Macro lens question...

[thebeginning]

i know 1:1 is supposed to be 'life-size', but what if you put on a 2x teleconverter? it doesnt affect the min. focusing distance, so would it be a 2:1 representation??

 

[wharrison]

TheBeginning:

Nope! If you place the 2X convertor on a 50mm macro lens, you would, in effect, have a 100mm macro lens. Obviously, you would photograph your subject from a greater distance, but the reproduction ratio would be the same.

In order to increase the ratio of reproduction, you would have to mount an extension tube(s) between the camera and the lens. The ratio of reproduction would be dependent upon the "length" of your extension tube(s).

You could easily find your "new" ratio of reproduction by using a ruler vertically next to the subject. If you can see 1 inch from top to bottom, your ratio of reproduction would be 1:1; if you can see 1/2 inch, your ratio of reproduction would be 2:1; and so on and so forth.

I am not certain as to whether the use of a 2X convertor would affect the minimum focusing distance, but I suspect it would.

I'm curious: Why the use of a 2X convertor to do macro work, especially given the loss of image quality, light, etc?

Hope this is useful!

Bill

 

[thebeginning]

oh i wasnt going to try it, i was just curious. i know they do not affect the minimum focusing distance, because i've tried it before. and besides, a converter does go in between the camera and the lense, doesnt it? what is the difference between that and an extension tube?

 

[Digital Matt]

An extension tube has no glass, and therefore does not magnify the image. It only allows you to mount the lens further away from the film plane/sensor, allowing you to focus that much closer.

 

[thebeginning]

ahaaaaa

 

[Big Mike]

And because tubes have no glass, they do not adversely affect the image quality.