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Roland Karlsson

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http://en.wikipedia.org/wiki/Apodization ‎

There exist one apodization lens I know about - the Minolta/Sony 135 mm SLT lens.

I assume apodization is the holy grail to image quality. All high quality optical systems, being it laser systems or microscopy needs apodization. Doing FFT or other signal treatment you always do apodization.

In a photographic lens it assures that OOF parts are unsharp, i.e. smooth. OOF parts if you do not do apodization consists of overlayed sharp circles, which of course adds noisy cr@p.

Apodization also should increase quality of in focus parts. How much I do not know.

Apodization also would greatly improve DOF stacking as you would not get faulty sharp hits by bokeh edges.

I also know that if you want to create depth maps from DOF stacks, apodization is a strong prerequisite.

In short - apodization is important if you want image quality.

I am quite perplexed by the lack of apodization optics for photography.

The downsides are of course cost and loss of light.

Any thoughts?

--
/Roland
X3F tools:
github.com

GitHub - rolkar/x3f: Tools for manipulating X3F files from Sigma cameras

Tools for manipulating X3F files from Sigma cameras - rolkar/x3f
github.com github.com
 
I think a leaf shutter can achieve this affect naturally: if it is always in motion and the speed of the leafs is adjusted to set exposure time- instead of always moving the leafs at maximum speed and extending the time they are fully open.

Of course if there is subject motion it might be rendered slightly weirdly using this technique.
 
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DSPographer said:
DSPographer wrote:

I think a leaf shutter can achieve this affect naturally: if it is always in motion and the speed of the leafs is adjusted to set exposure time- instead of always moving the leafs at maximum speed and extending the time they are fully open.

Of course if there is subject motion it might be rendered slightly weirdly using this technique.
Click to expand...
Thinking about this some more, I think you would probably want to open the aperture most of the way quickly, then slowly cycle it between say the last half-stop and back during the exposure, followed by quickly closing it all the way. With an electronic servo-motor driving the leafs I think this would be doable. This would also make the Apodization function adjustable.
 
DSPographer said:
DSPographer wrote:
DSPographer said:
DSPographer wrote:

I think a leaf shutter can achieve this affect naturally: if it is always in motion and the speed of the leafs is adjusted to set exposure time- instead of always moving the leafs at maximum speed and extending the time they are fully open.

Of course if there is subject motion it might be rendered slightly weirdly using this technique.
Click to expand...
Thinking about this some more, I think you would probably want to open the aperture most of the way quickly, then slowly cycle it between say the last half-stop and back during the exposure, followed by quickly closing it all the way. With an electronic servo-motor driving the leafs I think this would be doable. This would also make the Apodization function adjustable.
Click to expand...
Yepp - there was a Minolta Maxxum camera that had an apodization mode. It used the aperture, not a leaf shutter. Leaf shutters are not all that common in system cameras.

But - leaf shutters might actually do it unintentionally - at least at high speeds.

--
/Roland
X3F tools:
http://www.proxel.se/x3f.html
https://github.com/rolkar/x3f
 
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Actually, now that I think about it, the technique I mentioned won't work right. One point of apodizaqtion is to change the point spreading function: typically greatly reducing its level for large offsets from the peak. That aperture affect comes about from the way each photon's wave function coherently interacts with the aperture. Since for each photon the leaf is a specif position with a hard edge, the distant point spread function levels won't be reduced.

The leaf shutter technique will incoherently combine the effects of different photons though, so you may get most of the bokeh effects that you are looking for.

I think you could replace the aperture inserts in a LensBaby lens with ones with a graded edge to get proper apodization. Unfortunately, LensBaby doesn't typically try for maximum optical performance so their lenses' aberrations might make adjusting the aperture function pointless.
 
Last edited:
Roland Karlsson said:
Roland Karlsson wrote:

http://en.wikipedia.org/wiki/Apodization ‎

There exist one apodization lens I know about - the Minolta/Sony 135 mm SLT lens.

I assume apodization is the holy grail to image quality. All high quality optical systems, being it laser systems or microscopy needs apodization. Doing FFT or other signal treatment you always do apodization.

