"*effective* focal length is imprecise"? That's the term coined by many
users of various digital formats. Even camera manufacturers use it. My
Minolta A2 has a 7.2-50.8mm lens on it. But KM says it has an effective
focal length of 28-200mm. Do users really care if the lens is actually a
7.2-50.8mm one? I know I don't. I care about what FOV (field of view) it
gives me for picture taking.
Yes, you are correct in that a film/ccd size doesn't change the actual focal
length. But when you out shopping for your next digicam don't tell them you
want an "actual" 28-200 lens. FOV is the key, not the "actual" focal length.
The easiest way for most to compare FOV between formats is to use the term
"effective" focal length, which correlates the FOV in comparison to the 35mm
format (because it's the most popular and best understood).
Paul
-----Original Message-----
From: olympus-owner@xxxxxxxxxx [mailto:olympus-owner@xxxxxxxxxx]On
Behalf Of Piers Hemy
Sent: Thursday, March 09, 2006 9:17 AM
To: olympus@xxxxxxxxxx
Subject: [OM] Re: 80mm macro experiences?
I *think* I disagree with your first sentence, Paul, but I can't be sure ...
because the terms you use in the second sentence are, umm, imprecise, though
I accept that they don't seem so to you, because you know what you mean!
I think all that we can agree on is that putting the 90mm lens on any camera
(Pen F, OM, E-1 or 4 x 5 plate camera) doesn't change it's *actual* focal
length.
--
Piers
-----Original Message-----
From: olympus-owner@xxxxxxxxxx [mailto:olympus-owner@xxxxxxxxxx] On Behalf
Of Paul Martinez
Sent: 09 March 2006 16:55
To: olympus@xxxxxxxxxx
Subject: [OM] Re: 80mm macro experiences?
That's incorrect. If you put the same lens on an E1 the object will be twice
the size because the *effective* focal length of the lens has doubled.
Paul
-----Original Message-----
From: olympus-owner@xxxxxxxxxx [mailto:olympus-owner@xxxxxxxxxx]On
Behalf Of Piers Hemy
Sent: Thursday, March 09, 2006 8:47 AM
To: olympus@xxxxxxxxxx
Subject: [OM] Re: 80mm macro experiences?
Walt's right. Here's another way of thinking of it.
That lens on an OM camera will fill the frame with an object 24 x 36 mm. On
your E-1, the same lens will show the same object at the same size - but you
won't see so much of it because the frame is smaller.
--
Piers
-----Original Message-----
From: olympus-owner@xxxxxxxxxx [mailto:olympus-owner@xxxxxxxxxx] On Behalf
Of NSURIT@xxxxxxx
Sent: 09 March 2006 16:02
To: olympus@xxxxxxxxxx
Subject: [OM] Re: 80mm macro experiences?
In a message dated 3/9/2006 9:58:21 AM Central Standard Time,
hiwayman@xxxxxxx writes:
If I took my 90/2.8 Tamron macro and put it on one of my Graphics and shot
something 1:1, I would get a circle in the middle of a much larger piece of
film, but it would still be 1:1. Same thing if you use it on an itty-bitty
piece of film, or sensor, and only get part of it. 1:1 is 1:1.
OK. I think I have it . . . unless it leaves me again. Bill Barber
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