Tamron SP 70-210mm F/3.5-4 Model 52A: Tamron's SP 70-210,
introduced in 1979, changed the thinking of optical engineers throughout the
industry by showing what could be achieved in terms of properly balancing
optical performance throughout a 3:1 zoom range and throughout a
continuous focusing range of infinity to 1:2 macro at 0.75 meter. There were no
macro buttons to press, and this lens could even be zoomed while in macro mode
without affecting the focus. This lens clearly offered far more
convenience and flexibility compared any other telephoto zoom lens available at
the time of its introduction, with the exception of Vivitar's Series 1 90-180mm
medical macro zoom, and is an excellent example of Tamron's frequent genius for
optical design. Tamron's lens features a broader zoom range plus better control
off off-axis aberrations compared to the Vivitar Series 1 lens.
While overall optical performance is average (in terms of a
conventional telephoto zoom lens), the inherent features of this lens were in a
class unto itself when this lens was introduced to the marketplace. Some have
suggested that this model 52A lens is better than Tamron's completely
redesigned and later model 19AH lens merely because this lens reaches 1:2 in
macro mode whereas the 19AH lens only reaches 1:2.66 in macro mode. This quite
simply is not the case. Tamron's later SP 70-210 model 19AH is significantly
sharper and produces much higher contrast for the fine details within the
image, and is superior in all respects except for maximum macro magnification.
Nevertheless Tamron's Model 52A, for a zoom lens, provides very good close
focus and macro performance.
The SP 70-210 was the first 3:1 telephoto zoom lens which
continuously focused from infinity to 0.75 meter and which was capable of 1:2
telephoto macro magnification at the long end of the zoom range. Previously,
telephoto zoom lenses which featured a "macro" mode employed a button which was
pressed to allow rotation of the zoom collar past the minimum focal length
setting and into macro mode. Optically, this operation merely shifts the
position of the compensator group such that the lens will only focus on
extremely close subjects. The problem with this compensator group shift method
is that, while on-axis macro performance will be acceptable to fairly good at
best, off-axis macro performance will usually be quite poor. Tamron's lens
resolves these issues rather successfully. Look carefully at the four elements
employed in the front focus group within this lens, as shown above. You will
note that these elements are quite thin and feature very gentle curves. Why,
you wonder? Quite simply because this type of optical prescription minimizes
focus induced aberrations such as spherical aberration, off-axis astigmatism
and off-axis coma.
Did you know that this lens came in two flavors, both labeled as
model 52A? Look closely at the focus scale in the photo at the top of this page
and the photo to the right (click on photo at right to view a high resolution).
Note that the foot scale in the top photo reads 20 and then infinity whereas
the foot scale in the photo to the right reads 30 and then infinity. The
original mechanical version of this lens featured a mere 1/2 turn of the focus
ring to go from infinity to the minimum focus distance of 0.75 meters. The
later mechanical version looks identical except for the focus scale. The later
version features a 3/4 turn of the focus ring to go from infinity to the 0.75
meter minimum focus distance. The focus on the later version, unlike the
earlier version, doesn't creep when the lens is tilted up or down. The original
version is fairly rare since it was quickly replaced with the later version
within a matter of a few months.
Two other manufacturers, one an independent (Vivitar) and the
other an OEM (Konica), produced functionally similar lenses to the Tamron.
Vivitar introduced their their Series 1 90-180mm F/4.5 in either 1976 or 1977,
and Konica soon introduced 80-200mm F/4 UC Hexanon AR a year after the Tamron.
Both of these lenses, like the Tamron, featured continuous focusing to 1:2
macro at the telephoto end of their zoom ranges. For a while these three lenses
were the only telephoto zooms which provided continuous focusing 1:2 tele-macro
capabilities. The performance of the Tamron and Vivitar lenses, considering the
features and optical design parameters, was quite good for the era and
represented the best that could be achieved by any manufacturer. The Konica
lens, as tested by Modern Photography, displayed some decentering on the
optical bench and would have performed better had Modern sought out another
example as was normally their policy. Unfortunately the Konica test report fell
prey to the publishing deadline and a correctly manufactured example was not
obtained by Modern for testing. Konica fanatics, please keep this in mind when
reviewing the Modern Photography test reports shown further below, as a good
production example of the Konica lens performs somewhat better compared to the
results which Modern Photography published.
The Tamron's 3:1 zoom ratio is more versatile than the 2.1 and
2.5:1 zoom ratios of the Vivitar and the Konica lenses respectively. It should
be noted that the Tamron SP 70-210, unlike the Vivitar and Konica lenses,
possesses virtually zero chromatic aberration or lateral color. Also note that,
while the Vivitar and Konica lenses do display some off-axis lateral color, the
lateral color in these lenses is considered to be small in amount compared to
conventional zoom lenses. Off-axis astigmatism and coma are very well
controlled within the Tamron since, in addition to the four element focus
group, Tamron chose to also use four elements in the zoom group and four
elements in the compensator group. Thus Tamron was able to achieve fairly high
off-axis aberration correction and performance throughout a somewhat broader
3:1 zoom range and throughout the very wide focusing range.
