Data sheet: Tamron 38–100 mm f/3.5 BBAR Multi C (adaptall)

Pekka Buttler, 07/2026

Specifications

The table below summarises the lens’ key specifications (measurements based on pictured sample with Pentax K adapter):

Brand:	Tamron	Lens name	Auto Zoom 1:3.5 f=38~100mm BBAR Multi C.
Focal length(s) 1	38–100 mm	Angle-of-view 2	59°–24°
Maximum Aperture	f/3.5	In Production	1973–76
Lens mounts (native)	Tamron Adaptall	Other lens mounts	See article on Adaptall
Length 3	110,5 mm (without adapter) 115,8 mm(with Pentax K adapter)	Diameter 4	75,2 mm
Filter ring diameter	72 mm	Weight	771 grams (without adapter) 834 grams (with Pentax K adapter)
Lens element count	unclear 5	Lens group count	unclear
Aperture blades 6	6 S	Focus throw	180 °
Minimum focusing distance (measured)	128 cms (@38mm) 128 cms (@100mm) 29 cms (in macro mode)	Maximum magnification (measured)	1:4 (in macro mode)
Has manual aperture ring	YES	Has manual focus ring	YES
Aperture mechanism type	Automatic	Aperture click stops (on preset ring) 7	3.5-4•5.6•8•11•16•22

Further notes:
• This lens was designed to use the Tamron Adaptall intermediate mount
• 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 “Model SZ-38”.
• This lens was introduced in 1973 as the standard zoom to appeal to the demanding photographer, with its attractive zoom range and unchanging f/3.5 max aperture. It also came with a price-tag that made photographers reconsider (until the 1974 introduction of the Tamron 200–500/6.9, this was Tamron’s most expensive lens). As a result it remained quite rare.
• In 1976 Tamron upgraded the design (the mainline specs and basic functionality were unchanged) and launched the CZ-38M⁸.

• This is a two-ring zoom, with one ring controlling focal length and another controlling focusing distance.
• There are two further rings, one for controlling aperture and another for controlling the close-up mode.
• The zoom and focus rings are grippy, but the rubber compound used by Tamron in the mid 70s is notorious for drying and cracking.
• The zooming motion of the lens is internal (the lens’ shape does not change while zooming), but focusing toward MFD lengthens the lens by some millimetres. The filter ring rotates when focusing.
• Engaging the close-up-mode lengthens the lens.

• Like many early standard zoom lenses, the lens’ minimum focusing distance (≈1,3 metres) is somewhat restrictive.
• The lens has a macro mode that is referred to as a close-up mode, that offers up to 1:4 maximum magnification.
• The macro mode is engaged by pressing the macro lock button and twisting the macro mode ring (between aperture ring and zoom ring)
• The macro mode works by shifting a major part of the lens forward (technically it is an adjustable extension tube) , leading to a somewhat unpredictable behaviour in that the highest maximum magnification is reached at the 38 mm zoom setting (where, arguably, the restricted MFD would be most limiting).

• Notably, this lens is as close to parfocal as I can determine (outside the close-up mode).

Versions

The Tamron Model SZ-38 was in production for only a short while and only one version seems to exists.

Adapting

Given that this lens uses an intermediate mount, there are several ways to go, depending on what your intention is

If you intend to adapt your Tamron Adaptall lens to a dSLR…

There are original Tamron Adaptall adapters to both Pentax K and Nikon F (Ai) available. These adapters allow you to use the tamron Adaptall lens as if it was a native (manual focus) lens (including aperture and aperture priority exposure automation). There are also modern adapters available from several adapter manufacturers, but – in general – these adapters are dumb adapters and do not allow aperture control.

If your dSLR is a Canon EF or Sony/Minolta A and Four thirds camera, you can get an aftermarket dumb adapter, but will have to manually control aperture.

To film SLRs?
You’re in luck, because there used to be Adaptall/Adaptall-2 adapters made for pretty much every mainstream SLR system available before the mid-70s, (including at least⁹: Canon FD*, Contax/Yashica*, Fujica X†, Konica AR*, M42 (several variants¹⁰), Mamiya Z°, Minolta SR*, Miranda°, Nikon F° (Pre-Ai and Ai), Olympus OM*, Pentax K (K° and A† versions), Praktica B†, Rollei QBM° and Topcon RE° (Exakta). 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).

Notes:
* Available both as Adaptall 1 and 2 (with different features)
° Available only as Adaptall 1
† Available only as Adaptall 2

To Mirrorless
If you already have a number of adapters from the typical SLR mounts to your mirrorless camera (e.g. Canon FD / M42 / Nikon F / Olympus OM / Pentax K …) your best choice is to either:

• get an original Tamron adapter from Adaptall to whatever your most favoured SLR era lens mount is or
• get a modern Tamron adapter to mirrorless adapter from one of the contemporary adapter manufacturers (K&F Concept seems to offer dumb adapters for Adaptall to most mirrorless mounts)

Of these, the earlier option is likely to be cheaper and the later less finicky.

Footnotes

1. 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’. ↩︎
2. 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 ↩︎
3. Length is given from the mount flange to the front of lens at infinity. ↩︎
4. Diameter excludes protrusions such as rabbit ears or stop-down levers. ↩︎
5. Information on the construction of this lens is scarce. It is likely closely related to the 13 elements in 10 groups construction of the successor lens (the CZ-38M) ↩︎
6. S=straight; R=rounded; C=(almost)circular at all apertures. ↩︎
7. Numbers equal aperture values on aperture ring; • intermediate click; – no intermediate click. ↩︎
8. The basic design of the CZ-38M was retained, but cosmetically changed and the resulting lens was offered to rebranders, including the Expert 40–105/3.5 [data sheet] ↩︎
9. This list will only contain adapters that we at JAPB have witnessed.  ↩︎
10. There were both adaptall adapters to vanilla M42 mounts as well as some of the M42 variants (such as Fujica M42, Mamiya M42, Praktica electronic M42). For details, see the JAPB article on the m42 mount.
    
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