alessi@gondor.cs.psu.edu (Eric S. Alessi) (10/30/88)
Hello All,
I am in the market to purchase a digital film recorder for my Mac II.
Does anybody have current information? It would be greatly appriciated.
I would like to know:
* the name of the company
* how to locate them
* the product that they sell
* and, if possible, the price
Thanx in advance everyone.
Please reply by e-mail.
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Eric S. Alessi UUCP: alessi@gondor.uucp
Internet: alessi@gondor.cs.psu.edu
Bitnet: alessi@psuvaxg.bitnet
"If you can't find me, you're looking too hard."
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::jvandegr@bbn.com (Jeffrey Vandegrift) (11/01/88)
In article <4071@psuvax1.cs.psu.edu> alessi@gondor.cs.psu.edu (Eric S. Alessi) writes: > >I am in the market to purchase a digital film recorder for my Mac II. >Does anybody have current information? It would be greatly appriciated. > If by Digital Film Recorder, you mean some kind of video camera and stand with a digitizer board that plugs into a small computer and digitizes 2D images, then check with: Digital Vision 66 Eastern Ave Dedham MA 02026 (617) 329-5400 I know they make such things for several personal computers (including a recent color version). I don't know which MACs they support. According to a couple of reviews I read, they make a very affordable, high quality, slow scan (seconds per image) digitizer. - jeff - jeff, x3832
haake@uhura.cc.rochester.edu (Bill Haake) (11/11/88)
Sorry if this shows up twice but I posted it about a week ago and it never showed up so here goes again... In article <4071@psuvax1.cs.psu.edu> alessi@gondor.cs.psu.edu (Eric S. Alessi) writes: >I am in the market to purchase a digital film recorder for my Mac II. >Does anybody have current information? It would be greatly appriciated. > I am also about to purchase a film recorder but for a network of Suns with 2 Pixar II image computers attached. I am particularly looking at the Lasergraphics LFR and the Mirus FilmPrinter. I would like to start a discussion about the pros and cons of different types of film recorders. Since I am only interested in recording raster images not presentation graphics and will probably be writing my own drivers for whatever I buy, I am mostly interested in an evaluation of the hardware. Some questions I have are: How well does the addressable resolution match what actually gets on the film? What is the resolution of different films both color and b/w? How much of a difference does the size of the imaging screen make in the quality of the output? How does an electrostatic display work and why might it be better than a magnetic deflection CRT? Here is what I know about the recorders I mentioned above: The LFR is a magnetic deflection CRT and filter wheel style recorder with addressable resolutions of 4096x2732 or 2048x1366. 24 bits per pixel. Comes standard with 35mm film back 3 1/4" x 4 1/2" is optional. My salesman says that the device has a 6" imaging tube which is larger than others, but I can find no mention of tube size in the LFR technical specs (or anyone else's for that matter). Typical exposure time of 80 secs at 4096x2732 resolution. Available with a SCSI interface as MAC/LFR. List price $9750 The Mirus is based on an electrostatic imaging screen which is supposedly very high quality. It also uses a color filter wheel and has 24 bits per pixel. It comes with a 35 mm film back but no optional backs are yet available. The addressable resolution is advertised as "547 to 8191 lines". I think this means both horizontal and vertical but I am not sure. This is billed as an "all digital" film recorder because the exposure level is determined by the length of time the screen is lit rather than the intensity of the screen. Unfortunately this results in very long exposure times. I went for a demo and we killed an 8000 line slide after about 30 minutes and it hadn't even finished the first pass of a three pass RGB image. 15 min. for a 2000 line RGB image. SCSI interface. List price $5995. Anyone have any comments? I have no connection with Lasergraphics or Mirus other than as a potential customer. Bill Haake 274 Meliora Hall University of Rochester Rochester, NY 14627 PHONE (716) 275-8680 INTERNET: haake@cvs.rochester.edu (128.151.80.13)
kaufman@polya.Stanford.EDU (Marc T. Kaufman) (11/11/88)
