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Olympus OM enthusiasts' digital prayers have been answered ...

 
 
Bruce
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      02-07-2012
"Trevor" <(E-Mail Removed)> wrote:
>"Bruce" <(E-Mail Removed)> wrote in message
>news:(E-Mail Removed).. .
>>>>>Haven't used one on 4/3, but I'm puzzled how they suffer from any
>>>>>significant vignetting when your only using the middle half of the lens
>>>>>circle?
>>>>
>>>>
>>>> I explained it in my previous post. You replied to that post but
>>>> snipped the relevant paragraph.
>>>
>>>No, you explained why it would happen if you were using the full lens
>>>image
>>>circle, but since your not, I can't see how it's a big problem?

>>
>>
>> You obviously didn't read what I wrote. Your loss.

>
>Nope I read it, and it doesn't match my experience, so I queried what YOUR
>experience was? (rather than theory)
>Maybe it's only a major problem with Olympus 4/3 sensors perhaps, but as I
>said, it's all relative.



Not only don't you understand what I wrote, but you seem wilfully
determined not to understand. As I said, it's your loss, but you
might like to consider the meaning of the terms "telecentric" and
"oblique".

As for experience, I have bench tested many lenses in addition to real
world testing, and advised one of Europe's largest camera importers on
the issue of compatibility of lenses that were designed for film with
digital sensors. That involved testing every single lens in their
current range, plus some older lenses, on their early digital SLRs.

It was more of a problem with Olympus (Kodak) sensors than with other
brands because the Kodak sensors were specifically designed to be used
with near-telecentric lenses, and performed particularly badly with
lenses that were far from telecentric. The Zuiko Digital lenses are
remarkably telecentric and produced outstanding results on Kodak
sensors.

Alas, the OM Zuiko range included many lenses that were far from
telecentric; Olympus's quest for small size and lightness meant that
light rays from many Zuiko lenses hit the film/sensor at seriously
oblique angles. Hence the need for Olympus to list (1) the lenses
that would work well on digital, (2) the lenses that would work less
well (perhaps with limitations on aperture) and (3) those that
wouldn't work at all well.

If there wasn't a problem, as you so confidently assert, why on earth
would Olympus have gone to such lengths?

Your Head In The Sand Club membership card is in the mail.

 
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Kennedy McEwen
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      02-07-2012
In article <(E-Mail Removed)>, Bruce
<(E-Mail Removed)> writes
>
>If there wasn't a problem, as you so confidently assert, why on earth
>would Olympus have gone to such lengths?
>

To justify making small 4-turds sensors in the first place!
That's when they came out with the "telecentric is best for digital"
myth in the first place and it was shortly proven to be wrong by
measurement. The light fall-off due to non-telecentricity is *LESS* on
Olympus (and Canon FF sensors for that matter) than it was on film!

OM lenses work just as well on digital as they did on film, which
doesn't mean telecentric lenses can't work better, but the argument was
false to begin with and was merely an attempt by Olympus to justify
their investment in cheap chips.

Try the counter argument: if there was a problem, why are the 4-turds
consortium the only folk that have it? Whilst Leica do take steps to
reduce the issue on their sensor, neither Canon, Nikon nor Sony do.
--
Kennedy
Yes, Socrates himself is particularly missed;
A lovely little thinker, but a bugger when he's ****ed.
Python Philosophers (replace 'nospam' with 'kennedym' when replying)
 
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Kennedy McEwen
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      02-07-2012
In article <(E-Mail Removed)>, Bruce
<(E-Mail Removed)> writes
>Mort <(E-Mail Removed)> wrote:
>>
>>I still have about a dozen OM lenses for my two OM-4T bodies. It
>>certainly would be nice to have a new Olympus digital body with the OM
>>lens mount and auto diaphragm, and I would not mind manual focus. I
>>suppose that it is just daydreaming.

>
>
>Unfortunately yes, that is just daydreaming. Olympus rejected the
>idea of a digital OM because of the incompatibility of many OM lenses
>with digital sensors, which I explained in the post you replied to.
>

Which is just nonsense - I have several OM lenses that work just as
well, perhaps even better, on my Canon FF sensors as they did on film in
an OM body.
--
Kennedy
Yes, Socrates himself is particularly missed;
A lovely little thinker, but a bugger when he's ****ed.
Python Philosophers (replace 'nospam' with 'kennedym' when replying)
 
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Kennedy McEwen
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      02-07-2012
In article <(E-Mail Removed)>, Alfred Molon
<(E-Mail Removed)> writes
>In article <(E-Mail Removed)>, Kennedy McEwen
>says...
>> OM looks outside don't compensate for the tiny 4-turds sensor inside.

>
>If you need a camera with a bigger sensor, feel free to buy one. But
>especially the lenses will be bigger and heavier.


I have one, and the original OM lenses work very well on it thank you
very much. In fact, I posted some measured results from them on this
forum about 5 years ago - try Google!
--
Kennedy
Yes, Socrates himself is particularly missed;
A lovely little thinker, but a bugger when he's ****ed.
Python Philosophers (replace 'nospam' with 'kennedym' when replying)
 
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Kennedy McEwen
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      02-07-2012
In article <(E-Mail Removed)>, Bruce
<(E-Mail Removed)> writes
>
>Many, if not most OM Zuiko lenses present significant problems when
>used on a (Micro) Four Thirds digital sensor. The sensor design
>strongly prefers telecentric lenses, where most of the light rays are
>approximately perpendicular to the sensor when they hit.
>

