A fellow
photographer
on
www.fotostart.dk
has
encouraged
me to write
a review of
my
(relatively
rare)
catadioptric
mirror tele
lens. It is
with some
hesitation
that I take
up this
challenge,
(my first
gadget revie
ever)
because
although
I've
photographed
since I was
11 (and here
we write
1960) I am
not what one
might call
an
experienced
and
competent
photographer
And when one
- as an
amateur
without
“unbiased”
high-tech
test gear -
reviews a
lens, there
is certainly
always the
risk that
one cannot
give that
lens its
right’s
deserve:
Because one
will by
necessity
have to use
a specific
camera and
above all
one’s own
abilities –
or lack of
same - as a
photographer
to
demonstrate
the
properties
of that
lens.
Furthermore,
although I
have
photographed
digitally
since 1999 I
have only
photographed
with DSLR
since April
2009.
Anyway, now
I have taken a
deep breath
and plunge
into my
subject by
displaying
an image
right away:
Two things
immediately
jump into
one’s eyes:
1) The
limited
depth of
field - lens
cannot be
stopped down
and 2) the
very special
bokeh. There
are many who
would
vigorously
refuse to
touch a lens
that might
show such a
bokeh in any
situation
and they may
then leave
at this
point. If
there are
anyone left,
here comes a
little more
A bit of
background
for the lens
(hereinafter
simply
called the
06B).
06B was
produced
only during
a limited
number of
years, from
1981 to
1985, unlike
its bigger
brothers,
Models 55B
and 55BB, SP
500 mm f / 8
which were
produced
from 1979 to
1983 (55B)
and from
1984 until
2006 (55BB).
The lens is
of the
Adptall-2 SP
(Super
Performance
") series
and requires
a special
adapter ring
for
different
camera
brands. The
Adaptall-2
system is
fairly
widespread,
and adapters
for most
brands are
easily found
on the
internet for
such lens
mount types
that were in
use up to
the early
2000’nds. If
you have a
newer camera
with a
mounting you
may resort
to a
standard M42
Adaptall-2
mount plus
an M42
adapter for
your
specific
camera –
that way,
you should
be able to
get a
suitable
match after
all.
The focal
length of
350 mm was
not randomly
chosen: In
fact, this
is very much
the shortest
focal length
that a
compact
mirror lens
may have,
should the
light
fall-off
towards the
edges (vignetting
- inevitable
for this
type of
lenses) be
kept to an
acceptable
minimum for
a 35 mm film
format, or a
full-frame
sensor in
current
times. When
the 06B lens
was
released, it
had a list
price of
48,400 yen
while the
55BB had a
list price
of 59,000
yen. This is
actually a
little
surprising:
As most
amateur
astronomers
will know a
"fast"
mirror
telescope
(from about
f / 5 or
less)
requires
significantly
higher
standards of
accuracy in
the
manufacturing
and
alignment
techniques
than a
"slow"
telescope
(from around
f/10 and
up). One
might
speculate
that the
actual price
differentiation
was dictated
by market
considerations
(?)
Anyway, the
limited
product
lifetime of
the 06B
indicates
that it did
not really
respond to
market needs
in those
days. Maybe,
people who
bought this
type of
optics were
mostly after
a real "moon
lens" or,
perhaps the
manufacturing
costs of the
06B (in an
acceptable
quality
after
Tamron’s own
standards)
turned out
to be too
high for the
price the
market would
bear for a
fixed
aperture
telephoto
lens in the
300mm range?
A bit about
my own 06B,
s/n 110231
In 1981 I
bought a
small
astronomical
mirror
telescope (a
Vixen 4 "
f/10
Newtonian
Polaris
R-100L), and
with that
came the
desire for
astrophotography.
Next
investment
then, was
then a
Pentax K1000
that same
year, as my
old Porst
Reflex S was
completely
worn out. I
soon
discovered
that I had
better use
my Newtonian
telescope as
a guide
telescope
and acquire
a shorter
telephoto
lens which
could ride
(‘piggyback’)
on the back
of the
telescope. A
mirror
telephoto
lens -
simple,
robust and
relatively
cheap -
seemed just
the thing,
and I had
just seen
such on
offer where
I bought my
K1000. The
55BB and 06B
(and the
refractor
type Model
54B, SP
300mm f/5.6)
cost almost
the same
except for a
few scores
of EUROs. I
pondered
quite a bit
for quite
some time
about
whether it
should be
one or the
other, but I
finally
resolved
that the 06B
together
with a
Tamron SP
teleconverter
Model 01F
and my Vixen
telescope
would
provide
appropriate
focal length
steps of
350mm - 700
mm - 1000 mm
and with
that I could
cover a
little bit
of
everything.
