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08-09-2011, 09:09 PM   #16
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QuoteOriginally posted by jjhenders Quote
too bad. thanks for the reply. I was hoping I'd be able to extend my 70-300 for next to nothing, but I'll take your word for it and leave them at ebay.
Here's some history: Wide and tele add-ons (mount on the front of the lens -- I call them strap-ons) were popular for consumer-grade film RF's and TLRs, and for film and digital cine-video cams. They worked OK with film stills as long as the images weren't printed too large. They work OK with cine-video because the distortions and aberrations are swamped-out by image motion -- the eye doesn't see any individual frame long enough to notice, and you're busy watching the action anyway.

But for digital stills it's a different story. I have some high-quality strap-ons that my dad used on camcorders. Mounted on a 5mpx P&S, the tele isn't too bad, but the wide kinda sucks. Mounted on a lens on my K20D, they both suck noticeably. These are 0.5x (wide) and 1.5x (tele), not extreme by any means. But they suck.

Now, the TC's. Your choices are: totally manual (M-type or M42), usually cheap, and worth every centavo; aperture automation (A-type), usually fairly cheap; and autofocus with auto-aperture (AF), costly. I may use a manual TC if I don't care about image quality. I've removed the glass from my A-type TC's to use them as macro tubes. And I can't afford an AF TC; don't need one, not a birder.

You've maybe heard this: If it was easy, everyone would be doing it. That's how it is with lenses. Longer lenses (say 100mm+) usually have TC's built into them, called the telephoto group. Adding more such externally and retaining optical quality... ain't easy, which is why everyone ain't doing it. Fast long lenses with matched TC's are splendid. They can also cost as much as a new house in some countries. Ouch.

Yes, a strap-on or a TC will extend your lens' focal length. No, you probably won't like the results.

Last edited by RioRico; 08-09-2011 at 09:14 PM.
08-10-2011, 10:51 AM   #17
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QuoteOriginally posted by jjhenders Quote
I see some very cheap close up lenses on ebay for $13, which includes a 1, 2, 4, and 10 + lenses. Does anyone have any experience with these lenses?
I'd spend the $13 & play with 'em. Whether you like the results depends on the effect you're going for. I once bought a set of +1,+2,+3 screw-on lenses for $11 in a pawn shop, & it's probably been the most fun I've ever had for $11. They screw on my 80-200 lens & I use them for closeups of flowers. There's very little depth of field at +3 so you have to focus really carefully, but I'm usually going for abstracty flower centres so they are perfect. They are also ok for anything closer than the 'macro' range on my other zoom, & if you are shooting either a fairly flat plane or want a shallow depth of field, the image quality is pretty good.
08-11-2011, 09:04 AM   #18
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QuoteOriginally posted by jjhenders Quote
too bad. thanks for the reply. I was hoping I'd be able to extend my 70-300 for next to nothing,
You can. It's called cropping, and it works better with most lenses than any teleconverter, whether rear or front mounted. Plus it doesn't rob you of light or diminsh the effectiveness of AF.

As fo a stepping ring, it's just a threaded metal ring that allows you to attach a filter of one size on a lens of another. As I recall, the Raynox filters have a 43mm mount, so you'd buy the ring that allows a 43mm filter to be mounted on whatever the thread size pf your lens is. Might not exist for larger lenses, but it works great with the 49mm threads of the "M" series primes I use it with. Anyhow, even the supplied adapter isn't particularly onerous; just a bit bulkier than I would prefer.
08-11-2011, 09:30 AM   #19
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Quite right, Marc. Cropping beats TC's. And the Raynox clip-on adapter is a little large but works fine (for me) on lenses with threads between and including 52mm and 67mm. It can *barely* be forced onto a 49mm-thread lens, but a 49-43mm step-down ring is more elegant.

I'm a perv. I also keep a 42-43mm step-up ring with my Raynox DCR-250. Why? To mount it on M42 bellows or tubes. The DCR-250 is +8 dioptre which is 125mm. And its inner diameter is 37mm, which makes it f/3.8. The Raynox has 49mm front threads; add a +2dpt closeup lens and we've got a 100/2.7 lens. Substitute a +10dpt lens and we have a 55/1.5, real cheap and nasty. Make that TWO +10's and it's about 36/0.95! And the image quality? Bloody awful... but it's fun to play with closeup lenses, eh?


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