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[OM] Re: ebay 500mm lens

Subject: [OM] Re: ebay 500mm lens
From: Moose <olymoose@xxxxxxxxx>
Date: Fri, 23 Feb 2007 14:44:15 -0800
Allen Coltrin wrote:
> Can anyone comment on this lens on ebay? If you have anything along these 
> lines I would like to hear from you. I am already aware about the Pentagon 
> issues. I wish it was in the U.S.  260089918320
>   
LOL Well, at least your tastes are exotic.

I understand. It's difficult to know what you are doing in a new and 
complex field.

As others have pointed out, this is a huge and heavy beast. Take a close 
look at the picture. That tiny little thing sticking out of the back end 
is the mount for a 35 mm camera.

The Pentacon is a MF camera, meaning in this context one using 120/220 
film with an image size on film of between 45x60 mm and 60x90 mm. Yes, I 
know the nomenclature is confusing, this is a MF (Manual Focus) lens for 
a MF (Medium Format) camera, but I didn't do that.

Anyway, a lens of any given focal length and speed that produces a 
sharp, evenly illuminated image that is somewhere over 90 mm in diameter 
is more difficult and costly than for the 45 mm image circle required 
for 35 mm film, let alone for the even smaller sensor of the E-500. The 
optical requirements also result in larger, heavier lenses than those 
for the smaller formats.

So the Pentacon lens is big and heavy for perfectly rational reasons, 
but for a use you don't have.

Yes, it may be used on 35 mm or 4/3, but should it? All optical design 
involves trade-offs. One common one in the design of lenses for MF 
equipment is slightly lower absolute resolving power. While the much 
larger image size on the film/sensor will generally capture more fine 
image detail, the detail resolution of the small portion of its large 
image circle captured when used on a small format film/sensor may well 
have less detail than would a lens of the same focal length and speed 
specifically designed for the smaller image size.

With the small sensor of your E-500, you are already tossing out much of 
the image circle of lenses designed for 35mm. It's not a bad idea, in 
this case, for two reasons. First, with most lenses, the outer part of 
the image circle is less perfect the the central portion. This isn't 
universal, some super wide lenses, like the Zuiko 18/3.5, are not that 
way, but it's a good generality for long lenses.

Second, DSLRs mostly have AA (Anti Alias) filters that limit the 
absolute resolution of the image that reaches the sensor, for reasons 
I'll skip here. So a modest resolution camera like the E-500 doesn't 
really use the full resolution of the best 35 mm lenses anyway.

Still, it seems silly to buy a lens like the Pentacon, then use about 7% 
of the image it is designed to produce while putting up with its great 
size and weight.

Heck, I have a Tokina 150-500/5.6 lens for 35 mm that weighs much less 
that the Pentacon, less than five pounds. Takes nice pictures too 
<http://www.moosemystic.net/Gallery/MPhotos/Home/Towhee.htm>. You might 
be interested in that lens or the Tamron 200-500/5-6.3, a little slower 
at the long end, but under three pounds.

But you aren't likely find the lens you need just flailing around on the 
'Bay. Neither of the ones that I just mentioned are common, but they do 
show up for those who know what they want and have patience. I think 
you'd be better thinking through what you want to accomplish, reading 
the excellent information on the many links folks have posted recently 
and asking here what lenses are likely to be suitable for accomplishing 
stated goals, than crashing around in the 'Bay.

You may be frustrated, feeling that those here who could help you aren't 
being helpful enough. I, for one, am frustrated at trying to be helpful 
to someone who shoots around in all directions, so it's hard to know 
what he wants and needs.

Being really honest, if your goal is really fine, sharp, clear photos of 
far away critters, the E-500 probably isn't the finest tool available, 
no matter what lenses you get. It's a relatively inexpensive, entry 
level DSLR. Nice enough, but not great.

And really, the Zuiko 300/4.5 on 4/3s is a pretty long fast lens. A lot 
of great tele shots on 35 mm have been made with less than the 600/4.5 
lens it is roughly equal to on 35 mm. Have you settled down to really 
learn how to use what you already have to best advantage? Long tele work 
isn't just falling off a log.

Moose

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