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Thursday, 21 August 2008

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For the ignorant among us, can you explain what a "cemented 3-4 doublet" is, exactly? I assume one of the groups of elements but I'd actually be pretty interested in a good definition.

Hmm.. maybe lens terminology and whatnot could be a post....

Stephen,
The third and fourth elements, counting from the objective (the left), the ones that don't have an airspace between them. These lenses have 9 elements in 8 groups, the two cemented elements comprising one group.

Mike J.

Mike, it looks great, sure... Until you check it out on b+h where it reads:
"Important Notice!
Only fits on the EOS Digital Rebel series or 40D, 30D & 20D SLR cameras".
So this lens cannot be used as a *real* 35mm on a Canon either!
Sad...

Mike, could this be right--tech info from B&H.
Pentax--SP (Super Protective) coating made of a special fluoride compound has been applied to the front surface of the new lens through the use of a unique evaporation process. As a result, the lens offers excellent water- and oil-repellant performance and makes for easier cleaning should the lens be accidentally smeared with fingerprints or cosmetics.
Tokina--WR (Water Repellent) coating made of a special compound has been applied to the front surface of the lens through the use of a unique evaporation process. As a result, the lens offers excellent water- and oil-repellent performance and makes for easier cleaning should the lens be accidentally smeared with fingerprints or cosmetics.
Maybe it's just a misprint. All macro's are about the same anyway, what's the big deal.

Not to give in to the conspiracy theory, but does the reply you got from Pentax rule out that the *Tokina* lens may be a joint design?

The DA ltd design may still be 100% Pentax, but Pentax may well somehow have licensed part of that design...

They are apparently designing digicam lenses for several manufacturers.

Cyril,
No, not at all--in fact I think it's likely. Lens companies are understandably leery about consumers' prejudices about reputation, since those prejudices are can be both very strong and also quite detached from reality. It seems likely that several of the zooms that the two companies share were originally Tokina designs, and if this lens was entirely a Pentax design then they probably returned the favor to Tokina. I'm just speculating, mind you.

Mike J.

Nick,
Dedicated lenses for the reduced sensors sizes are hardly new, from Pentax or any other manufacturer. It's one of the reasons why the performance is higher.

Mike J.

In case what Mike pointed out isn't clear - I hadn't noticed it myself - the fifth element from the right has a different profile between the Pentax and the Tokina. Very similar, but it doesn't look as though you could simply swap them out.

If Tokina licensed the basic design from Pentax, I wouldn't be surprised if it did the same for the lens coatings. Rollei apparently used the Zeiss * coatings on its own-branded lenses for the 6000x series but called them something else.

FWIW in my experience of actually assembling camera lenses the lens schematics are just that - schematics for publicity purposes, not detailed engineering drawings. I wouldn't read too much into the way a lens cross-section is rendered in the schematic myself(e.g. the meniscus element referred to by raincity4 above). They don't show the individual lens prescriptions (which will typically include many design details such as radius, thickness, glass type, coating, and quality requirements such as surface figure, wedge, surface quality etc). Given that, these two lens designs can be said to have identical schematics. This may be simply because, given the numerous practical constraints in designing such a camera lens, two designers working independently but having to solve the same problem using the same range of glasses, coating technologies and mechanical assembly approaches (and optical design software) might well come up with essentially the same solution.

I've been considering this lens recently, but I've been unable to find reviews or comments by anyone who has used it. If someone has experience with this lens I would appreciate your thoughts.

Also, I notice that the (I believe) 4th, 5th and 8th lens elements have beveled corners. What effect would this have?

Finally, I second the thought that a lens construction and terminology post would be interesting.

Jeff M: the bevels are most likely not intended to achieve any optical effect; probably are simply to do with the mechanical mounting scheme (the only optical effect they could achieve would be to reduce the clear aperture for that element but that can be done with the mechanics used to mount the lens.)

Oops, the lens I referred to as a meniscus lens in my post above is actually a biconcave type (FTR elements 1,2 from left ARE meniscus lenses).

You could fit what I know about lens design into a thimble. Give me more Mike and Dave Elden!

"I've been considering this lens recently, but I've been unable to find reviews or comments by anyone who has used it. If someone has experience with this lens I would appreciate your thoughts."

