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January 17th, 2007, 08:50 PM | #61 |
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Optics
I've been spending a lot of time thinking about the optics of these devices. I recently went to the movies and slipped out of "Little Children", which is a beautifully lensed film, with clear optics that are the hallmark of well-shot studio films, and slipped into Lynch's "Inland Empire".
Immediately, I noticed the crappy lens look I have grown very used to, shooting on my own prosumer digital camera. I am tired of the optics that come from these little zoom lenses. I have been looking at the possibility of renting mini35/HD100 for my next big project this Spring. Part of the reasoning is that with a relay lens that is not a zoom (I own a couple handmade adapters that I screw onto to my hc1's zoom lens), but a relay lens that is prime. I have to admit it's been a while since I looked at that pro35 DVD P+S Technik sends out for free; I'll have to dig it up; I wasn't as sensitive to the effects that differing lens qualities can have on an image when I originally watched that DVD. ANYWAY, my question is twofold: 1) Concerning adapters which use relay lenses that attach directly onto the camera body, bypassing a zoom (such as a HZ-CA13U or P+S Technik with proper adapter)--can it be expected that these adapters will produce images that are as distortion free as the fine images we see in a lot of 35mm studio fare? In other words, how much distortion/etc. is added by the relay lens and focussing screen? 2) I know the JVC rep doesn't get into it too much in this thread, and this thread seems to be the most definitive source on the subject so far, BUT, what were the quality considerations that lead to the HZ-CA13U being 16mm only? The JVC rep's explanations didn't make complete sense to me; was it an issue of cost? Was it an issue of cost/performance--that by sacrificing JVC customers' ability to use newer Zeiss and Cooke lenses, the HZ-CA13U would nevertheless be able to beat the mini35's quality, but only by focussing on the 16mm lenses exclusively because of some technical optical issues, OR SOMETHING LIKE THAT? What is the optical quality outlook on the mini35 vs HZ-CA13U question (for JVC hi-def cams)? |
January 17th, 2007, 09:45 PM | #62 | |
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January 24th, 2007, 08:11 PM | #63 |
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this question is heretofore withdrawn
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January 24th, 2007, 08:19 PM | #64 |
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the story of 16mm lenses
similarly, this comment is heretofore withdrawn
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January 25th, 2007, 07:10 AM | #65 |
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Fischer Spooner, as good a song as "Emerge" is I doubt very much doubt that that's your real name. But whatever.
In regards to the prime versus zoom issue for the relay lens, don't expect much of a difference. A good zoom is way better than a bad prime, and all the relay lens does is photograph a flat surface and because it's a flat surface there is inherently no chromatic abberation (and since it's shot at a reasonable focal length, no barrel distortion, either.) The mini35 doesn't play nice with HDV, by the way, so I'd be wary. Children of Men is an Academy Award nominated medium budget film with a fantastic DP. Inland Empire is David Lynch playing around with a pd150. The reason one film looks better than the other has to do with a lot more than zooms versus primes. The HZ CA13U sounds awesome, though, and designed specifically for the JVC, unlike the mini35. You can get some fantastic 16mm lenses (for a lot less than 35mm lenses) that open up to f2 or even f1.4 and if depth of focus is a concern, shoot at f2. (Most 35mm is shot at f4 and it will look about the same.) If resolution is a concern, don't worry--HDV will be the limiting factor 90% of the time. Also, check out the second page of this thread ( http://www.dvinfo.net/conf/showthrea...t=83854&page=2 ) as it has some interesting info on optical adapters and, more specifically, why JVC chose 16mm--since a purely optical 35mm solution might have been prohibitively hard (and expensive) to develop. |
January 28th, 2007, 07:02 PM | #66 |
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HZ-CA13U First Look Findings
Matthew,
Thanks very much for contributing to this thread with the extensive discussion on the lens adapters. The discussion on the engineering of the adapters appear dead on. The major difference between the Angenieux/Zeiss CLA 35 HD is that the HZCA13U does not invert the image. To incorporate this feature, my guess is that it would make the adapter longer and would need additional optical elements - the HZCA13U has 11 in its design. Jon Fauer, ASC, has done extensive testing with the HZCA13U and the GY-HD250 side by side with an Aaton 16mm film camera and arrived at the following results: "Focal plane marking should be 52mm behind the flat surface of the lens mount – all PL mounted lenses, 16mm or 35mm, are measured and calibrated that way. So it should be scribed on the barrel. It looks to me like an aerial image – but still, that’s where it’s being focused, right? I was delighted to find that 16mm, super16 and 35mm motion picture PL lenses all worked equally well, from the 4mm to the 180mm lenses we tested. Very sharp—as good as the best zooms dedicated to the 1/3” format. (Note: Jon's resolution tests were in comparison with the Fujinon HTs18x4.2BRM HD lens) Use: this fills a huge need in 1/3” format: prime lenses. I supposed a Digiprime 2/3” lens could be mounted, but this provides a use for the large and idle inventory of older 16mm lenses, as (C. Yanagi) well predicted. When would I used this? In situations where I want to rack or follow focus with minimal “breathing” – ie: apparent change of image size (sort of a zoom effect) when focusing – which happens