What is the technique used to capture this image? How can the result be achieved? I know that it can be achieved in a digital darkroom but how can I replicate the effect straight out of the camera?

Sample image


4 Answers 4


This photo is taken with a petzval lens which corrects all aberrations decently except for, well, petzval aka field curvature. Because the edges are in focus at a further distance, the blur is smaller there. Because the lens is fairly highly vignetted, the lens also effectively has a larger f number towards the edges, again reducing the blur. The result is the swirly bokeh you see in this photo.

  • How does this happen on non-Petzval designs?
    – Blrfl
    Jul 4, 2015 at 16:14
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    Petzval is not unique to petzval lenses =) Vignetting is also there in all camera lenses to some degree. Astigmatism will cause a difference between the tangential and sagittal planes, so you may bokeh with a quasi-anamorphic look, but it is not the same. Jul 4, 2015 at 16:17
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    Is it just me, or does the photo appear to have been shot centered on the model (at approximately her belly) and then the right side and bottom cropped to make the petzval effect off center?
    – Michael C
    Jul 4, 2015 at 17:58
  • I have seen this effect called everything from "field curvature" to "crazy swirling bokeh" before but have never heard the term petzval before. Thanks for introducing me to a new term. Jul 6, 2015 at 4:17
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    @thomasrutter Petzval is a specific optical feature - if a lens has zero astigmatism but uncorrected field curvature, the true image plane is known as the Petzval Surface. To calculate it, one uses the relationship that T-P = 3(S-P) where T is the tangential focal plane, P is the petzval surface, and S is the sagittal focal plane. Jul 6, 2015 at 4:31

This is a swirl-y bokeh, an often desirable flaw commonly found in some vintage lenses and lenses. There are some lenses known for this this characteristic, most notably the soviet made Zenit Helios 40-2 85mm F1.5 which is still being manufactured. You can find this lens on ebay for ~$600. If you are adventures enough you can convert the Cyclop night vision 85 mm f1.5 device (does not have a diaphragm built in) but it is apparently the same glass for 10% of the price.

There is also another focal length of Helios that can produce this effect, albeit not as well, and is MUCH less expensive (I paid $47 USD for mine ordered from Ukraine but if you look hard you can find it cheaper) version of this lens the Zenit Helios 44-2 58mm (f/2). HOWEVER, a: you have to work it a bit and get the right kind of busy background/back light b: you probably need to use a full frame camera and c: you have to shoot wide open.

I really like the Helios 44-2 and I also have a chipped adaptor to get a focus confirm which works pretty well. The lens renders really nicely and has many imperfections which lend the images character but I cannot focus to infinity on my Canon full frame body because the rear element protrudes too far back and the mirror will hang on it. I can only use it up to about 8m from the subject - good enough for portraits. There are suggestions online to shim the adapter but that creates other issues - the inability to focus at infinity for one... I hear there are no mirror hang issues when used on Nikon bodies?? Also, no issues with my cropped sensor body but the swirly bokeh is much easier to get when the lens is mounted on a full frame body.

EDITED: I now have a solution on how to fix the mirror catch (only confirmed for specifically the Helios 44-2 58mm f/2 on Canon full frame bodies): http://jakubsisak.tumblr.com/post/128680966703/helios-44-2-58-mm-modification-for-canon-full

  • I have used the Helios 44-2 58mm and it works very well for that with a lit background. Without it, it will look normalish. Feb 29, 2016 at 23:59
  • Good point. The busier the background and the better it is lit the better the result. Mar 1, 2016 at 12:46

If you have a fast lens, create a circular cover over it, and it should swirl the background. It's best seen with foliage.


I have never tried the following trick myself, but it seems to be a simple and very cheap alternative to buying yet another lens (yes, it's even cheaper than the Helios 44-2):

  1. Take a piece of light-proof paper, cut a hole in it.
  2. Attach it to the lens hood and put hood on lens.
  3. Swirly bokeh!

See PetaPixel: Homemade Petzval Swirl Bokeh with a 50mm Lens. The effect does not seem to be as strong as in your sample pictures, but it is a very easy and fun way to start experimenting.

  • 1
    Check out Brandon's comment to an answer on a related question, here — the effect is strongest/best when there is both field curvature and vignetting.
    – mattdm
    Jul 7, 2015 at 12:08

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