SinarBron Wide Format Camera.
To produce a large format banner, poster, or sign that will make people stop and look, it helps to start with a large format image, minimally 4x5 inch large format. A large format printer can produce a considerably better wide format print if you feed it a large format image to begin with.
Yes, you can do wonders creating a large format poster with a 35mm slide if you have a Scitex EverSmart scanner or a drum scanner (Fuji, ICG or Optronics for example) and an Encad, Roland, or Colorspan large format color printer. But just calculate how much better your large format image would be if you started out with a 6x6, 6x9 medium format or 9x12 cm image (9x12 cm = 4x5 inch format).
With an entry level desktop 35mm slide scanner (such as Nikon, at 2700 optical dpi) you can enlarge a slide on a large format printer to at least 18x24 inches. This is minimum, depending on the nature of the image you could possibly push it to 24x36 inches. With a Scitex scanner you can enlarge 35mm slides to 24 x 36 and get outstanding professional quality. If your slide is flawless you can enlarge it to 36 x 42 depending on the nature of the image and how well it hides the grain of the film. At 5000 dpi your scanner is enlarging all the grain structure of the film as well as the actual image. Anything over 3000 dpi is mostly film grain. With a large format digital camera there is no grant whatsoever.
With a medium format image (120 or 220 size film, 6x6 to 6x9, or, with roll film holder on a 4x5 camera, 6x12 cm) no good entry level scanner will do a professional quality job, since 600x1000 dpi will not do much to enlarge a 2 1/4 inch transparency to large format. With a 1200 dpi flatbed scanner (a scanner in the range of a LinoColor Saphir Ultra2) you can print a large format image about 24x36 inches, in other words, the same size as with 35mm. Basic mathematics is against you when you use medium format transparencies.
At the Digital Imaging Technology Center we prefer to work with 4x5 format, using a BetterLight digital scanning back.
No, it is not worth the price to buy a dedicated medium format scanner just for doing medium format. They are either overpriced or do only 1000 dpi. Keep in mind that most scanners achieve their claimed dpi only down their sweet spot, a strip down the middle. Fortunately the sweet spot should be wide enough to handle medium format and in many cases a 4x5 chrome.
So, if you have medium format images and need to cover the side of a building, you need a Scitex EverSmart Pro II or EverSmart Supreme, Fuji C-550 Lanovia, Heidelberg Topaz (both high end flatbed scanners) or a good drum scanner. Of course if you cover the side of a building with your large format print you can get by with a 300 dpi print, or actually less. The actual image needs correspondingly less dpi, since a 120 dpi file prints just fine on a 300 dpi printer and even on most 600 dpi printers. Billboards can be printed large format at 75 dpi for example.
But if you start off with a 4x5 transparency and if your flatbed's sweet spot is wide enough to cover the 4 inch width, then you can start achieving professional quality banners, posters, or trade show signs even from a midrange flatbed scanner. You can achieve about 3 feet by 6 feet if you use an Imacon scanner and considerably larger and better if you use a Scitex EverSmart, Fuji or Heidelberg Topaz. It is not merely the increased dpi that makes the Scitex, Fuji or Heidelberg superior, it is the software, the stability of the scanner, the special glass on the flatbed (anti-Newton Ring glass), the optics, and the precision of the motor which moves the scanning system.
Is it better to start off with a large format digital image? If you are using a Better Light or PhaseOne large format digital back your image will be about 72x90 mm in size, using a 4x5 camera to hold the digital insert. This digital image is nowadays generally accepted as being as good as and often better than a 4x5 chrome. It would be worthwhile comparing digital shots with film shots in large format, using a rollfilm holder to simulate the field of the digital capture. A rollfilm back would provide 60x90 mm. Either way, a large format camera is essential if you want professional large format ink jet enlargements. As always, when you scan film you sooner or later end up scanning into the grain pattern. With a digital camera there is no grain pattern. We are speaking of a true large format scan back that produces a file of 130 to 200MB or more, without interpolation or other software tricks. Thus only BetterLight and PhaseOne are available at this level of quality. Of these two, BetterLight was judged superior by an independent jury at the PMA trade show several months ago. PhaseOne came in last out of the three entries. See Digital-photography.org for details.
Over the last two years of testing large format printers and large format cameras we found that L-shaped cameras sagged from the considerable weight of the digital insert combined with the drag of the SCSI cables. This eliminates Linhof Technikardan and about a third of the other 4x5 cameras.
Cameras (usually portable 4x5 cameras) whose movements are guided by sliding braces with simple knobs to turn to stop the movement, are a disaster when used in macro mode or in any situation requiring fine focus. This eliminates virtually all the "old fashioned" 4x5 cameras such as Zone VI. These old-fashioned cameras with picturesque brass fixtures are okay for outdoor photography of distant objects at infinity but are the worst possible choice for product photography or anything requiring precision movements or alignment up close. If you do macro photography be sure you have a Sinar X, Arca-Swiss or Cambo Ultima camera. Anything less will waste your time trying to do alignments with cheap equipment where the alignments sag more on one side of the camera than the other.
Cameras which require you to flip a lever or otherwise turn something to stop or hold the position may also cause dis-alignment You can see this on the monitor when you focus. You focus electronically, then turn or move the lever/knob to tighten the position. This move will throw the camera out of alignment on most portable systems, such as the Linhof Technikardan, especially the original models.
Then what 4x5 large format camera works the best?
A Sinar X (and naturally the larger Sinar models as well) is made in Switzerland to Swiss tolerances. I lived in Zurich for several years so I have first hand experience that Swiss tolerances are rather strict. I then had a Swiss girlfriend for five years (while living in Austria); their tolerances are also strict. In effect, either of the Swiss cameras (Arca-Swiss or Sinar) is constructed rigidly enough to produce the best images for enlarging on a wide format printer. We just spent several pleasurable months testing a Sinar X. We have plenty of experience with several other brands of 4x5 cameras so noticed the differences rather quickly.
Don't forget to use a good lens, a digital lens if doing digital. Sinar Bron has the best lenses for the Sinar Bron camera. If you happen to have a Toyo or other 4x5 camera, then at least use a Schneider or Rodenstock lens, at least an APO and preferably a digital APO.
Summary Your large format image will look much better if you use a 4x5 chrome or a large format digital image to start with. If you have only a 35mm slide or medium format film, be sure that you utilize the best scanner available. For additional information on the optimal scanner to use for wide format printing, check out Flatbed-scanner-review.org.