[filmscanners] Re: film vs digital test
First of all, I wouldn't consider the test to be valid bearing teh huge gap in lens qualities. You'apparently putting Hasselblad's lens (i.e. Zeiss ine, even though zoom) against this all-in-one kind 28-300 Tamron turist's orineted zoom. I think to provide correct base under your estimation, you have to line-up your lenses achieving at least comparable optical qualities, particulalry if considering high-resolution scanning afterwards. If yuo work with Kodak - the appropriate one would be probably Nikon high-quality prime or professional zoom. Just my opinion. Alex --- Norm Carver [EMAIL PROTECTED] wrote: I am in the midst of doing a basic comparison between my Hasselblad and the new Kodak SLR Pro (14mb, full frame). I don't need a super accurate test, just reasonably fair. My work is half color, half bw with the end product in books and large exhibition prints 20 to 40. I invite suggestions and/or critiques of my approach as outlined here: I gave up the dark room several years ago after too many decades. So I must compare scanned film against digital RAW. Also, though it may invite scorn from some purists, I am comparing the actual tools I work with most of the time, not the ultimate options in lenses. These are: Hblad 203fe with 60-120 zoom Kodak SLRpro with Tamron 28-300. I take the test images from the same position and adjust the Tamron zoom factor to match the approximate vertical coverage of Hblad zoom. To avoid any focus hocus pocus I am measuring distances. I care mainly about the clarity issue --ie details and sharpness and less about color accuracy as this is more easily adjusted. The digital raw is 16 bit, 4500x3000 @ 300 rez which equals about 10 ht image. The 220 films, (CN400) and Ektachrome VS 120 are scanned on a Minolta MultiPro (a Nikon 8000 is also available). But here is where I need some advice. I believe I should scan to end up with the same 300 rez but to what file size? Here are two I have tried and the thinking behind each: 1. Scan the 2.10 x 2.10 area at maximum of 4800 dpi which gives an image size of 34 sq and a file size of 604 mb which is simply too unwieldy. 2. Scan at the nearest even dpi to approximately double the image size since the 220 film is a little over 2x the ht of the Kodak orig of 1 which means 3200 dpi and image size 22.7, file size 268. I stand ready for any further ideas. At the end, if any one is interested, I shall try to post the results on my web site, normancarver.com Thanks for any help, Norm Carver Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: film vs digital test
Norm, Although both of the below sites compare the 1DS (similar to your SLR/n) with a Rollei and a Mamiya 7 (more sq. mm than your Hassy), I found the sites to be informative and ran tests much better than I could hope to do. http://www.photographical.net/canon_1ds_mf.html http://www.wlcastleman.com/equip/reviews/Eos1Ds/build/building.htm Hope this helps. Warren --- Norm Carver [EMAIL PROTECTED] wrote: I am in the midst of doing a basic comparison between my Hasselblad and the new Kodak SLR Pro (14mb, full frame). = Warren Xato For where to go when you know when [EMAIL PROTECTED] __ Do you Yahoo!? New and Improved Yahoo! Mail - Send 10MB messages! http://promotions.yahoo.com/new_mail Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: film vs digital test
Norm, I think you're on target with the what works approach but will echo the comments about the Tamron 28-300. I have the 28-200, which is fine but a friends 28-300 is disapointingly soft. If memory serves, that was also noted in reviews of the lens (and photography mags tend only to damn with faint praise). I have a Tamron macro as well, so I'm not adverse to the company's products. The shorter Tamron or Nikon glass would be preferable, but again -- if the system works for you, it works. Bernie Norm Carver wrote: I am in the midst of doing a basic comparison between my Hasselblad and the new Kodak SLR Pro (14mb, full frame). I don't need a super accurate test, just reasonably fair. My work is half color, half bw with the end product in books and large exhibition prints 20 to 40. I invite suggestions and/or critiques of my approach as outlined here: I gave up the dark room several years ago after too many decades. So I must compare scanned film against digital RAW. Also, though it may invite scorn from some purists, I am comparing the actual tools I work with most of the time, not the ultimate options in lenses. These are: Hblad 203fe with 60-120 zoom Kodak SLRpro with Tamron 28-300. snip Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: Moire - Scanners vs Digicams