a lot on most zooms. Also for critical dramatic scenes where we have to follow focus: following an actor. Field of view appeared to be very close, if not exactly, to normal 16mm format. I wouldn’t call it “optimized” for normal 16 in your ads or pr: just say that it accepts, without vignetting, all PL mount lenses, 16, s16 and 35. Field of view of 16mm and 35mm format lenses appeared the same. Same with depth of field. Depth of field can be further checked using one of Zellan ZGC’s Putora charts...." We had the HZCA13U outfitted with a Zeiss 16mm/16mm on the GY-HD200 and recorded .m2t files at 60p into a DR-HD100 to demo the system at the HD House event in Sundance last week. Tim Dashwood has posted the test in QT: http://web.mac.com/timdashwood/iWeb/...A13U_Test.html It should also be noted that Andrew Young played a major role in testing the initial prototypes - it was his testing results that led to the refinement of the optics design. Andy's findings were that the field of view didn't cover that of S16 or 35mm, but rather took a "center cut" of the 16mm diagonal of the lens, which resulted in no vinetting of either S16 or 35mm lenses, a characteristic which he preferred to see from using his SuperSpeeds. Here lies the difficulty in determining what type of lens to base the design of the adapter. JVC chose 16mm as these lenses are the most abundant with film schools and rental houses, as well as ownership by most indie photogs. To consider S16 or 35mm would signify competing with the available lens adapters out in the market today, which is not the intent. The adapter is to provide a means for independents to use the most abundant and affordable film lenses available. The result of the final design can be considered as an unexpected bonus (as per Jon Fauer's findings) in that you can use S16 and 35mm lenses with the adapter if you so choose, and expanding the use of the ProHD camcorder system. It should be noted, though, that lens test findings may vary as lens selection is a subjective matter, so it is highly recommended that everyone tests before determining what lens to use for their projects. Tim Dashwood will also be conducting his own tests and I've asked him to share his results for us. Also, as an update, the HZCA13U should ship from the factory at the end of February. The extension to the delivery date was due to implementing some additional late adjustments to the product design.
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January 29th, 2007, 08:55 PM | #67 | |
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Here's perhaps a better way to phrase the question: a zoom lens--by merit of being a zoom--adds a certain amount of optical aberration (indeed, any additional optical elements add a measure of optical aberration). How much optical aberration does the focusing screen/relay lens add? My own rig definitely produces distortions. I use SLR Canon FD prime lenses. For example, a F2 28mm wide angle lens using the video camera's zoom lens as a relay produces definite, visible distortions--optical aberrations of the character that I noticed in the blown up PD150 footage in Inland Empire (that are unrelated to grain, noise and resolution). I suspect that the optical abberations introduced by the focusing screen are minor campared to the aberrations introduced by the zoom/relay. I suppose I'll find my best answer at some point by testing out the gear myself, but in anticipation of the HZ-CA13U's release, I thought perhaps there might be some intelligent discussion here.. |
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February 23rd, 2007, 01:11 PM | #68 | |
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thanks, marshall |
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February 23rd, 2007, 07:46 PM | #69 | |
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February 23rd, 2007, 09:26 PM | #70 | |
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I also conducted two days of tests at Clairmont with every lens we could think of (from Cooke S4 to anamorphics) and the depth of field results seem to match the charts of 16mm almost dead on (assuming a "16mm" CoC of 0.0015mm) I'm still waiting for my 16mm film to come back and be scanned for practical comparison of DoF. Right now I'd happily use this product in a production. Once you set the backfocus there is no messing around with it and it behaves predictably, just as the lenses would on 16mm. More to come in a few weeks.
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February 24th, 2007, 09:38 AM | #71 |
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Rental houses?
Unfortunately, this is not in my budget anytime soon, let alone the crunchy glass cylinders to go with it....
BUT, it will be awesomely transforming to have one available along with primes to rent. My impression is that the family of 35mm converters with ground glass etc, would take a day to properly set-up for a noobie, and still take some serious getting used to. Not as practical for the rental situation, unless staff there was really helpful. I'm in NYC, so I assume renting the HZ CA13U will be a realistic expectation. Abel-cine is probably a good target, since they are JVC dealers, and they have a nice selection of 16mm PL lenses for rent. I don't see the 13x JVC lens there though - that is another item I'd love to have occasional access to. So Noo Yawkers, lets think about petitioning A.C. when this puppy gets released. Or maybe doing a coop purchase. Sorry Craig! It's either this or nothing for the short haul!
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February 24th, 2007, 09:41 AM | #72 |
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c-mount lenses!?
Another thought! I do still have 5 lenses for my Bolex 16mm reflex...
(got to admit, it's ALREADY dusty & it's looking even older recently ;) A couple are actually decent. Is there a c-mount to PL conversion? I'd assume that the smaller c-mount could fit inside, so it could still have the right focus plane. Hmmm.
