Achromatic Diopters - how can you tell how strong they are? at DVinfo.net

Go Back   DV Info Net > Special Interest Areas > Alternative Imaging Methods

Alternative Imaging Methods
DV Info Net is the birthplace of all 35mm adapters.


Reply
 
Thread Tools Search this Thread
Old March 17th, 2005, 12:02 PM   #1
Major Player
 
Join Date: Dec 2004
Posts: 749
Achromatic Diopters - how can you tell how strong they are?

I have a friend with a Achromatic Diopter that he picked up at a flea market, but we have no idea how strong it is - are they ways of telling?
Leo Mandy is offline   Reply With Quote
Old March 17th, 2005, 01:35 PM   #2
Major Player
 
Join Date: May 2004
Location: The Netherlands
Posts: 204
You should be able to tell the focal length by going out on a sunny day, hold the diopter above a surface and try to make a hotspot (the smallest you can make) from the sunlight. When you've got it measure the distance between the (middle of the) lens and your object. Since you can safely assume the sun to be infinitely far away, the distance from lens to hotspot is also your focal length.

Then you divide 1 by that distance you found (in meters of course), and there you have your diopter strength! -example: if the distance is 200mm=0,2m , diopter is 1/0,2= +5

Have fun,

Steven

PS: Didn't you burn little pieces of paper as a kid? (or spiders - :O oh no I didn't say that :P )
Steven Fokkinga is offline   Reply
Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

Professional Video
(800) 833-4801
Portland, OR

B&H Photo Video
(866) 521-7381
New York, NY

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

Precision Camera
(800) 677-1023
Austin, TX

DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > Special Interest Areas > Alternative Imaging Methods

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 07:12 AM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network