And so it
happened
that I
became the
owner of a
lens that
was somewhat
overlooked
in its days,
which has
therefore
become
somewhat of
a rarity and
which today
- in some
circles -
has achieved
almost
mythical or
cult status.
(Be
prepared:
All things
considered,
it is not
THAT good!).
I got out of
the store
with those
purchases
along with a
Tamron
Wide-field
Tele-view
adapter
which is a
20 mm right
angle
eyepiece
that allows
me to use
the lens as
a spotting
scope also.
The whole
package – if
I remember
correctly -
cost me a
good 400
EURO – but
remember,
that was in
good solid
1982
currency.
As said, I
bought this
lens with
astrophotography
in mind and
I still
mostly use
it for that;
so, for a
start, here
are just a
few samples
(full,
un-cropped
images):
Lunar
eclipse on
31 December
2010
Sunset in
1986
(quick-and-dirty
digital
camera
duplication
of a
Kodachrome
slide
- no more
about
astrophotography
in this
review! In
fact, I have
kind of
discovered
that the
digital
camera age
offers
better usage
(for me at
least) of
this special
lens in a
number of
other areas.
Specifikations
and Design:
Basically, a
mirror
telephoto
lens (a
catadioptric
lens or just
“CAT”, as we
say in
astronomy
circles)
consists of
a convex
main mirror
that
captures and
focuses the
light and a
concave
secondary
mirror,
which
"breaks" the
beams and
sends the
light back
towards a
hole in the
main mirror
and into the
camera. In
practice,
there is
also a
large,
aspheric
corrective
front lens
and a few
other rear
lens
elements to
make the
design work
in a
photographic
context. The
design and
specifications
for the 06B
and 01F are
shown in the
tables and
schematics
below.
And here are
some
pictures
that show
what the
system
actually
looks like:
All parts:
Lens and
Camera:
Lens back:
All parts
joined as
spotting
scope:
Note the
large
central
obstruction,
which is
base for the
secondary
mirror. In
the 06B this
obstruction
is about 4
cm in
diameter out
of the total
aperture
diameter of
82 mm. This
IS a lot,
and much of
what you
read about
problems
with mirror
lenses in
general
(peculiar
bokeh, focus
difficulties,
sharpness,
contrast)
can be
traced back
to this
design.
"Test
Set-up":
I regularly
assess my
telescopes,
lenses and
cameras on a
"test
bench",
which
consists of
an office
building
around 3-400
meters away
and a
steeple
about 1 km
away.
I dagens
anledning
har jeg
endvidere
udvidet med
en primitiv
opstilling
til test af
skarphed og
kontrast på
den minimale
fokuseringsafstand
på 110 cm i
form af 1
stk.
For today’s
tests, I
have
expanded
this
“test-bench”
with a
primitive
setting for
testing the
sharpness
and contrast
at the
minimum
focusing
distance of
110 cm in
the form of:
perspective
drawing
paper, a
small ruler
and a stamp,
as shown
below:
Before we
get to my
"test"
images and
the rest of
the pictures
in this
review, just
a few
general
observations:
Resolving
Power: The
theoretical
resolving
power of a
lens depends
only on the
absolute/effective,
physical
size of the
aperture
opening. For
06B this is
about 2 arc
seconds. A
beam with
this space
angle will
form a spot
in the focal
plane of
0.0033 mm
with 350 mm
focal length
and just
under 0.007
mm at 700 mm
focal
length. One
DSLR pixel
element is
typically
around 0.006
mm in linear
dimension
and
therefore,
it gives no
sense to
discuss
resolving
power of
such a lens
based upon a
DSLR image
that may
typically
only resolve
some 75
lines per
mm.
Contrast: On
the other
hand, it
makes good
sense to
assess to
which degree
the camera +
lens
combination
can
distinguish
between
different
shades of
gray. In
this aspect,
it makes
sense to
compare
different
lenses using
one and the
same camera.
Focus,
distortion,
sharpness,
saturation:
For the
serious
camera
brands, all
CCD- and
CMOS sensors
come from a
handful of
highly
qualified
manufacturers.
These
sensors come
with very
similar
specifications
and quality
within each
sensor
size/pixel
number
class. Poor
lens quality
will always
show up
regardless
of the
choice of
(quality)
camera
brand. But
there may be
other,
visible
differences
that can be
attributed
to each
camera
manufacturer’s
use of
imaging
processing
“engines”
inside or
outside the
camera (e.g.
in their
RAW-conversion
software).
