Pentax Telephoto 55mm f/1.4 DA* SDM Autofocus Lens for Digital SLR

Model #21790

USA Version
Pentax 21790 1
Pentax 21790 1
Pentax 21790 5
Pentax 21790 3
Pentax 21790 4
Pentax 21790 2
How it works
  • You name the price you want to pay for a product.
  • We send your offer to a network of Certified Retailers.
  • If the retailer likes your offer, you get that price for the product.
Greentoe Guarantee
  • All Products are New and from Certified Retailers
  • 30 day return policy
  • Free Shipping
    No Additional Fees

Name your price


Lowest Price Online: $646.95


Your Chances of Success
lowest price online $646.95
average price online $646.95

Your chances of success

Online Prices
We have done the shopping for you! Here is a list of the lowest prices currently found online. Beat those prices with Greentoe!
Enter your zip code to see how much we will be saving you!
Showing prices for zip code 94103 change
Retailer Base Price Tax Shipping Total
Adorama $646.95 $0.00 $0.00 $646.95
**Pricing is for informational purposes. Not all retailers have direct relationship with Greentoe.


Weight 13.23 oz (375 g)
Dimensions (dxl) Approx. 2.8 x 2.6" (7.11 x 6.60 cm)
Filter thread 58 mm


Diaphragm blades 9
Format compatibility Pentax Digital (APS-C)
Focal length 55 mm
Comparable APS-C Focal Length: 82.5 mm
Aperture Maximum: f/1.4
Minimum: f/22
Magnification 0.17x
Maximum reproduction ratio 1:5.7
Groups/elements 8/9
Camera mount type Pentax K
Angle of view 28.6°
Minimum focus distance 1.48' (45 cm)


Autofocus Yes
Tripod collar No
Image stabilization No
Expert Reviews
What digital camera.32818507
24 June 2010

It seems like a shame that Pentax’s 55mm fast prime does not have full-frame coverage, but given that there is currently no full-frame Pentax body (other than older film cameras) this may not be such an important gripe.

  • +

    Excellent ergonomics

  • -

    Fringing in MTF images

Slr lens and camera reviews.33034498
18 July 2009

Pentax smc DA* 55mm f/1.4 SDM is one of the latest addition to the company's growing portfolio of lenses specifically designed for digital SLR cameras. This is also one of the first KAF3 mount lenses in the company's potfolio.

17 May 2009

Gary Wolstenholme takes a close look at this short telephoto lens from Pentax. This 55mm f/1.4 lens from Pentax is designed to be used with their latest generations of DSLR cameras and sports a bright maximum aperture of f/1.4 and silent SDM focusing for around £600, which I feel is a little pricey...

  • +

    Excellent optical quality from f/2 onwards, Fast focusing, Weather selling, Low distortion and CA

  • -

    Limited compatibility with older Pentax DSLRs, Price, A little soft at f/1.4

User Reviews
B h photo.32817553
9 February 2016

I got this lens to use for portraits of family and for day-to-day photography (yes I know it's not a typical street-photo focal length). I find the images crisp and the lens responsive. It's heavy, but it seems worth it, and the manual focus is easy and satisfying to use.

  • +

    Durable, Easy To Use

22 April 2012

A wonderful lens, really nice smooth bokeh. Not as sharp as a Carl Zeiss but it is autofocus. Also had no problems using it out in the rain, if the weather is bad this is the lens I'd want to have with me.

  • +

    Consistent Output, Easily Interchangeable, Lightweight, Nice Bokeh, Rugged

Photography review.32822891
19 April 2009

Severe back-focus on my K10D and I don't understand why Pentax changed the (in my opinion great screw-motor) with the slower SDM, the image quality (manually focused because the SDM AF shows back-focus) is great by the way.

  • +

    very sharp, great build and weather-sealing

  • -

    price is too high, back-focus problems on the K10D (I guess on the K100Ds too) and the accuracy of the SDM system

Product Highlights
    Average Expert Score
    Average User Score
    In The Box
    • Pentax Telephoto 55mm f/1.4 DA* SDM Autofocus Lens for Digital SLR
    • PH-RBH Lens Hood for SMC DA* 55mm f/1.4 SDM Lens
    • O-LC58 58mm Lens Cap
    • Rear Lens Cap (B) for Bayonet Mount Lenses
    • Lens Case S90-100 (Soft)
    • 1-Year Pentax USA Warranty
    Still Have Questions?
    We can help via Live Chat, Email or you can call us 1-888-840-0464


    Please log in or sign up to continue


    Validating Credit Card...

    It will not be processed until the offer is accepted by a merchant.

    Notifying Retailers...

    Notifying our merchants and checking to see if they accept this offer.

    Offer Submitted!

    3-digit code in the back of your credit card