Filter thread
A filter thread is a connection thread for photo and video lenses to accommodate optical filters . This thread is usually located on the front just before the front lens. For capturing baffles most lenses have a separate connection.
construction
The thread is an internal thread on the lens and an external thread on the filter, both chamfered and with a flat stop on the outside.
In contrast to the 42 mm Praktica lens thread, the angular position of both threads is not fixed. While this lens thread has to be screwed in almost 3 turns as far as it will go, the light, short filters are already tight after 1.5 to 2 turns.
Linear polarizing polarizing filters and also directionally sensitive effect filters (such as star rays or color gradients) are designed to be rotatable.
Filter thread dimensions
There are u. a. following filter thread:
"M" declares the metric dimension in millimeters of the outer diameter x pitch.
On lenses, however, this "E" screw thread diameter is often marked with "E" nn (nn = outer thread diameter in mm) - to distinguish it from the outer diameter of the lens barrel, for example for a slip-on sun visor.
Filter thread with a pitch of 0.50 mm:
- M 19 × 0.5 (very rare)
- M 24 × 0.5 (very rare)
- M 25.5 × 0.5 (very rare)
- M 27 × 0.5 (frequent) (video)
- M 28.5 × 0.5 (essentially only 1.25 "astronomy = 31.75 mm tube diameter)
- M 30.5 × 0.5
- M 34 × 0.5 (very rare)
- M 35 × 0.5 (very rare)
- M 35.5 × 0.5 (frequent) (video)
- M 36.5 × 0.5
- M 37 x 0.5
- M 37.5 × 0.5
- M 39 × 0.5 (video)
- M 40 × 0.5 (very rare)
- M 40.5 × 0.5 (frequent) (video)
- M 41 × 0.5 (very rare)
- M 43 × 0.5 (very rare)
- M 45 × 0.5
Filter thread with 0.60 mm pitch:
- M 28.5 × 0.60 (essentially just 1.25 "astronomy)
- M 48 × 0.60 (essentially only astronomy 2 ")
Filter thread with 0.75 mm pitch:
- M 25 × 0.75
- M 27 × 0.75 (very rare)
- M 28 × 0.75 (very rare)
- M 28.5 × 0.75 (very rare)
- M 30 x 0.75
- M 30.5 × 0.75
- M 37 × 0.75
- M 38 × 0.75 (very rare)
- M 43 × 0.75
- M 46 × 0.75
- M 48 × 0.75 (including astronomy 2 ")
- M 49 × 0.75 (often; particularly compact KB-SLR up to 50 mm focal length and 1: 1.7 aperture)
- M 52 × 0.75 (very common; typical for KB-SLR up to 50 mm and 1: 1.4)
- M 55 × 0.75 (often)
- M 58 × 0.75 (very often)
- M 60 × 0.75
- M 62 × 0.75 (very often)
- M 67 × 0.75 (very often)
- M 69 × 0.75
- M 72 × 0.75 (very often)
- M 75 × 0.75 (rare)
- M 77 × 0.75 (very often)
- M 82 × 0.75 (often)
- M 100 x 0.75
Filter thread with a pitch of 1.00 mm:
- M 86 × 1 (also called C 86) (often)
- M 95 × 1 (also called C 95)
- M 100 × 1
- M 105 × 1 (also called C 105)
- M 122 × 1
Filter thread with a pitch of 1.50 mm:
- M 112 × 1.5
Usually only the filter diameter is given, but not the pitch of the filter thread, since most filter threads are clearly characterized by this.
Super telephoto lenses as well as fisheye lenses do not have a filter thread to accommodate filters in front of the front lens, since these 1. would be extremely large and expensive there, and 2. would generate scattered light or, because of the board of the front lens, could only be geometrically realized as a curved dome. As a replacement, however, some lenses have the option of attaching filters to the rear (mostly M 27 × 0, ??).
For strong wide angles, expensive curved filters were rarely offered in order to reduce vignetting due to reflection due to flat incidence of light.
Filter adapter
Due to the variety of filter threads, there are filter adapters to connect filters to lenses with different filter thread diameters. So that the filter does not generate additional vignetting , it only makes sense to connect larger filters to smaller threads.
The designation 52 → 55 indicates that a 55 filter can be adapted to a 52 lens.
See also
Web links
- Filter Mounts ( Memento from February 11, 2013 in the web archive archive.today )