Kodak Ektar/Kodak Anastigmat 13.5 inches f3.5

[renditiont]

Kodak Aero-Ektar (interchangeably Kodak Anastigmat ) 13.5 inches f/3.5 . My own schematic drawing ; it is of 5 elements in triplet configuration

https://c1.staticflickr.com/5/4429/36778592036_0725809047.jpg

[Mark Sawyer]

Closer to a Tessar, I think, but really not quite either one. A very nice bright lens either way. I have a coated one, although I see uncoated ones from time to time. Mine has no aperture, but apertures are for sissies anyways!

https://farm5.staticflickr.com/4372/36778902546_920ea54a36_z.jpg (https://flic.kr/p/Y32unq)Triplet Tessar (https://flic.kr/p/Y32unq) by Mark Owen Sawyer (https://www.flickr.com/photos/carrots_eh/), on Flickr

[renditiont]

It is definitely closer to a Tessar. It seems the second element from the left of Zeiss Tessar diagram is split in two. I am impressed by its sharpness, definitely better than Pentac lens wide open. And yes, there are coated and uncoated versions. I have both.

[Mark Sampson]

Do you have one of these lenses? 135/3.5 Aero-Ektars are uncommon. I've never seen one, despite working for 25 years in the Kodak building where they were made. The other 135/3.5 Ektar that Kodak made was in a mount for the Hasselblad 1000F/1600F. Those are quite rare and I recall donating a battered one from my department's 'junk box' to the George Eastman Museum.

[Dan Fromm]

135/3.5 Aero-Ektar? Is there such a thing?

The OP has a 13.5"/3.5er. They're not that rare. There's currently one on offer on eBay and another has sold within the last 90 days.

[Mark Sampson]

Oops, my bad. I should read the fine print before I write.

[Mark Sawyer]

It is definitely closer to a Tessar. It seems the second element from the left of Zeiss Tessar diagram is split in two...

It's hard to say. I'm guessing from the layouts, and I think I'm right, but without knowing the glasses involved (different refractive and dispersive indices compensating for the whole system in different ways), it's impossible to know...