Opteka Extension tubes?

[SilverStag]

I saw these Opteka extension tubes on Amazon: Normally I stay away from the cheap glass, but there;s no glass here! Anyone have any experience with these? (They’re less than 1/2 the cost of the Nikkor set.)

http://www.amazon.com/Opteka-Focus-Extension-Digital-Cameras/dp/B002YIY44O/ref=sr_1_2?ie=UTF8&s=electronics&qid=1275899120&sr=8-2

Also, I’m pretty oldschool when it comes to macros, I do an awful lot with a 50mm lens on a reversing ring, and am not fond of the results I get with the add-on diopter lenses. Any words of advice on using extension tubes?

[caradoc]

I hope you’re using a tripod at those close-focus distances. When I’m using an actual macro lens + an extension tube, my own heartbeat/pulse can throw focus off.

[Elsinore]

I have the Kenko version of that set, and I like it a lot. I do find that with my Tamron 28-75 with the 36mm extension tube (or the 12mm and 20mm together sometimes), AF just can’t handle things anymore, probably because of the light loss induced by moving the lens so far from the sensor. Just means it has to be manual focus at that point, and that’s how most people handle extreme macro anyway. I sometimes have to play with exposure compensation a bit, probably for the same reason. DOF of course is crazy shallow, even at f/10, but as you said, there’s no glass, so image quality is as good as good as the lens you’re using. I like the tubes since they’re cheap way to go macro, and they can be used for any of your lenses (with the probable exception of wide angle lenses where depending on the tube length you’re using, you might be moving the focus distance to some place *inside* the lens 😆 ). Like caradoc said, though, tripod is a good idea.

[sleeping]

there’s no glass, so image quality is as good as good as the lens you’re using.

This tends to depend on the lens, actually. You may find that some of them don’t work well for this at all, because they aren’t well corrected for closeup work (e.g. field curvature will be exaggerated a great deal as you increase extension). Also, if you’re using a lens which has some degree of optical correction for close focusing, you’ll only get the maximum benefit at the closest focusing distances (which means you won’t get the best results if you try to use the lens’s focusing mechanism to focus on extension).

with the probable exception of wide angle lenses where depending on the tube length you’re using, you might be moving the focus distance to some place *inside* the lens 😆 ).

If the filter diameter is small enough to do it conveniently you can usually fix that with a reversing ring. With some lenses that may also improve the image quality, particularly as your magnification gets up beyond 1:1 (at that point the the sensor – lens distance is becoming greater than the lens – subject distance, so they tend to be optically corrected better backwards at that point)

[Elsinore]

Well now that’s all very interesting, sleeping, thanks.

[nobigdeal]

I have the Opteka set. They work fine with all my lenses. My 70-200 loves them. So does my 50mm.

[lokisbong]

Well now I need to ask for the canon version for my b-day or x-mas. that and at least one more battery for my Rebel xs. I need a job dammit. this hobby is expensive as hell when employed . Forget about it when jobless.

[SilverStag]

Thanks for all the help! Looks like I’ll be getting a set soon!

[ravnostic]

Well now I need to ask for the canon version for my b-day or x-mas. that and at least one more battery for my Rebel xs. I need a job dammit. this hobby is expensive as hell when employed . Forget about it when jobless.

I feel ya. I was unemployed for several months up to 3 months ago, which is why (with a pilfered neighbor’s net connections) I got into the farktography end of fark to begin with (lots of time, and no money.) I’m fortunate that the job I landed has overtime available; as this group brings out the smeagol in all of us (ask ennuipoet!!)

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