I think you've just said what I had in a different way...
At 12:30 PM Thursday 24/05/2001, you wrote:
Seems to me that even at the same 'magnification', the 90mm is further from
the subject than the 50mm. Therefore, a 1 degree movement of the film plane
will cause the image to shift more on the 90 than the 50. To put it another
way, look at the hands of a clock at 12 o'clock, both pointing straight up.
If you move the hour hand so that the minute and hour hand tips both touch
the same point (the subject), they now each have a different axis (film
plane)on the line from the center of the clock to the top point. If the
minute hand moves 6 degrees, it now points to 1 minute past the 12. If the
hour hand now moves 6 degrees in the same direction, it will end up parallel
with the minute hand, but it's point (view of the subject) won't have moved
as far. If this made any sense at all, you'll see that the 50 will show less
motion given the same degree of movement. The 90mm, given the same degree of
movement sweeps across more image area causing MORE blur of the image. It
isn't the angle of movement, it's the shift in the field of view that makes
the difference. The 90 will shift more than the 50 for the same angular
movement.
OK, I've tired myself out. Hope this helps... ;-)
Mickey
----- Original Message -----
From: "Wayne Harridge" <wayneharridge@xxxxxxxxxxxxxxx>
To: "olympus @ Zuiko . sls . bc . ca" <olympus@xxxxxxxxxxxxxxx>
Sent: Wednesday, May 23, 2001 9:31 PM
Subject: Re: Re: [OM] Macro Questions
>
>
>
>
> > Dr. Oben Candemir <dunya.nospam@xxxxxxxxxx> wrote:
> >
> > John,
> >
> > Correct me if I am wrong; but I feel that the increased standoff
> > distance
> > at the same magification would increase the effect of camera shake.
> > The
> > reason being that the same amount of "angular" movement of the camera
> >
> > translates to a greater linear distance when the subject is further
> > away.
> > To see what I mean draw a triangle with the same angle.... the height
> >
> > increases the longer the base is.
> >
> > So using a 90mm f2 at 0.5x and a 50mm f2 at 0.5x gives you different
> > standoffs... but my reasoning would say that the 50mm f2 has less
> > camera
> > shake effect than the 90.
> >
> > Your views?
>
> My view:
>
> If the magnification is the same then the same angular movement of the
body
> would translate to identical blur of the image.
>
>
> Wayne Harridge
> http://members.optusnet.com.au/~w_harridge
>
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