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01-08-2007, 12:02 PM   #16
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QuoteOriginally posted by NaClH2O Quote
Usually when you see _X optical zoom, on a p&s camera it means that the the longes focal length is _times the shortest focal length. Say for instance that you have a fancy p&s that says it has a 12X optical zoom. Chances are that it would have something like a 18mm to 216mm (in dslr terms) zoom lens. (12 x 18 = 216) It is NOT comparable to the ratings of binoculars which IIRC give a direct magnification number.

Thanks, SaltWater, helps a lot.

Canon/Japan sponsors an excellent info site for the Canon S3 IS, and there, I found this info that I hadn't paid attention to before because I didn't understand it very well:

QuoteQuote:
Lens: 6.0 (W) - 72.0 (T) mm (35 mm film equivalent: 36 - 432 mm)
f/2.7 (W) - f/3.5 (T)
With the help of the folks in this forum, I think I understand these specs better now. Focal lengths on that camera run from 6mm to 72mm, which as you said is a factor of 12 (6 x 12 = 72). So that explains the "12x" claim in their marketing. It's interesting that they translate this into 35mm terms. I guess that means that it's about the equivalent of the 300mm lens I have for my K100D, at least in terms of field of view.

Will

01-08-2007, 12:34 PM   #17
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Sorry about that, Will. Understand now? FYI, Phil also lists these specs on dpreview for various cameras. It's more or less a marketing thing; try explaining 430mm to a customer who barely understands how to turn the camera on.

For the S3IS:
Zoom wide (W) 36 mm
Click for help Zoom tele (T) 432 mm (12 x)
01-08-2007, 01:47 PM   #18
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" Originally Posted by jfdavis58 View Post
Only one end of the lens has the macro capability; usually the long end (200mm). The lock holds this zoom position and it's important that it does. In the 200mm position the internal arrangement of lens elements occupies the greatest space. To focus at macro subject distance the motion of internal elements uses this maximum space. At any other focal length those internal elements collide, risking internal damage as the AF motors slam the elements together seeking correct focus. Or in manual focus as the user attempt to twist the focus ring to the extreme close-up focus at other than full focal length."

sorry my friend but your information is wrong applied to the tamron 18 x 200.. the lock is purely to stop the lens drooping when being carried or stored and is only capable of being operated when the lens is fully closed..

it has no other purpose at all.. i own the lens and know exactly how it works.. i dont think u do.. sorry..

there is no macro facility as such the lens will focus down to 17 inches whether its at 18 or 200mm..

we are talking about the tamron 18 x 200 are we not.. ???

trog
01-08-2007, 02:30 PM   #19
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QuoteOriginally posted by trog100 Quote
the lock is purely to stop the lens drooping when being carried or stored and is only capable of being operated when the lens is fully closed...

... we are talking about the tamron 18 x 200 are we not.. ???
Yep, that's the one!

Have to thank John (bfdavis58) for his post. Sounds like it will be correct for another lens, and while it appears he's mistaken about the lock on the Tamron 18-200, his post led to trog's correction, and the net result is that I've finally gotten the answer to my last remaining question about the lens. I did try to some macro shots this afternoon. I tried to use the lock, but I simply could not get it to work at all. Trog's post explains why: it only works when the lens is zoomed all the way down to the shortest length. Just tested it and that's right.

I think the lock is a bit of an odd feature. Maybe it will get "looser" over time, but right now, I can't get the lens to droop when I hold the camera lens down. Nevertheless, I'm happy to know what that button is for.

Will

01-08-2007, 04:04 PM   #20
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i had kinda mentioned what it was for in my earlier reply about the lens.. most of what gets written in these longer threads dosnt get read thow.. he he.. nip back and read it there might be some other usefull information that got missed..

its more for when u walk about with the camera/lens hanging from a strap around your neck .. it might even stop it getting busted one day..

to me its a "quality" feature.. not essential but usefull..

trog
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