Camera
Settings:
When you
shoot in
RAW, you
obviously
must make a
choice in
regards of
settings for
contrast,
sharpness in
the
conversion
to JPEG. (If
you don’t,
you still
do: You just
rely on the
manufacturer’s
choice of
standard
settings).
When one,
like me,
frequently
just shoots
in JPEG, one
must also
take into
account the
in-camera
settings for
the
conversion
that takes
place in the
camera
“conversion
engine”. I
prefer to
shoot in the
"soft end"
of the scale
- no
"bright" or
"vivid"
colors and
no
aggressive
settings of
contrast and
sharpness
for me
thanks! I
can always
adjust and
correct for
"soft"
settings and
add a little
sharpness,
contrast or
saturation
in
post-processing.
But it is
impossible
to go the
other way
(e.g. from
”too
contrast” to
”more
normal”) and
still retain
all the
detail that
would have
been in an
original
“softer”
image. All
mirror
lenses
produce in
all but the
very best
lightning
conditions
somewhat
weaker
contrast
than
conventional
lenses do
and they are
– as all
long-focal
tele lenses
– very
sensitive to
the
slightest
haze in the
air. In the
old analogue
days you had
to take this
into account
in the
choice of
film type
and the
development/printing
in the wet
darkroom.
Now, you
must do the
same in your
choice of
camera
default
settings and
/ or
post-processing.
(And THAT
has made
things much
easier
today!!!).
And now it
is time for
some "test"
shots. The
images shown
were taken
with a
Pentax K200D
and most
images are
with
hand-held
camera:
06B, 350 mm:
06B, 700
mm:
06B, 350
and 700 mm (100% crop):
From these
results and
others I
will allow
myself to
conclude:
Sharpness:
Yes,
the lens is
sharp, both
with and
without the
teleconverter
down to the
minimum
focus
distance of
110 cm,
where one
obtains a
reproduction
ratio of
1:25
respectively
1:1.25.
Focus:
Those who
claim that
06B cannot
take sharp
pictures are
wrong. BUT,
I admit that
the beast
can be hard
to focus and
today's
smaller and
darker
viewfinders
have not
made life
easier in
this
respect.
What makes
this lens
tough to
focus is the
fact that
images are
formed from
the parts of
the light
bundles
coming
through the
outer parts
of the front
lens. Thus
one turns
the focusing
ring quite a
lot to reach
the proper
distance and
then – just
a tiny, tiny
change will
make a lot
of a
difference
as to how
sharp the
image will
be. And
regarding
the dim
finder view:
In low light
there is
only one
thing to do.
And that is
to Shoot,
check, fine
adjust,
shoot,
check....
Even under
good
lightning
conditions
it can be
frustrating
until you
have
achieved a
certain
exercise
(and you
should still
expect quite
a few
misses); a
right angle
viewfinder
with 2X
magnification
can be very
helpful for
tripod-based
shots.
Distortion:
For all
practical
purposes –
there is
nothing to
see or
measure.
And
the
notorious
bokeh?
Well,
that one has
to live
with. Some
claim that
they
actually
like it and
exploit it
artistically.
Personally,
I'm not
crazy about
it - to say
the least -
and always
try to
compose
myself out
of the
situation by
selecting
scenes and
shooting
angles where
the subject
is well
separated
from the
background.
However,
there is
another
problem with
mirror
lenses,
namely
Hotspot:
As
mentioned,
Tamron
designers of
that time
put a great
effort in
minimizing
the decrease
in
brightness
towards the
image edges.
But the
effect (vignetting)
is still
there, and
to
illustrate
this I have
taken a
picture of
an ordinary
piece of
patterned
paper in
normal,
ambient room
lightning
conditions
(i.e.
without
flash):
We see that
the lens +
camera
combination
nicely
captures the
weak lines
and even the
imprint of
lines on the
back of the
paper,
something I
could never
see with the
naked eye.
But when I
enhance the
contrast for
a better
view of the
lines, the
hotspot
effect is
evident.
This effect
is seen when
one takes
pictures of
large,
uniformly
lit surfaces
such as the
sky, but the
effect has
largely
disappeared
at 700mm
focal
length,
where the
entire
sensor is
apparently
located
inside the
hotspot. In
the old days
of analogue
film, there
was
virtually
nothing to
do, and it
could be
very
annoying at
times. Today
one
fortunately
has
software,
designed to
remove
vignetting,
that can
compensate
for this
effect, as
the
following
example
shows:
And let's
just have a
look at this
scene in
full view
With Tamron
18-200 mm
zoom at 35
mm
06B, 350 mm
With 06B,
350 mm -
(100% crop)
- Handheld
on a gray
February day
in 2010; I
guess that’s
quite OK?