That statement is simple repetition of Olympus's original false
justification for making the 4-turds sensor smaller than FF in the first
place, and that was disproved when FF sensors were demonstrated to work
perfectly well with OM lenses. There is NOTHING in the Olympus sensor
design which "strongly prefers telecentric lenses" and several 4-turds
lenses are just as non-telecentric as their equivalent OM lenses were.
--
Kennedy
Yes, Socrates himself is particularly missed;
A lovely little thinker, but a bugger when he's ****ed.
Python Philosophers (replace 'nospam' with 'kennedym' when replying)
 
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Pete A
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      02-07-2012
On 2012-02-07 13:12:37 +0000, Kennedy McEwen said:

> In article <(E-Mail Removed)>, Bruce
> <(E-Mail Removed)> writes
>>
>> If there wasn't a problem, as you so confidently assert, why on earth
>> would Olympus have gone to such lengths?
>>

> To justify making small 4-turds sensors in the first place!
> That's when they came out with the "telecentric is best for digital"
> myth in the first place and it was shortly proven to be wrong by
> measurement. The light fall-off due to non-telecentricity is *LESS* on
> Olympus (and Canon FF sensors for that matter) than it was on film!


Illumination falloff for a non-telecentric lens is approximately a
cosine to the fourth power. The only way a digital sensor can suffer
_less_ falloff than film is by altering the angle of the non-central
micro-lenses. In all other cases, a digitital sensor will suffer more
light falloff than film.

>
> OM lenses work just as well on digital as they did on film, which
> doesn't mean telecentric lenses can't work better, but the argument was
> false to begin with and was merely an attempt by Olympus to justify
> their investment in cheap chips.
>
> Try the counter argument: if there was a problem, why are the 4-turds
> consortium the only folk that have it? Whilst Leica do take steps to
> reduce the issue on their sensor, neither Canon, Nikon nor Sony do.



 
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Trevor
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      02-08-2012

"Bruce" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Not only don't you understand what I wrote, but you seem wilfully
> determined not to understand.


DITTO!


> If there wasn't a problem, as you so confidently assert,


I only suggested it didn't match my experience and you have now explained
why. Thank you!


> Your Head In The Sand Club membership card is in the mail.


Your unnecessarily antagonistic club membership card is in the mail, no
wait, not worth the postage.

Trevor.


 
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Kennedy McEwen
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      02-08-2012
In article <2012020714103581999-pete3attkins@nospamntlworldcom>, Pete A
<(E-Mail Removed)> writes
>On 2012-02-07 13:12:37 +0000, Kennedy McEwen said:
>
>> In article <(E-Mail Removed)>, Bruce
>><(E-Mail Removed)> writes
>>> If there wasn't a problem, as you so confidently assert, why on
>>>earth
>>> would Olympus have gone to such lengths?
>>>

>> To justify making small 4-turds sensors in the first place!
>> That's when they came out with the "telecentric is best for digital"
>>myth in the first place and it was shortly proven to be wrong by
>>measurement. The light fall-off due to non-telecentricity is *LESS*
>>on Olympus (and Canon FF sensors for that matter) than it was on film!

>
>Illumination falloff for a non-telecentric lens is approximately a
>cosine to the fourth power. The only way a digital sensor can suffer
>_less_ falloff than film is by altering the angle of the non-central
>micro-lenses.


Wrong.

3D microlens v's 2D flat film surface. A tennis ball has the same cross
section no matter what angle you view it from, while a flat sheet of
film has a cross section that is cos^2. Any 3D view of the microlens
means less than cos^4 fall-off. Also, if the "image" from the
micro-lens is smaller than the sensitive area of the pixel, the
illumination fall-off on a digital sensor will *always* be less than
film - by 2 of those four cosines!

Try measuring it, its not that difficult but too many folk would prefer
to regurgitate the dogma than find out the truth for themselves!
Alternatively, google my measurements from 5 or 6 years ago where this
was discussed to death - the Olympus dogma death!

The Olympus "telecentric" argument was just an excuse for selling tiny
cheap chips. Nothing wrong with that - there is a huge market for
cheaper cameras - but they lost all credibility by trying to justify an
economic argument with fake science.
--
Kennedy
Yes, Socrates himself is particularly missed;
A lovely little thinker, but a bugger when he's ****ed.
Python Philosophers (replace 'nospam' with 'kennedym' when replying)
 
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Bruce
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      02-08-2012
"Trevor" <(E-Mail Removed)> wrote:

>"Bruce" <(E-Mail Removed)> wrote:
>> Not only don't you understand what I wrote, but you seem wilfully
>> determined not to understand.

>
>> If there wasn't a problem, as you so confidently assert,

>
>I only suggested it didn't match my experience and you have now explained
>why. Thank you!



You're welcome. But I didn't add anything that wasn't already in the
post you decided not to read.

 
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Rol_Lei Nut
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      02-08-2012
On 2/7/2012 14:12, Kennedy McEwen wrote:

> OM lenses work just as well on digital as they did on film, which
> doesn't mean telecentric lenses can't work better, but the argument was
> false to begin with and was merely an attempt by Olympus to justify
> their investment in cheap chips.


I have a Panasonic M43 and use *lots* of made for film lenses on it
(M42, Zeiss, Leica both M & R, M39 & others).

Some lenses, especially fast one, often don't work well at their faster
apertures (by "not well" I mean visibly less well than on a film camera).
It's hard to predict which will do well and which won't: a 85mm 1.4 only
gets good at 2.8 whereas a 35mm 1.4 is very good wide open. Also,
rangefinder lenses don't necessarily do worse than SLR lenses, just as
telephoto lenses (like the 85mm I mentioned) don't always do well.

But my definite conclusion is that, many lenses (perhaps as much as 50%)
*don't* work as well on a M43 sensor as they do on film. So there is
something going on...

 
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