Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site dicomed.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!ihnp4!dicomed!papke From: papke@dicomed.UUCP (Kurt Papke) Newsgroups: net.graphics Subject: Re: Film Recorders Message-ID: <651@dicomed.UUCP> Date: Mon, 18-Nov-85 09:06:06 EST Article-I.D.: dicomed.651 Posted: Mon Nov 18 09:06:06 1985 Date-Received: Tue, 19-Nov-85 05:39:47 EST References: <471@sdchema.sdchema.UUCP> <648@dicomed.UUCP> <14752@onfcanim.UUCP> Reply-To: papke@dicomed.UUCP (Kurt Papke) Organization: DICOMED Corp., Minneapolis Lines: 62 Summary: In article <14752@onfcanim.UUCP> dave@onfcanim.UUCP (Dave Martindale) writes: >In article <648@dicomed.UUCP> papke@dicomed.UUCP (Kurt Papke) writes: >>A brief overview of the Film Recorder marketplace: >> >> Manufacturer/model Price Comments >> Celco $150k 4k, newly introduced 8k >> Dicomed D48 $250k 4k/8k > >A comment on "8000-line" film recorders: The newly-introduced "8k" resolution >Celco is not new at all. The CFR-4000 already had a 13-bit vertical DAC >and so could plot 8000 lines; calling the new model the CFR-8000 is just >marketing. The real difference is that the 8000 mounts the electronics >in a full-height rack, rather than the stubby rack designed to fit under >a table. The older Celco was called the "4000" because its useful >resolution was on the order of 4000 distinct lines - this is limited by >CRT spot size, not DAC resolution. ============== True, but not complete. CRT spot size is the one of the most important factors contributing to the actual "res": resolvable line pairs/mm on the film plane. Other important factors which can compromise the spot size are the quality of the optics in the lens, the color filters (Dicomed filters are actually lenses to correct for chromatic aberrations), and mechanical stability. At 8000 lines the spot can be blurred just by someone walking across the floor unless the tube, optics and camera are mounted well and properly damped mechanically. >I believe the primary reason for >plotting 8000 lines was that if you plotted on very large sheet film >(8x10) you could start seeing spaces between the lines if you plotted >only 4000. But you still couldn't resolve 8000 distinct lines, since >the CRT image isn't sharp enough. This is perhaps true on the Celco, but Dicomed does not have problems with inter-line gaps at 4000 lines. >The Dicomed, I believe, has 15-bit vertical and horizontal DACs. These Correction: 16 bit !! These suckers are expensive !! >allow precise formatting of the on-screen shape of "pixels" and allow the >drawing of very smooth vectors. But the number of pixels it can resolve >on screen is also in the same range as the Celco's - again limited by >CRT spot size. This can be hotly debated. The primary difference between Celco and Dicomed in this area is that Celco uses an intensity modulated beam, whereas Dicomed uses time modulation with constant intensity thus maintaining uniform spot size. The Dicomed spot is under 0.8 mils, but Celco's is tough to measure. It is a distribution based on spot intensity. >>There is obviously a wide discrepency between the price at the bottom of >>the market, and that at the top. This arises from the cost of pushing the >>performance envelope in the 8k region -- film recorders are complex >>electro/mechanical/optical devices. > >The amazing thing is how well they are built. Our Celco seems to use >mostly military-spec parts. The weakest link in both the Celco we >have and a Dicomed I've seen is the camera. What weaknesses do you find in the camera. Marron Carrel makes some pretty good stuff !! "The views expressed herein are not those of Dicomed Inc. They are my own personal, biased, slanted opinions".