Nikon F Large Format Backs


In general, the Speed Magny system is designed for use with Polaroid instant-development film. This is most useful for checking lighting and for very fast reportage. Later on, third parties (generally Marty Forscher) would produce special backs for Nikon's F series which allowed direct (i.e. not through the complicated optical gyrations that the Speed Magnys provided) taking of instant pictures.

When the light leaves the rear of the lens, it would normally strike the film residing at the film plane. With a Speed Magny back attached, the light strikes a condenser field lens, reflects off a first-surface mirror set at 45 degrees to the light's path, is sent through an EL-Nikkor relay lens to magnify the image, and reflects off another first-surface mirror at 45 degrees, finally striking the large-format film. In order to make the Speed Magny attachments somewhat compact, Nikon chose to make the two mirrors perpendicular to each other, rather than parallel (as in a periscope), so the film chamber resides under the lens, with the emulsion side facing away from the subject.

Mounting a Speed Magny is fairly easy, since it replaces the current back completely:

    1. ensure that the condenser lens is dust-free
    2. attach the back to the F via the open/close key
    3. screw the Speed Magny to the tripod socket via the small thumbscrew
    4. lock the thumbscrew with the larger dial sitting immediately next to the camera

Note that because 3.25 x 4.25 and 4x5 have different aspect ratios than a standard 35mm frame, the viewfinder shows slightly more area than will be captured on film. The actual area is approximately 95% of the vertical and 74% of the horizontal; perhaps the T screen would be somewhat useful in outlining this area. This is independent of the vignetting caused by different lens's focal lengths (which in turn is governed more by the location of the lens's exit pupil). These are tabulated below.

Vignetting Characteristics:
Severe: (projected image forms a complete circle on film, with a continuous black border)
  • 28mm f/3.5
  • 45mm f/2.8
Moderately Severe: (projected image forms almost a complete circle on film, with a two-piece black border)
  • 7.5mm f/5.6
  • 8mm f/2.8
  • 20mm f/3.5
  • 50mm f/2
Moderate: (projected image is darkened in all four corners)
  • 24mm f/2.8
  • 28mm f/2
  • 35mm f/2
  • 55mm f/3.5 from 1:10 to infinity
  • 43-86mm f/3.5 at 43mm
Minor: (projected image is darkened in three corners)
  • 35mm f/2.8 PC
  • 55mm f/3.5 at 1:5
  • 85mm f/1.8 at f/8-22
  • 105mm f/2.5 at f/5.6-22
None: (no image darkening)
  • 35mm f/1.4
  • 50mm f/1.4
  • 55mm f/1.2
  • 55mm f/3.5 at 1:3 and up
  • 85mm f/1.8 at f/1.8-5.6
  • 105mm f/2.5 at f/2.5-4
  • all lenses 135mm and up
  • 43-86mm f/3.5 at 86mm
  • 50-300mm f/4.5
  • 80-200mm f/4.5

Speed Magny 100

Overall Length:
170mm (7.5 in.)
Width:
190mm (8.7 in.)
Height (from prism to bottom):
245mm (9.8 in.)
Weight:
1 900g (4.3 lb.)
Film Format:
3.25 x 4.25 in.
Magnifiying Relay Lens:
EL-Nikkor 50mm f/2.8
Magnification Ratio:
3.2:1 (i.e. multiply 35mm focal length by 3.2)
Films to be Used:
(mainly) Polaroid Land Film Type 107 (ASA 3 000)
Polaroid Land Film Type 108 (ASA 75 [Polacolor] -- replaced by Polacolor 64 Tungsten and Pro 100, T-79)
Polaroid Land Film Type 105 (ASA 75 [Pos/Neg] -- obsolete and no replacement)
Exposure Factor:
18 (i.e. divide ASA of film in use by 18)
Film Holder:
built-in (Polaroid CB-100?)
Relay Lens Cap:
included, acts as darkslide

This Speed Magny is supplied with a relay lens cap, which caps the EL-Nikkor and allows the Speed Magny to be removed without fogging the remaining film. Rotate the knob clockwise so that the "C" mark lines up with the white dot on the body of the Speed Magny. Earlier models do not have this capping feature.