The SP 70-210's only weakness is a lack of contrast in fine
details at all zoom settings when photographing distant subjects. Why? Because
the correction for spherical aberration within the four element focus group was
optimized for closer distances rather than for infinity. This is fairly similar
to the Vivitar lens which was optimized for 1:10 magnification, yet is much
more tolerant for both further and closer focusing distances. The result in
slight spherical aberration at infinity, particularly at the telephoto end, and
is why we noted that this lens is merely "average" when used as a conventional
telephoto lens for distant subjects. When shooting subjects which are more than
20 feet away from the lens, stop this lens down to F/8 to suppress the slight
spherical aberration. Image quality is noticeably sharper within the 5 to 10
foot range. Why? Because the front focus group is optimized for this range,
producing nearly zero spherical aberration.
The macro performance of the Tamron SP 70-210 and Vivitar Series 1
90-180 lenses is superior to the Konica lens. The Tamron's macro performance is
very good on-axis, but shows some off-axis astigmatism with larger apertures at
the shorter zoom settings. When in macro mode, stop the Tamron down to F/8 or
F/11 and the off-axis astigmatism disappears to yield very good image quality
across almost the entire field. The Vivitar lens, when in macro mode, exhibits
some off-axis coma and lateral color which are reduced by using smaller
apertures. Again, note that the Tamron lens exhibits virtually zero lateral
color. Overall, the Tamron lens has somewhat better off-axis image quality
compared to the Vivitar when both lenses are used in the 1:4 to 1:2 macro
magnification range.
The SP 70-210's ergonomics are much better in comparison to the
Vivitar lens. The Tamron's focus, zoom and aperture rings are all of the same
diameter which makes moving your hand back and forth for adjustments much more
convenient. The Tamron also has a much wider zoom ring (in terms of gripping
area along the barrel, not diameter) compared to the Vivitar and features a
focus ring which, unlike the Konica and Vivitar lenses, does not move
forward when turned. Ergonomics of the Konica lens are surprisingly good with
the exception that the focus ring does move forward when the lens is focused
toward closer focus distances. In terms of ergonimics, the Tamron ranks first,
the Konica second, and the Vivitar a more distant third.
Both the Tamron and Vivitar lenses feature nicely labeled macro
reproduction ratio scales. The Tamron scales are most convenient since they are
color coded for three zoom focal lengths, namely 70, 135 and 210mm, whereas the
Vivitar lens features three individual orange colored scales which are labeled
for focal lengths of 90,135 and 180mm. Note that the Konica lens does not
feature any macro reproduction ratio scales. Although the Konica lens was a
beautifully engineered and constructed lens, the lack of color coded macro
scales to match the color coded zoom ring definitely was a detriment to sales
of the Konica lens. The Konica lens could have, should have, and would have
sold much better in its day had Konica provided similar color coded scales as
featured on the Tamron lens. The room was there on the barrel of the Konica
lens. It is not that these scales would have been particularly handy; but
rather would have immediately implied to the prospective buyer that the Konica
lens was indeed something special in terms of inherent features.
The Vivitar lens featured a built-in tripod socket whereas the
tripod ring for the Tamron was an optional accessory. The Konica lens didn't
feature any tripod ring, and Konica never produced an accessory tripod ring.
Notably, both the Tamron and Konica lenses featured built-in lens hoods which
are quite useful for shading these lenses against flare.
So, what are our overall conclusions regarding these three
lenses?
- Overall, this Tamron lens features not only a broader zoom
range, but also features slightly better off-axis macro performance compared to
the Vivitar Series 1 lens.
- This Tamron lens features virtually zero chromatic aberration
and lateral color, making it virtually an APO lens in terms of these
aberrations which, by nature, define an apochromatic lens. Why didn't Tamron
promote this feature, we will never know! We consider this to be a gross
oversight in Tamron's advertising for this lens.
- This Tamron lens features extremely tight control of off-axis
aberrations yet exhibits spherical aberration for subjects which are further
than about 15 or 20 feet away.
- This Tamron lens, since spherical aberration is its only
predominant aberration for distant subjects, responds very well to mild to
moderate unsharp mask techniques in image processing programs such as PhotoShop
to yield very good results.
- Both this Tamron lens and the Vivitar Series 1 lens perform
very similarly in macro mode; its just a difference in off-axis
aberrations.
- The Konica lens performs somewhat below both the Tamron and
Vivitar lenses in macro mode, particularly in terms of off-axis
performance.
Lens Specifications:
Lens Model |
52A |
Focal Length |
70 210mm |
Aperture Range |
f/3.5~4 32, AE |
Angle of View |
34°~11° |
Optical
Construction (Groups / Elements) |
15 / 16 |
Min. Focus from Film
Plane |
29.5" (0.75m) |
Macro Mag. Ratio [w/2X
Converter] |
1:2 [1:1] |
Filter Size |
58mm |
Diameter in. (mm) |
2.5" (64.5mm) |
Length at
[w/Nikon mount] |
6.5" (165mm) [6.7" (169.5mm)] |
Weight oz. (gm) |
26.5 oz. (750g) |
Lens Hood |
Built-in type, retractable. |
Accessory |
Accepts SP 2X tele-converter #01F. Tripod
mount ring available as optional extra. |
|