what about this one?

www.orio.ws/temp/3depth-2-frame2.jpg

No postwork trick. Pure lens result.

And consider that the JPG conversion kills half of the perception compared to 16bit TIF (n/k).


PostPosted: Sun Jun 17, 2007 7:48 am    Post subject: Reply with quote

I guess, you could call that "3D"! Shocked
Nice!!!


PostPosted: Sun Jun 17, 2007 9:08 am    Post subject: Re: Lately we often discussed the "3D effect"... Reply with quote

Orio wrote:
... what about this one?

www.orio.ws/temp/3depth-2-frame2.jpg

No postwork trick. Pure lens result.


Nice, but most of the 3D effect is, after all, due to the distance haze, which before the invention of the use of perspective in painting was extensively used to create an illusion of distance, also e.g. in the Japanese woodcuts, which can be very effective in this respect.

A full frame down-sampled for the web often loses most of the real 3D effect you can have in a sharp original. Here is a crop from a shot taken with the 60 mm Macro-Elmarit-R mounted on a 350D, unsharpened except for the minimal amount required to counterbalance the AA filtering:



A very slight, almost imperceptible amount of extra sharpening will still enhance the effect:


In a second crop from the same frame, the clear separation between the foreground subject material and the cloud background still enhances the 3D effect, but this is mainly a compositional effect augmenting the effect of DOF within the foreground. The distance from the camera to the subject is several meters, and at f/5.6 the background clouds retain their forms instead of dissolving into an out-of-focus mass.




There is an almost tactile feel in photos like this when they are printed or otherwise reproduced at large enough a size.

Veijo


PostPosted: Sun Jun 17, 2007 9:53 am    Post subject: Reply with quote

Wow, Veijo, those are great!


PostPosted: Sun Jun 17, 2007 4:39 pm    Post subject: Reply with quote

Very good result, Veijo.


PostPosted: Sun Jun 17, 2007 5:37 pm    Post subject: Reply with quote

I have personally begun to realize a few environmental conditions that help a lot the perception of roundness:

1) Light direction, the more lateral the usually better - although I have seen very "round" images even with frontal lighting

2) having different "wings" in the framed scene, at different distances

3) the "aerial perspective" of Leonardo heritage, which you appropriately mentioned

4) Having round or cylindrical objects in the frame (e.g: a tree trunk; a human face; etc.)improves the perception of depth for the whole image; Cubic objects, even of greater physical depth, help this perception less. Other wise said, a small trunk or human face can help more than a huge wall, ever if the wall is at slanted position in the frame. Of course this is also related to the points "a" and "d" (more below)

There are of course photographers choices and conditions that are equally and probably even more important:

a) with regards to point 2 above, it is important to have a lens that has a smooth gradual transition from focused to blurred. The smoother the transition, the greater the depth perception

b) like your rope image proves again, having a photo with a low macrocontrast and a high microcontrast not only helps a lot, but is also a key element

c) provided that the other conditions are there (especially point "a"), some wisely applied sharpening does enhance the effect of the microcontrast and thus boost the depth perception. it is important, however, that the sharpness is not so strong to also bring out too much detail from areas that are placed in a different scene wing. This also works in relation to the following point "d"

d) the DOF is a very important choice to make. And of course it varies with the lens you use, so it's difficult to make an overall rulo for that. Based on my experience, however, I'd say that neither extremes (wide open or too narrow) work well. When wide open, you end up flattening the perspective too much, and make things visually end on one same "image plane" where they would actually be separated by good distance.
When stopped down too much, you also have a similar consequence of flattening, because having too many objects at different distances in perfect focus, also flattens the perspective. Opposite action, but same consequence.
The most accentuate depth perception effect is for me obtained with moderate apertures - say in the range from f/2.8 to f/5.6

