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Old Feb 19, 2006, 6:30 AM   #1
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Hi all,

I'm a newbie, thinking of buying an E-500, and I need some advice on the lenses.

I need to know what is meant by 17.5-45mm, and 40-150mm.

Also, Olympus say equivalent to 35-90mm and 80-300mm because of the 4:3 system?

What I am really asking is how do I work out the actual optical magnification offered by the lenses expressed as a "times n" type of figures?

I would like around 10x optical zoom for bird photography, would the 40-150 lens achieve this?

Please excuse my ignorance.

YorkshireBill.



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Old Feb 19, 2006, 8:30 AM   #2
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First, FORGET things like 10x...they don't mean anything! It's only the difference between the wide and telephoto positions on the lens. I can have a 20mm-200mm, a 26-260mm, or a 38-380mm, and they are ALL 10x lenses.

Now, measurements in mm mostly refer to the 35mm equivalent film camera lens. A C-700 camera is said to be 38-380mm but that's the 35mm film camera equivalent...in reality it's 5.9-59mm and that's due to the smaller CCD size when compared to the size of a frame of film. Digital camera users use 35mm film equivalents so that there's a common frame of reference...the C-700 was a 5.9-59mm, the C-750 was a 6.3-63mm due to having a larger CCD, but they were both 38-380mm equivalents.

In 35mm film terms, the human eye is about 50mm, so at that adjustment the camera sees like you do. If you go higher than 50mm you are going towards telephoto or zooming in, bringing things closer. If you go less than 50mm you are widening the scene or moving things away.

Finally, the CCD size in the Olympus E-system cameras is half the diagonal size of a 35mm film frame. The actual measurements of one of the kit lenses is 14-45mm, but to get the 35mm film camera equivalent you double it or get the equivalent of a 28-90mm. The Olympus lenses are usually marked in their true measurements, and if you want to get the 35mm equivalent you have to double it.

The only Olympus lens that is a 10x (that I can think of) is the 18-180mm or equivalent of 36-360mm...some aren't fans of this lens because it can be soft (not as sharp picturewise due to the extreme range), and it is what is called "slow" (needs a longer shutter speed to compensate for a larger number F-stop).

Many will actually use what's called a PRIME lens, a lens that doesn't zoom...the reason being that will give you the sharpest picture because there's no adjustment.

Gotta go now.
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Old Feb 19, 2006, 10:17 AM   #3
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YorkshireBill wrote:
Quote:
What I am really asking is how do I work out the actual optical magnification offered by the lenses expressed as a "times n" type of figures?

I would like around 10x optical zoom for bird photography, would the 40-150 lens achieve this?
The x10 is probably meaningless for your purposes; you could have a "1mm to 10mm" zoom lens and it would be a "10x zoom," but your greatest telephoto focal length would still be only 10mm! The "x" factor only tells you the ratio of the smallest to the largest value, not what those values actually are! For example look at the following chart, but just exchange 10x instead of 3x. There's lots of different "10x" zooms you could have that would be meaningless for "bird shooting" (what if you were shooting birds in a cage in your kitchen?).

What you really need is to learn to think in terms of field of view, or at least, maximum focal length in terms of conventional 35mm cameras.




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Old Feb 19, 2006, 12:38 PM   #4
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Thanks guys,

I didn't think it would be straighforward :-)...

Can I assume that if the human eye is 50mm, then a 100mm lens is x2 and a 200mm lens is x4?.

Failing that, I assume the only way you can tell how much magnification you will get is by fitting it to the camera and looking through it?

I like the sound of the PRIME lens, and maybe that's what I need for my proposed application. I assume they are numbered in a similar way (mm).


Thanks for your help

YorkshireBill.



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Old Feb 19, 2006, 4:19 PM   #5
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Thip page lists all the current lenses for the E-500 (and other E-system cameras):
http://www.wrotniak.net/photo/oly-e/lenses.html
EFL=35mm equivalent


More general info at:
http://www.wrotniak.net/photo/oly-e/index.html
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