Those of you with Crown Graphics will be pleased to note that you can use 3.25 x 4.25in. film with this Speed Magny, too, although you can't remove the film holder, so you're stuck with what Polaroid chooses to supply, although they do have quite a range of films to choose from.

Speed Magny 45

Overall Length:
190mm (7.5 in.)
Width:
220mm (8.7 in.)
Height (from prism to bottom):
250mm (9.8 in.)
Weight:
1 900g (4.3 lb.)
Film Format:
4 x 5 in.
Magnifiying Relay Lens:
EL-Nikkor 50mm f/2.8
Magnification Ratio:
4.1:1 (i.e. multiply 35mm focal length by 4.1)
Films to be Used:
(mainly) Polaroid Land Film Type 57 (ASA 3 000)
Polaroid Land Film Type 58 (ASA 75 [Polacolor] -- now obsolete; use Polacolor 64 Tungsten or Pro 100, T-79)
Polaroid Land Film Type 55 (ASA 55 [Pos/Neg])
Polaroid Land Film Type 51 (ASA 640 (Pos), ASA 80 (Neg) [HC Pos/Neg])
Polaroid Land Film Type 52 (ASA 400, [PolaPan])
any type of 4x5 sheet film (with appropriate film holder)
Exposure Factor:
20 (i.e. divide ASA of film in use by 20, so Type 57 becomes ASA 150, effectively)
Film Holder:
extra (Polaroid Sheet or 4x5 cut-film holder)
Relay Lens Cap:
not included (film has built-in cap)

This is the most versatile of all the Speed Magnys, as it allows the film holder to be swapped between the standard Polaroid 4x5 sheet film holder (familiar to most of us who've done microscope photography) and the even more familiar 4x5 cut-film holders (e.g. those from Speed Graphics -- but I'm not sure if it will accept a Grafmatic holder).

Speed Magny RF

Overall Length:
178mm (7 in.)
Width:
318mm (12.5 in.)
Height (from prism to bottom):
254mm (10 in.)
Weight:
2 090g (4.8 lb.)
Film Format:
3.25 x 4.25 in., roll-film
Magnifiying Relay Lens:
EL-Nikkor 50mm f/2.8
Magnification Ratio:
3.2:1 (i.e. multiply 35mm focal length by 3.2)
Films to be Used:
Polaroid Land Film Type 42 (ASA 200 [PolaPan])
Polaroid Land Film Type 47 (ASA 3 000)
Polaroid Land Film Type 48 (appox. ASA 75 [Polacolor])
Polaroid Land Film Type 410 (ASA 10 000)
Polaroid Land Film Type 46-L (ASA 800 [Coninuous-Tone Transparency Film])
Polaroid Land Film Type 146-L (ASA 800 [Line Copy Transparency Film] -- sensitive to blue only)
All films now appear to be discontinued
Exposure Factor:
18 (i.e. divide ASA of film in use by 18)
Film Holder:
Polaroid CB40 Land roll-film adapter
Relay Lens Cap:
included, acts as darkslide

This Speed Magny is supplied with a relay lens cap, which caps the EL-Nikkor and allows the Speed Magny to be removed without fogging the remaining film. Rotate the knob clockwise so that the "C" mark lines up with the white dot on the body of the Speed Magny. Earlier models do not have this capping feature.

This is probably not a great Speed Magny to use -- a quick browse through the Polaroid website makes me think that all film in this format has been discontinued. I suppose that you could probably adapt 120/220 to this back, but if you want to run medium format with Nikkor lenses, the Bronica focal-plane SLRs are a much more elegant solution ...


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