What then,
may you use
this lens
for?
As said, for
me it was
astro
photography
(and budget)
that drove
my choice in
1982. Of
course, one
of the
contemporary
Tamron 300
mm f/2.8
lenses
(there were
two models
released,
one just
after the
other) are
both faster
and provide
better
images but
they also
cost just
below and
just above
300,000 yen
- and then
they both
had a weight
around 2.1
kg, while my
06B only
weighs 577
g.
Portability
and the
possibility
for
handheld,
long-focus
telephoto
shooting
were by no
means
granted sake
then. Today
we can
change ISO
with a
simple
finger
flick; we
have image
stabilization
(for those
of us who
are
fortunate to
have the
stabilization
in the
camera
body!); and
modern
construction
materials
have made
all lenses
much more
lightweight.
But I would
still argue
that the
compact size
and moderate
weight make
06B a good
companion on
the days
where you
just want to
take a
stroll and
shoot with
long focal
length as
opportunities
now presents
themselves.
For me, the
ability to
switch ISO
and image
stabilization
in the
digital age
have given
this modest
lens a
second
youth; I
have started
using it for
other things
than
astrophotography,
and I
started
practicing
how to
achieve
decent
focus...
The Macro
Capability
by virtue of
the modest,
minimum
focusing
distance
(1:2.5 or
1:1.25 at
110 cm) has
always been
as a big
plus to me.
Admitted, I
do not
photograph
stamps with
it, but what
about a
hornets’
nest? Or the
elusive
butterflies?
Or insects
in flight?
Another
example is
that a
couple of
wrens had
built their
nest just
above the
door to our
patio at the
cottage in
the summer
of 2009.
When we
arrived for
the summer,
the couple
was busy
feeding
their young
ones, and I
obviously
had to
photograph
that.
-
Problem
(1): The
wren is
the
second
smallest
bird
around
where I
live.
Not
exactly
humming
bird
sized,
but it
IS very
small.
So, even
with 700
mm focal
length,
I had to
come
close to
their
nest
(2-3
meters).
-
Problem
(2): The
nest was
in the
deep
shade
under
the
eaves -
and
wrens
are VERY
fast
flyers
for such
small a
bird.
-
Problem
(3): The
birds
refused
to fly
to and
from the
nest if
we were
closer
than 5-6
meters.
Here modern
technique
once again
came to
rescue:
Camera up on
a tripod in
the right
distance,
ISO up to
1600 to get
a decent
exposure
time (in the
rather deep
shade) and
then a
radio-controlled
shutter
release.
With this, I
could stand
in
respectful
distance and
shoot when
the birds
sat at the
entrance to
the nest.
The results
we see here
(again, as
full,
un-cropped
images):
06B, 350 mm
(Pentax *ist
DL)
06B, 700 mm
(Pentax *ist
DL)
06B, 700 mm
(Pentax *ist
DL)
Sample
Images:
Let me
conclude
with a few
more or less
processed
images.
Others have
taken better
pictures
with this
lens, but
these are my
own.
Conclusion:
Is this a
lens that I
think about
to part
with? - NO
WAY! It is
not the
perfect
telephoto
lens by any
standard.
Focus IS
difficult
(but
practice
makes
master) and
the bokeh IS
very
special. It
is fairly
slow, DOF
and
versatility
is limited
due to the
fixed
aperture of
f/5.6.
But it is
fun to use,
it is
extremely
compact and
easy to
carry
(almost)
everywhere
and it can
certainly
deliver
better
results than
I have been
able to show
here. I
shall
continue to
exert myself
in getting
the most out
of this lens
in the
digital
ages.
Is it a lens
that I may
confidently
and
unreservedly
recommend to
everybody? -
No, only if
you make the
restrictions
clear in
advance and
have a very
good idea of
what you
will use it
for, how and
why; (well….
of course
there's also
always the
collector’s
gene lurking
in many of
us).
What should
one be
willing to
pay? -
Difficult
questions. I
have seen it
go for
around 300
and up to
500 USD in
2008; around
GBP 150 in
2009 and in
late 2009 I
saw a copy
offered for
EUR 295. It
is probably
a matter of
luck or lack
of the same
- especially
if there are
multiple
bidders,
bidding each
other up.
Anyway,
because it
has become a
collector’s
item, you
must
unfortunately
be prepared
to pay some
“overheads”
to that
account
Literature:
http://www.adaptall-2.org/lenses/06B.html
http://photo.net/nature-photography-forum/00IdpJ
View: Sample
Images
Slideshow
Brochure:
Tamron SP
350mm f/5.6
Model 06B
