Home
M-42 Screw Mount
Forum
Please Email tom@dangphoto.net to register, Thanks!
An inexpensive alternative to new auto-lenses is to adapt older lenses and accessories, such as "manual focus" Pentax & Yashica screw mount (also called M42) to fit newer bodies. While not always be the best alternative, they can add inexpensive variety to your kit.
The adapters fit between lens & body, converting the lens mount from a screw thread (pictured in center). Many combinations allow focusing to infinity, but check for your specific combination before purchase.
These adapters are thicker (pictured bottom left in photo) than "lens to body adpaters", and have a different "thread pitch" than M42. Many T-Mount lenses are still available, and offer an inexpensive alternative to purchasing duplicate lenses if using various brand bodies requiring specific mounts.
Other Adapters:
There are also adapters made to convert Minolta to Nikon mount (as example), but require additional lens elements in their construction. The added length would otherwise act as an extension tube, and the lens wouldn't focus to infinity. Most are cost restrictive, and degrade overall lens quality. I personally can't recommend them, research carefully before buying.
Flange Adapters:
Some adapters are available which allow changing the mounting flange on camera bodies to accept different lens brands. This is something I haven't personally tried, but here is information: Canon DSLR flange to Minolta MC/MD Rokkor manual focus lens adapter.
When using adapted manual lenses on DSLR bodies, it's necessary to shoot in aperture priority, or manual modes. Focus is done manually, but auto exposure works in aperture priority. I personally can't recommend use of adapted lenses for photographing live insects. Since auto-aperture functions are lost, they require manually stopping down before shooting. While usually not a problem with stationary objects, the viewfinder becomes extremely dark. Since focus is critical for maximum insect detail, I highly suggest auto lenses instead.
Some manual lenses have "aperture stop down pins" which are claimed could contact the mirror causing damage, as shown in photo A. However, when mounted to the adapter (photo B), it doesn't allow the pin to protrude past the adapter. Crop Sensor DSLR's have smaller mirrors which often allow use, but Full Frame Film Digital Bodies are more likely damaged due to mirror size.
Other lenses have an outside aperture connection which is said doesn't allow their use. Before adapting any accessory, check with place of purchase for compatibility, and use at own risk.
Pentax Super Takumar 55 f/1.8
Included in my favorite manual lenses is this Asahi 55mm f/1.8 produced in the 1960's. It's a nice lens of excellent construction offering sharp photos, with excellent dof control. There's several normal Takumar lenses which can be found, including a 1.4 version.
Yashinon DX 135 f/2.8
Another Preset M 42 lens I've found extremely reasonable is this Yashica DX 135 f/2.8. For adding lens choices, it was too good to pass up. As with similar lenses from the 60's, it offers reasonable results with nice construction, including a pull out lens shade.
Asahi 50mm f/4 Macro-Takumar with Pentax Bellows II mounted to Canon DSLR
Lens elements: 4
Maximum reproduction: Life Size (1:1) without bellows
Minimum focusing distance .77 ft. (0.234m)
Maximum
focusing: Infinity
Angle of view: 46 degree
Focus: Manual
Diaphram:
Manual
Mount: M-42 Screw mount
There's a few different versions of the Takumar 50mm f/4 macro which were made, and to my knowledge, the "Macro-Takumar" first released in 1964 is the only Pentax lens of the series which offers 1:1 Life Size magnification. The SMC (Super Multi Coated), and newer manual models only magnify to half (1:2) life size.
While newer versions such as the "SMC" have multi coating, this lens does an excellent job with it's double coating. It produces nice colors, contrast & bokeh, plus added magnification. The newer Super Takumar screw mount lenses, have an added pin, which is said, might protrude into the body cavity when mounted on digitals via adapters. The pin is used to stop down the aperture on original film bodies, and claimed to strike the mirror on digitals. I can't confirm this since the pin doesn't protrude past the inside of the adapter on lenses I have, but could be critical with full frame bodies such as the 5D or other makes. Other lens models having a "stop down" connecting pin outside the lens/body mount are claimed to be problamatic also. So I suggest before mounting any lens to your body, measure for yourself. Also, I wouldn't recommend them as an alternative to a new automatic lens if shooting live insects, since the need to manually stop down dims the viewfinder making it difficult to focus. Check for compatibility where you purchase, and use at own risk.
Other Accessories:
Other model lenses made specifically for bellows can also be found. Pentax, among others, produced a couple of them. The Pentax 100mm "bellows specific" lens allows magnification up to 10X used in combination with the bellows.
Information concerning Asahi Extension Tubes.
Pentax Bellows II "Slide Copier" Attachment.
When using the Slide copier attachement, it's necessary to move the camera body all the way forward on the bellows rail. Lens is generally set to infinity focus, and actual focusing is done by expanding the copier bellows. If purchasing a used copy section, be sure the additional rail is included since it has engraved adjustment markings, and flat bottom for the adjustment screws to tighten against. If missing, proper diameter tubing from a hardware store will suffice, but be somewhat less stable in actual use.
Please mouse click thumbnails to view full size.
 1 |
 2 |
 3 |
 4 |
 |
 502 |
 503 |
 |
 |
 |
 sample1 |
 |
Product names are registered to the respective owner, and used for discussion purpose only.