Strange Aero Ektar results (bokeh?)

Denis P. · Oct 23, 2005

Hi,

I finally managed to hack a mount for Aero Ektar 178/2.5 for my 4x5 Speed Graphic, and yesterday I took some test shots.

Aside from the subject(s) who wouldn't stand still, I noticed rather strange bokeh in the upper part of photos - see attached scans.

I admit I haven't seen many Aero Ektar shots before (only David Burnett's campaign shots and a few shots from Frank Peronio, all online), but these look strange...

Are those harsh "circles" normal? I suspect the lens might have been disassembled and incorrectly assembled again... Since such "effects" are usually result of improper spacing between elements or incorrect orientation of one of the elements...

Both elements on my lens look relatively OK (apart from some imperfections in the back element, like tiny drops/smudges of oil).

Any ideas as to reason for such harsh bokeh artifacts?

Just the way Aero Ektar behaves, or should it be better?

Regards,

Denis

PS: Efke PL100, Rodinal 1+60, 5 minutes, JOBO processor (high speed )

medform-norm · Oct 23, 2005

I would place my bet on a lens design issue, although I find it difficult to explain my reasoning. Something to do with the diffraction of light inside the lens affecting mainly the highlights in your shots at the borders of the image. Maybe someone more at home in the lens tech jargon could step in and explain?

Regards, Norm

df cardwell · Oct 23, 2005

Anybody recall the intended lens-to-subject distance of an Aero Ektar ?

.

Denis P. · Oct 23, 2005

df cardwell said:
Anybody recall the intended lens-to-subject distance of an Aero Ektar ?

I'm aware it was intended for aerial photography (i.e. to be used at infinity)....

However, several other shots I've seen on the Web show that it can be used at closer ranges - and quite successfully.

Perhaps it is just a lighting situation which Aero Ektar doesn't handle well: this type of shot (light coming through the leaves in the background) is my standard "rigorous lens bokeh test", and there are many lenses which are otherwise OK, but in this particular situation produce similarly harsh OOF results (to a lesser degree, though...).

Denis

df cardwell · Oct 23, 2005

Through an unsymmetrical double gauss type lens, optimized for a very great distance, and shot wide open, I'm not surpised at the out-of-focus effects of the light through leaves. This is like shooting a 50 mm lens at f/ .7 !

Since so many Aero Ektars were military surplus, and purchased by folks curious what was inside, many, if not most, were disassembled by folks incapable of correctly re-assembling them. I would not be surprised, therefore, if the spacing is not as Mr. Aklin intended. Aeros are one of those lenses home mechanics need to show proper respect .

I see some optical vignetting and some spherical abberation. Stopping down would help. On the whole, it doesn't seem fatal, and most of the character of the image, to me at least, is due to the huge aperture, and the working distance.

It's a wonderful and amazing lens: don't give up on it !

.

jd callow · Oct 23, 2005

I love the out of focus areas. What bothers me is what appears to be flare. I suspect the lens needs a shade and that it might not be coated or coated well.

I would love to see what this lens does with colour.

OTOH I am no expert and a scan is a crapy way to judge flare.

Denis P. · Oct 23, 2005

df cardwell said:
Since so many Aero Ektars were military surplus, and purchased by folks curious what was inside, many, if not most, were disassembled by folks incapable of correctly re-assembling them. I would not be surprised, therefore, if the spacing is not as Mr. Aklin intended. Aeros are one of those lenses home mechanics need to show proper respect .

Thanks for the warning. I suspect the lens might have been disassembled previously - but there are no obvious marks of mishandling.

Also, your comment above discouraged me from trying any DIY "repairs"

Anyway, I still have to "cure" it a bit - it's still yellowish, so I'll have to let it soak the sun for a few days (not easy here, we've been lucky with a few sunny days lately, though...). Otherwise, I'll have to get a UV lamp

Anyway, I'll have to shoot some more with it, see what it does in different bacgkround light, at different distances.

