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04-06-2016, 01:53 PM   #1
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Lens element count and the end of 3D pop

I have recently become fascinated with really cheap m42 lenses as sort of a low grade LBA affliction. I've been looking at the 50mm to 58mm range and have noticed something. The sonnar lenses (6 elements in four groups) tend to have more of a 3D depth than lenses with more elements even when the multi-element lenses have higher MTF ratings. I know there are exceptions and they begin with Z or V or sometimes P, but the overall impression was striking. So, I started looking it up and came up with this link:
The flattening of modern lenses or the death of 3d pop ? YANNICK KHONG
Yannick Khong makes the case that from a physics standpoint, the more elements you have, the less potential there is for a 3D effect. He does some comparisons between the highly rated and expensive Sigma 35mm 1.4 Art and a cheap Nikkor 35mm AF F2D that makes his point pretty effectively. In some ways the flaws in old lenses make it possible for the human eye to perceive depth which is counterintuitive, but seems to work. In part, this may be the root of the endless wrangle over whether the Pentax DA Limited 15mm is an average or a great lens. Incidentally, Khong walks the walk, his pictures with the cheap nikkor on his Flickr page are stunning.

The linked picture below was taken by me with a cheap Pentacon 35mm f1.8 lens from the DDR on a Pentax K30 (now dedicated to m42 since the aperture control block died.) It is probably at f10 at the Pentacons very short minimum focusing distance. For me, this is an example of cheap and 3D and I doubt that I could make a more effective version of this scene with my Sigma 70mm macro.

https://www.flickr.com/photos/13383244@N00/25669597994/in/dateposted-public/lightbox/

04-06-2016, 02:32 PM   #2
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Discussed to death in multiple threads already.
04-06-2016, 02:49 PM   #3
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An interesting topic I hadn't thought of that aspect before
04-06-2016, 02:59 PM   #4
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QuoteOriginally posted by pathdoc Quote
Discussed to death in multiple threads already.
I probably did not look at every 3D thread, but the ones I did look at fell into a few categories - great lenses for 3D (followed by ensuing argument), no it's really the lighting, picture galleries containing some pictures which look 3D, and the ever popular all you really have to do is create it in LR. I could easily be wrong, but this is the only thread that advanced a theory for why it works. Incidentally Khong continues well beyond this article, going into frame sizes, pixel density and raw bit count and even a discussion of why Panasonic gets it for M4/3 and Olympus doesn't. If there are any threads that advance the same theory (and not just that sonnars have a "glow") I'd really like to read them and perhaps learn a little more.

04-06-2016, 03:40 PM   #5
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Instead of searching for 3D, you should have searched for "Yannick Khong". He recently posted another article, saying pretty much the same things, which spawned a number of PF threads, including:

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/315566-simp...gn-better.html
https://www.pentaxforums.com/forums/169-pentax-full-frame/317364-new-glass-ol...revisit-2.html
https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/318138-whats-your-take.html
04-06-2016, 04:57 PM - 1 Like   #6
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I am glad that Yannick has managed to do what thousands before him failed at, that being to qualify exactly what 3-D effect is and to how it is accomplished.

FWIW, I got about half-way through the article before I concluded that he is mildly confused on his physics (glass is a capacitor...and creates impedence? Spiral light?) and needs to revisit how he makes comparison photos (Mickey on the left has at least 1/2 stop more exposure than Mickey on the right). His premises don't follow.


Steve

Last edited by stevebrot; 04-06-2016 at 05:10 PM.
04-06-2016, 05:21 PM   #7
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QuoteOriginally posted by kernos Quote
The linked picture below was taken by me with a cheap Pentacon 35mm f1.8 lens from the DDR
I searched in vain to find out more about this lens, but came up dry. Do you have any more information?


Steve
04-06-2016, 05:43 PM - 2 Likes   #8
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QuoteOriginally posted by stevebrot Quote
I am glad that Yannick has managed to do what thousands before him failed at, that being to qualify exactly what 3-D effect is and to how it is accomplished.

FWIW, I got about half-way through the article before I concluded that he is mildly confused on his physics (glass is a capacitor...and creates impedence? Spiral light?) and needs to revisit how he makes comparison photos (Mickey on the left has at least 1/2 stop more exposure than Mickey on the right). His premises don't follow.


Steve
This is an interesting youtube video on the decision process to use what amounts to an antique design Cooke cine lens instead of a Summilux C for a commercial movie with recognizable stars. The same sort of side-by-sides that Khong had show up here in this comparison, but in this case with lenses that cost thousands of dollars a pop.. It is twelve minutes and makes the point from an aesthetics standpoint without recourse to what may be dodgy physics.
From my own standpoint, I can see exceptions to Khong's ideas. My DA Ltd. 15mm effortlessly produces images that pop even though it has 9 elements. But, it is only logical that something will be lost if you put too much glass between the subject and the sensor array. What the Khong's article says to me is to not obsess about $900 lenses and look at opportunities that are right in front of you.

