Bokeh, Specular Highlights, Guess The Lens - A Surprising Result

carpents · 01-08-2008, 11:33 PM

I read through a fascinating thread over at the Bad Forum:
A specific question on bokeh, by JonasB

From his thread:

My question: What lenses, any brand and in the FL range 50-100mm, do you know of that consistently produces either good or neutral background bokeh according to the definitions *below*? I'm interested in the rendering abilities wide open, and stopped down 1 and 2 stops.

Hint: Don't give me the SMC 50/1.4 or FA31 or A85/1.4 or... According to this somewhat tough definition they don't consistently produces good or neutral background bokeh. They can all render beautiful pictures that are pleasing to the eyes, but this is purely about the rendering of background highlights at different distances.

You can read the rest of his thread (and the many great responses) if you're so inclined. I point this out because: (a) I missed it before; (b) we can talk about it here, and; (c) I have a lens that produces 'good' highlight bokeh by Jonas' definition.

So...here is my 'test shot' that I took (wide open) for Jonas:

And here is a crop of the highlights at 9 o'clock:

Anyway, I think it is a fascinating subject, even if it rarely shows itself in 'real world' shooting. Anyone care to guess the lens I used? (No one will guess it. Yes it is a Pentax.) Anyone have any of their own to add? Has anyone used the Nikon DC (Defocus Control) lenses? How about those Canon L lenses?

**roentarre** · 01-09-2008, 01:07 AM

Hi Sean. I would have to say this is coming from A 50mm f1.2 that it does high light source really well in the bokeh department.

Last time I received an email from Jonas was still about rumination of bokeh quality and I paid him respect for his relentless pursuit of bokeh analysis in which it is subjected to personal preference and background matters. He is now paying a lot of attention into foreground bokeh and making up his mind on Voigtlander 58mm f1.4 in which I am waiting for its arrival to my doorstep.

I can add a few bokeh shots from my Canon L prime lens bokeh. In general, Canon bokeh tends to be lower contrast (that I had to enhance them myself) but handle the highlight source quite well in the bokeh. My favorite primes in the L line up are 24/1.4L 50/1.2L and 85/1.2L

24/1.4L

50/1.2L

85/1.2L

With the pentax lenses,

DFA 100 macro - bokeh prone to clipping

Fa 31 Ltd handles highlight bokeh better than other Fa ltd

A* 200mm macro - handles light source and foreground poorly

Fa 77 ltd is an all round lens with bokeh

Fa 43 bokeh is so so

Fa* 300/4.5 + Fa* 80-200 do well with green background bokeh only

A 50 f1.2 is an all round lens with pleasing bokeh and I personally think this lens beats Canon 50/1.2 easily in the optical department. Jonas aggreed with that too.

A* 300/2.8 bokeh is just purely creamy and nice but the subject focus is always an issue.

These are just my ramblings.

blende8 · 01-09-2008, 01:15 AM

Let's say that you have different lenses of the same focal length and all are stopped down to the same value and you photograph the same scene:
Has the OOF circle of confusion the same size always?
I think, not sure, that it possibly depends on the position of the apperture within the lens.
If this is true, the lens with the larger circle is probably "nicer".

If the circle has a defined border depends on (over)correction of certain lens aberrations.
You always have to strike a balance between everything.
So, often lenses that show a "neutral bokeh" are not the best in the DoF area.

Gruoso · 01-09-2008, 06:03 AM

Super takumar 50 f1.4?

*borno* · 01-09-2008, 06:31 AM

O.K. I'll guess a takumar 105 f2.8 wide open (I've got a really old pre-set one)

d.bradley · 01-09-2008, 07:19 AM

85mm f2.2 soft focus is my guess

deejjjaaaa · 01-09-2008, 07:24 AM

> 24/1.4L

ugly one !

kenyee · 01-09-2008, 07:49 AM

roentarre: thanks for posting those pics from L lenses...I'm always curious how Pentax lenses compare :-)
I'd rank the bokeh 50/1.2, 85/1.2, then 28/1.4.
So given those samples, I think carpents is running a 50mm lens ;-)

carpents · 01-09-2008, 08:29 AM

Originally Posted by Gruoso

Super takumar 50 f1.4?

