Re: Extension Tubes

Posted by Bruce on September 26, 2001 at 05:47:01:

In Reply to: Extension Tubes posted by Andy on September 25, 2001 at 21:23:37:

Andy,

With the 2:1 setup, the depth of field is extremely shallow, only about the thickness of the wire framer itself. The only part of the image that will be in sharp focus is whatever is "inside" the framer. Anything beyond the framer is going to be out of focus. That's a limitation of the extension tube setup. If you want macro images with good depth of field you have to use a prime lens without tubes: an RS or a housed SLR. The Nikon Micro 60 or 105mm lenses will give you 1:1, and I have heard that adding a 2x Tele Extender (NOT a macro tube) will take them to 2:1, but I've never tried it myself.

Bruce.
: I would like advise regarding stacked extension tubes. I am using a 2:1 set up on a nikonos 35mm lens set at f22, focus is set at the minimum distance shooting provia 100f using a sb 105 strobe on full manual synced at a 60th on a nikonos III with strobe held at 6 inches distance. The tiny framer is held right at the subject with the framer attached to the tube stacked closest to the subject. My shots appear to be properly exposed and in focus but all most all of them appear to be very soft throughout the depth of field under an 8X Schneider loupe. The lens elements are clean and produce tac sharp results when used with the nikonos close up kit I have. I don't use my nikonos 35mm lenses for anything other than macro or close up. I realize 2:1 is very tiny and I am careful with my technique to stabilize the system while shooting. I would appreciate any ideas. I have never run into this problem before possibly because I have only recently been obsessed with 2:1 macro using extension. Going 2:1 with my housed camera and 105mm lens seems technically more difficult given the close working proximity but I am open for new ideas or advise on if I am doing anything wrong.

: On a different note are any companies making focusing devices for extension tubes? I heard that aquacraft used to. Thanks Andy
:

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: Andy, : With the 2:1 setup, the depth of field is extremely shallow, only about the thickness of the wire framer itself. The only part of the image that will be in sharp focus is whatever is "inside" the framer. Anything beyond the framer is going to be out of focus. That's a limitation of the extension tube setup. If you want macro images with good depth of field you have to use a prime lens without tubes: an RS or a housed SLR. The Nikon Micro 60 or 105mm lenses will give you 1:1, and I have heard that adding a 2x Tele Extender (NOT a macro tube) will take them to 2:1, but I've never tried it myself. : Bruce. : : I would like advise regarding stacked extension tubes. I am using a 2:1 set up on a nikonos 35mm lens set at f22, focus is set at the minimum distance shooting provia 100f using a sb 105 strobe on full manual synced at a 60th on a nikonos III with strobe held at 6 inches distance. The tiny framer is held right at the subject with the framer attached to the tube stacked closest to the subject. My shots appear to be properly exposed and in focus but all most all of them appear to be very soft throughout the depth of field under an 8X Schneider loupe. The lens elements are clean and produce tac sharp results when used with the nikonos close up kit I have. I don't use my nikonos 35mm lenses for anything other than macro or close up. I realize 2:1 is very tiny and I am careful with my technique to stabilize the system while shooting. I would appreciate any ideas. I have never run into this problem before possibly because I have only recently been obsessed with 2:1 macro using extension. Going 2:1 with my housed camera and 105mm lens seems technically more difficult given the close working proximity but I am open for new ideas or advise on if I am doing anything wrong. : : On a different note are any companies making focusing devices for extension tubes? I heard that aquacraft used to. Thanks Andy : :

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