The Pentax SMC 4/100 Macro is a small and affordable macro lens from the 70’s. In this review I check if it can still deliver on today’s 24 Megapixel Sony a7.
|Filter Diameter||49 mm|
|Close Focusing Distance from the sensor||45 cm|
|Number of aperture blades||6|
|Elements/ Groups||5/ 3|
What is it good for?
Today 100mm Macro lenses are very popular because they are so versatile. You can use them for a very wide many applications ranging from macro over portraits to landscapes.
The rather slow speed of the Pentax 4/100 limits it’s usefulness as a portrait lens but it is very light and not that big which make it a good choice for a small and versatile tele lens.
The Pentax Macro is built very well, everything is made from metal or glass and markings are engraved.
Both aperture- and focus ring move precisely.
Size and Weight
The Pentax 4/100 Macro is of average size, typical for 100mm lenses, my Tokina 2.5/90 Macro and Minolta MC 2.5/100 are similar in size. If you consider that both lenses are more than a stop faster you wonder what Pentax needed all that space for. One ncie aspect is that the front lens is so far recessed that you can throw the lens into your bag without having to worry about getting it scratched.
he lens is well balanced on the Sony a7 but adding a L-bracket improves the balance further.
You have to turn the focus ring clockwise to focus further away, Nikon and Pentax users are used to this focus direction but for me who is used to Minolta SR and Canon FD lenses it was harder than expected to adopt to it.
The focus ring turns about 80 degress from infinity to 1m and a further 250 degress to the dshort focusing distance of 45cm.
This is quite good for macro work but the focus throw is a bit short for portrait and landscape work. The focus ring is harder to turn than I like it, my Tokina 2.5/90 feels much smoother. My copy is in excellent condition so it is unlikely that it is just my copy.
The aperture ring feels very solid and precise.
There are full stops from f/4 to f/5.6 and f/22 to f/32 and half stops in between. The aperture has 6 straight blades which are clearly visible around defocused highlights.
Typical for a lens of that era the Pentax 4/100 Macro loses contrast if you point it towards a brighter light source.
I think bokeh is quite smooth but the hexagonal structure of the aperture is a bit distracting when you stop down.
At infinity the performance is quite unremarkable. f/4: The center shows very good resolution with lower contrast, towards the corners sharpness drops to okay levels.
f/5.6: Very sharp in the center, sharp in the midframe and corner regions.
f/8: Very sharp across the frame.
At closer distances it is a bit better but I would advise to stop down to f/5.6 to make the contrast reducing spherical aberration go away.
I bought the Pentax 1:4 100 Macro because I was looking for a small and light weight macro lens because my current macro the Tokina 2.5/90 felt a bit too large and heavy at times and I was looking for a replacement for those times when size and weight are essential.
The Pentax is a solid performer but it didn’t meet all of my expectations. Yes it’s nearly 200g lighter than my Tokina but not any smaller. I could have learned that from the specifications but because several people wrote about how small it is so I didn’t bother. The mechanics are all right but the focus ring is not as nice of that my Tokina and this subtracts from my ecperience.
Optically the Pentax is again a good performer but neither has it the great bokeh of my Tokina nor can it match it’s exceptional sharpness and it shows more axial chromatic aberations.
If I consider the rather affordable price of the Pentax I have to conclude that it offers pretty good value.
The only reason my conclusion is a bit negative is that I compared it to the truly exellent Tokina 2.5/90 Macro which bests it in several aspects so the weight reduction isn’t worth the many tradeoffs I would have to accept if I live with.
All in all the Pentax SMC 4/100 Macro is a good lens without any serious weakness and a solid performance for a good price.
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Full resolution samples
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