Why is the Cooke so big?

[combatentropy]

Nikon 18-200mm:
http://www.reduser.net/forum/uploaded/2100_1203567438.png (http://www.bythom.com/18200lens.htm)

Cooke 18-100mm:
http://www.reduser.net/forum/uploaded/2100_1203567413.png (http://www.cookeoptics.com/cooke.nsf/secondary/s4t3zoom)

Does it have to be?

[Harry Clark]

Holds resolution and exposure across entire frame even when the image is blown up many hundreds of times. Spread out focus and zoom scales. No Aperture Ramp. No "Zoom Effect" when focusing. Provision for internal filter. Close focus. No plastic parts. Basic form factor (its forefather, the 20-100, debuted in 1971) predates modern CAD machining and design.
Not sure why else... ;)
Chers,
Harry

[combatentropy]

Thank you very much, Harry.

I wonder how small could they make it if they used modern techniques and kept just the optical qualities (sharpness, consistent aperture, no breathing) and jettisoned the other features (bigger markings, filter space, continuity with size and shape of forefathers).

I know, it sounds like an academic question. I just look forward to a smaller lens but with good optics, strong build, and at least a 6-to-1 zoom range. Maybe the new Red lens will do the trick: http://www.red.com/store/product_detail/77

[Harry Clark]

Well, there are modern lightweight zooms. Angeniuex has their Optimo lightweights (15-40 and 28-76) and Zeiss has the LWZ 17-35. there is an older, cleverly rehoused still-lens series by Century (28-70 and one other, can't remember the focal length) and of course Panavision has been coming up with some stuff here too (LWZ2 17.5–34, LWZ3 85–200, LWZ 27–68)
My Cooke 15-40, while small, is not as small as most of these. But it does open up to a T.2 which is pretty amazing.
And keep in mind, the lightweight still photo lenses are not really built to be "bulletproof" production lenses that get mounted and unmounted dozens of times per day, twisted all day long on focus and zoom, bounced around on car rigs, traveled around the world in less than ideal conditions. These dedicated motion picture lenses are made to a higher build quality and manufactured in extremely small runs. Many of the techniques and materials used necessitate a slightly larger form factor.
But I'm sure all of these companies will continue to push the envelope here.
Cheers,
Harry

[Harry Clark]

And on a side note, I'd compare all of these discussions about lenses on these forums sort of akin to the question of high-end mics in the music recording business. The advent of every kid (lietally) with a copy of Pro Tools has NOT meant the end of the super expensive, heavy studio mic.
You can buy a tiny, cheap Chinese mic for $99 and it will sound pretty good. You can even make a hit record with one. But why do top producers still use giant, heavy, $7,500 (and up) Neumann, Schoepps, Gefel, and other "high-end" mics? Like lenses, the discrete steps in quality get closer and closer together as you go higher up in standards.
Shooting for the big screen MIGHT require Master Primes, despite their size, weight and cost. Shooting for Podcasts may allow for just about ANY glass to be used. The vast number of projects that we will all work on rest in between somewhere. Sometimes, speed and light weight will rule. Sometimes, absolute picture quality.
It's great to live in these times when many options are available to us all.
Cheers,
Harry

[Brent J. Craig]

Nikon = f5.6 at full zoom
Cooke = T3.0 at full zoom

It's those extra 2 stops that make the difference. Compare an Optimo 24-290 (T2.8) to any comparable f5.6 stills lens and it would be about 10x bigger and 30x heavier.