Tubes and a 500MM

[Jim Fenton]

Since Nikon doesn't make longer MM extension tubes which meter or AF, I will likely buy a Kenko 25MM.

The question becomes, at what distance does this no longer function adequately (as in image degrades OR the gained magnification due to the extension become irrelevant)?

The intent is to use this solely for small perched birds, dragonflies, etc.

Thanks,

[Charles Glatzer]

Jim,

The more extension placed between the lens and focal plane the closer you can achieve focus. There is also greater light loss with more extension, and a greater loss of focus at distance. Everything is a trade off.

I frequently have a 25mm tube on my 600mm when photographing small birds.

I know a few who have bought used Nikon teleconverters and removed the glass for use as auto-extension tubes.

Best,

Chas

[Jim Fenton]

Now all I need to do is find one with busted glass :)

[bobhandal]

I believe that the low cost kenko converters (2x) the center glass piece can be unscrewed and used as a extension tube. Or you can buy Kenko's full extension set tubes, they are great.

[Dan Brown]

Hi Jim, I have the Kenko tube set and have used it with 105, 200 and 80-400mm lenses in different combos with good results. The tubes are great with the 105, but if you try using the full set (68mm?) with the longer lenses, they kind of flex with the weight of the lens (still works good though).

Your image quality will not degrade due to the tubes because of the lack of glass. But, with extension, you will loose light (and shutter speed). That's the bad news, the good news is that with a 500mm lens, you would have to use 500mm's of extension to loose one stop of light, (according to my copy of "Field Photography" by Alfred Blaker) so, 25mm's of extension looses you only about 1/20th of a stop which is not even worth measuring! Get the set and use it with wreckless abandon:D:D. But, beware of the time when you have the tubes on for a warbler and the cougar kills a deer just out of your now less that infinity far focus distance:eek::eek:.

[MichaelM]

Another vote for the Kenko's.. Fully auto on the Nikon bodies. Used it yesterday on the 500 for shore birds and works like a charm. The tolerances on the Kinko F-mount aren't as tight as the TC14e, so there is a bit of wiggle that could be worrisome, but I never lost AF. That would be a reason to cannibalize the TC14e..but otherwise, the Kenko was just fine for me.