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10/14/2006 11:07:56 PM · #1 |
I have an older macro lens and im not sure how its rated. I also have a mcro kit and the +10 thats in the kit doesnt seem to have the same power as the old one. How can i figure its focal power?
If anything its just a few clicks better then the +10 |
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10/14/2006 11:10:08 PM · #2 |
do you mean closeup filter sets? I think the + rating only means it can change your focusing distance by a factor of 1/n. So 2 = 1/2 the focusing distance and such.
I could be way wrong on that.
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10/15/2006 12:32:29 AM · #3 |
Wavelength nailed it. THe +1 (or 2 or n) is the power of the lens expressed in dioptry (sp?). The dioptry = 1/focal length.
What it does when you put it on e.g. 70-200 lens that cannot focus on anything closer than 1.5m, it allows you to come closer and still be able to focus, hence making a bigger image. It does not enlarge anything by itself.
Beware of the quality, though. With the reduced focal distance, also comes the narrow depth of field. If the glass is not built correctly (read: cheap), you may get extra softness even if you stop the lens down a bunch.
I hope this all makes sense. |
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