In a photographic lens it assures that OOF parts are unsharp, i.e. smooth. OOF parts if you do not do apodization consists of overlayed sharp circles, which of course adds noisy cr@p.

Apodization also should increase quality of in focus parts. How much I do not know.

Apodization also would greatly improve DOF stacking as you would not get faulty sharp hits by bokeh edges.

I also know that if you want to create depth maps from DOF stacks, apodization is a strong prerequisite.

In short - apodization is important if you want image quality.

I am quite perplexed by the lack of apodization optics for photography.

The downsides are of course cost and loss of light.

Any thoughts?
Click to expand...
Can´t this be done in software, in-camera?

We already have face-detection, nearest-eye detection, left or right-eye-detection, focus-peaking, etc. How about in-camera OOF area smoothing?

It should be a given in mFT cameras, making FF camera equivalent OOF rendering for the same numerical aperture :)
 
DSPographer said:
DSPographer wrote:

Actually, now that I think about it, the technique I mentioned won't work right. One point of apodizaqtion is to change the point spreading function: typically greatly reducing its level for large offsets from the peak. That aperture affect comes about from the way each photon's wave function coherently interacts with the aperture. Since for each photon the leaf is a specif position with a hard edge, the distant point spread function levels won't be reduced.

The leaf shutter technique will incoherently combine the effects of different photons though, so you may get most of the bokeh effects that you are looking for.

I think you could replace the aperture inserts in a LensBaby lens with ones with a graded edge to get proper apodization. Unfortunately, LensBaby doesn't typically try for maximum optical performance so their lenses' aberrations might make adjusting the aperture function pointless.
Click to expand...
I do not think this is a great problem for non coherent light.

What might be a problem though is making double exposure with several positions of the aperture.
 
rubank said:
rubank wrote:

Can´t this be done in software, in-camera?

We already have face-detection, nearest-eye detection, left or right-eye-detection, focus-peaking, etc. How about in-camera OOF area smoothing?

It should be a given in mFT cameras, making FF camera equivalent OOF rendering for the same numerical aperture :)
Click to expand...
You can make some of it in software of course.

But ... it is quite computational expensive and it will add noise ... and it is always best to start with a good original.

--
/Roland
X3F tools:
http://www.proxel.se/x3f.html
https://github.com/rolkar/x3f
 
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One downside you did not mention is that used of an apodization element interferes with PDAF (possibly contrast detect also). I have the 135 STF, and it is a manual focus only lens. I can use focus peaking (which works perfectly), but the green focus confirm square does not light up (it does when I manual focus any of my other lenses, including the LensBaby).

The element certainly soaks up light, but this is mostly at the widest aperture.

I am not sure if the effect can reliably be reproduced in software from a single image. Multiple exposures with varying aperture might get pretty close, that's how the old Minolta in-camera STF function worked. I assume focus stacking of such a set might do the same thing, and give you a little more control of the process.

The 135 STF is a tricky lens to use, but you do get the hang of it after many, many shots. And just to be clear— I absolutely love it and use it as much as I can, even when inappropriate (like kid's soccer games). The optical trick is unique, but requires compromises (which I am more than willing to pay for). I would love for another technology to be developed that does not require as many compromises.
 
MediaArchivist said:
MediaArchivist wrote:

One downside you did not mention is that used of an apodization element interferes with PDAF (possibly contrast detect also). I have the 135 STF, and it is a manual focus only lens. I can use focus peaking (which works perfectly), but the green focus confirm square does not light up (it does when I manual focus any of my other lenses, including the LensBaby).
Click to expand...
Hmmm ... I wonder why. And if it is generally so., or only with your camera.
MediaArchivist said:
The element certainly soaks up light, but this is mostly at the widest aperture.

