Pentax-M 100mm f/4.0 Macro SMC

Pentax-M 100mm 4.0 Macro SMC  -3

Pentax-M 100mm f/4.0 Macro SMC. If you’re looking to purchase this lens I always check Adorama and Ebay for good deals. It helps me if you purchase it through one of these links here in this review. When you purchase through these links it financially enables me to devote time to develop this site further. Thanks for the help! -Todd

Pentax-M 100mm 4.0 Macro SMC  -2 Pentax-M 100mm 4.0 Macro SMC  -1


12.3 oz (350g)

Focus Type
Manual Focus.

Focus Ring
Rubber on Metal.

Close Focus
1.48 feet (0.45 meters).

Filter Threads
49mm, Metal.

Aperture Ring

6 blades stopping down to f/32.

Metal Pentax K.

Made in

Bokeh Blur

f/4 | f/8



100% Crop


Corner at f/4

Corner at f/4

Macro Close Focus
Pentax-M 100mm 4.0 Macro SMC Closest Focus-1

f/4 Not too bad at f/4 with moderate contrast and with a bit of spherical aberration.
f/5.6 Nicely sharpens up with better contrast.
f/8 Sharp with great contrast.


A little bit of vignetting at f/4 and mostly gone by f/5.6


The blur is not too bad just a little distracting.


A little bit of pincushion distortion.


On MF Camera
Optics:          ★ ★ ★
Mechanics:   ★ ★ ★ ★ ★
Ergonomics:  ★ ★ ★ ★
Usefulness:    ★ ★ ★ ★
Availability:     ★
Overall:           ★ ★ ★ ★

On AF Camera
Ergonomics: ★ ★ ★
Overall:         ★ ★ ★
Out of 5

This lens and the superior Pentax-A 100mm 2.8 Macro are definitely worth looking for! They are not common offline but they are easy to find online. If you want great macro optics stopped down this lens is amazing from f/5.6 onwards. F/4 is still decently sharp, but with the amount of spherical aberration it clouds over the sharpness so it looks like it’s soft but it’s actually just covered up.

This lens is small and light and built extremely well. It features the common 49mm filters which is nice. My one beef is that while being a macro there are other macros that can get closer. If you intend to use it just as a portrait lens then even $10 3rd party 100mm 2.8 or 135mm f/2.8 lenses will give you better images stopped down to f4.

If money is not an issue and you want to focus closer, better optics, less distortion, common build, better background blur, and more light then the Pentax-A 100mm 2.8 Macro is the way to go. If cost is an issue then this Pentax-M 100mm f4 is a steal of a deal today and you can’t go wrong.


Did this review help?
My hopes are to take the time to continue developing this website with more test photo based reviews. If you are ever interested in purchasing this lens or other photography equipment please do so through these links here in this review. I always check Adorama and Ebay for good deals. This helps support my family and allows me to take more time for the site. The best part is this site is free for you and I link good deals I find!

Sometimes these links will actually give you better deals then typical retail prices! I personally buy from the links I have listed whether looking for new gear or fun old stuff. I can personally attest to their good & safe service from years of experience. Thanks again to you, our readers, for supporting us! -Todd