e) White balance: with regards to point 3 especially, I have found out that warmer tones tend to reduce the depth perception, while cooler tones tend to enhance the depth perception. This has of course to do with the fact that the air actually has the blueish colour of the sky, so to have a cooler tint to the image means to reinforce the impression that there is more air amongst the objects.
This of course does have to be subtle, because if the cool cast is too heavy, it will have the opposite consequence of flattening the perception of the space, because the stronger the cast, the more it reduces the number of different colours in the image. This is also related to the following point "f"

f) Having a greater number of different colours in the image seems to enhance the perception of depth, although slightly. Of course the placement of colours also matters: having warmer colours in the front and cooler colours in the background helps to keep things within the Leonardo aerial perspective rule

g) Exposure: based on my experience, I have noticed that slightly underexposed images render more perception of depth for the foreground objects especially, and in general for the focused objects. I have not thought about this much to analyze the reason why - yet it's something that I can visually appreciate in my tentatives. Perhaps this is linked much to point "b", as it seems that the more microcontrast a lens can render, the more pronounced is the depth effect of the underexposure of the focused subject and foreground.

h) ISO, the lower the better. I find that image noise or grain can largely kill even the best achieved depth perception result.

OK these are more or less the results of several weeks of tentatives and reasoning. Maybe there is something else that escapes my memory now, but mostly i'd say that this is it for the current state of my research.

_


PostPosted: Sun Jun 17, 2007 7:00 pm    Post subject: Reply with quote

A very sound disquisition, Orio.

Just let me ask about an example. Which of those photos would you attribute the most intense "roundness"?

No.1



No.2



No.3



No.4


Which "ranking" would you compile? I mean there are obvious differences, right?
I just ask to check if I have understood your idea.


PostPosted: Sun Jun 17, 2007 7:30 pm    Post subject: Reply with quote

I find number 2 the most effective, followed by n.3

Analyzing number 2 you find several elements, like the round objects, the many "wings", the various passages in the DOF, the textural detail.

Of course the image resize is an obstacle, I bet that at a full screen resize (that for me would be 1600 pixels) the perception of roundness would be even higher.

Number three has the foreground quite round, but the background is a bit flat. I attribute this to the fact that the background seems to all be on the same level of focusing-detail. Ideally, should see a gradation of both detail and focus, from the nearer part on the right, to the farther part on the left.

Perhaps also the absence of a point of interest in the background makes it easier to perceive a background flatness.

An interesting comment is that #3 takes advantage of a lateral light, while #2 illumination is more frontal. Yet, this does not seem to be a big obstacle. So perhaps the role of the illumination in the perception of roundness has to be somehow revised compared to what is usually thought.

Number 1 has a very good relief of the detail, but I am hesitant in comparing it with the other images, because here we don't really have a scene, just a detail of an object, and the relief is mostly if not exclusively rendered by the lateral light.
I think that my reasoning, is really to be applied to whole scenes rather than just closeup detail of an object. When you have basically nothing else, or little else, than the focal plane, we enter a different game, i think.

Number 4 is obviosuly the most flat looking. We can note that there is practically no round objects in major evidence. The lighting from above does not help either, but as we have seen, the importance of this factor must be reconsidered. I think that what is more important here is that we don't really have any differentiation in the level of detail from the foreground to the background. The too closed aperture causes a practical effect of perception of flatness.

Perhaps I should ad another categories to the ones above. It seems that the perception of roundness can benefit from the presence, in the frame, of both large surfaces and busy detail. When a scene is all composed of flat surfaces or of tiny details (which is mostly the case of number 4), there are more problems in the perception of the roundness.
But I think that a reasoning should also be made about the arrangement of these flat and busy parts in the image. I don't think that all arrangements are the same, or that different images with same percentages of the two elements, will necessarily produce the same amount of depth perception.


