Interesting about the cat door. Did Schrodinger have a cat door? Or
could his cat could be simultaneously inside and out?
Regarding step up rings: I've always used the inexpensive ones. They
sometime stick (especially if left on a long time) but eventually they
will come off. I tend to use step down rings frequently for reverse
mounting lenses and one that are close in diameter (e.g. a 52 to 49mm
step down) can be a real pain to remove, but patience usually prevails.
Mark
On 7/21/2015 5:50 PM, Igor PDML-StR wrote:
[Lyrical digression] (albeit on the topic of CATs)
There is a legend attributing the invention of a cat flap door to
Isaac Newton (the physicist famous for formulating the foundations of
mechanics and gravitation), who was annoyed by the cat asking outside
and asked a carpenter to make one in his door.
There is an extension of that that says that Newton asked to make two
doors: a large one for the mother cat, and a small one for the kittens.
(See, e.g.:
http://science.howstuffworks.com/innovation/famous-inventors/5-isaac-newton-inventions2.htm
)
[/Digression]
How is that story related to photography?
I just realized that at least as a temporary step, I can just buy a
step-up ring and use the 77mm CP on my 67mm lenses.
So, the question is: Any recommendations for the step-up rings?
I see Goja step-up rings sold for about $6 on Amazon, with a bunch of
positive reviews, Sensei on B&H for the same $6, while B+W on B&H is $18.
Both are aluminum. A brass one from Sensei is $37, Heliopan - $47.50.
Is there any reason to spend 3-times as much on B+W aluminum ring?
Yet another question, how much of binding comes from aluminum rings?
Is it worth spending 6-times as much on a brass one?
Igor
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