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02-26-2010, 11:26 AM   #16
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QuoteOriginally posted by RioRico Quote
Then there's the M42 Zenit 17-69mm f/1.9 manual zoom lens for Krasnagorsk 16MM cine cams. But a 16MM or Super16 frame is much smaller than even a 110 frame, let alone an APS-C sensor. So yes, it's a Pentax screwmount, but I suspect the vignetting would be unbearable even on a Pentax 110 SLR. I'll try to find specs on that lens...

Look here [ The Krasnogorsk-3 (K-3) 16MM Film Camera - Filmmaking ] at that lens on a windup K3 cine cam, and you see that it's short but wide. Looks like a fun camera to use.

format ----- frame size -------- diagonal (min. image circle)
-------------- -------------------- -----------
16MM ------ ~10.25x7.5mm -- 12.7mm
Super16 --- ~12.5x7.4mm --- 14.5mm
110 format: 17x13mm -------- 21.4mm
ApS-C dSLR ~25x16.7mm ---- 30mm

EDIT1: The lens is called the Meteor 5-1 (or maybe Meteor 3-2). I'm still looking for specs. I search eBay for METEOR ZOOM LENS and find various offerings, all CHEAP CHEAP CHEAP and probably unusable on our SLRs. Bother...

EDIT2: Here [eBay.ph: METEOR-3-2 ZOOM LENS 1.9/17-69mm FOR KRASNOGORSK-3I (item 230369372265 end time Mar 18, 2010 21:39:23 PHT) ] is the lens on eBay. From the fuzzy photos, the rear element looks to extend quite a way into the camera body. A SLR's mirror probably wouldn't like that very much.
Film camera zooms are often much faster, because they either cover a much smaller sensor/film area and they also do show some more abbereations, especially in the distortion department (even old Zeiss lenses on the 16mm Arris really poduced horripble distortion, compared to still image lenses). Or they are out of this world pricewise.

Ben

02-26-2010, 01:07 PM   #17
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QuoteOriginally posted by Ben_Edict Quote
Film camera zooms are often much faster, because they either cover a much smaller sensor/film area and they also do show some more abbereations, especially in the distortion department (even old Zeiss lenses on the 16mm Arris really poduced horripble distortion, compared to still image lenses). Or they are out of this world pricewise.
Cine lenses are notoriously rotten -- but it mostly doesn't matter. That tiny 16mm or cine 35mm (half of 135 FF size, about the same as APS-C) is projected onto a screen 10 or 20 or 40 or 60 feet wide, and unless the audience is too close, nobody notices. (If you're far enough from the display of ANY image, it's fine.) And the flickering images, chugging by at 24 fps or whatever, don't allow you to see fine details. Your brain may EXPECT those details, so you'll 'see' them as much sharper than they really are. Details only matter on closely-observed still pictures.
02-27-2010, 04:24 AM   #18
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QuoteQuote:
EDIT2: Here [eBay.ph: METEOR-3-2 ZOOM LENS 1.9/17-69mm FOR KRASNOGORSK-3I (item 230369372265 end time Mar 18, 2010 21:39:23 PHT) ] is the lens on eBay. From the fuzzy photos, the rear element looks to extend quite a way into the camera body. A SLR's mirror probably wouldn't like that very much.
I think that's a Helios lens.
02-27-2010, 04:35 AM   #19
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QuoteOriginally posted by Ben_Edict Quote
There is also a Tokina with the same f/2.6 max. aperture. But that is not a real advantage over the standard f/2.8 zooms, just about 1/4 f-stop. I guess, if it was an "improvement" Tokina would still produce it, but it was superseded by the more common f/2.8 version.

Ben
As far as I know, Tokina bought the lens design from Angénieux ;-)

02-27-2010, 01:08 PM   #20
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QuoteOriginally posted by Zav Quote
As far as I know, Tokina bought the lens design from Angénieux ;-)
That is possible, can't remember. The lens is already so long pulled off the market… for a reason, I guess, though it was highly praised by the few owners.

Ben
02-28-2010, 08:33 PM   #21
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>>> METEOR-3-2 ZOOM LENS 1.9/17-69mm FOR KRASNOGORSK-3I

QuoteOriginally posted by chromo Quote
I think that's a Helios lens.
Helios are made at the same factory, so that's likely. It's just named METEOR.

Meanwhile, I further checked on camera compatability. Nope, this cine lens CAN NOT be mounted on an M42 SLR. The rear element extends too far, would be slapped by the mirror. Sigh. Even with a smaller image circle, it would be nice to have such a fast wide zoom. Maybe when the M42 EVIL cams are made, it'll have a new home.
03-01-2010, 07:43 PM   #22
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QuoteOriginally posted by RioRico Quote
You have to consider: what does f-stop mean, aperture-wise?

The f/number is a ratio of focal length to aperture opening. At f/2, the aperture is 1/2 the focal length. I'm holding a SuperTak 55/2; focal length is 55mm, aperture wide-open (f/2) is 27.5 mm; front lens diameter is about 33mm. To make that an f/1 (ignoring all necessary corrections), the rear lens and aperture would be 55mm, and the front lens would be correspondingly larger, as would the lens body. A slower lens, an Industar (Russian) 50/3.5, is little more than a pancake. Fast means fat.

So, think about designing a fast long lens -- a prime, not a zoom. We'll make it a simple long lens, no fancy folded elements. We want a 300/1.5. The rear element needs to be 200mm across -- that is EIGHT INCHES!! The front element would probably be 250-300mm -- TEN TO TWELVE INCHES!! Even with aspherical plastic lens elements, that's gonna be one heavy, clumsy SOB. Make it a zoom, with distortion corrections at every focus, and it gets worse, much worse.

