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02-20-2009, 04:04 AM   #166
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Photographers or lens controllers??

much talks about bokeh, backround ect ect.....Comeon! One of the simpliest rules nr.1 in photography is to choose a clear backround, and now people is speaking about a hard bokeh, bokeh, soft bokeh.. bla bla bla....

I think that we are getting to fixed in what the lenses could do for our photos that we forgett the simple rules ....A lens can improve the photography maybe...but we look more like lens controllers then photographers...

it's really sad looking this

02-20-2009, 04:48 AM   #167
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QuoteOriginally posted by jake123 Quote
The Sigma 50mm would be my choice at a lower price with much smoother bokeh.
Well, the Sigma is (only) 13% cheaper (in EU). My main concerns with the Sigma are that is is bulky and that I am concerned how precisely the AF would nail focus.

Has anybody heard about AF precision with DA*55 vs. Sigma50?
QuoteOriginally posted by RaduA Quote
you're wrong and this puppy will have both better and more even resolution than Sigma
I hope so
QuoteOriginally posted by TKH Quote
The mistakes I make with my camera and the DA*55 are greater than the mistakes the lens makes
Maybe, you didn't nail the focus and RaduA is correct. As I said, I hope so.
QuoteOriginally posted by blende8 Quote
Judging bokeh can only be done in comparison with other lenses and this in a controlled environment (tripod ...)
This is only partly true. If you can see a point light source out of focus, you actually can see the defocus PSF. The standard PSF looks like a bright disk with a sharp border. Lenses optimized for great bokeh tend to have a PSF with a somewhat brighter center and a somewhat softer edge, while being perfectly round.

UPDATE:
Some of the DA*55 images actually showcase its PSF. I have cropped the PSF from two of the photos in this thread, and a PSF from photozone's test of the Sigma 50. On the attached image, the left two snippets are from the DA*55 while the right snippet is Sigma 50. All at f/1.4.

It definitely has a dimmer center and quite hard edges. Sometimes, the edge doesn't appear as hard as other times (cf. left and middle center). Nevertheless, a clear tendency to circular rather than disk like PSF.

The Sigma 50 shows signs of an onion-like PSF. Which is criticized as well (only at f/1.4). In comparison, the Pentax PSF is smoother in the inner part but has a much harder border. I think there is enough evidence to be at least concerned about the DA*55 bokeh.

Last edited by falconeye; 06-15-2011 at 05:28 AM.
02-20-2009, 05:15 AM   #168
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QuoteOriginally posted by falconeye Quote
This is only partly true. If you can see a point light source out of focus, you actually can see the defocus PSF. The standard PSF looks like a bright disk with a sharp border. Lenses optimized for great bokeh tend to have a PSF with a somewhat brighter center and a somewhat softer edge, while being perfectly round. Some of the DA*55 images actually showcase its PSF. It definitely has a dimmer center and quite hard edges. A tendency to circular rather than disk like PSF. I think there is enough evidence to criticize the DA*55 bokeh.
This is in theory correct, but I know of no modern lens that does not show such overcorrected SA to a certain extent.
Do you know of a lens that shows "brighter center and a somewhat softer edge" in the background bokeh? I don't.
(Perhaps the old 100mm Macro Heliars? Never tested them.)

Of course it would be nice to have a lens that shows such a bokeh.
But apparently it is not that easy to establish without sacrificing important other parameters.

Well, I am no expert in these matters ...
02-20-2009, 05:23 AM   #169
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QuoteOriginally posted by blende8 Quote
Do you know of a lens that shows "brighter center and a somewhat softer edge" in the background bokeh? I don't.
Well, there seems to be a lens from Sony with a Gaussian PSF. Which is a special lens and has other drawbacks. There simply aren't many lenses "optimized" for great bokeh.

I only mentioned this to illustrate that a good PSF tries to keep its energy near the center, not its border.

I updated my prior post to illustrate why I think that Sigma may have done a somewhat better job in this regard.

P.S.
Lens tests of lenses with apertures wider than f/2 really should contain a radial energy plot of the PSF...


