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SMC Pentax-A 100mm F4 Macro Review RSS Feed

SMC Pentax-A 100mm F4 Macro

Reviews Views Date of last review
12 90,006 Fri March 31, 2023
Recommended By Average Price Average User Rating
100% of reviewers $171.67 8.83
SMC Pentax-A 100mm F4 Macro

This lens is similar to the M version; a dental version with a special scale for dental photography was also available.

SMC Pentax-A 100mm F4 Macro
©, sharable with attribution
Image Format
Full-frame / 35mm film
Lens Mount
Pentax K
Aperture Ring
Yes (A setting)
Automatic, 6 blades
5 elements, 3 groups
Mount Variant
Check camera compatibility
Max. Aperture
Min. Aperture
Min. Focus
45 cm
Max. Magnification
Filter Size
49 mm
Internal Focus
Field of View (Diag. / Horiz.)

APS-C: 16 ° / 14 °
Full frame: 24 ° / 20 °
Not needed
Hard case HB-120
Lens Cap
Weather Sealing
Other Features
Diam x Length
65 x 78 mm
340 g
Production Years
1984 to 1989
Engraved Name
smc PENTAX-A MACRO 1:4 100mm
Product Code
User reviews
A variant with a special scale for dental photography was also available: smc PENTAX-A DENTAL MACRO 1:4 100mm
Manual FocusAperture RingAutomatic ApertureFull-Frame SupportDiscontinued
Price History:

Add Review of SMC Pentax-A 100mm F4 Macro
Sort Reviews by: Date | Author | Rating | Recommendation | Likes (Descending) Showing Reviews 1-12 of 12
New Member

Registered: April, 2011
Location: Dorset , UK
Posts: 6
Review Date: March 31, 2023 Recommended | Price: $120.00 | Rating: 8 

Pros: handling, focus
Cons: sharpness
Sharpness: 8    Aberrations: 9    Bokeh: 9    Handling: 10    Value: 9    Camera Used: various   

it`s a good macro lens but there are many other good and often better lenses available (like Tamron 52BB).

++ great size and weight
++ super smooth focus
++ bokeh wide open at f4
+ good sharpness

-- prone to internal haze
-- only 1/2 life size
New Member

Registered: January, 2020
Posts: 4
Review Date: January 17, 2020 Recommended | Price: $150.00 | Rating: 10 

Pros: Tak Sharp even wide open, no distortion (totally straight lines!), fantastic bokeh at no CA,
Cons: any?
Sharpness: 10    Aberrations: 10    Bokeh: 10    Handling: 10    Value: 10    Camera Used: Canon 7D and 5DII (adaptor)   

It is the same optical formula as Takumar and Pentax-K or M.
VERY sharp even wide open. The contrast is amazing. It is noticed that it is better in the FF system than APSC. Since the maximum aperture is at f4, the bokeh is perfectly circular at f4.

People should note that the depth of field is MUCH larger with macro lenses, so you should use this factor to your advantage. When it comes to macro lens f4 is more than enough for bokeh.

It's a specialized lens - that's why the aperture normally starts at f4 onwards. Up to f22 you get astounding sharpness without much diffraction (impossible to achieve this on a standard lens).
No, it's not a "portrait lens," so don't be fooled to compare with portrait lenses. No, this is not good for taking landscape photos either.
New Member

Registered: April, 2015
Posts: 11
Review Date: August 31, 2019 Recommended | Price: $120.00 | Rating: 7 

Pros: Handy lens
Cons: Very low contrast and colour. Not sharp enough.
Sharpness: 8    Aberrations: 8    Bokeh: 9    Handling: 9    Value: 4    Camera Used: K-30   

This lens has low contrast and colours (correctable in PP) but it is a good macro lens. Sharpness is acceptable for mot purposes, but perhaps a bit below average by today's standards--particularly at f/4. Chromatic aberration is present at f/4, but most of it disappear at f/5.6. This lens performs terribly if the sun is in the frame, or anywhere in front or above even when its not in the frame. A big hood is recomended like this:
Veteran Member

Registered: December, 2017
Posts: 469
Review Date: June 27, 2019 Recommended | Price: $115.00 | Rating: 9 

Pros: Excellent built quality
Cons: none
Sharpness: 9    Aberrations: 9    Bokeh: 7    Handling: 9    Value: 10    Camera Used: K20d   

A perfect successor of the 100 mm M lens I had before.
The "A" version is a delight to use with DSLR bodies, an underrated extra.

