On 10/30/2011 3:49 PM, P. J. Alling wrote:
That's what the simple math would imply. I doubt that the lensbaby
optical designs are complicated enough to alter that.
On 10/30/2011 1:46 PM, Mark C wrote:
I was working with the trusty Pentax 6x7 today and put on the
Lensbaby 3G that I bought for it a while back. The lens baby uses a
set of apertures that are just steel metal rings held in place by
magnets in the lens. To my horror, I was unable to find the aperture
kit anywhere in the bag. It appears to be lost for good. All I have
is the 5.6, which was in the lens. At home, I tried one of the
aperture rings from my Pentax K Lensbaby Muse. The f2.8 ring for the
Muse is exactly the same size as the f5.6 ring for 3G. The Muse is a
50mm focal length, the 3G is 100mm.
So - am I correct in assuming that is the Muse f2.8 ring is the same
size as the 3G f5.6 ring, the two stop differential applies to other
aperture rings? So Muse f4 = 3G f8, Muse f5.6 = 3G f11, etc... I
assume that they logically would have to be consistent, but maybe the
world is not so orderly...
The 3G for medium format has been discontinued for some time but
replacement rings for the Muse are available. I ordered a set hoping
to relabel them for the 3G, at worst I'll have backup for the Muse.
Thanks -
Mark C.
Thanks - I just checked Wikipedia and got the equation for the area of
an f-stop: Area = PI x (focal length / f-stop)^2. Comparing 50mm and
100mm confirms that the size of a 100mm f-stop is the same as the f-stop
two stops lower in number on a 50mm. So, the Muse aperture rings should
work...
Now I just have to print up some tiny labels to stick on them.
Mark
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