Trying to Resist Buying this Horrible Lens

[madFive]

I was randomly searching around super-telephoto lenses on B&H and Amazon (the vast majority of which I can't afford, since they cost more than my car), and ran across this one:

Kenko 420-800mm + 2x Teleconverter for ~$180

This thing with the teleconverter is capable of 1600mm focal length! It has no aperture blades, so I guess it could be considered relatively fast. It also apparently has relatively low focus distance, so you could sort-of do macro with it. It will obviously not be sharp at all and have horrible IQ, but for the price it's really hard to resist buying it just to play around with a 1600mm.

Anyone here used anything remotely similar before? Care to talk me out of buying this? On a D90, would the lack of cpu-contacts and no aperture settings cause the camera to error out and refuse to fire?

 

[psychoace]

Actually reading reviews of similar lens they seem to be pretty slow. Typically stuck (the f stop is not adjustable through the camera) at f22 and reading a comment on that page would be impossible to use on a windy day with a tri-pod. Last those sample images look horribly soft. Almost unusable if you wanted to actually use them. If you just wanted to see what an extreme telephoto lens is like then yeah try it but don't expect anything usable from it.

 

[madFive]

yeah - I misread the aperture info first time around. It doesn't have aperture blades, and doesn't have adjustable aperture, but still somehow has an F8-F16 aperture listed. Does that mean it changes as you zoom in, or is that a permanent F8 that is doubled to F16 when you use the teleconverter? Definitely not a fast lens by any means - could only be used in broad daylight or with strobes (strobes would at least solve the motion-blur problem - that should help a little).

Despite the horrible softness of the images from this lens, I'm still tempted to pick one up just for fun... we'll see.

 

[Gee1785]

Looks like a mirror lens. Here is some more info:

http://www.photozone.de/mirror-lenses

I would say if you have the money give it a shot. Experimenting with different lenses is always fun. You might be able to find a used copy on ebay and save a couple bucks.