thrice wrote:
The Cooke Triplet dates to 1893, the Zeiss tessar dates to 1902. The difference is cementing an additional element into the rear group, otherwise identical. Wikipedia gives a much more elaborate and glorifying (to Paul Rudolph - Zeiss designer) path to discovery, but no matter his path to the Tessar design, it is extremely similar to a Cooke Triplet.
Similarly the Heliar design is like a Tessar with a cemented doublet at the front as well as the back, but they do admit their lineage to the Cooke Triplet.
Absolutely. These designs to share a lot of similarities. Which is why I mentioned all 3 in the same paragraph Like I said, the Tessar is not derived from the Cooke Triplet, yet the Heliar is.
The point I was trying to make though is the path to that design is important when you say something like, 'the Tessar is a modified Cooke Triplet.' That's not exactly true...
thrice wrote:
Not many 'real' Tessar's around these days are there? Isn't it a modified Cooke Triplet design?
Tessar's should be a 4 element design, by virtue of their name
Tessar comes from Tesser, which is greek for 4. Don't question me on this one, I know this for a fact. :P [tesseract = 4 rays].
Tessars are actually dual cemented doublets.
Cableaddict wrote:
While we're on the subject, someone should explain Jenna & Flektagon.
Jos Tesseract wrote:
Tessars are actually dual cemented doublets.
4 elements, 3 groups, rear cemented doublet. Heliar is 5 elements, 3 groups - front and rear cemented doublet. This has already been covered in this thread.
Jos Tesseract wrote: Jena is from where the Factory was.
Like I said, the Tessar is not derived from the Cooke Triplet, yet the Heliar is.