In article <325@ur-cc.UUCP> haake@.cvs.rochester.edu (Bill Haake) writes: >The Mirus is based on an electrostatic imaging screen which >is supposedly very high quality. It also uses a color filter >wheel and has 24 bits per pixel. It comes with a 35 mm film back >but no optional backs are yet available. The addressable resolution is >advertised as "547 to 8191 lines". I think this means both horizontal >and vertical but I am not sure. This is billed as an "all digital" >film recorder because the exposure level is determined by the >length of time the screen is lit rather than the intensity of the >screen. Unfortunately this results in very long exposure times. >I went for a demo and we killed an 8000 line slide after about 30 >minutes and it hadn't even finished the first pass of a three pass >RGB image. 15 min. for a 2000 line RGB image. SCSI interface. >List price $5995. >Anyone have any comments? The choice of electrostatic or magnetic deflection is significant only to the extent that the sweep is non-linear. The Mirus generates nice rectangular images. Addressable resolution is 500-8000 points horizontally, 2/3 of that vertically (if you want square pixels). "normal" resolution is 2000 x 1333. This compares with film resolution of ~40 line pairs /mm, which is 2800 lines (not pairs) in 35 mm. (this for something like Ektachrome 100HC film). It is not particularly useful to attempt to image at resolutions higher than the film can support. Color tables are supplied for each film that provide gamma correction (linearization of the perceived intensity steps). Yes, it is slower than some, but that is the normal complexity tradeoff -- which hopefully should be reflected in the price you pay. The basic interface is SCSI, with RGB raster images. The Mac II driver does the rasterization with Quickdraw. There is not currently a SUN driver. There is also a PC version with a Centronics type parallel interface. DISCLAIMER: I am biased. I wrote the FilmPrinter firmware and the Mac Driver. Marc Kaufman (kaufman@polya.stanford.edu)
dave@onfcanim.UUCP (Dave Martindale) (11/19/88)
In article <325@ur-cc.UUCP> haake@.cvs.rochester.edu (Bill Haake) writes: > >Some questions have are: >How well does the addressable resolution match what actually gets on >the film? The two are pretty independent. The addressable resolution just depends on the width of the DACs and other digital hardware chosen by the manufacturer (and in some cases is determined by analog means that have no specific limits). The useful resolution depends on several things. First, take the diameter of a fully-illuminated spot on the CRT face (the tube's spot size) and divide it into the diameter of the usable portion of the tube face. Celco claims 0.8 mil for their best recorders, Dicomed claims 1.0, most others are probably substantially larger (particularly if the spot size is not specified). Typical CRT diameters are 7 inch and 5 inch, with some smaller. The result of the division above will be a number in the range of several thousand; this is the useful resolution for the image diagonal. For a typical image of about 4:3 aspect ratio, multiply by 0.8 to get the horizontal width of the picture in pixels. Ideally, the lens should have considerably higher resolution than the CRT and the film, so it isn't the limiting factor. In practice, there is also a desire to use as fast (large) a lens as you can to decrease exposure times, and a faster lens is either less sharp or more expensive. Tradeoffs, tradeoffs. >What is the resolution of different films both color and b/w? Medium-speed colour negative film can hold about 30 line pairs (that's 60 pixels) per mm at a 1.6:1 contrast ratio, going up to about 100 lp/mm if the original's contrast ratio is 1000:1. For a good ballpark figure, assume you need about 50 lp (100 pixels) per mm of negative width for something that looks "really sharp". You may be able to get away with substantially less than that for computer-generated scenes that don't actually have enormous amounts of background detail. But if you want something that compares to a photographic original, you need lots of resolution. >How much of a difference does the size of the imaging screen make >in the quality of the output? See above. The larger the screen, while keeping spot size constant, the more useful resolution. But it's the ratio between spot size and screen size that is important, not the absolute value of either. >How does an electrostatic display work and why might it be better >than a magnetic deflection CRT? Electrostatic deflection applies an acceleration perpendicular to the electron beam, while magnetic deflection deflects the beam by a certain angle (the deflection is always perpendicular to the electron's instantaneous velocity). With electrostatic, the amount of deflection is directly proportional to the deflection voltage, while with magnetic deflection the angle is proportional to the current and the total displacement to the tan of the current. As a result, circuitry has to be used to linearize the deflection. Worse yet, horizontal and vertical deflection interact with each other, which causes the image to suffer "pincushion" distortion, requiring further correction circuitry. So why do people use electromagnetic? It gives a smaller spot size, and the deflection circuitry operates at low voltage.