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Bigmango's Yashica ML 2.8/35
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PostPosted: Tue Jun 12, 2007 1:07 pm    Post subject: Reply with quote

Hi Orio

You got me into this. Please see attached photo if there is any 3-D or it is just my imagination. It seems if I increase contrast, it looks closer to 3-D. What is the difference?

Thanks

Nipon
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PostPosted: Tue Jun 12, 2007 1:15 pm    Post subject: Try again Reply with quote

Looks like the photo failed to attach. Let me try again.

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PostPosted: Tue Jun 12, 2007 1:45 pm    Post subject: Reply with quote

Actually Nipon, according to people who knows more than me, the overall contrast (or "macrocontrast", that is, the differences between the large dark and bright areas) detracts from the dimensional perception.
You can see that your tree trunk, is almost completely black, and looks more like a cutout silhouette than a spacial object.
What would help instead is the "microcontrast", that is the ability of the lens to differentiate between similar tones. The microcontrast brings out the texture of the objects, and this is one of the elements that -according to many- enhances the depth perception. For this to really work, the picture has to have a lower macrocontrast, in order to allow for detail to be readable in the shadows and in the highlights.


PostPosted: Tue Jun 12, 2007 3:04 pm    Post subject: Reply with quote

What also is of importance here is the dynamic range.
If a lens/sensor set is able to record a huge dynamic range, there can be more "microcontrast" in a picture with the same level of "macrocontrast" and vice versa.
This of course shows that not only the lens is responsible for what Orio nicely calls "3D-effect", the sensor or film also is...


PostPosted: Tue Jun 12, 2007 3:45 pm    Post subject: Reply with quote

LucisPictor wrote:
what Orio nicely calls "3D-effect",


I actually prefer to call it "perception of depth" or "perception of roundness", which I think are more precise terms because it really is all a matter of how our minds read it - since the photographic surface is always flat.
I end up using "3D effect" since this is the way that everybody else calls it.


PostPosted: Tue Jun 12, 2007 4:08 pm    Post subject: Reply with quote

Orio

This is intriquing. Not sure I understand it fully, leading to my another question.

"For this to really work, the picture has to have a lower macrocontrast, in order to allow for detail to be readable in the shadows and in the highlights."

What exactly is macrocontrast? and how to you have lower macrocontrast picture?

LucisPictor

Thanks for your comment.

Cheers

Nipon


PostPosted: Tue Jun 12, 2007 4:27 pm    Post subject: Reply with quote

I will not use my own words, instead I will copy from a forum message that explains it better than I ever could:

Quote:
Micro-contrast refers to the ability of an optical system to accurately separate tones in very fine detail. There we are referring principally to the 40 line pairs per millimetre.

As Erwin puts it - Very Happy -, 'microcontrast refers to the relative luminances of two adjacent very small subject areas. It has special relevance to very fine textural details. If some object detail is just recorded, but the contrast is below the visual threshold, we are not able to see it. What we will see however is a kind of image noise, that reduces the clarity of the picture'.

I shall again turn to Erwin for contrast, or overall contrast (or macro-contrast), since his explanation is crystal-clear: 'Macro contrast is the difference between the deepest black and the lightest highlight of a scene, that the lens is able to record faithfully.'


Another forum message:
Quote:

Here is a (over)simplified explanation:

Macro contrast is the ability of a lens to render black areas very black and white areas very white. A lens with poor macro contrast will scatter (or flare) light from the bright areas to the dark areas, hence rendering the dark area lighter and the light area darker. In the dark area, there will be no texture present, just a slight density present in the negative where it should be clear (black is reproduced as clear in the negative). The light area is likewise slightly darker due to the flare, because some of the light has been robbed from it and sent into the dark areas of the image.

Micro contrast is the ability of the lens to differentiate between adjacent areas of the image that differ only very slightly from one another in contrast - hence rendering very fine textural detail in both the highlight and shadow areas of the image. Due to excessive flare, poor macro contrast can thus adversly affect micro contrast as well as creating the aforementioned problems in an image.


Some links:

http://www.rangefinderforum.com/forums/archive/index.php/t-30158.html

http://photo.net/bboard/q-and-a-fetch-msg?msg_id=002lb8

http://www.yet2.com/app/list/techpak?id=22906&sid=90&abc=0&page=tpprint

http://www.imx.nl/photosite/leica/mseries/testm/M10-50.html


PostPosted: Tue Jun 12, 2007 4:43 pm    Post subject: Reply with quote

Thanks, Orio.


PostPosted: Tue Jun 12, 2007 4:45 pm    Post subject: Reply with quote

A good example is a picture I made (not to blow my own horn - I hate this - just because it turned out that way without any merit from my part, and I happen to have it handy), I have already shown it but maybe after those descriptions it can make more sense:



There you can see that the macrocontrast in my image is low, but the differentiation amongst similar tones (microcontrast) is very high, and this (together with the DOF which is an important element) enhances the perception of depth.

If the macrocontrast was higher, it would have killed the readability of detail, thus making microcontrast action less effective.

So this is what they mean in those links I posted, when they say that big macrocontrast "depresses" microcontrast.


PostPosted: Tue Jun 12, 2007 6:43 pm    Post subject: Reply with quote

That's a beautiful shot, Orio. There's certainly a contrast between
my pics and yours of similar subject matter. To get mine to look like
this, they would have to be sprinkled with magical fairy dust. Laughing

Bill


PostPosted: Tue Jun 12, 2007 6:58 pm    Post subject: Reply with quote

Katastrofo wrote:
That's a beautiful shot, Orio. There's certainly a contrast between
my pics and yours of similar subject matter. To get mine to look like
this, they would have to be sprinkled with magical fairy dust. Laughing
Bill


I can not claim merit for this picture, except for two things: the composition, and if you want, the "nose" for being able to smell a good photographic circumstance (which can also be regarded as good luck).

For the rest, all the merit goes to the lens I had mounted on the camera. If I had a different lens, the photo would probably have not been so effective.
It's the thing about expensive lenses, they sometimes (not always, as Veijo said) reward you with results that are above the standard.
On the other side, after having purchased them, my wallet is empty.
It's all a give and take, you don't get something for nothing etc... Wink


PostPosted: Wed Jun 13, 2007 11:43 pm    Post subject: Reply with quote

Well, Nipon, found this lens on ebay for me, but I got beat out in the
last 5 seconds of the auction! Curses! It was in the low $30s when I bid
$55.55 the last 10 seconds and the winning bidder comes in with $56.55
to win. Sad Shee-ottt!

Bill


PostPosted: Thu Jun 14, 2007 2:40 am    Post subject: Reply with quote

Know how you feel. That happened to me last week too. Try again next time.

Nipon


PostPosted: Thu Jun 14, 2007 2:45 am    Post subject: Reply with quote

bigmango wrote:
Know how you feel. That happened to me last week too. Try again next time.

Nipon


I know. I want to thank you for finding it, anyway! Wink

Bill