Pentax 15mm lens

This is one of those lenses I mentioned that, if I ever sold it and was filled with remorse, I couldn’t afford to replace.

How I came to buy it originally was luck. It was a rare and expensive lens – Pentax can’t have sold a dozen of these a year. And yet a branch of Jessops nearby had one on sale. This was in the days when Jessops were useful. When I asked about it, the reason was because a customer had ordered it but then declined to buy it. It was such an extreme lens that the shop must have thought they would never shift it. So they had it on sale for the same amount I had separately paid for a secondhand MX body. Even then I swithered about it. How many people really need a 15mm lens?

And yet it’s rather marvellous. It has a 100 degree horizontal field of view, but it is also rectilinear. This means that straight lines stay straight and don’t bow like a fisheye lens. There is a whole rabbit warren to drop down if you want to learn about the different ways an extreme wide angle can work, but it basically comes down to two things: do straight lines curve or not and do circular things stretch into ovals at the sides of the frame?

This is an estate agent’s lens. Pop this on a tripod, get it level and you can make a phone box look like a ballroom. All the lines stay straight, so there is no obvious distortion. You can get a lot in the frame without the usual fisheye distortion or get in close and get some strong diminution effects.

It may not look much, but that’s the point. I was nearly close enough to touch the building.

Those that know give the lens a mixed reception and say it’s soft in the corners wide open and suffers from flare. I like it a lot, but use it less than perhaps I could. The built-in yellow and orange filters are useful for black and white and there’s also a UV and skylight filter for colour. The built-in lens shade does at least belp to keep the front element from harm.

In terms of handling it’s a bit of a beast. It’s heavy, for a start – 595g. The large front element and built-in hood need a deep slide-on lens cap that is better described as slide-off. I’ve got a strip of masking tape round the end of my lens to make the cap a tighter fit, but it’s still covered in dings from its escape attempts. Despite being heavy, it’s easy enough to carry though. I did a photo-walk and used this lens. The camera was actually a nice balance and quite discrete for hand-carrying. With the lens on a Pentax MX body weighing 495g the point of balance was to carry the outfit by the lens body with a wrist strap for safety.

Strap 1

It has a lovely smooth focus action, just as you’d expect from a Pentax lens. The extreme wide angle means that the throw of the focus ring is quite short – perhaps 60 degrees to get you from infinity to it’s minimum focus of something like 25cm. The depth of field is also pretty extreme – at f8 it covers from infinity to about 50cm. Circles do become elliptical at the sides of the frame though, but that’s to be expected with an extreme angle of view.

Does it flare? It can, yes, but the picture below was taken into the sun. I have had some flare streaks before, but it seems to be from shooting across the sun rather than into it. Up with it you are going to have to put though, as you’re not going to get a bigger lens hood on this baby (unless you make one).


The built in filters are more convenient than some fisheye lenses that need separate filters fiddled onto the rear of the lens. They also stay clean and are part of the lens’s formula. The down side though is that you can’t easily swap one of the filters for something else. I had an Arsat 30mm fisheye for my Kiev 60 that took screw-on filters on the rear of the lens, so it would be possible to take say the green filter apart and replace it with a neutral density. I did this trick with my Horizon camera to give me an IR filter.

So, is it worth the expense? Maybe, if you can get one at a good price. You really need the lens cap with it, as nothing else will fit and that front element sticks out a lot. It would be interesting (in a nerdy kind of way) to compare it with some other extreme wide angle lenses such as Samyang. But then you descend into the madness of rectilinear versus fisheye rendering (see link above) and end-up buying one of each. But, if you can find or borrow one, try it. It really is a new way of looking at the world.

Author: fupduckphoto

Still wishing I knew what was going on.

3 thoughts on “Pentax 15mm lens”

  1. Nice job! I am envious that you have one of these 15s. Your lens was originally developed as a SMC Takumar thread mount lens. My wife bought a 28mm Takumar in 1978, and a red booklet came in the package. A yellow insert sheet states,

    “Note: Since this operating manual was printed, Asahi Pentax has developed a new interchangeable lens – the SMC Takumar 15 mm ƒ/3.5.

    The aspherical, ultra-wide lens is, like other lenses listed on page 7, completely automatic. Like those lenses listed on page 11 of this manual, it has fixed focus marks on the diaphragm and distance scales.”

    If it did have aspherical elements, it was part of a rare optical brotherhood back in the 1970s that included the famous Leitz Noctilux and the Nikon Noct-Nikkor. These latter are seriously expensive now!

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