Denis

Denis P. · Oct 23, 2005

mrcallow said:
I love the out of focus areas. What bothers me is what appears to be flare. I suspect the lens needs a shade and that it might not be coated or coated well.

I would love to see what this lens does with colour.

There might be some flare - I used the original lens "shade" (very wide and shallow), nothing extra, so flare is quite possible.

I don't know about coating - although it seems like it has some kind of coating (bluish reflection).

As for color shots, I won't do any for a while - at least until I get rid of the yellowing (see my reply above) - the back element is yellow, and several sources on the Web suggest that exposing the lens to sunlight or a good UV lamp might help to improve it.

You can check out Frank Petronio's blog: http://frankpetronio.com/archive/200507.html
- he has several very nice color shots (portraits) with Aero Ektar.

Denis

jd callow · Oct 23, 2005

If the lens has an "L" inside of a circle near the name or S/N than it is coated. To my knowledge most professional Kodak lenses were single coated after ~1939.

Denis P. · Oct 23, 2005

mrcallow said:
If the lens has an "L" inside of a circle near the name or S/N than it is coated. To my knowledge most professional Kodak lenses were single coated after ~1939.

No "L" (for "Lumenized") that I can see. That designation ("L") is true for "general public" lenses, like the usual Ektars sold with Speed Graphic cameras, but perhaps the Aero Ektars did not have that marking at all? - given that they were special purpose lenses, not intended for "general public" - and available to the "general public" only after the war, as surplus...?

Anyway, the photo of the lens is attached - a bluish reflection can be seen - although I can't vouch for the color balance of my dig**al toy.

Denis

jd callow · Oct 23, 2005

Assuming that the S/N conventions used on their other lenses is the same for this lens and that the first 2 digits are 'E's than I would assume the lens to be made in 1944. In my not so expert opinion (based upon my internet reading -- could their be a more suspect source of information?) is that it is probably luminized/coated.

Anyways who cares? It looks to be a fine fine lens (albeit with funky bokeh). I'm jealous I've wanted one of these monsters ever since I learned of their existence.

MichaelBriggs · Oct 23, 2005

All the Aero-Ektars that I have examined are coated. Kingslake in his article on WWII aerial lenses says that all Kodak WWII aerial lenses were coated: the very first soft coated, later ones hard coated. The hard coating is probably vacumn deposited magnesium fluouride. The Aero-Ektars I have seen are hard coated. I think that Kodak started the Luminized term and circle-L symbol after the War, for marketing to civilians.

The mechanical construction of the 7 inch Aero-Ektar is fairly simple and it would take incompetence to get the spacing wrong in putting the lens back together.

Have you seen my page on the Aero-Ektars? http://home.earthlink.net/~michaelbriggs/aeroektar/aeroektar.html

With a BLB blacklight fluorescent bulb, it takes week to clear the color. I haven't tried sunlight.

Denis P. · Oct 23, 2005

MichaelBriggs said:
The mechanical construction of the 7 inch Aero-Ektar is fairly simple and it would take incompetence to get the spacing wrong in putting the lens back together.

Have you seen my page on the Aero-Ektars? http://home.earthlink.net/~michaelbriggs/aeroektar/aeroektar.html

With a BLB blacklight fluorescent bulb, it takes week to clear the color. I haven't tried sunlight.

Thanks for the info about lens construction, Michael.

Yes, I've seen your Web site - it was my main source of reliable data on lens radioactivity. Suffice to say I don't keep it stored in the same room with me. It lives in the attic.

Funny thing, I was just thinking these days I should send you the info about my specimen, as soon as I get some spare time. But now you don't need that, once you saw the actual photo of the lens

The S/N is EE2260, in case it's not readable... Same S/N is also "scratched" on the front and rear element barrel - so no monkey business there
No dots of any color...

