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Sigma 4.5mm F2.8 EX DC HSM Circular Fisheye

Reviews Views Date of last review
3 24,403 Wed May 8, 2013
Recommended By Average Price Average User Rating
100% of reviewers $685.33 8.33
Sigma 4.5mm F2.8 EX DC HSM Circular Fisheye


The Sigma K-mount 4.5mm f/2.8 EX DC HSM Circular Fisheye Lens produces a circular image with an expansive 180° angle of view. The lens features a Hyper Sonic Motor for quick and accurate autofocus performance.

The fast F2.8 maximum aperture makes the lens suitable for low light photography.

Sigma 4.5mm EX DC HSM Circular Fisheye
©, sharable with attribution
Image Format
Lens Mount
Pentax K
Aperture Ring
Automatic, 6 blades
13 elements, 9 groups
Mount Variant
Check camera compatibility
Max. Aperture
Min. Aperture
AF (in-lens motor)
Min. Focus
13 cm
Max. Magnification
Filter Size
Internal Focus
Field of View (Diag. / Horiz.)

APS-C: 180 ° / 180 °
Lens Cap
Weather Sealing
Other Features
Rear Filter Mount,Fisheye
Diam x Length
76.2x77.8 mm (3x3.06 in.)
470 g (16 oz.)
Production Years
USD current price
Product Code
User reviews
Accepts gel filters at the rear

Buy Lens: Buy the Sigma 4.5mm F2.8 EX DC HSM Circular Fisheye
Price: $799
Mount Type: Pentax KAF3 (in-lens AF only)
Price History:

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Man With A Camera

Registered: June, 2010
Location: The Great Pacific Northwet
Posts: 23,624
Lens Review Date: May 8, 2013 I can recommend this lens: Yes | Price: $395.00 | Rating: 9 

Pros: Love the 180° circular image! It has an adapter for the lens cap with threads so a haze filter, CPL, or a neutral density filter can be used, although this does cause some vignetting.. The HSM is fast and quiet.
Cons: What?
New Or Used: New   

I had a bumpy start with this lens. When it arrived in my PO box the other day I excitedly pulled it out of the box and mounted it on my K10D. What's this? The autofocus doesn't work? I tried everything, digging deep into the camera menus and settings.


So by the time I got home I was about to contact the guy I bought it from and ask him to take it back.

But first I posted a thread here on the forum, and Adam asked what firmware version was on my camera.


So I updated the firmware (something I had not ever done since I bought the camera new!), and the autofocus works now!

Anyway, to the review. I really like to create images with extreme wide angle lenses, and this lens is a top performer in that regard. With the circular image layout, and the 180° field of view it does not disappoint. The HSM is fast and quiet. It was dark when I finally got things working, and time for bed, but I went outside to snag a couple shots before retiring for the evening. Even though they are hand held, and I had to bump the ISO to get something somewhat decent, I think this lens is going to make a great addition to my lens lineup.

I literally stole this lens. I saw it on eBay for $549, "Buy It Now" or "Best Offer". It didn't sell, and a few days after the seller re-listed it, I made an offer, and to my surprise he accepted it! This lens sells new for $1250, and Sigma has had it listed for $100 off lately. So to get it for $395 I feel like I got a "screamin' deal"!

(I must add here that I made a comment a while back that I would never own another Sigma lens. This was after having a couple issues with a 600mm F8 Cat I have had for over 30 years and the poor response from the tech staff at Sigma. Those issues are still unresolved. But here I am with another Sigma lens in my camera bag. I guess you should never say never!)
Veteran Member

Registered: June, 2012
Location: Boise Idaho
Posts: 466
Lens Review Date: January 15, 2013 I can recommend this lens: Yes | Price: $799.00 | Rating: 8 

Pros: Widest lens available for Pentax at the time, Fast wide angle, Great for Astrophotography
Cons: A little too wide at times
New Or Used: New   

I went to a camera shop and tried the lens for about half an hour. The shots I took, I brought back home and checked out. I was very impressed. It's almost 180 degrees. it's just beautiful. If you ever get the chance to try it out, it's something every photographer should see.
Site Supporter

Registered: February, 2010
Location: Salt Lake City, UT
Posts: 1,855
Lens Review Date: July 25, 2010 I can recommend this lens: Yes | Price: $862.00 | Rating: 8 

Pros: Nothing like it on the market, unique look and feel to your photos, excellent build quality.
Cons: You must disable in camera SR, no EXIF data for focal length, Protruding front element, no option for screw in filters

This lens really has some incredible properties.

Here's a few of my fav shots so far. These are all right off the camera (and uploaded to FB).

So, there's the good. The lens is really pretty amazing. The lens obviously distorts everything so it's hard to decide how sharp it truly is. I think sharp enough for the type of pictures you'll be taking with it.

The DoF & out of focus blur is hard to get a handle on with this lens. Almost everything is in focus most of the time unless your focus point is up close.

The HSM focusing is smooth, but doesn't always result in it focusing on what you think it should.

My partner says it's like being in the glass globes from the movie Labyrinth, and if she's shooting, this is the second most likely for her to use.

Here's the bad:

Your feet will be in the picture. Having the full 180 field of view is fun and bizarre, but it means that you have to be super aware of where everyone, including yourself are. I've gotten my fingers in the picture just from holding onto the lens, and as for your feet, it's almost guaranteed to capture them.

This lens isn't reporting focal length to the K-7 body, or the K-7 body isn't accepting the focal length, and you cannot choose the focal length like you can with an A lens.

The SR on the k-7 goes absolutely NUTTY. It looks and feels like it's trying to correct an 800mm lens rather than a 4.5mm lens. If you turn on live view and wobble the camera, you can actually feel the SR jerk the camera about and watch the image move all over the screen.

If you do not use the work around of turning off SR, you simply cannot take a sharp or useful picture with this lens, even at 1/2000th you'll get double images.

You must always use center weighted or spot metering since the edges will be all dark.

All in all, if you're looking to create a unique, artsy feel to your pictures, there's no lens like this one right now.

If not for the setup of disabling SR (and then remembering to re-enable it) every time I swap this lens, I'd have given it a 9.
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