Hi Al, I believe both Austin and David have provided you with information on the specifics of why moiré is more likely to occur on a digicam image than a scanned film image. I do not know how much of the technical jargon provided was comprehensible, so I will try to simplify the message, although my explanation may take more words to accomplish. Both digital cameras and film scanners are monochromatic (they really record only gray scale or luminescence information). However, as we all know, they seem to reproduce color images. How is that possible? Both use color separation filters to accomplish that feat, but the way they do so is quite different. As you probably know, the way color separation is accomplished is by using color filters over the sensor and then have that sensor acknowledged in software or firmware to be recording luma information for that color only. By measuring the amount of light which falls upon the sensor after filtered through a red, a green or a blue filter, when those three data values are brought together, the color of the light that was projected on the sensor can be determined. So, if a sensor has a red filter over it, is can measure the amount of red light in the light source projected upon it (through the filter) and so one with green and blue. With a film scanner (or a flat bed for that matter) one of two methods are likely to be used. With the vast majority of scanners there are three sets of CCD sensor strips. Each strip is covered with one of the three filter colors. As the slide or neg (or the reflected image color) is projected on the CCD sensor strip through the filter above it, each sensor point records the value of the light of the filter color hitting the sensor. Each point for which a sensor exists (such as 2820 per inch) is read by each of the three sensor strips, and the three data values are brought together so that each sensor point is expressed as a value for RED, GREEN and BLUE light. Thus each sensor point is given a value to indicate a specific color value. So, in this case, the film color values are recorded 2820 times per inch in both dimensions. That's a lot of sampling. The second method is similar, and used by Nikon film scanners. It uses one CCD strip with no filter over it, but the color of the light projected through the film changes three times, from RED to GREEN to BLUE, and the CCD sensor for each point takes a reading for each color change. You get the same amount of samples and information. Now, let's look at how most Bayer patterned cameras. Again, remember that the CCD sensor is still only reading luminescence values, not color. In order to allow the camera to record color, we again have to make color separations. In a perfect world, each data point would get 3 readings: one for Red, one for Blue and one for Green, using filters in front of the sensors to make the color separating information. But since digital cameras have to operate much faster, they need a whole chip of sensors to capture the whole image in one capture, unlike scanner which use just a strip of sensors one sensor wide which are moved (or the film is moved) until they cover the whole image (as you know this can take several minutes to accomplish). To do this with a digital camera would require 3 CCD sensor chips each with a color separating filter in front of it (R, G and B) with a beam splitter to distribute the light to each of the three CCDs. It would make the cameras much larger and more costly, and might even slow it down quite a bit, since the light hitting each CCD is cut in third or more. So, instead the Bayer pattern is used. This is a filter that has blocks of color (R, G or B) the exact size of each sensor in the CCD. This pattern is designed as follows: RGRGRGRGRGRGR GBGBGBGBGBGBG RGRGRGRGRGRGR GBGBGBGBGBGBG In this case, R=Red, G=Green and B=Blue. As you can readily see, a couple of problems exist. One, there are twice as many of sensors with a Green color separation filter in front of it than either Red or Blue. Two, any one sensor location only gets information about one of the colors. The advantage to this system is it requires only one CCD chip, the image can be captured rapidly with no mechanical or other alterations or filters. The disadvantage is that each sensor point only gets one piece of the color image data. So, the R(ed) covered sensor has to guess what the Green and Blue values were, the Blue has no idea what the Red and Green values were at that exact spot, and the same holds true to the Green, or which half the total sensors numbers are covered with. This requires the image to be processed with algorithms which look at surrounding data to make reasonable color guesses (interpolation) about those missing data points, and with sophisticated soft or firmware, a reasonable facsimile can be created. Where this system tends to be weak and create artifacts, is when there are very many contrast or color changes with
[filmscanners] Re: film vs digital test
He apparently doesn't realize that Tamron and Tokina make privately branded lenses for a number of camera mfg. I've always found both brands to be very satisfactory. Which is how they test out, also. Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
