K-5 review the kiss of dead for the E5?

Started Dec 18, 2010 | Discussions thread
bobn2 Forum Pro • Posts: 52,317
Re: Hmmmm

Rriley wrote:

bobn2 wrote:

found that OM 70-200/2.8 yet ?

Irrelevant except for a line of reasoning strained even by your usual illogical standards.

logic, lets see now
35-100/2 is just a 70-200/2.8 with a 0.5x focal reducer choked down a stop

problems ?

  • dont have a 70-200/2.8 lens


  1. Brush off that lab prototype labelled 'don't tell Riley about this'.

  2. Look in that file of lens computations and not send Riley a copy of it.

  3. Buy a design from someone else and forget to send Riley a photocopy of the contract.

  4. Copy another company's design and omit to email Riley to say you're doing it.

  5. Design a 70-200 from scratch but don't bother to ask Riley's permission first.

and probably several others I haven't thought of.

heres the the thing, you cant do this with any normal 70-200/2.8, it just wont go, there isnt enough back focus behind the lens to fit a focal reducer in the first place.

If only your skill at inventions was as great as you skill at fabricating objections to the truth out of thin air. You just keep them coming, but as you said to me, always, always check. The whole point about the Kodak patent is that it extends the back focus while reducing the image. It has to, the Kodak patent is for a wide converter you can use like a teleconverter - at the back of a normal lens. In any case, we're talking here about a lens possibly designed for a register of 46mm to be used with a register of 38.67mm, and 7 mm helps considerably - and thirdly very many such zooms have a long back focus anyway.

The group for the 35-100 has around 50mm of back focus space to fit the focal reducer when only 6mm is available on available SLR designs.

I don't think the wide converters anything like that thick so you're overestimating the probelm.

At the very least they would have had to design an entirely new lens, which is what they did.

A possibility I have never discounted, see above.

You misread JW's intent from the start, there was no OM 70-200 to begin with,

I never, ever read JW's post to be saying that, and he never said that. I never said that. You said that.

what he described is a conventional alternative to making a fast lens, the only difference is its a zoom and 0.5x is quite a bold move. It was not a matter of pulling a 70-200 from the drawer and simply adding an FR in a local workshop, which is clearly how you saw it, seized upon it, and broadcast it like you knew something.

Please post the link to where I ever said any such thing. You are arguing against your own fabrication. I guess the fabrication has been invented because you've spent so much time trashing the idea, you've checked with JW and found its right, so now you have to rewrite history to pretend that you never made a fool of yourself. So you're pretending that what was said is that the f/2 zooms are OM zooms with a wide converter on the back. No-one ever said that except you .
There's a word for that - spin.

i mean, it must be relatively simple right

Even simpler, its totally unneeded..

and heres the 'other thing'. They had no choice in building this lens in this way,

So now you are saying it is designed with a wide converter. Make up your mind. people could be excused for getting a little upset when you accuse them of lying for saying something you then decide is true.

the other way to do it would have been to drag the elements in a double gauss configured lens, but on looking at 35-100 sections you can see that the individual elements would become so thick there wouldnt be enough room between them.

You're just putting together words you don't understand to try to sound impressive. Plenty of zoom lenses f/2 and faster have been designed without recourse to the wide converter, and in essence its simply a matter of scaling to. I'm quite sure that there were alternative solutions available. I also think JW is right in his speculation that the intent in adopting the wide converter was an f/1.4 but the converter wouldn't go that wide.

That sort of collision only needs to happen once within element groups and the whole idea for design is scrap.

I'm sure Olympus engineering would have sufficient precision to ensure they didn't collide. They do that kind of thing quite well, you know.

So, let's recap, we are now agreed:
The SHG f/2 zooms are FF designs with 0.5x wide converters on the back.

and Rriley never called anyone who said that was how it is a liar, or insulted or abused them.
That it?

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