I bought the normal A version that showed the much feared haze on the front element.
The seller offered to exchange the lens for the rarer Dental, optically the same lens but more collectable.

Picture made using the 2,8/50 A macro lens with K20d body.
Finding a clean 100 mm macro lens from this era is hard, it must be my lucky day.

Please note:

Complaints about the performance of macro lenses at infinity do not do justice to these lenses.
Macro lenses are designed to give optimum performance at close range.
Therefore they can not deliver good results at infinity.

Non macro lenses are all designed to perform well at infinity.
That is why there are also macro designs.
amateur dirt farmer

Registered: December, 2014
Location: probably out in a field somewhere...
Posts: 41,600

3 users found this helpful
Review Date: October 31, 2015 Recommended | Price: $100.00 | Rating: 9 

Pros: build/handling, color rendition, sharpness
Cons: focal length can be too long in some cases

I used this lens for the Single in September challenge:

This is an amazing piece of kit - well-built, a dream to handle and focus, stunning detail and color rendition to die for. The only short-coming would actually be on me: sometimes I found the 100mm length tricky to use and I wished it was a 50mm or 85mm lens.

That's it - everything else about it is just about perfect. So nice, in fact, I named my copy "Butter"... soooo smooooth...

Veteran Member

Registered: January, 2014
Posts: 370

2 users found this helpful
Review Date: September 4, 2014 Recommended | Price: $175.00 | Rating: 9 

Pros: Sharp, wonderful colors
Cons: Not so good on infinity
Sharpness: 9    Aberrations: 8    Bokeh: 7    Handling: 9    Value: 9    Camera Used: K3   

I just purchased this lens after a good experience with the M series (still have it). The version I have has seen more mileage than the M I own, but still excellent condition. Really like the combination of this lens and the K3, very rich colors, can use high ISO and still get very well defined results.[ I love using the M series for landscapes, wonderful color, and will try the A series out to see if I have the same experience.

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Forum Member

Registered: August, 2010
Location: Edinburgh
Posts: 91

1 user found this helpful
Review Date: September 4, 2011 Recommended | Price: $200.00 | Rating: 9 

Pros: Big smooth focus ring, image quality
Cons: 1:2 maximum magnification, modest max aperture
Sharpness: 8    Aberrations: 10    Bokeh: 10    Handling: 9    Value: 9   

This is my one of my favourite lenses, and I find the sharpness and bokeh to be extremely pleasant.

The focus ring is huge and silky smooth - with a tiny bit of pressure from my little finger I can shift the focus precisely with no play at the start of end of the motion, yet it doesn't drift when there is no pressure applied - a joy to use, particuarlly compared with modern plastic-body lenses.

At f4 the sharpness is a little unimpressive and itís somehow a little muddy, but 5.6 is a really big step up, and at f8 the results are excellent- smooth, clean and sharp, with great colours Ė and capable of top class photographs.

I use this for macro photography of insects and birds, and also for professional headshot photography for local actors.

As a telephoto lens I find the results not quite as good the close range performance, particularly at infinity focus. Itís not bad though Ė to my eye, the chromatic aberration seems worse, when Iíve taken infinity focus pictures of the sea the white highlights have yellow fringing. Iíve never seen these at close focus.

Itís also a pity it only magnifies to 1:2, and as it is f4 the use of extension tubes is going to make things rather dark.

I would upgrade to the D-FA 100mm f2.8 of this lens if funds allowed for the weather resistance, 2.8 max aperture, 1:1 magnification, circular blades and autofocus, but for the time being this is an excellent alternative!

