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

[carpents]

Originally Posted by lithos

Hmmm...

I admit, I like "technically imperfect" bokeh as much, if not more, than the perfect Gaussian stuff. The perfect stuff could've been done in Photoshop...

Sort of - just because the lens is perfect doesn't mean the photos are. But I would much rather have such a lens on my camera, as it certainly won't hurt the end result.

(And sometimes it is really hard to mimic in Photoshop, especially when the line between focus and out-of-focus is disjointed.)

Originally Posted by lithos

Anyone wanna give me some feedback on mine, please ?

As they pertain to this thread, they all fail Jonas' request for no hard edges. If you want an overall critique, why not post them in the 'Critique' section or even in the 'Post Your Photos' one? They're good shots.

[carpents]

Originally Posted by jake.astig

I like the bokeh of my SMC Pentax A 50mm 1.7.



Also the Super Takumar 55mm 1.8

Your top photo shows hard edges pretty seriously. Check out the difference between that shot and Abbazz's shot with the Takumar 58mm.

The bottom photo doesn't really say much about the bokeh of the lens. Pretty much any wide aperture lens would produce the same result from focusing on a very close object when the background is distant. It is analogous to trying to tell if someone is good at golf by watching them sink a three-inch putt!

[carpents]

Originally Posted by hinckc

It suddenly made sense to me why it seems to me that the FA-J 75-300 "mis-focuses" so frequently.

The OOF dispersion circles in the FA-J 75-300 is much like "example #1" or even more "example #2" of Jonas' blur dispersion examples nabbed from Ken Rockwell's site, though more like #2. The OOF area itself has "sharp edges" between contrast areas. I'm guessing that this causes the AF's contrast meter to decide the scene/subject is "in focus" and thus the high % of shots where AF is confirmed, but is actually short of "correct" focus.

I never thought about it - the contrast in the hard edges of the bokeh is throwing off the auto-focus. Interesting hypothesis.

Originally Posted by hinckc

You can see what I mean in this "100% crop" of this picture. It's @ 300mm-f/5.8-1/250s-ISO200, wide open and full zoom. The greens bleed through the wings of the plane in the OOF background.

Part of this looks like regular old CA (white objects against dark backgrounds are tough) but there is also some camera shake. I don't doubt that the FA-J lenses are troublesome in their bokeh, but this crop is probably hurt by other effects.

[d.bradley]

To throw something completely different into the bokeh mix, check out these examples:





Shot with the Minolta 35/1.4, you can see concentric circular texture in the specular highlights...never figured that one out...

[borno]

Thats strange looking db, gives a new meaning to circle of confusion

[carpents]

Originally Posted by d.bradley

Shot with the Minolta 35/1.4, you can see concentric circular texture in the specular highlights...never figured that one out...

Maybe internal flare?

[creampuff]

The concentric circular texture could be due to the aspherical element. I have seen shots with the Voigtlander 40mm f/2 which also has an aspherical element and the specular highlights look similar. Perhaps someone with a FA 31mm f/1.8 Ltd can post some images as it too uses an aspherical lens element.

[OniFactor]

carpents, what do you think of the boke from the beercan? since we're getting on about minolta equipment, lol

[carpents]

Originally Posted by OniFactor

carpents, what do you think of the boke from the beercan? since we're getting on about minolta equipment, lol

I love the beercan. (Minolta 70-210/4 for those who don't know.) It sometimes makes me wonder about the Pentax-A 70-210/4, and I'm a little surprised that the Pentax doesn't have the cult following that the beercan does. Maybe because the Pentax isn't autofocus?

I love this shot that I took with a beercan, although it doesn't talk too much towards its bokeh as much as just nice overall rendering:


My good friend Kathy has a copy of this lens. It has some blue/red fringing, but overall it renders very nicely. See the following for some bokeh shots with it (all shots are clickable for bigger sizes):


Good foreground here:


Some blue fringing in the bottom right on this one:



One of the Minolta lenses that I love (possibly because it is a bargain) is the regular 135/2.8. See this shot:

[Abbazz]

This morning, I did some more testing with the Takumar 58/2.4 with busy backgrounds featuring some highlights. Here are 3 pictures taken at f/4 (sorry for the boring flower shots):







I also made a few similar shots with the SMC-Takumar 100/4 Macro as a comparison, as this lens is also a Heliar type lens, just as the Takumar 58/2.4. Here are three pictures taken at f/4 (wide open):







Of course the 100mm at f/4 has much shallower depth of field than the 58mm at f/4, but the two lens have indubitably the same pleasant rendering. The only problem of the 100mm lens is that it features a 6 blade iris, which produces some unpleasant shapes when stopped down, compared to the clean bokeh of the nearly circular 10 blade iris of the 58mm lens.

Cheers!

Abbazz

[carpents]

Originally Posted by creampuff

The concentric circular texture could be due to the aspherical element. I have seen shots with the Voigtlander 40mm f/2 which also has an aspherical element and the specular highlights look similar. Perhaps someone with a FA 31mm f/1.8 Ltd can post some images as it too uses an aspherical lens element.

Look at that. I love it when I learn something new.

These are my party lights, taken with the 31/1.8 Limited:


A 100% crop of the middle light:

[d.bradley]

VERY cool sean! Identical pattern to the minolta!! So you think it's the aspherical element?

This is actually not insignificant in terms of specular highlight rendering, imho...

Good eye.

[carpents]

Originally Posted by d.bradley

VERY cool sean! Identical pattern to the minolta!! So you think it's the aspherical element?

This is actually not insignificant in terms of specular highlight rendering, imho...

Good eye.

I think the credit goes to creampuff - I just followed his instructions! I agree, it certainly impacts highlight rendering, but I have heard complaints about the bokeh of aspherical lenses in general. This is probably one of the reasons why.

[carpents]

I have one more thought on this subject. I came up with an idea using the Minolta 135 STF that we've talked about so much here - we can call it my invention. If you steal my invention and market it, I just ask that you give me a bunch for free in 49mm, 52mm, and 67mm filter threads.

So, take a look at this link:
Create Your Own Bokeh (Warning - kitsch link)

My invention is this: take this idea of putting strangely-shaped cover over the lens and replace it with a graduated neutral density filter. The filter must have the gradations in a concentric circular pattern - darker towards the edges than in the middle. This will result in a softening of those out-of-focus highlights, creating a nice Gaussian blur instead of the typical hard edges. This might also help correct axial chromatic aberrations, which we've established here are pretty common.

What do you think?

[blende8]

I think these filters are already available. Just do a test.