PostPosted: Sun Jun 17, 2007 8:08 pm    Post subject: Reply with quote

Thanks for your thoughts about this topic. If I think about it, I can agree to every point you wrote. Smile

Michael


PostPosted: Sun Jun 17, 2007 8:38 pm    Post subject: Reply with quote

Here's an analysis of my image in the different "wings":



The foreground (wing 1) is determined mostly by the DOF

The second (2) wing is determined mostly by the presence of textural detail and microcontrast.
Note that the quality of the lens plays a key role here. The lens must be able to render good microcontrast to bring out detail from a uniform field of grass. Also, and more importantly, the lens has to have a smooth bokeh-to-focus transition, which is the case here, because a good gradual transition makes you "feel" the depth better

The line of trees (3) is the third wing and it coincides with the focal plane.
It therefore has to contain the most textural detail and this is the part that benefits more from a little sharpening if applied wisely. An unwise sharpening would add too much detail to (2), thus making the planes flatter. I think I have been good here, I only sharpened just as much as it was needed to balance the AA filtering of the camera. It was a conservative sharpening, that left he way the lens has interpreted the reality, substantially untouched.

Behind the line of trees we have wing four (4) which is the most amazing part of this image in my opinion. Why? Because I shoot this one with a 135mm, which, normally, would just flatten out everthing that is beyond the focal plane.
Here, instead, we can perceive a clear spatial difference not only between (3) and (4), which is normal, but also between (4) and (5), which is NOT normal, and this shows well I think the importance of having those expensive lenses. A normal 135mm would not have brought this out I think. The Elmarit did.

Behind (4) we have two wings of hills, (5) and (6). Here, the Leonardo aerial perspective enters powerfully the play.
Note that the more haze, the less textural detail and the less macrocontrast also.
There is a big difference in the macrocontrast of (3) and that of (5) and (6), like we were actually looking at two images made in separate moments, but they are all there at the same time. So yes this is a lucky coincidence where the haze helps, but I think I have shown that from (1) to (4), we have also great great depth perception without the haze playing any role.

So my conclusion after this analysis is that depending on the part of the image, different elements may enter the play and add (or detract!) from the perception of roundness.

In other words, it's not only a matter of "this does that and this does not", but also a matter of "where".

_


PostPosted: Mon Jun 18, 2007 6:33 am    Post subject: Reply with quote

Thanks, Orio!

- I did choose those examples on purpose and I find it very comforting that you utter perceptions similar to mine.
- No. 1 was just added to indicate the difference of detail and scenery. And to show how light can cause a 3D-effect even in a detail.
- No. 4 was added since I also thought that the parameters and the absence of round objects would second your definition.

Thanks for your new example, since now I know what you mean with "wings". I have always called this "planes".

Cheers,
Carsten


PostPosted: Mon Jun 18, 2007 8:39 am    Post subject: Reply with quote

This is easier to understand for me, though not all. Thanks Orio.

Nipon


PostPosted: Mon Jun 18, 2007 8:52 am    Post subject: Reply with quote

LucisPictor wrote:
Thanks, Orio!
- I did choose those examples on purpose and I find it very comforting that you utter perceptions similar to mine.
- No. 1 was just added to indicate the difference of detail and scenery. And to show how light can cause a 3D-effect even in a detail.
- No. 4 was added since I also thought that the parameters and the absence of round objects would second your definition.


Yes, strangely enough, it seems that I have put together a series of observations that actually work! Laughing

LucisPictor wrote:
Thanks for your new example, since now I know what you mean with "wings". I have always called this "planes".


Yes I call them the same as you do in Italian, but I was afraid that in English was not clear so I used the word wings because it's the theatrical word.


PostPosted: Wed Jul 04, 2007 5:47 pm    Post subject: Reply with quote

A casual bored shot made with the Summicron-R 90 now while taking a break:



I think it really gives a perception of depth, in spite of the opposing circumstances (the use of tele lens, the relatively flat subject)

It's amazing how some lenses can give something special to even the most boring roof shot.


PostPosted: Wed Jul 04, 2007 7:37 pm    Post subject: Reply with quote

Orio wrote:
... I used the word wings because it's the theatrical word.


OK, I know what you mean.