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February 24th, 2007, 11:11 AM | #73 | |
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Interesting findings about the stop readings. I wouldn't have thought you'd have lost so much light through a modern zoom lens (some of the old 16mm 10:1 zooms from the 1960s lose a stop) - 1/3 to 1/2 stop would be usual. Perhaps this is because the light is now being concentrated onto a smaller area - a reverse of the x 2 extender which has a drop off in light because it's being spread over a larger area? Or even a bit of both? |
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February 24th, 2007, 02:12 PM | #74 |
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Thanks Brian,
I figured it might be a long shot.... Thanks for the detailed explanation.
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March 25th, 2007, 07:43 AM | #75 |
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No matter how good, the price is disproportionately high
Like others who have posted on this, one of the reasons I bought this camera was to have the option of using other lenses. I have been very happy with the camera -- it's the only video camera that I have ever used that I could even begin to say that about -- the Cine Alta is not in the cards for me, and is no doubt much too big for what I do. To do away with interlacing and have a real, manual lens makes it like a film camera. I have been an experimental filmmaker for years using 16mm, and would never have gone into the field had interlaced video been the only game in town. Even the 6-frame GOP (on my early HD100u) produces no perceptible artifacts when handholding. With an AJA Kona card, I get good-looking DVCProHD 720p24 images. Thanks to JVC on that score, for making a video camera that is like enough to film for a filmmaker to be reasonably happy with.
However, the lens that shipped with it has a persistent chromatic abberation which is subtile but almost always there. It's not so much as to make it unusable, but those purple and green edges that occasionally appear were not actually there in the subject. A lens that introduces information that was not in what it's shooting falls short of the ideal. But I put up with it, thinking that eventually I'l be able to use the 16mm lenses I already have, and buy adequate used primes for several hundred dollars that will blow away the stock zoom -- in all my years of filmmaking, I have never seen a chromatic abberation problem like the one I see here. But now it comes out that list price is around $4k. $4k? That's almost as much as the camera -- for a lens adapter? I understand that it's "a complicated bit of optics," that it has 11 optical elements, etc., but given that I could put a prime lens on it that cost me $400 and get a beautiful image, spending 10x as much on the adapter seems out of line. It's not going to take anything nearly as expensive as a new Zeiss prime -- however much I wish I had a set! -- to get a really nice image. But at $4k, I can't afford the adapter, and I make that assessment with a great, almost bitter sense of disappointment. Filmmaking matters to me, and I'm not really in it for the money. I'm not an aspiring "indie" filmmaker trying to get my feature out and score. I don't work in the "industry," and have no desire to move to Hollywood. I have great respect for those who do work really hard to get good films out in the commercial world -- more power to you! -- but there are others of us out here who make films for other reasons. We are not aspiring to do that, and we lack the financial expectations of hoped-for "success". Maybe new gear was always too expensive for experimental filmmakers, and after the remarkable price drops in quality equipment like this camera, maybe this adapter is just a reversion to that same harsh reality. But clearly I am part of a market segment -- the personal, or experimental, or "fine art" filmmaker -- that has jumped on this camera because of its transforming video into something visually acceptible, but that has been shut out of the further progress that this adapter makes possible by its price. I feel ill knowing that between the better lenses that I already have and this camera that I already have lies an adapter that I can't afford. I am left with several questions. 1) how did JVC establish the price for this? I've been puzzled to see reaction here that this price is reasonable, but then it gets compared to other film-video lens adapters and, indeed, they are expensive. But then, is this just a price that was picked because that's what everyone else is charging, or is it a meaningful reflection of how much it costs JVC to produce? I know it sounds old fashioned to say it, but shouldn't prices reflect production costs and not just how much the market will bear? 2) by pricing it this high, JVC has dramatically reduced the number of them that will sell. Why not charge less, and sell more units? 3) so, it's essentially a relay lens, that reprojects a focused lens image onto the camera's sensor. That's complicated, and also relatively bulky. Why not make a simpler adapter that accepts a pl lens (or a c-mount, for that matter) and changes the back-focal length so that it hits the camera sensor directly? Granted, I am not particularly knowledgeable about optics, but is this not a simpler idea (to have just the camera sensor focal plane) than a full-on relay lens system that essentially results in two (matching) focal planes? Couldn't such an adapter be less bulky, have fewer optical elements, and be less expensive? 4) could JVC make something simpler (in addition to the HZ CA13U, now that it's developed), like the above, that didn't work so hard to preserve the focal length and depth of field properties of the original 16mm lens? A 1/3" sensor is more like a Super-8 frame than 16mm, so clearly this required some doing. Why not just make the simplest possible adapter, and let the user compensate for differences? What they've released, by all reports, works really well, but for me it doesn't work at all since I don't -- and likely won't -- have one. So, why not also make a cheaper version that would allow the rest of us to at least be able to use our better lenses, even if the focal length and dof are changed? 5) could anyone out there convince me that this adapter really is worth the money, and that I ought to find it and buy one? Thanks, Robert Schaller |
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