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Forum: Lens Clubs
02-24-2011, 05:27 PM
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From first principles:
From the manufacturer's specifications*, the Raynox dcr250 is an 8 diopter "enlarging" lens.
So, it has a focal length of 1,000/8 = 125mm 12.5cm or about 5 inches).
If attached to a prime lens (any prime lens) set to "infinity", then the working distance should be about 5 inches (the same as the focal length of the accessory close-up lens).
In the case of a "full frame" sensor, magnification should be:
Focal length of prime lens x diopter strength of attached accessory lens/1,000
=(in this case) 200 x 8/1,000 = 1.6 times (or 1.6:1).
Quite impressive :)
Should the prime lens be extended (using its helical), the magnification will be increased, and the working distance reduced.
(In either case, the depth of field will be very limited -as can be seen- and there will be some image degradation, especially towards the edges.)
* http://www.raynox.co.jp/english/dcr/dcr250/indexdcr250eg.htm |