Long fast lenses are physically difficult and economically hazardous, at least.
One way around this is to put the aperture at the nodal point of the lens so you can make the opening smaller and still have the same effect, while taking up much less space.
03-01-2010, 07:52 PM   #23
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I just ordered a Panasonic Lumix LX3 with a 5.1-12.8mm f/2-2.8 lens ... That's a pretty fast 24-60mm (equivalent fov) lens. Of course it's easier if you're only needing to cover a tiny sensor...

03-01-2010, 09:01 PM   #24
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they will be bigger or heavier than those...
PENTAX prime - the biggest - FA*600mm f/4 on Flickr - Photo Sharing!
SIGMA APO 200-500mm F2.8/400-1000mm F5.6 EX DG on Flickr - Photo Sharing!
03-02-2010, 08:33 AM   #25
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QuoteOriginally posted by heliphoto Quote
I just ordered a Panasonic Lumix LX3 with a 5.1-12.8mm f/2-2.8 lens ... That's a pretty fast 24-60mm (equivalent fov) lens. Of course it's easier if you're only needing to cover a tiny sensor...
Good choice! I opted for the slightly more pocketable S90, but the LX3 appears to be a nice compact too
03-02-2010, 01:38 PM   #26
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QuoteOriginally posted by RioRico Quote
You have to consider: what does f-stop mean, aperture-wise?

The f/number is a ratio of focal length to aperture opening. At f/2, the aperture is 1/2 the focal length. I'm holding a SuperTak 55/2; focal length is 55mm, aperture wide-open (f/2) is 27.5 mm; front lens diameter is about 33mm. To make that an f/1 (ignoring all necessary corrections), the rear lens and aperture would be 55mm, and the front lens would be correspondingly larger, as would the lens body. A slower lens, an Industar (Russian) 50/3.5, is little more than a pancake. Fast means fat.
Though I agree with your general assessment, your maths is simply not correct.

The open aperture is defined by the entrance pupil, not by the exit pupil.
There is no reason, why the rear element of a 50/1.0 needs to be 55mm in diameter. Reality proofs that: The Noctilux would not fit into the M-bayonet if it where that size. According to your theory the rear element of a simple Pentax DA 200/2.8 would be more than 71mm in diameter - how is that supposed to fit the camera at all?

QuoteOriginally posted by RioRico Quote
So, think about designing a fast long lens -- a prime, not a zoom. We'll make it a simple long lens, no fancy folded elements. We want a 300/1.5. The rear element needs to be 200mm across -- that is EIGHT INCHES!! The front element would probably be 250-300mm -- TEN TO TWELVE INCHES!! Even with aspherical plastic lens elements, that's gonna be one heavy, clumsy SOB. Make it a zoom, with distortion corrections at every focus, and it gets worse, much worse.
The reality is: a 300/2.0 would afford a 150mm diameter front lens! It may be a couple of millimeters bigger to allow for some image formation before the ray bundle goes through the iris (aperture), which would need to provide the full 150mm diameter seen from the front.
I have set that in bold, because this is important: we are not talking about the mechanical dimension of the aperture, but about its projection, as viewed through the front lenses, aka the entrance pupil.

The diameter of the rear element is a totally different proposition, because it has not much to do with the question whether a lens is fast or slow. The diameter of the rear element plays mainly a role in vignetting and in illuminating a certain film/sensor format. Thus a lens for a medium format camera would need a bigger rear element, than one designed for 4/3 cameras. But that has nothing to do with the max. aperture!

Ben
03-02-2010, 04:37 PM   #27
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QuoteOriginally posted by Ben_Edict Quote
Though I agree with your general assessment, your maths is simply not correct.
You are quite right. I was fatigued, and roughing-it with my argument. I need to review material on optics and lens design before I start blathering with numbers. (Memo to self: Wake up and engage brain before opening mouth.) I should have said that for a 300/1.5, the FRONT element would be 200mm, an 8" diameter heavy booger. (I think I'm right this time.) But we do agree that for APS-C and larger frames, faster-longer lenses (especially zooms) are necessarily BIG.
03-02-2010, 05:02 PM   #28
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Leica Dicomar Lens 35-420mm F1.5-F2.8 zoom


HDC-HS700/HDC-TM700/HDC-SD700 | HD Camcorder | Panasonic Global




Sigma 200-500 F2.8

Zoomatar 240mm F1.2 on Pentax 6x7

Last edited by jogiba; 03-02-2010 at 05:11 PM.
03-02-2010, 05:23 PM   #29
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QuoteOriginally posted by egordon99 Quote
Good choice! I opted for the slightly more pocketable S90, but the LX3 appears to be a nice compact too
<hijack="this thread">

Heh - total hijack here but... Yeah, I went back and forth on those two, but it came down to the wider lens 24mm vs. 28mm on the Canon, HD video, and fear of the rear dial on the S90 (I would love it in normal shooting, but I'm buying the little camera to have something I can shoot while flying a helicopter, so I need bump resistant controls and that control wheel could give me trouble).

</hijack>
03-02-2010, 06:54 PM   #30
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QuoteOriginally posted by jogiba Quote
Leica Dicomar Lens 35-420mm F1.5-F2.8 zoom
C'mon now, it ain't really a 35-420 -- that's the 35mm EQUIVALENT. The lens is really less than 1/10 that -- 3.45-41.4mm -- and at f/1.5-2.8, that's actually kind of slow. An f/1 of that size shouldn't be hard to make, nor be a behemoth. Has Leicasonic gone lazy?

That Sigma is a real pig. Where do I buy the slave(s) to schlep it around? I'd like to have the Zoomatar, get a tilt-shift adapter for my K20D, work it out. It would be the only one on the block, for sure.
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