I am not sure if the effect can reliably be reproduced in software from a single image. Multiple exposures with varying aperture might get pretty close, that's how the old Minolta in-camera STF function worked. I assume focus stacking of such a set might do the same thing, and give you a little more control of the process.
Click to expand...
It is probably near to impossible to simulate it without multiple shots.
MediaArchivist said:
The 135 STF is a tricky lens to use, but you do get the hang of it after many, many shots.
Click to expand...
Whats the problem?
MediaArchivist said:
And just to be clear— I absolutely love it and use it as much as I can, even when inappropriate (like kid's soccer games). The optical trick is unique, but requires compromises (which I am more than willing to pay for). I would love for another technology to be developed that does not require as many compromises.
Click to expand...
What compromises do you see?
 
Roland Karlsson said:
Roland Karlsson wrote:
Roland Karlsson said:
MediaArchivist wrote:

One downside you did not mention is that used of an apodization element interferes with PDAF (possibly contrast detect also).
Click to expand...
Hmmm ... I wonder why. And if it is generally so., or only with your camera.
Click to expand...
That's the way it is for the a77 and a99, it might work differently with other cameras, or future cameras. There is no focus motor or screw connector, so the lens is 100% manual focus.
Roland Karlsson said:
Roland Karlsson said:
The 135 STF is a tricky lens to use, but you do get the hang of it after many, many shots.
Click to expand...
Whats the problem?
Roland Karlsson said:
I would love for another technology to be developed that does not require as many compromises.
Click to expand...
What compromises do you see?
Click to expand...
There are only two problems/compromises: lack of AF and maximum (effective) aperture of f/4.5. Focus peaking mitigates the AF issue. It does not eliminate it, but MF is hardly a chore and I still get lots of keepers. Since the lens' aperture opens to (technically) f/2.8, I can't help but wonder (dream) if one could be made at 85mm with a f/1.4 aperture, yielding an effective f/2.4 (or so). But of course, that would mean other compromises. As it is, even wide open the 135 STF has zero vignetting on FF, as well as almost no loss in sharpness corner to corner. So I really have little to complain about :)
 
MediaArchivist said:
MediaArchivist wrote:
MediaArchivist said:
Roland Karlsson wrote:
MediaArchivist said:
MediaArchivist wrote:

One downside you did not mention is that used of an apodization element interferes with PDAF (possibly contrast detect also).
Click to expand...
Hmmm ... I wonder why. And if it is generally so., or only with your camera.
Click to expand...
That's the way it is for the a77 and a99, it might work differently with other cameras, or future cameras. There is no focus motor or screw connector, so the lens is 100% manual focus.
Click to expand...
OK
MediaArchivist said:
MediaArchivist said:
MediaArchivist said:
The 135 STF is a tricky lens to use, but you do get the hang of it after many, many shots.
Click to expand...
Whats the problem?
MediaArchivist said:
I would love for another technology to be developed that does not require as many compromises.
Click to expand...
What compromises do you see?
Click to expand...
There are only two problems/compromises: lack of AF and maximum (effective) aperture of f/4.5. Focus peaking mitigates the AF issue. It does not eliminate it, but MF is hardly a chore and I still get lots of keepers. Since the lens' aperture opens to (technically) f/2.8, I can't help but wonder (dream) if one could be made at 85mm with a f/1.4 aperture, yielding an effective f/2.4 (or so). But of course, that would mean other compromises. As it is, even wide open the 135 STF has zero vignetting on FF, as well as almost no loss in sharpness corner to corner. So I really have little to complain about :)
Click to expand...
Lack of AF I can live with.

F4.5 I can live with.

The main problem for me is that I use Pentax SLR cameras.

So ... to be able to use the lens I have to get a Sony camera or a mirror less with adapter.

The lens is rather reasonable priced on eBay.

--
/Roland
X3F tools:
http://www.proxel.se/x3f.html
https://github.com/rolkar/x3f
 
Last edited:
rubank said:
rubank wrote:
Click to expand...
rubank said:
Can´t this be done in software, in-camera?
Click to expand...
In principle deconvolution software can remove or at least reduce the blur from diffraction, but this would require a sensor with a high pixel density which can record an accurate image of the shape of the blur.
 
