ORTHO 25
  1. Orthochromaticly sensitised film.

  2. Low speed, with a sensitivity of ISO 25

  3. Spectral sensitivity range 380 - 610nm

  4. Extremely fine grain and high sharpness

  5. High resolving power, up to 330 lines/mm

  6. High contrast with a steep gradation curve

  7. Can be used for technical applications or half-tone pictorial

    purposes.

  1. Special non-curling layer to promote film flatness

  2. Clear PET film base, which is ideal for scanning

Characteristics:

NAVIGATION:

 
Links and Data:

Rollei Ortho 25 ended up in my camera by a desperate attempt for me to shoot 35mm film in the F5 again.

I find 35mm hard to scan, and the results often lacking behind that of medium format. Ever since I got my Rolleiflex, the F5 has been greatly neglected. The drastically different pictorial results of Ortho 25, along with its incredibly high resolution, makes shooting it in 35mm format appealing. The film scans really well with amazing detail and high contrast. Its a great film to shoot unfiltered to achieve very striking results.


So what is an ortho film? Orthochromatic films are only sensitive to a part of the visible spectrum, ranging from blue to the end of green.

Orthochromatic films were the film used around the 1880’s to 1920’s, before films were manufactured with a red sensitive dye.

Rollei Ortho 25 is sensitised from 380-610nm, which creates interesting effects in pictorial applications. All red colours become dark or black, and everything blue becomes white or light coloured. Landscapes would typically have bright skies with little or no definition of clouds. To tame this high blue sensitivity, I recommend using a green/yellow or  straight yellow filter.


My first results were impressive. I like high contrast images, or at least I like my images not to have those flat grey tones throughout the image.

Rollei Ortho, by nature, has a steep gradation, which makes it a high contrast film. Only with special low contrast developers, or highly compensating developers, can this film’s curve be bent in oder to achieve a palatable contrast. Rollei Ortho is, in that sense, quite a flexible film when it comes to contrast, and will react differently to different developers, but it will always be high in contrast.


The film has a very fine grain structure, and offers very high resolving capabilities. This is very easily seen when scanned at high resolution, and the film is capable of resolving detail that a digital camera would struggle with. The above image shows finely defined pine needles to a level I cannot expect to see from a D-SLR such as the D700. Follow the sample image link at the top of the page to see a crop of the above seen image.

The image above is scanned on an Imacon 343, at a resolution of 3200 ppi, which equals roughly 12 or 13 megapixels depending on the crop.

Now, this film will definitely have more detail than my scanner is capable of resolving, but even with current hardware it still is very impressive.

Coming back to the grain, this film is understandably best developed in a fine grain developer if one wants to achieve the lowest and smoothest possible grain.


With the first attempt at developing this film, I used a dilution of Rodinal 1:50. While Rodinal is not known for its fine grain, it is known as a high acutance developer. It’s a reality that goes hand in hand; higher acutance or perceived sharpness is going to result in more accentuated and defined grain, and vis-a-vis. Of course this is a over simplification, but it is an obvious relationship.

My results in Rodinal had clear signs of grain in certain areas and tones, but not much more than Rollei Low Speed. It’s my observation that darker tones (where the neg is thinnest) shows more grain that in lighter areas. Also, when an image is filled with detail, the visible grain is greatly reduced. This is partly due to how we process detail vs grain. In order to achieve fine grain results, it is imperative to expose properly and then choose the appropriate developer most suited for the subject matter.


When developed in Rollei-Low-Speed developer, the images have noticeably smoother detail, but somehow that detail is masked away a little more than the Rodinal results. When sharpened to comparative levels, the RLS developer looses the advantage over Rodinal. I will have to experiment  with these combinations some more. I’m actually very pleased with the Rodinal results, as they are quite sharp and don’t require much sharpening for print. Besides the fact that RLC developer costs much more than Rodinal, I’m somewhat relieved with my Rodinal results thus far. With RLS developer, there is slightly less contrast than the Rodinal dilution 1:50, however contrast can be controlled by altering the dilution of Rodinal. One can always use 1:100 or 1:200. Also, in an attempt to reduce grain a little more when developing with Rodinal, one can always agitate less. Agitate every 2 minutes instead of one, and increase the developing time a little longer....may be 5-10%. One could also try sand developing!


This film takes full advantage of high resolving lenses. Due to the size of 35mm systems, these lenses most often have better resolving power than medium format lenses, purely because the medium dictates this in oder to achieve certain “good” or “excellent” results. Smaller formats have tighter specs, because, relative to a given print size, smaller formats require greater enlarging. So give this film a run for its money, and compare prints off this film against digital ones. The results will be quite surprising.


Be sure to check out the sample images and web gallery in the links above...

Personal Review:
  1. Development Data by www.digitaltruth.com

All images remain the copyright of Martin Zimelka