Bought an Achromatic lens, now what is it for?

S

svdelle

New member
Hi,
Building my own 35mm adapter. Bought this Achromatic lens, as I read all over the web it is essential. Now, it really doesn't make much (if any at all) difference when placed in front of the camera and zooming in on the ground glass. I bought it from handy35.com, and it should work for things like this.

I'm using a Canon Legria HF S10, and seem to have trouble zooming in on the ground glass. Now I expected the achromatic lens to be a help here, but it seems to make absolutely no difference at all.

Does any of you guys have any input to what I might be doing wrong (in trying to focus on the ground glass with the camera)?

Any help is appreciated, thanks.
 
My best guess is that it is like a magnifying glass, thus the camera doesn't have to zoom so far to fill the image in the frame. Without it, the lens focal length would most likely be increased and the close focus ability lost.

My best guess.
 
Correct, but that's only part of the answer. Achromatic lenses are, by nature, macro lenses as well. The amount of magnification varies from achromat to achromat. However, their real use is to cut down on chromatic aberration. You can read more about achromatic lenses here.
 
Is that camera auto focus by any chance. The achromat is a glorified closeup adapter. it enables focusing closer but with better edge to edge quality than a single lens diopter would. Its conceivable that if your video lens is in auto focus you might not realize it made a difference. If you still can't focus on the ground glass then maybe the achromat isn't strong enough . Just a guess. Make sure it is pointed in the right direction by the way, occasionally they get sent out with the threads reversed.
 
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