[filmscanners] Re: film and scanning vs digital photography
Hi James, Thanks for the formula. I guess we need to go back to glass plates ;-) Art James L. Sims wrote: Art, There was a depth of focus formula in the American Cinematographer Handbook that was gospel until proven wrong. The depth of focus, given a specific blur circle size, is a trig function of the cone angle Tan ½Angle = .5 x f# ÷ Lens Focal Length. Without special pressure plates or vacuum plates, the film bow in 35mm cameras is typically .003. 2¼ square format cameras have film sag that ranges from about .006 to .010. At large apertures, these dimensions can make a significant difference in image sharpness. The flatbed scanners that I'm familiar with have great depth of field, suggesting the lenses have very small apertures. However, image sharpness degrades as the lens aperture is reduced. I'm not sure what this effect is with flatbed scanners, because each lens is recording one element of the image per increment. Jim Arthur Entlich wrote: There seems to be two main issues with depth of focus with film. One, when the image is captured within the camera, and two, when it is then reproduced, either as a print, or made into a digital file. With 35mm frames, in my experience, the second one is not that significant as long as the digital scanner has a decent depth of focus, which is determined by the aperture of the lens within the scanner. On standard optical CCD film scanners, at least with 35mm frames, if the light source is sufficient, it isn't a great issue, and is easy to test for... either the grain (dye clouds) are evenly in focus or they aren't. The places I have seen a real problem are with larger format films, which may require special mounting, glass carriers, or some other method of maintaining flatness and with film scanners that have inadequate light sources which lead to needing to use a rather wide open lens to capture the image, causing limited depth of focus. The CCD flat bed scanners I have used seem to have substantial depth of focus. I have scanned 3d objects with very reasonable resolution and sharpness. The in camera issue is another matter. I don't know the actual depth of focus at film plane different apertures allow for in camera. Perhaps someone has a chart that indicates the depth of focus relative to aperture. It would be interesting to know. 35mm film is physically small enough that I expect the deviation is of less significance, but I can see how larger roll films or sheet film could end up problematical. Does anyone know if there is a chart which shows depth of focus at the film plan versus aperture of lens used? That could be valuable to know. Art James L. Sims wrote: All other arguments aside, flatness is much more important that some realize. Back in the eighties, I had a lengthy dialog with a well known research lab about depth of focus - it ain't exactly what the American Cinematographer's Handbook says it is. Film bows and sags. That's hard to control. Jim gary wrote: One last point here. Film will probably never be as flat as a piece of silicon. Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: film and scanning vs digital photography
Just a detail, Rob, but the Oly E-1 has a weather-sealed magnesium body. It's quite solid. I don't know if any of their other models have the magnesium body, or if that feature is reserved for their pro line. Berry On 7/5/07 8:52 PM, R.Jackson [EMAIL PROTECTED] wrote: On Jul 5, 2007, at 4:44 PM, David J. Littleboy wrote: Kind of hard to justify coughing up $5000 for a lens to put on a little $600 plastic 4/3 camera. Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: film and scanning vs digital photography
Yeah, I had an E-1. I actually gave it to a friend of mine last year and he's enjoying it. They've just taken so long replacing it that there's really no choice in a high-end E model right now, though the leaked document about the E-1 replacement looks promising. -Rob On Jul 6, 2007, at 7:00 AM, Berry Ives wrote: Just a detail, Rob, but the Oly E-1 has a weather-sealed magnesium body. It's quite solid. I don't know if any of their other models have the magnesium body, or if that feature is reserved for their pro line. Berry Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: film and scanning vs digital photography
Art, Well, we've sort of done that with digital cameras. They have also put my old Pentax cameras out of service, and after all the work I did fabricating a pressure plate that kept the film reasonably flat. At my age, I'm also an advocate of image stabilization - I'm taking sharp pictures, again - hand-held! Jim Arthur Entlich wrote: Hi James, Thanks for the formula. I guess we need to go back to glass plates ;-) Art James L. Sims wrote: Art, There was a depth of focus formula in the American Cinematographer Handbook that was gospel until proven wrong. The depth of focus, given a specific blur circle size, is a trig function of the cone angle Tan ½Angle = .5 x f# ÷ Lens Focal Length. Without special pressure plates or vacuum plates, the film bow in 35mm cameras is typically .003. 2¼ square format cameras have film sag that ranges from about .006 to .010. At large apertures, these dimensions can make a significant difference in image sharpness. The flatbed scanners that I'm familiar with have great depth of field, suggesting the lenses have very small apertures. However, image sharpness degrades as the lens aperture is reduced. I'm not sure what this effect is with flatbed scanners, because each lens is recording one element of the image per increment. Jim Arthur Entlich wrote: There seems to be two main issues with depth of focus with film. One, when the image is captured within the camera, and two, when it is then reproduced, either as a print, or made into a digital file. With 35mm frames, in my experience, the second one is not that significant as long as the digital scanner has a decent depth of focus, which is determined by the aperture of the lens within the scanner. On standard optical CCD film scanners, at least with 35mm frames, if the light source is sufficient, it isn't a great issue, and is easy to test for... either the grain (dye clouds) are evenly in focus or they aren't. The places I have seen a real problem are with larger format films, which may require special mounting, glass carriers, or some other method of maintaining flatness and with film scanners that have inadequate light sources which lead to needing to use a rather wide open lens to capture the image, causing limited depth of focus. The CCD flat bed scanners I have used seem to have substantial depth of focus. I have scanned 3d objects with very reasonable resolution and sharpness. The in camera issue is another matter. I don't know the actual depth of focus at film plane different apertures allow for in camera. Perhaps someone has a chart that indicates the depth of focus relative to aperture. It would be interesting to know. 35mm film is physically small enough that I expect the deviation is of less significance, but I can see how larger roll films or sheet film could end up problematical. Does anyone know if there is a chart which shows depth of focus at the film plan versus aperture of lens used? That could be valuable to know. Art James L. Sims wrote: All other arguments aside, flatness is much more important that some realize. Back in the eighties, I had a lengthy dialog with a well known research lab about depth of focus - it ain't exactly what the American Cinematographer's Handbook says it is. Film bows and sags. That's hard to control. Jim gary wrote: One last point here. Film will probably never be as flat as a piece of silicon. Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