Last edited by falconeye; 02-20-2009 at 05:32 AM.
02-20-2009, 05:24 AM   #170
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QuoteOriginally posted by blende8 Quote
This is in theory correct, but I know of no modern lens that does not show such overcorrected SA to a certain extent.
Do you know of a lens that shows "brighter center and a somewhat softer edge" in the background bokeh? I don't.
(Perhaps the old 100mm Macro Heliars? Never tested them.)
Yes, the Sony STF 135 f f/2.8 [T4.5] comes to mind. This lens has two diaphragms:



And it looks like this:



Samples of wat this lens can do, compared with other lenses:



Real world example:



02-20-2009, 05:32 AM   #171
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TKH, thanks for getting us all going :-)

I have no regrets buying this lens - I just love it. I think it's a perfect compliment to my 31 and 77.

I still hope to compare it to a Nokton and I'll be shooting side by side with a Nikon D700 user with an 85mm f/1.8 soon - that will be an interesting comparsion too.
02-20-2009, 05:56 AM   #172
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@dkittle and @TKH warm thanks for all your efforts in the benefit of the community!

Regards,
Radu
02-20-2009, 05:58 AM   #173
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QuoteOriginally posted by Asahiflex Quote
Yes, the Sony STF 135 f f/2.8 [T4.5] comes to mind.
Right, of course.
Awesome!

I would like to see such a thing from Pentax!

02-20-2009, 06:21 AM   #174
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QuoteOriginally posted by blende8 Quote
Well, perhaps not well phrased.
What I wanted to say is that the bokeh will certainly not be particularly bad, if they put special emphasis on it.
And I don't think that this is only marketing talk.
But also we will not see wonders.
I suspect the bokeh to be similar to the FA50 or Nokton, which are basically identical.
I was thinking the same thing--they must know what they're doing, right?
02-20-2009, 06:37 AM   #175
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QuoteOriginally posted by losecontrol Quote
much talks about bokeh, backround ect ect.....Comeon! One of the simpliest rules nr.1 in photography is to choose a clear backround, and now people is speaking about a hard bokeh, bokeh, soft bokeh.. bla bla bla....

I think that we are getting to fixed in what the lenses could do for our photos that we forgett the simple rules ....A lens can improve the photography maybe...but we look more like lens controllers then photographers...

it's really sad looking this
Welcome to the "Lens Discussion" Forum.
02-20-2009, 07:42 AM   #176
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QuoteOriginally posted by TKH Quote
First of Thanks Don for your pics.
Its very difficult to work with a lens in f1.4. Please note that the DOF is only 2 cm (later edit: wrote first 2mm) in a distance of 1m! So the most pics who dont satisfy can be possible only out of focus.

My result in playing around a few days with the DA*55? Just sold my FA43...

Rainer
how many times must you learn not to sell the FA43
02-20-2009, 10:06 AM   #177
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Oh Simon, you got me...
Its the third time that I sell a copy of the FA43. I think its the last time.
For me the DA35 and the DA*55 are so f...ing good lenses I dont think that I will miss the 43 to mutch.

You Simon as a gunner will understand: I must hurry to reach my fellow believers in our prayer house. The mother of all local derbies: Royal Blues desperate for revenge against Dortmund

So only three new pics to feed the bokeh discussion. All at f1.4:







Keep you fingers crossed for my boys!

Rainer
02-20-2009, 10:13 AM   #178
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QuoteOriginally posted by TKH Quote
Its the third time that I sell a copy of the FA43. I think its the last time.
For me the DA35 and the DA*55 are so f...ing good lenses I dont think that I will miss the 43 to mutch.

...

Rainer
But now you won't be able to do this:





...you'll be back


(edit: yes, that was a f 2.8 43mm bokeh joke--took it on the way to the grocery store last night to see for myself)
02-20-2009, 10:17 AM   #179
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.


OK.


Now this is getting serious.

That bokeh is Nokton-quality, but different.

I'm hereby declaring "bokeh-not-good" declarations completely taste-based, because to my taste, that's excellent.

And I thought I could forget about this lens for a couple months... Thanks a lot. *&^U^%$&^$






.
02-20-2009, 10:41 AM   #180
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The flowers.. I saw another echoing bokeh.
But I must say THX, it will be my main reason not to buy this lens.

As a f/1.4 lens, bokeh quality must be really pleasant as it will be used wide open frequently.
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