I guess the funky bokeh is not due to improper assembly, since the seller (a friend) told me he did not do any disassembly, and the lens looks the same as the other two Aero Ektars that he has.

Denis

Phillip P. Dimor · Oct 23, 2005

My results are somewhat similar when shooting into specular light wide open.

I made a lens hood out of an oatmeal cannister that was spray painted flat black.
Not pretty but it works.
Also, if your lens is strongly tea-colored (due to the thorium radiation) you can bleach it out under a strong UV source (sunlight)..

My sample is very sharp stopped down as well. Nice pictures!

Frank Petronio · Oct 23, 2005

I don't think the circles in the highlight area are odd at all. That's what happens in the burned out areas with any "bokeh" type lens with a nice round aperture opening. If you want to see ugly circles, try stopping down the five blade aperture of a 50/1.4 and doing the same photo - you'll get really horrid pentagons. So be glad you get circles from the Aero-Ektar.

Thanks for the compliments. To be honest I no longer use one -- I use digital and a sharp lens, plus lots of Photoshop. Sorry...

laz · Oct 23, 2005

Denis P. said:
Anyway, I still have to "cure" it a bit - it's still yellowish, so I'll have to let it soak the sun for a few days (not easy here, we've been lucky with a few sunny days lately, though...). Otherwise, I'll have to get a UV lamp

Okay, I give up, What the heck are you talking about?
Confused Bob

MichaelBriggs · Oct 23, 2005

laz said:
Okay, I give up, What the heck are you talking about?
Confused Bob

The WWII Aero-Ektars were the first lenses to use glass with thorium. Thorium is mildly radioactive, and with time damages the glass, forming what are called color centers. This imparts a color that most people call yellow. I prefer tea oramber. This color obviously reduces the light transmission of the lens. The color can be bleached away with UV light -- the UV removes remove the electrons from the color centers.

There are many non-military lenses with thorium glass, up to circa 1970: from Kodak, Schneider, Pentax, Nikon, Voigtalnder, ....

laz · Oct 23, 2005

MichaelBriggs said:
The WWII Aero-Ektars were the first lenses to use glass with thorium.

Thanks! Very intriguing; time to Google!

Lee L · Oct 23, 2005

Nothing definitive, just my observation and comments.

Looks like nisen boke(h) (AKA cross-eyed or double line bokeh) to me; the bright hard edges and darker center on specular highlights, and notice the edge of the wall doubling up into separate vertical lines instead of a smooth, even transition. FWIW, what I've read claims this is a product of overcorrected spherical abberation.

Look at the OOF spectral highlights on the Frank Petrino site, in the photo of the blonde in the green top with sequins. I see the same thing there, so it may be characteristic of the lens, and not a result of mis-assembly of your sample. Just noticed when closing that browser tab, look at the gold cross on her necklace, it's a good example of double line (nisen) bokeh.

Lee

Ole · Oct 24, 2005

Looks like overcorrected spherical aberration to me too!

But remember that these lenses were corrected for infinity, so it is very likely that pictorial qualities beyond the focal plane were not exactly a priority.

Not that most telephoto lenses are precisely opposite - nice blur behind, really ugly in front. It's all got to do with the priorities in the design, which are again determined by the intended use of the lens.

Robb Scharetg · Oct 24, 2005

"Strange Bokeh"

Hi Denis

I have a few of those Aero lenses as well as other fast glass. My experience has been that when you're shooting wide open, especially when your subjects are backlit any point source of light (in this case it looks like reflections of light off tree leaves)will end up looking like the circles of light you have in the top part of your frame. You'll get this with fast, old glass. And if it's color the flare will kill your contrast. But, FWIW I think your shots look good. Keep at it.

Robb Scharetg

Murray@uptowngallery · Feb 24, 2006

Aero-Ektar disassembly

I'll defer to anyone who disagrees because I have not done much with mine other than look at them (309 mm f/2.5, 610 mm f/6).