Nope! Although that lens is capable of excellent results, the shot below (click for bigger size) shows that it easily fails Jonas' test:

Originally Posted by borno

O.K. I'll guess a takumar 105 f2.8 wide open (I've got a really old pre-set one)

Nope! This lens is sharp as a tack, but IMO that comes at the expense of the bokeh.

Originally Posted by d.bradley

85mm f2.2 soft focus is my guess

Nope, I don't own one of those. I think Jim King offered to show those in Jonas' thread, but I didn't see the images.

Originally Posted by deejjjaaaa

> 24/1.4L

ugly one !

(I agree!)

Originally Posted by kenyee

So given those samples, I think carpents is running a 50mm lens ;-)

Oooh, so close...

carpents · 01-09-2008, 08:33 AM

Originally Posted by blende8

If the circle has a defined border depends on (over)correction of certain lens aberrations.
You always have to strike a balance between everything.
So, often lenses that show a "neutral bokeh" are not the best in the DoF area.

Yes, I think that was one of the conclusions you can get from Jonas' thread. This is a very specific thing IMO - how the lens renders highlights in the out-of-focus region within 2 stops of wide open. Many Pentax lenses perform spectacularly on green or muted backgrounds (like the 77 Limited) but do poorly when, for example, shooting the guitar shot I posted above. Someone in Jonas' thread posted amazing shots with a 300/4.5 - only to have someone else show up with awful shots from the same lens. It is as much about subject/background as it is about the lens itself.

d.bradley · 01-09-2008, 08:38 AM

Sean so it's gotta abe a 55mm or a helios 40mm.

You know with all that talk of perfect bokeh, I have to admit that the shots taken with the Minolta STF I find are sometimes rather boring. It's a real love-hate relationship with images from that lens...linky

carpents · 01-09-2008, 08:40 AM

Originally Posted by roentarre

Hi Sean. I would have to say this is coming from A 50mm f1.2 that it does high light source really well in the bokeh department.

50/1.2L

Hi James!

I think we agree (generally) on bokeh. You and I share tastes and I don't see anything wrong with your Pentax list either. The picture remaining above, however, shows that even the ($$$$$$) Canon 50/1.2L would fail Jonas' test. The highlights in the upper-right corner have serious hard edges.

Anyway, you're guess is only half right! But the A50/1.2 doesn't do exactly what I posted above. Look at the following shot - it does indeed have a pleasant background, but you can see hard edges in the background. It does better in the foreground, but this is one of those shots that shows off the Pentax axial CA - green in the background bokeh, purple in the foreground bokeh.

carpents · 01-09-2008, 08:48 AM

Originally Posted by d.bradley

Sean so it's gotta abe a 55mm or a helios 40mm.

You know with all that talk of perfect bokeh, I have to admit that the shots taken with the Minolta STF I find are sometimes rather boring. It's a real love-hate relationship with images from that lens...linky

Nope! Actually, the Helios-40 does poorly for this characteristic. It does exceedingly well in others though. The Helios-44 does better than its 85mm cousin, but it isn't perfect either.

Now, why are you hating on the STF?!? It is the one and only reason that I still look for Sony to bring out a decent camera! I don't find those pictures in your link boring (from a lens rendering characteristic) at all.

For those who don't know about the Minolta 135 STF (Smooth Transition Focus) lens - it is a one-of-a-kind bokeh machine. It actually has TWO aperture rings (with lots of curved aperture blades in each) which are separated by a disk that has graduated shading towards the edges. This edge darkening minimizes the adverse effects of the aperture blades themselves, as light doesn't go nicely around hard corners. It is a really neat, really unique lens.

blende8 · 01-09-2008, 08:55 AM

Originally Posted by carpents

It is as much about subject/background as it is about the lens itself.

Very true.
Sometimes a lens behaves good, sometimes not so good.
Can one evaluate this scientifically?

carpents · 01-09-2008, 09:03 AM

Originally Posted by blende8

Very true.
Sometimes a lens behaves good, sometimes not so good.
Can one evaluate this scientifically?

Sure you can. It has so many variables, however, that unless you keep a long list of notes with you while shooting it would be difficult to remember them all.

I also might add (and I think this was d.bradley's point above) that just because a lens has 'perfect' bokeh doesn't mean it always makes pretty pictures. I will add that vice versa, just because a lens performs less-than-optimally on a particular setting doesn't mean that it won't produce a profound and moving photograph.