Pekka Buttler, 07/2026
Specifications
The table below summarises the lens’ key specifications (measurements based on pictured sample with Canon FD adapter):
| Brand: | Tamron | Lens name | Auto 1:4 f=70~220 mm Zoom |
| Focal length(s) 1 | 105 mm | Angle-of-view 2 | 23° |
| Maximum Aperture | f/2.5 | In Production | 1972-73 |
| Lens mounts (native) | Tamron Adapt-a-matic | Other lens mounts | See Adapt-a-matic article |
| Length 3 | 86,8 mm (with adapter for Canon FD) 75,5 mm (without adapter) | Diameter 4 | 70,1 mm |
| Filter ring diameter | 52 mm | Weight | 482 grams (with adapter) 419 grams (without adapter) |
| Lens element count | 4 | Lens group count | 4 |
| Aperture blades 5 | 9 S | Focus throw | 225 ° |
| Minimum focusing distance (measured) | 113 cms | Maximum magnification (measured) | 1:9 |
| Has manual aperture ring | YES | Has manual focus ring | YES |
| Aperture mechanism type | Automatic | Aperture click stops (on preset ring) 6 | 2.5••4•5.6•8•11•16-22 |
Further notes:
• This is a short tele lens manufactured by Tamron for its Adapt-a-matic intermediate mount. It was introduced 1972, which makes it a very late addition to the Adapt-a-matic mount.
• In 1973 as the Adaptall mount was introduced to replace the Adapt-a-matic mount, also this lens was discontinued in favour of a newer, more compact 105 mm portrait lens [data sheet].
• Tamron has always had its own coding scheme for lens designs. This coding scheme is extremely useful to discern between two (or more) lenses that have the same mainline specifications (focal length and maximum aperture). According to the Tamron coding scheme, this lens is “Jog-25Au”, whereas the Adaptall version that replaced it is the “CT-105”.
• This lens features an integrated, pull-out lens hood as well as a small switch that acts as depth-of-field preview.
Versions
JAPB has found no data that would indicate that the Tamron 105 mm f/2.5 lens for the adapt-a-matic mount would have existed in more than one version.
Adapting
Given that this lens uses an intermediate mount, there are several ways to go, depending on what your intention is
To film SLRs or dSLRs?
You’re in luck, because there used to be Adapt-a-matic adapters made for pretty much every mainstream SLR system available before the mid-70s, (including at least1: Canon FD, Exakta, Konica AR, M42, Minolta SR, Miranda, Nikon F, Olympus OM, Pentax K, Petri FT). What you need to do is head to your favourite online classifieds platform and procure an adapter (adapters for dSLR mounts are still available new).
To Mirrorless
Again, not a challenge. If you do not yet have a Adapt-a-matic adapter to an SLR mount, you can buy any combination of an Adapt-a-matic to SLR and SLR to mirrorless adapter.
History of Tamron
A short history of Tamron can be found as part of the Tamron company profile.
Footnotes
- Focal length is (unless stated otherwise) given in absolute terms, and not in Full-frame equivalent. For an understanding of whether the lens is wide/tele, see ‘Angle-of-view’. ↩︎
- Picture angle is given in degrees and concerns the diagonal picture angle. Rule of thumb:
> 90 ° ==> Ultra-wide-angle
70–90 ° ==> Wide-angle
50–70 ° ==> Moderate wide-angle
40–50 ° ==> ‘Standard’ or ‘normal’ lens
20–40 ° ==> Short tele lens
10-20 ° ==> Tele lens
5-10 ° ==> Long tele lens
< 5 ° ==> Ultra-tele lens ↩︎ - Length is given from the mount flange to the front of lens at infinity. ↩︎
- Diameter excludes protrusions such as rabbit ears or stop-down levers. ↩︎
- S=straight; R=rounded; C=(almost)circular at all apertures. ↩︎
- Numbers equal aperture values on aperture ring; • intermediate click; – no intermediate click. ↩︎
- This list will only contain adapters that we at JAPB have witnessed. ↩︎