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03-27-2008, 03:18 PM   #1
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constant f4 zooms..

okay, i know i've kind of gone on about this, before.. but.. i'm really getting annoyed, now. is it too much to ask for for a high quality, internal zoom, constant f4 70-200 or 210 or so? maybe i just HAVE been spoiled from my old minolta beercan.. is there ANYTHING similar in Pentax history? here's a shot of it, compared to the 55-200 kit lens..

widest, focus ring fully retracted..



longest, focus at full extension..



it just... is so nice.. i want on for my DSLR! lol

03-27-2008, 03:40 PM   #2
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I wish something like Canon's ultra sharp 70-200/4 existed too...would make a great travel lens. Hopefully, the upcoming 60-250/4 will be good, though I suspec t it'll be pretty heft from the pics posted :-)
03-27-2008, 04:24 PM   #3
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QuoteOriginally posted by kenyee Quote
I wish something like Canon's ultra sharp 70-200/4 existed too...would make a great travel lens. Hopefully, the upcoming 60-250/4 will be good, though I suspec t it'll be pretty heft from the pics posted :-)
70-200/4 that thing looks pretty big for a travel lens.

i was just gonna ask if it was a beercan then read the text!

sorry if this has been asked before, but what are the advantages of a constant aperture?
03-27-2008, 04:40 PM   #4
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70-210, actually.

the nice thing about constant aperture is that, well, it's still fast at maximum zoom. that, and generally when they design such lenses, they're of a higher quality design.

03-27-2008, 04:42 PM   #5
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You can see the list of Pentax zooms here:

Pentax Zoom Lenses with Long Focal Lengths
03-27-2008, 05:51 PM   #6
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QuoteOriginally posted by k100d Quote
70-200/4 that thing looks pretty big for a travel lens.

i was just gonna ask if it was a beercan then read the text!

sorry if this has been asked before, but what are the advantages of a constant aperture?
As the light dims, and the "reach" gets longer, you get double whammied. An f/4-5.6 70-210 which needs 1/250 @ f/4, a usable combination at 70mm, would be 1/125 @ f/56 at 210mm, which is a difficult combination to hand hold. At least with the constant f/4 aperture, you can use 1/250 @ 210 mm, which with care can give an image without too much movement.
03-27-2008, 05:57 PM   #7
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QuoteOriginally posted by Jerry Thirsty Quote
You can see the list of Pentax zooms here:

Pentax Zoom Lenses with Long Focal Lengths
sigh. and this just proves that there are no IZ telephoto's in pentax's history. why is that??
03-27-2008, 06:02 PM   #8
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Alot of pentax zoom lenses were internally zooming like the SMC A70-210/4 and the M80-200/4.5 to name a few.

Both are sharp and leave little to be desired in terms of IQ.

03-27-2008, 06:06 PM   #9
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QuoteOriginally posted by FotoPete Quote
Alot of pentax zoom lenses were internally zooming like the SMC A70-210/4 and the M80-200/4.5 to name a few.

Both are sharp and leave little to be desired in terms of IQ.
A 70-210/4

and

M 80-200/4.5 (version 1) and M 80-200/4.5 (version 2)

look like push pull zooms, to me..
03-27-2008, 06:16 PM   #10
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You can also get the vivitar series 1 70-210 F3.5, I know it is MF but since you are looking for a history lesson

Check the lens data base, Pentac also made a 70-210 F4 KA mount, an 80-200 F2.8 FA mount and some earlier 80-200 (approximate) F4.5 zooms
03-27-2008, 06:39 PM   #11
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QuoteOriginally posted by Lowell Goudge Quote
You can also get the vivitar series 1 70-210 F3.5, I know it is MF but since you are looking for a history lesson

Check the lens data base, Pentac also made a 70-210 F4 KA mount, an 80-200 F2.8 FA mount and some earlier 80-200 (approximate) F4.5 zooms
lowell, from what i've seen, of the Pentax models, only the FA 80-200 2.8 is internal zoom, the rest have barrels that change length while zooming.. but thanks for pointing out the constant apertures
03-27-2008, 06:41 PM   #12
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What are you considering to be internal zoom? Lenses that don't change length when they zoom, or something else? I would have considered the Pentax push/pull lenses to be constant length.

In terms of older manual focus constant aperature lenses that move internal elements to zoom, my Dad still uses an M42 Tamron 70-210 F3.5 he bought for his spotmatic in the '70s and it works beautifully in aperature priority on a K10.
03-27-2008, 07:46 PM   #13
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The A70-210/F4 is a push-pull zoom that does not extended when zooming and only extends 5/16" between its closest focus and infinity. Granted, it's not a AF zoom, but I'd put it up against any constant F4 out there. It's a really good lens.
03-27-2008, 07:57 PM   #14
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QuoteOriginally posted by maxwell1295 Quote
The A70-210/F4 is a push-pull zoom that does not extended when zooming and only extends 5/16" between its closest focus and infinity. Granted, it's not a AF zoom, but I'd put it up against any constant F4 out there. It's a really good lens.
how is it a push pull, without changing length? the push-pull's ive had (2 sigmas for Minolta Alpha mount), there were 2 barrels, one slid over the other, and changed the total length. does the pentax work any differently? it looks the same as the sigmas, since it has the aperture lines on the barrel, like the ones i've used..
03-27-2008, 08:04 PM   #15
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QuoteOriginally posted by Steinback Quote
What are you considering to be internal zoom? Lenses that don't change length when they zoom, or something else? I would have considered the Pentax push/pull lenses to be constant length.

In terms of older manual focus constant aperature lenses that move internal elements to zoom, my Dad still uses an M42 Tamron 70-210 F3.5 he bought for his spotmatic in the '70s and it works beautifully in aperature priority on a K10.
on the minolta 70-210 (beercan), as you rotate the zoom ring, it moves the elements inside of the body, to change the focal length, but the front element stays the same distance from the rear mount. the only time the beercan's overall length changes is during focusing.
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