D Cox said:
D Cox wrote:
D Cox said:
rubank wrote:

Can´t this be done in software, in-camera?
Click to expand...
In principle deconvolution software can remove or at least reduce the blur from diffraction, but this would require a sensor with a high pixel density which can record an accurate image of the shape of the blur.
Click to expand...
Apodization is not about removing blur, rather the opposite. It adds two things to the image.
  1. It makes the OOF blur really unsharp, i.e. smooth.
  2. It makes the in focus parts to have higher quality. This is more subtle and may, or may not, have any real significance.
And regarding removing diffraction blur. That is much easier to do if the lens is an apodization lens. Otherwise it is hard to understand what is detail and what is an OOF artefact.

But, the easiest way to remove OOF blur I think is to use a coded aperture. That is an aperture with an unique form so that it is easy to find in the unsharp parts. But, I assume there is a risk for strange artefacts and noise doing so.

--
/Roland
X3F tools:
github.com

GitHub - rolkar/x3f: Tools for manipulating X3F files from Sigma cameras

Tools for manipulating X3F files from Sigma cameras - rolkar/x3f
github.com github.com
 
Roland Karlsson said:
Roland Karlsson wrote:
Apodization is not about removing blur, rather the opposite. It adds two things to the image.
  1. It makes the OOF blur really unsharp, i.e. smooth.
  2. It makes the in focus parts to have higher quality. This is more subtle and may, or may not, have any real significance.
Click to expand...
The quality improvement in the in focus parts is due to a reduction in diffraction.
Roland Karlsson said:
And regarding removing diffraction blur. That is much easier to do if the lens is an apodization lens. Otherwise it is hard to understand what is detail and what is an OOF artefact.
Click to expand...
Roland Karlsson said:
But, the easiest way to remove OOF blur I think is to use a coded aperture. That is an aperture with an unique form so that it is easy to find in the unsharp parts. But, I assume there is a risk for strange artefacts and noise doing so.
Click to expand...
You can get smooth bokeh without using apodisation. It seems to depend on how perfectly circular the aperture is, and on where it is in the lens.
 
D Cox said:
D Cox wrote:

The quality improvement in the in focus parts is due to a reduction in diffraction.
Click to expand...
Yes, it both reduces diffraction and make the diffraction cleaner.

This is one of the reasons why I started this thread. I really think apodization lenses is one important method for achieving maximal image quality. It is a pity that the world does not understand that :)
D Cox said:
D Cox said:
And regarding removing diffraction blur. That is much easier to do if the lens is an apodization lens. Otherwise it is hard to understand what is detail and what is an OOF artefact.

But, the easiest way to remove OOF blur I think is to use a coded aperture. That is an aperture with an unique form so that it is easy to find in the unsharp parts. But, I assume there is a risk for strange artefacts and noise doing so.
Click to expand...
You can get smooth bokeh without using apodisation. It seems to depend on how perfectly circular the aperture is, and on where it is in the lens.
Click to expand...
You can get smoother bokeh by introducing spherical aberration. Look a bit down on this page.

http://www.bokehtests.com/styled/

You then get nice smooth bokeh behind sharp objects. But, unfortunately, you get two problems. The bokeh in front of the sharp object will be ring bokeh (ouch!) and the image will not be entirely sharp, when in focus.

This is the other reason I started this thread. Smooth bokeh I like.

--
/Roland
X3F tools:
http://www.proxel.se/x3f.html
https://github.com/rolkar/x3f
 
Last edited:
jonas ar said:
jonas ar wrote:

Although maybe not perfect, an interesting experiment

Markus Keinath - Apodization-Filter
Click to expand...
Yeah, I have seen that one. I have some Helios lenses and also a Jupiter lens. So, I might try it.

I assume positive film is not perfect as optical element. But, maybe it is good enough. It is made for being used in a projector.
 
Interesting.

With the current popularity of adapters for fitting older lenses to (short register distance) mirror-less cameras, might it be possible to build an adapter that also contained some interesting light-modifiers (at the right distance from the sensor)?

I'd be interested in a mechanically rotated wheel (ala the colour wheel used in certain image applications) that contained e.g. perfectly circular (top hat) apertures, gradually faded apertures (Apodization) and apertures incorporating ND-filtering (less light). Perhaps odd shapes (stars, encoded apertures) might be interesting as well...

-h
 
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