 MICROFILM ROLL or REEL film is much like the reels of film you would see in the movies. The main difference is microfilm commonly does not have sprocket holes in the film. This film is commonly 16mm wide or 35mm wide and 100, 120, 140 to 215 feet long. MICROFICHE is a single piece of film with image exposed onto the film. These commonly are used by STEP and REPEAT filmers to image paper or for Computer Output Microfilm or COM from digital data. MICROFICHE JACKETS are 2 sheets of plastic welded or glued to create sleeves or channels that microfilm is cut and slid inserted into. JACKETS are very common but also one of the most vulnerable as the welds and glue get old and brittle if not kept in a perfect environment. Old fiche is fiche is often found falling apart when kept in basements or warehouses. APERTURE CARDS are IBM style punch cards with a window in which a piece of film is adhered. Sometimes there is a sleeve in the window area or there is adhesive around the window that hold the film to the card but the APERTURE refers to the hole in the card where the film is placed. Very common in engineering and the military as the cards can be punched and found using a punch card system. MODES Filmed images are referred to as being filmed in a 'MODE' either COMIC or CINE. This refers to orientaion of right reading on the page and the edge of the film. To make this easier look at a comic strip in the news paper and think of that group of images connected all in a row. If you consider the bottom of the comic strip as the edge of the film that is where COMIC MODE came from. If you were to take a roll of film from biology class or your own home movies you would see the images are stacked one on top of the other with the sids of the images matching the edges of the film. CINE short for CINEMA and that is where that term came from. Simplex or Duplex One last thing you need to know, was the front and back imaged at the same time? If the film has one image between the edges of the film it is commonly called SIMPLEX film. If there are 2 images side by side across the width of the film that is probably a DUPLEX IMAGE. The camera filmed both the back and the front of the items at the exact same time. In banking and other industries you might have 4 of these across the width of the film. This is commonly DUO-DUPLEX. The camera operator filmed on one side of the roll, flipped it over then filmed on the other side of the roll. If you ever had a 8mm film camera the actual film was 16mm and we would film on one side and flip it film on the other then the lab would process, split the film in half and splice it end to end to create your home movies. REDUCTION RATIO No matter what kind of media you have what you need to get to are the images. When created the images are placed based on the ratio of the original size of the page as compared to the image created. This is very important to know to reproduce the image back to original size either by scanned image or onto paper. To figure out what image size you have get out a ruler and find an image on the film that you recognize and know the actual size of. For most of us that is standard letter size paper which is 8 1/2 inches X 11 inches. 16mm film for example, you might find an image you think is a letter sized image and you measure the image and it is a little short of 1/2 inch on the longest side. 11 divided by .5 is 22. The most common reduction ratios cameras filmed at are 24x, 32x, 34x, 42x, 48x so the images you probably have were most likely filmed at 24x. Round to the closest reduction ratio is the smart thing to do. It can be rare but there are others that filmed in strange non standard methods but most companies used these standards as recommended by the National Micrographics Association or the NMA. Examples of 35mm film. 35mm film is the larger film, with bigger images of originals often measuring 36 inches by 24 inches and larger. These are easier to measure and the most common ratios vary from about 14x to 21x. Film will commonly have the same ratio for the entire roll but a small percentage of the rolls found may have multiple ratios on the same film. This is because of the size of the image and how they were filmed. So now we know what kind of film we have: Roll, FIche, jacket or Card We know the width of the film :16mm or 35mm Or the size of the fiche : 4x6 or 3x5 If fiche the number of channels: count the rows of images that ewquals the number of sleeves and What the reduction ratio of the images on the film are. So what do I do with all of that. Calculate. If the a jacket has an average of 15 images per row and there are 5 rows on the jacket a full jack contains 15 x 5= 75 IF you have a great number of fiche, grab a rule and measure a few inches of fiche and remove them. Now count the total number of fiche. Count the number of full ones Count the number of non-full ones Based on what you see in partial full jackets calculate or estimate the average number of images in the partials. Let's grab 2 inches of fiche. Counting them we found 50 full fiche 50*70 =3,500 images Counting them we found 48 partial fiche averaging 3 rows 48 * 3 * 15 =2,160 images 3,500 + 2,160=5,660 images in the inches you measured. 5660/2=2,830 images per inch of storage. Measure the total number of inches you have in your storage multiply that by your calculated number and you have a good idea of how many images you have in your system. Calculating roll film can be very simple or much harder. Unlike jackets or fiche most rolls are full from end to end. We just need to estimate the number of images per roll. I will go by the rule of thumb or best estimation here. 24X images in COMIC MODE The average 100 foot roll of film with images at 24X contains about 2,400 images. The average 215 foot roll of film with images at 24X contains about 5,000 images. 42X images in Comic mode The average 100 foot roll of film with images at 42X contains about 3,100 images. The average 215 foot roll of film with images at 42X contains about 7,000 images. 42x images in CINE mode Duplex The average 100 foot roll of film with images at 42X contains about 5,500 images. The average 215 foot roll of film with images at 42X contains about 11,000 images. So figure out what kinds of film you have and estimate the number of rolls per foot of your storage just like doing fiche but instead of inches of fiche use feet of rolls. It is easier. No matter what it is not that difficult if you break it down and average the information. The old saying is "Do you know how to eat an elephant? One bite at a time." You may need to understand what you have but being exact is very difficult, trust your numbers they rarely are far off. |