04-06-2016, 06:19 PM   #9
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QuoteOriginally posted by kernos Quote
I have recently become fascinated with really cheap m42 lenses as sort of a low grade LBA affliction. I've been looking at the 50mm to 58mm range and have noticed something. The sonnar lenses (6 elements in four groups) tend to have more of a 3D depth than lenses with more elements even when the multi-element lenses have higher MTF ratings. I know there are exceptions and they begin with Z or V or sometimes P, but the overall impression was striking. So, I started looking it up and came up with this link:
The flattening of modern lenses or the death of 3d pop ? YANNICK KHONG
Yannick Khong makes the case that from a physics standpoint, the more elements you have, the less potential there is for a 3D effect. He does some comparisons between the highly rated and expensive Sigma 35mm 1.4 Art and a cheap Nikkor 35mm AF F2D that makes his point pretty effectively. In some ways the flaws in old lenses make it possible for the human eye to perceive depth which is counterintuitive, but seems to work. In part, this may be the root of the endless wrangle over whether the Pentax DA Limited 15mm is an average or a great lens. Incidentally, Khong walks the walk, his pictures with the cheap nikkor on his Flickr page are stunning.

The linked picture below was taken by me with a cheap Pentacon 35mm f1.8 lens from the DDR on a Pentax K30 (now dedicated to m42 since the aperture control block died.) It is probably at f10 at the Pentacons very short minimum focusing distance. For me, this is an example of cheap and 3D and I doubt that I could make a more effective version of this scene with my Sigma 70mm macro.

https://www.flickr.com/photos/13383244@N00/25669597994/in/dateposted-public/lightbox/
Don't want to sound like I am changing the topic, but what is that Pentacon 35mm f1.8 lens? I couldn't find anything about it.
04-06-2016, 06:22 PM   #10
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QuoteOriginally posted by IgorZ Quote
Don't want to sound like I am changing the topic, but what is that Pentacon 35mm f1.8 lens? I couldn't find anything about it.
Oops, I am an idiot. It is a Pentacon 29mm. I am so sorry to have brought your hopes up.
04-06-2016, 06:48 PM   #11
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QuoteOriginally posted by kernos Quote
What the Khong's article says to me is to not obsess about $900 lenses and look at opportunities that are right in front of you.
So true indeed! I tend to champion vintage and low-class glass and only own a few lenses of recent design. A couple of my favorite photos are these taken with my former-Soviet Helios 44M 58/2...(six element, double Gauss, Biotar-derived)






I attribute the 3-D effect less to the number of elements and more to the lens design. The Biotar/Helios lenses are characteristically center sharp at all apertures with good contrast and fairly soft corners. CA is very well controlled with little or no tendency to spawn purple fringing. Nice and very reasonably-priced lens.


Steve
04-06-2016, 06:49 PM   #12
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QuoteOriginally posted by kernos Quote
Oops, I am an idiot. It is a Pentacon 29mm. I am so sorry to have brought your hopes up.
f/2.8?


Steve
04-06-2016, 07:07 PM - 1 Like   #13
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QuoteOriginally posted by stevebrot Quote
I attribute the 3-D effect less to the number of elements and more to the lens design
This is my take on it as well. Also lenses with inherently higher contrast* will have a higher chance of producing this effect more than a lens simply designed for high resolution.


* the Pentax DA16-45mm f/4 Zoom lens has an impressive amount of lens contrast (but not much in the way of resolution due to issues with CA) for a zoom.

Last edited by Digitalis; 04-07-2016 at 02:01 AM.
04-06-2016, 07:44 PM   #14
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QuoteOriginally posted by stevebrot Quote
f/2.8?


Steve
The lens is a 2.8. I think it is an export model as it has "Made in GDR" on it. It is the all black version which I think is a later version, but I could be wrong. Originally what attracted me to the lens was that some of the flickr shots had soap bubble bokeh and it really did sharp close focus -the image I linked to is not a crop. As I've used the lens, I'm finding that it does not really start getting sharp until about f4, but it keeps getting sharper as it is stopped down at least to f11 which is getting near the limit for what I'm willing to do with stop down metering. At f4 the bubbly bokeh is gone. In looking at some of the shots that I admired, the two best were actually shot with a 9mm extension tube at f3.5. I'm thinking that it may be possible to get the bubbles and some sharpness with this combination for flowers or maybe small critters. More to experiment with. Incidentally, I really liked your pink rose, very painterly.
04-07-2016, 04:52 AM   #15
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QuoteOriginally posted by stevebrot Quote
So true indeed! I tend to champion vintage and low-class glass and only own a few lenses of recent design. A couple of my favorite photos are these taken with my former-Soviet Helios 44M 58/2...(six element, double Gauss, Biotar-derived)

I attribute the 3-D effect less to the number of elements and more to the lens design. The Biotar/Helios lenses are characteristically center sharp at all apertures with good contrast and fairly soft corners. CA is very well controlled with little or no tendency to spawn purple fringing. Nice and very reasonably-priced lens.

Steve
So true... I recently bought a 44K-4 and must say that I'm really happy... I've shot with it a lot in the past week.

Quite a number of pictures turned out with a marked 3D effect and, while it's almost unusable wide-open (no, I mean really... just for the odd portrait when you're already in ISO3200+ land), it's really warm and pleasant, with some CA but not of the nastiest kinds (I can name a few SMC lenses that have less pleasant CA) and a soft bokeh (yeah, it reads cliché, but it's really soft even when stopped down to f/2.4 or f/2.8, with no serrated edges where the blades join).

The swirl and the soap-bubble edges on the bokeh are the icing on the cake.
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