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Re: Good place to get used Olympus lenses?

 
 
Andreas Schmidt
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      04-01-2004
John Navas <(E-Mail Removed)> wrote in message news:<gLEac.2875$(E-Mail Removed)>...
> [POSTED TO rec.photo.digital - REPLY ON USENET PLEASE]
>
> In <(E-Mail Removed) > on 30 Mar 2004 21:48:14
> -0800, http://www.velocityreviews.com/forums/(E-Mail Removed) (Andreas Schmidt) wrote:
>
> >John Navas <(E-Mail Removed)> wrote in message news:<vehac.2663$(E-Mail Removed)>...

>
> >> >There is no focal length multiplier in the adapter.
> >>
> >> It's in the system (due to the small size of the sensor), and is high
> >> enough (along with image quality issues) to greatly diminish the value
> >> of such an adapter.

> >
> >Well, the angle of view becomes smaller, but still there is no focal
> >length multiplication.

>
> The image circle of Four Thirds (on which the E-1 is based) is about 1/2 that
> of 35mm, so the focal length of a 35mm lens is multiplied by about 2 (the
> reciprocal) **in 35mm terms** when mounted on a body with a 4/3 sensor; e.g.,
> a 35-70 zoom becomes a 70-140 zoom in 35mm terms.


Your description of the result is correct, but you are misusing terms.
Focal length is a physical property of the lens and is independent on
format of the film or sensor behind it. Your 35-70mm zoom will always
have a focal length of 35-70mm, but the resulting angle of view on an
E-1 will be about the same like a 70-140mm zoom on a 35mm camera.

It may look as just a matter of terms, but then when you write that
the OM to E-1 adapter provides focal length multiplication it becomes
plain wrong and confusing for people who do not know the adapter.
Because there are indeed adapters, which require a lens, like e.g.
those for adapting Canon FD lenses to EOS bodies. These adapters do
have a focal length multiplication, i.e. they work as light
teleconverters. The OM to E-1 adapter does not.

> >But why do I write this, just spoiling the second-hand
> >prices...?

>
> Because relatively few photographers come here?


I didn't want to say that...

Andreas
 
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John Navas
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      04-01-2004
[POSTED TO rec.photo.digital - REPLY ON USENET PLEASE]

In <(E-Mail Removed)> on 31 Mar 2004 19:00:16
-0800, (E-Mail Removed) (Andreas Schmidt) wrote:

>John Navas <(E-Mail Removed)> wrote in message news:<gLEac.2875$(E-Mail Removed)>...


>> The image circle of Four Thirds (on which the E-1 is based) is about 1/2 that
>> of 35mm, so the focal length of a 35mm lens is multiplied by about 2 (the
>> reciprocal) **in 35mm terms** when mounted on a body with a 4/3 sensor; e.g.,
>> a 35-70 zoom becomes a 70-140 zoom in 35mm terms.

>
>Your description of the result is correct, but you are misusing terms.
>Focal length is a physical property of the lens and is independent on
>format of the film or sensor behind it. Your 35-70mm zoom will always
>have a focal length of 35-70mm, but the resulting angle of view on an
>E-1 will be about the same like a 70-140mm zoom on a 35mm camera.


Of course, but the whole point of language is to communicate, which "focal
length multiplier" does. And I'm in good company:

<http://www.dpreview.com/learn/?/Glossary/Optical/Focal_length_multiplier_01.htm>:
"Focal Length Multiplier"

<http://www.imaging-resource.com/PRODS/ND100/D10P.HTM>:
"focal length multiplier"

<http://www.lonestardigital.com/multipler.htm>:
The "Multiplier Effect"

<http://www.dcresource.com/reviews/canon/eos_10d-review/index.shtml>
"multiply the lens focal length"

<http://www.steves-digicams.com/2003_reviews/10d.html#specs>:
"focal length conversion factor"

I think that last is arguably the best term, so I'll try to remember to use it
in the future.

>It may look as just a matter of terms, but then when you write that
>the OM to E-1 adapter provides focal length multiplication it becomes
>plain wrong and confusing for people who do not know the adapter.


I didn't write that -- I actually wrote:

The other obvious limitation is the focal length multiplier.

in response to:

>... I know the Oly OM lenses are supposed to work fine. I believe that you
>have to use manual focus only and stopped down metering (not sure about
>the metering).


I think it's pretty clear I was referring to the use of OM lenses on the E-1,
not the teleconverter itself, but I made that even more clear in a follow-up
response.

>Because there are indeed adapters, which require a lens, like e.g.
>those for adapting Canon FD lenses to EOS bodies. These adapters do
>have a focal length multiplication, i.e. they work as light
>teleconverters. The OM to E-1 adapter does not.


True, but the use of OM lenses on the E-1 does, and that's what I was
referring to.

Are we done now??

--
Best regards,
John Navas
[PLEASE NOTE: Ads belong *only* in rec.photo.marketplace.digital, as per
<http://bobatkins.photo.net/info/charter.htm> <http://rpdfaq.50megs.com/>]
 
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