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12-13-2011, 02:42 PM   #16
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Is there any alternative proven vendors to Leitax? I find the price charged by Leitax (about $100 shipped) quite high just for a few dollars mount.

12-13-2011, 08:38 PM   #17
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QuoteOriginally posted by vrrattko Quote
Looks good, the 35-70/3.4 is legendary....i was always interested if there is any truth in their marketing statement that it is equal to their primes. Unfortunately I think Leitax doesn't convert this lens to PK here in Europe.
Here is the interesting comparison of lenses featuring Contax Zeiss 35-70/3.4:
AdamM's Lens Tests: Contax 35-70mm f3.4 trounces all! (part #1)
I believe it's a little more difficult to convert this lens than the primes, usually a conversion is done in under an hour but they asked me to come back for this one.

I have that link bookmarked already - it's a pretty amazing comparison, blowing away Canon's best L glass !
12-14-2011, 12:08 AM - 1 Like   #18
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QuoteOriginally posted by Digitalis Quote
here is an interesting fact, the pentax K 28mm f/2 is basically the same as the Zeiss T*28mm f/2
Really?

K28/2


ZK28/2
12-14-2011, 01:09 AM   #19
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I can't afford one yet but have one question for those who has the luxury to own a T100 and a T85.

Which one would you prefer to shoot a video with ? T*100 or T85 ? My brother is trying to make the decision for mid-tele lens for shooting video.

My thinking is the T85 would be a better choice for shorter focal length (to me is the workabilty), my brother would prefer the T100 since the focusing travel is longer.

Any more insights ?

12-14-2011, 10:18 AM   #20
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QuoteOriginally posted by wlachan Quote
Really?

K28/2


ZK28/2
Wow, thanks for posting that. Definitely throws a wrench into something that I had accepted as truth.
12-14-2011, 04:59 PM   #21
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QuoteOriginally posted by wlachan Quote
Really?

K28/2

ZK28/2
They're not without their similarities. Besides, given that the ZK line is 30+ years newer than the old Pentax K, I would have expected that Zeiss to have made some modifications to the optical formula.

Either way, interesting nevertheless.
12-14-2011, 08:00 PM   #22
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QuoteOriginally posted by tackyat.2 Quote
They're not without their similarities. Besides, given that the ZK line is 30+ years newer than the old Pentax K, I would have expected that Zeiss to have made some modifications to the optical formula.
That's not the point. It has been commonly accepted that the 2 lenses are, in fact, optically identical. This shows that they are not.

I would guess that most, if not all28mm lenses would have some similarities. It's the subtle differences between them that create the different results.
12-14-2011, 10:05 PM   #23
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QuoteOriginally posted by wlachan Quote
Really?
Hey, don't go busting myths around here, buddy! The entire fabric of Pentax reality could start unraveling!

12-14-2011, 10:11 PM   #24
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Planar 85/1.4

A few Planar samples:

@f/4:


@f/5.6:




@f/1.4:
12-14-2011, 11:55 PM   #25
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yes, they really are wlachlan. The reason the two lens designs you depict are different is because of the use of lead free glass, If you had actually done some research you would have known this. The original Zeiss 28mm f/2 for the contax system* was optically Identical to the Pentax K. The newer Zeiss 28mm f/2** (made by Cosina) they had to make do with lead free glass so they had to add an extra element to make up for the differences in refractive index of the glass elements and a few elements had to be shaped differently as well because of the glass types used - but in essence all three lenses are Distagon lens designs.

*Originally made circa 1976, the classic 28mm f/2 was sought after for its well controlled distortion. The design was a classic Distagon - 9 elements in 8 groups, equipped with a six bladed aperture.It is important to note that the Contax 28mm f/2.8 does not have the floating lens element the f/2 version has,which means at closer focusing distances the Contax 28mm f/2.8 doesn't perform quite as well as the more expensive f/2 version.

**which suffers from some pretty bad distortion from what I have heard.

Last edited by Digitalis; 12-15-2011 at 12:14 AM.
12-15-2011, 12:50 AM   #26
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Almost but not quite. From what I have gathered, Pentax & Zeiss were developing a few primes as well as coating and bayonet mount during the early 70's together. 28/2 & 15/3.5 being some of them. But the relationship was short-lived and they had their own tweaks for the final products. Zeiss the T*, Pentax SMC for example. SMC 15/3.5 had the edge on distortion but inferior on sharpness against the Zeiss (and Nikkor & Leica too). Their 28/2 are indeed almost identical, but almost. We know a little change in optical design can have a huge impact on optical performance. Whether the old SMC 28/2 is on par with modern designs is an unknown and it would be interesting to see some valid tests which I am not aware of. Older SMC tend to be less vivid on colour reproduction though.

SMC 28/2


Original Zeiss 28/2
12-15-2011, 05:07 AM   #27
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QuoteOriginally posted by wlachan Quote
Their 28/2 are indeed almost identical, but almost. We know a little change in optical design can have a huge impact on optical performance
Indeed it can, however looking at the optical designs you can see that they are very close, close enough that it would be perverse to maintain the view that the pentax 28mm f/2 had nothing in common with the Zeiss. The Pentax K 28mm f/2 has always had a reputation for being a very good lens. I have used the Contax T* Carl-Zeiss 28mm f/2 Distagon a long time ago, I never thought to compare it to the pentax variant, regrettably I should have held onto my copy of that particular lens. I sold my Contax system along with all of my Leica R camera bodies and lenses*.


*however I do have copies of the Contax-Zeiss 50mm f/1.4, and the Leica-R 50mm f/1.4 in my fast 50 lens collection.
12-15-2011, 05:44 AM   #28
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I was told that according to Marco Cavina, who studied the subject (albeit in Italian) that Asahi used Zeiss-polished and coated glass elements in the K28/2. So it should not only bear resemblances to the 28mm f/2 Distagon, it IS a Distagon!
12-15-2011, 06:22 AM   #29
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It would be nice if a Pentax designer could stand out for an interview to confirm facts/fictions once for all.
It's about past and history, but as a Pentax fan, I may have to look beyond my life time to get in touch with the Maker...
12-15-2011, 10:32 AM   #30
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QuoteOriginally posted by Digitalis Quote
The newer Zeiss 28mm f/2** (made by Cosina) they had to make do with lead free glass so they had to add an extra element to make up for the differences in refractive index of the glass elements and a few elements had to be shaped differently as well because of the glass types used
So how does this mean anything other than that they are different?
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