Here ya go:http://www.fredmiranda.com/reviews/showproduct.php?product=354&sort=7&cat=41&page=1

One more, and inportant thing seems logical here, about the similarities between the discussed lenses: Both Pentax and Tokina are owned by Hoya Corp.
It makes good business sense that they explore this intragroup sinergy. The Pentax DA* zoom lenses certainly are (very well) built, in a very similar Tokina "way".
Certainly they are going to share their technology and use in efficient way their expertise in glass, lenses and cameras design and production.

Eudoro,
I'm going to have to challenge you on that. What evidence do you have that Tokina is owned by Hoya? Oren, who reads Japanese, has scoured the company websites for any indication of a connection, but hasn't found one. Hoya's ownership of Pentax is well integrated into its Japanese website, but the name "Tokina" doesn't even come up in a site search.

Until there's some evidence of this connection, I'm afraid I have to ascribe this assertion to "internet wisdom"--that is, I have to conclude that it's wrong.

Mike J.

Bill is right - edit ruthlessly. The digital equivalent of Fred Picker's editing by wood stove. Digital makes it easy to generate a huge number of images. This is great creatively because we can make a 100 variants of a shot to really see what it looks like.

But once we have done that, the odds are good that the shot really did not work anyway, and is not going to work any better 5 years from now. While it is probably best to delete all 100 images, you should at least delete the 98 that are really not close. Then six months later, look hard at those remaining two. I think that there is less chance of deleting an image you might like in another life than there is in drowning in images in this life.

Digital requires us to be careful in editing after we shoot. LF is the opposite, making us edit before we shoot because there is so much overhead in each shot. Both have their virtues. Neither works very well if you do not exercise discipline in the right step of the process.

The Tokina Hoya connection probably sits in the back of ones mind because they have the same US importer - THK Photo Products Inc.
A search for "tokina" on Hoya's English home page comes up with "nothing found".

Cheers, Robin

Pentax have had a long working relationship with Tokina. The SMC Pentax-DA Macro 35mm f2.8 Limited's design has been licenced by Pentax to Tokina. As has the design of the SMC Pentax-DA* 16-50 f2.8 and 50-135 f2.8.

With all these lenses the general understanding is that Pentax make and coat the glass elements, but EVERYTHING ELSE is designed and made by each manufacturer separately, Pentax and Tokina. The glass is the same, but the design, electronics, controls, manufacture and assembly are caarried out separatey by Pentax and Tokina.

ONE Pentax lens, though, is a Tokina design. The SMC Pentax-DA 12-24 f4 was designed by Tokina, but Pentax indepentantly manufacture their version of this lens.

Regards

Chris Stone

It has been argued before that the DA* 16-50, DA* 50-135 and DA 10-17 Fisheye were Tokina designs. However, if you search the patent databases on the net, you will find that the patents for the optical designs of all three were applied for by Pentax, that the DA* 50-135 was invented by the same person as the DA 70 and that the inventor of the DA 10-17 had also designed the FA 17-28 Fisheye. To me, this is sufficient evidence that these lenses were not designed by, but just licensed to Tokina.

Hi,Mike:

I scourged the net (not in japanese), too...and you are right. There's nothing that could tie Tokina to Hoya. My apologies and kowtows .
A friend of mine gave me the "information", which I passed to your site without checking it with the due dilligence.
Later I found that the "information" was based in THK, which distributes Tokina, Hoya and Kenko brands in USA.
Anyway, I was WRONG.

Eudoro "A little shaken and humbled" Lemos, Jr.

Hi Mike,

I too have pretty much thought there to be no connection of ownership between Hoya and Tokina. Until I read this from Popphoto's Tech Editor, Philip Ryan: "Hideto Fukazawa, Director of Hoya’s Tokina Industrial Division..." - Now I'm confused.

If interested please see the blog article dated July 17, 2008 titled "Filter Forward: What’s New at Hoya" http://flash.popphoto.com/blog/hoya/index.html

Perhaps not damning evidence, but maybe Pophoto knows something we don't?

(Strangely, this link does not work on Safari for windows, but does for Firefox).

Regards,

Nic

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