I was going to doubt that any disassembly other than front/rear cell separation was done because 1) the elements are cemented and 2)maybe I'm a puny weakling, but you need some serious tools to get stuff out of a lens that diameter.

My 12" lens is in a very strange greenish brass barrel; looks like a 35mm conversion down to a 1.5" exit aperture on a helicoid. I could not figure out how this lens could ever possibly cover a 9.5" square negative with that 'funnel' at the back. Removal quickly answered that question.

The 610 mm I have never even been able to separate the front & back from...I gave up. It's still in the shutter, so I'll just learn to use it like that.

The rest of you echoed all my other thoughts about bokeh personality types, usage at other-than-intended distance, etc.

Michael, can you clarify your color center clearing statement...you wrote 'takes week to clear'.

Is that approximately 'a' week, or unspecified weeks. I know it will vary with lamp used.

One more thought, regarding flare. A homebrew lens hood for those beasts has puzzled me for some time. Maybe a 1 gallon plastic bottle cut & spray painted flat black.

I don't know how often they pointed horizontally in aircraft, and if they were always pointed down toward the ground. I suppose there was always the flash bomb used in night photography to cause flare, always at lower altitude than the camera.

Oh, and I don't think any of the Aero Ektars were 'simply' double gauss like the Hypergon/Metrogon/Zeiss-Richter-I forget-what-o-gon. I recall reading that the Aeros varied from 6 to 7 elements and at least one was a Biotar. Maybe these are extensions of double Gauss...I just read alot.

Another error in my rambling...some of the Metro types were actually 5 element.

MichaelBriggs · Feb 24, 2006

Murray, after these lenses were surplused, various conversions were done. Likely you have one of these, which could no longer cover 9 x 9 inches in its modified form.

I have taken apart a couple of Aero-Ektars, though of course not the cemented elements. Its fairly easy. The trick is that a large threaded collar may be locked with a very small screw from the side. Once you find and remove the cross screw, disassembly is fairly easy. Old Schneider lenses tend to include similar locking screws.

I meants to say "several weeks" (plural) to clear the tea color from the color centers using BLB fluorscent bulbs.

MichaelBriggs · Feb 24, 2006

Murray@uptowngallery said:
......
Oh, and I don't think any of the Aero Ektars were 'simply' double gauss like the Hypergon/Metrogon/Zeiss-Richter-I forget-what-o-gon. I recall reading that the Aeros varied from 6 to 7 elements and at least one was a Biotar. Maybe these are extensions of double Gauss...I just read alot..

Most of the Aero-Ektars are double-Gauss variants, and so you are correct to say that they are not simply double gauss lenses -- see p. 124 of Kingslake, A History of the Photographic Lens, for the 7 and 12 inch f2.5 versions -- 7 elements in 4 groups. (But he mis-states the coverage of the 7 inch version, confusing it with the later 6 inch.)

The 24 inch f6 is a tessar. The 36 inch is some sort of telephoto.

JG Motamedi · Feb 24, 2006

In the late 1930s and early 1940s Eastman Kodak also produced a 13.5" f3.5 aerial lens, some were labeled Aero-Ektar and others as Eastman Anastigmat. These were not Double-Gauss but appear to be some variant of the triplet/heliar. To my knowledge very few were produced, although I have seen four on eBay over the past 5 years. Two, labeled Aero-Ektar from 1942 (EA), exhibited the "tea colored" stains Michael describes. The other two, labeled Eastman Anastigmat from ~1939 (serial no. 116, before "CAMEROSITY" dating) and 1940 (EY) did not have these stains.

For what it is worth, I have found the busy bokeh described above to be present in all of the 7" Double-Gauss type Aero-Ektars I have examined. Consequently, I don't find them to produce a very pleasant look for my less-than-aerial purposes. IMHO The triplet/heliar type produce a much nicer bokeh and look.

Strange Aero Ektar results (bokeh?)

Denis P.

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