Question: Kodak Commercial Ektar lenses for 4X5 view camera

Would appreciate your comments on a few questions regarding Kodak Commercial Ektar lenses for use on a 4X5 view camera equipped with a 158mm (6") square lensboard:

1) I purchased a Commercial Ektar 14" lens on eBay and intend to use it primarily for portraiture. Upon delivery, I examined the lens facing a strong light source with the iris and shutter wide open. I observe (i) slight swirl marks or cleaning marks on the face of the outer lens' element and, perhaps more importantly, (ii) I also notice three very small black specs on the face of the interior lens' element. The minute black specs (about the size of a grain of salt; not consistent with the appearance of organic growth such as mold) quite possibly are flecks of the black paint covering the interior sides of the lens barrel (?).

Question: Will the presence of these black specs affect image quality? Is it recommended that I have the lens professionally disassembled and cleaned, in order to remove the black specs and, if so, what hazard is there, if any, in disassembling, cleaning, and reassembling an Ektar 14" lens (made in 1964)?

2) I have read extensively that the Ektar 14" lens is an exceptionally fine lens (and I did pay a premium for it). Are the 10" and 12" Commercial Ektars equally fine in relation to their 14" counterpart in terms of resolution and contrast. For some of my portraiture work, the 14" lens on a 4X5 is going to be too long. Wondering whether I can achieve the same level of image quality with the Commercial Ektar 10" and 12" lenses as with the 14" lens -- or should I go with a different brand?

3) Finally, with regard to the Commercial Ektar 14" lens I mention in question 1 above, I also note that one side of the outer lens barrel has a slight ding on the edge such that it would be impossible to screw on an appropriately sized filter. Does the presence of a ding in the outer lens barrel suggest that the lens is optically compromised in any way? I see no apparent damage to the lens elements other than the cleaning marks and minute black specs mentioned in the previous two questions?

Your answers and comments, I welcome as a newbie to large format.

Thank you.

I use a 12" Kodak Commercial Ektar on 4x5. It is a good lens for portraiture, which is my main use for it. I wouldn't hesitate, however, to use it even in the most demanding of situations.

To attempt answers to your questions:

1. The speck won't matter one bit. My lens came with a similar spec on the inside of the rear lens component. I screwed it off, blew the speck off, and reinstalled the lens component. If you can't get to the speck that easily, I'd just leave it alone.

2. Yes, quality of Kodak Commercial Ektars are all the same -- excellent.

3. Kodak never envisioned the use of screw-on filters on the 10 and 12 inch Commercial Ektars; they use Series VIII slip-on adapters, 2-1/8 and 2-1/2 inch respectively. The 14 inch, according to the spec sheet, uses Series IX and a No. 91 screw-in adapter. I think that's 72mm. .

The Commercial Ektars were well-made four-element tessars with coated lenses. The tessar design works very well when stopped down, and these were limited to f/6.3 to ensure that they were stopped down to some extent. (The regular Ektars were f/4.5 lenses.) The main limitation to the tessar design is its lack of coverage, but for lenses longer than normal, coverage is not an issue and the tessars work at their best.

Specks such as you mention have zero effect. Dust has very little effect, unless it is on the front surface and the lens is inadequately shaded. It would probably be difficult to find a coated lens of that era that didn't show some cleaning marks--the coatings were a bit softer and photographers weren't yet anal about what they used to wipe their lenses. Again, there should be no effect of minor cleaning marks.

I have a 12" Caltar, which was Ilex's copy of the Commercial Ektar made for a few years after Kodak stopped making large-format lenses. It is also quite excellent. That particular implementation of the tessar was a good one.

Rick "who likes the look of tessar lenses for portraiture" Denney

Rick cites coorect and common wisdom on stopping down Tessar formula lenses, but that is not much of an issue for portraiture.

Here is example of 12 inch Kodak Commercial Ektar wide open. (a bit of rise or fall; no filter. HP5+, I think)

The Commercial Ektars are Kodak's very finest lenses. Cleaning marks are common on these, as they were heavily used. It shouldn't affect anything, nor should the specks. I have what is probably one of the very few 14" Commercial Ektars that has no flaws whatsoever. Very uncommon to find. Your lens barrel can be fixed with the proper tool. I forgot what they call it but it's made to straighten those dings. A large supplier like B&H surely has them. Filter size is 72mm.

My CE looked like the guy before missed with the metal cap daily and you wouldn't know it. Sanitary negs like a clean backside though.

Quote:

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Originally Posted by rdenney

The Commercial Ektars were well-made four-element tessars with coated lenses. The tessar design works very well when stopped down, and these were limited to f/6.3 to ensure that they were stopped down to some extent. (The regular Ektars were f/4.5 lenses.) The main limitation to the tessar design is its lack of coverage, but for lenses longer than normal, coverage is not an issue and the tessars work at their best.<snip>

Rick "who likes the look of tessar lenses for portraiture" Denney

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Rick, f/6.3 Tessars don't have the same prescription as the faster ones. An f/6.3 Tessar isn't simply a faster one (f/4.5, f/3.5, f/2.8) in a shutter whose diaphragm won't open wide enough to let the lens be used at full aperture.

One of f/6.3 Tessars' charms is that they have more coverage than f/4.5ers. Depending on who you ask -- I won't take a position -- they'll cover as much as 70 degrees. I have an 85/6.3 that covers, as in "puts good image in the corners," 2x3 at f/11.

Cheers,

Dan "lenses' trade names and cross-sections aren't prescriptions" Fromm

Quote:

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Originally Posted by Dan Fromm

Rick, f/6.3 Tessars don't have the same prescription as the faster ones.

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Didn't mean to imply such. Thanks for the clarification.

They are still, of course, tessar designs. But the designs on the slower versions are optimized around the smaller maximum aperture, giving them more coverage and better performance at their widest aperture.

The word prescription is not a term I have used, but to me it refers to the basic design of the lens, before being optimized for the specific application. For example, there are fast Sonnars and not-as-fast Sonnars, and they vary in the number of elements, focal length, coverage, and so on, but they are still the basic Sonnar/Ernostar design, subject to subsequent optimization for the requirements of the particular application.

Rick "who doesn't capitalize 'tessar' on purpose" Denney

Rick, a lens' prescription specifies the elements' radii, thicknesses, spacings, and the glasses used, also the diaphragm's position. It is a term of art that you just misused to mean "general layout."

For a less contentious example, consider the humble spectacle. Eyeglasses, in a word. "Single vision" eyeglasses are meniscii. If you wear glasses you'll know that any old meniscus is probably wrong for you. Your optometrist or ophthalmologist will give you prescriptions that specify radii, thicknesses, and glass type for the right pair of meniscii for you.

To see examples of prescriptions, visit www.dioptrique.info and look around. Here, for example, is most of the original f/6.3 Tessar prescription. http://www.dioptrique.info/OBJECTIFS2/00095/00095.HTM

Eric gives, in order, the surfaces' radii, refractive index, Abbe number (dispersion), and thickness, but doesn't give the spacings. Without the spacings its impossible to build the lens.

Here's a redesign: http://www.dioptrique.info/OBJECTIFS8/00375/00375.HTM

If you compare the two, you'll see that some of the radii and glasses have changed.

What actually happened was that Rudolph designed an f/6.3 lens. He and Wandersleb and, later, Merté, designed faster versions. When Rudolph designed his first Tessar he didn't optimize it "around the maximum aperture," he made it as fast as he could without giving up too much image quality and coverage. That's what they all do. Part of the art is in trading off image quality and coverage for speed.

Mr. Shaw,
Great Portrait!
Bernie Kaye