Here are some sample macros:
Site Supporter

Registered: December, 2008
Location: Zetten - The Netherlands
Posts: 9,050

2 users found this helpful
Review Date: August 31, 2011 Recommended | Price: $100.00 | Rating: 9 

Pros: Sharp, great colour rendering
Cons: Only 1:2 (but see below), only f/4
Sharpness: 9    Aberrations: 9    Bokeh: 8    Handling: 9    Value: 9   

I got this lens for about 80 Euros some years ago. The handling is just perfect, with a large focus throw. I think it is a pitty it only magnifies 1:2, and therefore I bought two 1:1 lenses. However, for some subjects a 1:2 magnification is just perfect, for instance butterflies and dragonflies/damselflies. The maximum aperture makes it a bit difficult to focus in situations with less light, and I think this is the main drawback of the lens.

Overall I would highly recommend this lens!

For those wanting some examples: SMC Pentax-A 100mm F4 macro - A set on Flickr
Veteran Member

Registered: August, 2009
Location: The British Isles
Posts: 2,402
Review Date: November 23, 2010 Recommended | Price: $100.00 | Rating: 9 

Pros: manual focus

Fine performer if you like manual macro lenses. Excellent detail in the shots.

Registered: September, 2006
Location: Copenhagen, Denmark
Posts: 4,408

1 user found this helpful
Review Date: April 5, 2009 Recommended | Price: $350.00 | Rating: 9 

Pros: Compact, sharp, solid build
Cons: A bit slow at f/4
Sharpness: 9    Aberrations: 9    Bokeh: 9    Handling: 8    Value: 9   

This is a great little macro lens. Although it has just 5 elements it is tack sharp as witnessed by this test photo:

The build quality is top notch.

The lens only goes to 1/2x magnification, to get closer you need extension tubes. I would probably grab my D FA 100 f/2.8 for 1:1 work due to the larger max. aperture which makes focusing easier at 1:1.

At the 1/2x magnification focusing the A lens is no problem at all with the K10D.
Inactive Account

Registered: November, 2006
Location: San Diego, California
Posts: 441

1 user found this helpful
Review Date: February 10, 2007 Recommended | Price: $300.00 | Rating: 9 

Pros: Very sharp lens with very low distortion
Cons: Maximum aperture of f4

The 100mm SMCP-A f4 macro is a very sharp lens from close-up to infinity. Very low distortion with good contrast and color rendering. Maximum magnification is 1:2 by itself, but you can add another 50mm of extension to reach 1:1 (or more for greater than life size). It uses the same optics as the 100mm bellows lens and the 100mm SMCP-M f4 macro (5 elements in 3 groups). It is all metal construction including the aperture ring (unlike some other A lenses).

In use, the focusing is very smooth with about 340 degrees of travel from infinity to close focus (0.45 meters). This allows very precise focus adjustment. Unfortunately, the f4 maximum aperture results in a dark viewfinder in lower light conditions making focusing harder. This is the main drawback of this lens as compared to the newer f2.8 macro lenses. I would recommend using a lens hood outdoors or in bright light. Flare can be seen if shooting close to the Sun in spite of the recessed front element (contrary to some opinions). I use the Pentax clip-on hard plastic 49mm hood marked for the 85mm f2, 100mm f2.8 and 100mm f4 and it works very well. I also recommend using extension tubes with the "A" electrical contacts for newer bodies (such as the digital *ist and K series) for easier exposure control and full P-TTL flash control. Unfortunately Pentax does not make such a tube, but third party products made by Vivitar and Kenko have the contacts. Be sure that all seven contacts are present.

The price I posted was for a used lens in mint condition about 15 years ago, and may not represent the current market price.
Senior Member

Registered: October, 2006
Location: Masachusetts
Posts: 243
Review Date: January 21, 2007 Recommended | Price: $230.00 | Rating: 9 

Pros: Very sharp, focuses to 1:2 without extention rings, and works just fime with them.
Cons: It would be nice if it went to 1:1, but a set of extention tubes can fix that.

This is a fantastic macro. I actually have the Dental Macro, which is the same lens with some mysterious markings meant for close-up attachments for dentists.

The front element is deeply recessed, making a lens hood unnecessary, unless you need to use a filter.

It is sharp and clear at magnifications up to 1:1 (with extension tubes), so it can be used for immense magnification.

It also functions well at infinity focus, so you can use it as a moderate telephoto if you need to.

In macro work, manual focus is better than auto. So no need to update this gem.

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