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SMC Pentax 100mm F4 Bellows

Sharpness 
 10.0
Aberrations 
 8.5
Bokeh 
 9.5
Handling 
 9.5
Value 
 10.0
Reviews Views Date of last review
3 28,146 Mon December 23, 2019
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Recommended By Average Price Average User Rating
100% of reviewers $113.33 9.00
SMC Pentax 100mm F4 Bellows

SMC Pentax 100mm F4 Bellows
supersize
SMC Pentax 100mm F4 Bellows
supersize

Description:
This lens has no focusing ring and is intended for use on a Pentax bellows unit.

SMC Pentax 100mm F4 Bellows
© www.pentaxforums.com, sharable with attribution
Image Format
Full-frame / 35mm film
Lens Mount
Pentax K
Aperture Ring
Yes (no A setting)
Diaphragm
Manual, 6 blades
Optics
5 elements, 3 groups
Mount Variant
K
Check camera compatibility
Max. Aperture
F4
Min. Aperture
F32
Focusing
Fixed
Min. Focus
Max. Magnification
Filter Size
52 mm
Internal Focus
No
Field of View (Diag. / Horiz.)

APS-C: 16 ° / 14 °
Full frame: 24 ° / 20 °
Hood
Not needed
Case
Dedicated hard case
Lens Cap
Plastic clip-on
Coating
SMC
Weather Sealing
No
Other Features
Diam x Length
60 x 40 mm
Weight
185 g
Production Years
1975 to 1998
Engraved Name
SMC PENTAX BELLOWS 1:4/100 (early version), smc PENTAX BELLOWS 1:4 100mm (later version)
Product Code
28240 (early), 28250 (late)
Reviews
User reviews
Notes
No focusing mechanism
Variants

Two variants were produced, only differing in the engraved name:
SMC PENTAX BELLOWS 1:4/100 (early variant),
smc PENTAX BELLOWS 1:4 100mm (later variant)

Features:
Manual FocusAperture RingFull-Frame SupportDiscontinued
Price History:



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Sort Reviews by: Date | Author | Rating | Recommendation | Likes (Descending) Showing Reviews 1-3 of 3
Loyal Site Supporter

Registered: September, 2017
Location: MedellŪn
Posts: 1,206
Lens Review Date: December 23, 2019 I can recommend this lens: Yes | Price: $120.00 | Rating: 9 

 
Pros: Wide open focusing with the Auto Bellows and/or extension tubes.
Cons: Most copies have separation.
Sharpness: 10    Aberrations: 8    Bokeh: 9    Handling: 10    Value: 10    Camera Used: Film cameras, K-5   

It's a nice lens for tabletop photography. Funny thing is, it focuses to infinity on the Auto Bellows. Works just as intended on it. Got everything as a kit from a forum member. I first used it with the original Asahi Pentax double cable release and a Canon T3 threaded cable release adapter and later with a modified Nikon AR-10.
Sadly, all copies I've ever seen suffer from a bit of separation on the edges, but that really doesn't seem to affect it since one rarely shoots wider than f/8 or wide open at infinity. That's not what this lens is for anyway, although there's still the option. I would rather take the 50 mm or 100 mm plus other auto tubes combined to use in the field. Less weight and still wide open focusing. Clip on hood works well. Fits all in the small case.
   
New Member

Registered: November, 2013
Posts: 7

1 user found this helpful
Lens Review Date: November 11, 2018 I can recommend this lens: Yes | Price: $100.00 | Rating: 10 

 
Pros: excellent cose ups lens
Cons: some few CA's
Sharpness: 10    Aberrations: 9    Bokeh: 10    Handling: 9    Value: 10    Camera Used: k-s1, k-x, k200d   

very good performer

for macro shootings you can improve sharpness by using a focal reductor, so you'll get a 2,8/70 with extreme sharpness on ballow

for photos taken in this way excellent results !!!
   
Site Supporter

Registered: October, 2008
Location: Vancouver, Canada
Posts: 6,627

1 user found this helpful
Lens Review Date: January 18, 2009 I can recommend this lens: Yes | Price: $120.00 | Rating: 8 

 
Pros: Size, quality and 100mm focal length.
Cons: Slow f4.0, limited usage as itís dependant on a bellows unit.
Camera Used: K Series film bodies (K1000, KM, KX, K2, K2DMD)   

The K100/4 Bellows definitely falls into the specialty lens category. Itís basically unusable without a bellows unit, as the lens has no focusing ring to control magnification. In my opinion this limits the K100/4 Bellows to indoor macro use only. For outdoor use I take my rail kit, extension tubes and regular macro lenses, which are far more durable than a bellows unit. The other option would be to use the K100/4 Bellows lens with the Pentax Helicoid (variable) Extension Tube, which I havenít tried yet.

The K100/4 Bellows has an automatic diaphragm which will be retained when used with the ďautoĒ bellows unit, or it can also be used on the ďregularĒ bellows unit as a manual diaphragm lens. Itís rather slow at f4.0, so you get a darker viewfinder especially if used indoors. I compensate the slow maximum aperture by using two 500 watt portable studio lights when Iím doing indoor macro shooting.

The 100mm focal length gives you a longer distance to subject ratio than the 50mm macro; this is nice when using the bellows unit on a tripod. Even though the lens element is recessed, you should use the dedicated plastic round clip-on lens hood. This hood is shared with the K85/1.8, K100/4 Macro & the K105/2.8 lenses. (52mm filter diameter)

For extreme magnification in macro photography, the 100mm focal length does not benefit when the lens is reversed. You are better off reversing the 50mm macro or the 28mm f3.5, for magnification greater than 1.0. The K 28mm f3.5 is still the best Pentax lens for this purpose.

All in all itís a valuable tool if you are into macro photography and have other macro lenses to compensate for some of its weaknesses.


Sample shots taken with the K100/4.0 Bellows. Photos are medium resolution scans from original negatives.

Camera: K2 Film: Kodak Portra 400VC ISO: 400





Camera: K2 Film: Kodak Portra 400VC ISO: 400

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