[butangmucat]

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So I was going through my shots of this summer (when I was still using Sony and a mixture of SR and K mount lenses), and found this:



The picture was taken with a Minolta 50mm F/1.7 Rokkor X (Minolta 50mm F/1.7 Rokkor X MD Mount Manual Focus Lens {55} | KEH Camera) and it was opened up to F4. The headlight showed obvious diffraction spikes even at this rather large aperture, which is something I have never seen. I do like this characteristic and I want to know if there are any M42 or K mount lenses with similar character in terms of diffraction spikes? I have considered https://www.pentaxforums.com/forums/54-pentax-lens-articles/56234-konica-mino...ld-lenses.html but I don't have the tools and I am not skilled in this kind of job.

I have recent ordered a LOMO Volna f1.8 as a replacement for this lens, and noticed the LOMO lens has a rather interesting diaphragm (see MC Volna 1 8 50mm LOMO USSR Lens Pentax Mount K from Almaz 103 s N 842268 | eBay), will this contribute to diffraction spike?

Sincerely

[pepperberry farm]

several topics on it; here's one of the more recent:

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/310177-best...st-lenses.html

[bdery]

The headlight showed obvious diffraction spikes

Long story short, the two best lenses for this are the DA 15 and 21 limited, but not the HD versions. You want straight aperture blades, and a lens design allowing for such a result.

[Just1MoreDave]

When you use a longer lens, the points of light which make the spikes obvious get bigger. Go out at dusk in an urban environment with an 18-55 and you can see the difference pretty quickly between 18mm and 55mm shots. You have to try harder to get visible spikes at 50mm, no matter what the aperture looks like.

One lens you might try at 50mm is the Pentax-M 50mm f4 macro, because it has a 5-blade aperture, excellent coatings and few elements. It produces a 10-point star when you get one, and is pretty flare-resistant. Pentax has a lot of older lenses wider than 50mm, like the M28/2.8. Still have to look for your shot at 28mm, but inexpensive fun.

[Unregistered User 8]

Lens with Diffraction Spikes?

I had never heard about this before, so did a little digging and found this. Thanks for starting this thread @butangmucat. Most of the members probably know about it already, but just in case some don't, this screenshot is the result of some of my digging.

[bdery]

pjv, this image is mostly correct, however there are other elements contributing to the final look. Most of the time by diminishing the amplitude of the effect.

[butangmucat]

When you use a longer lens, the points of light which make the spikes obvious get bigger. Go out at dusk in an urban environment with an 18-55 and you can see the difference pretty quickly between 18mm and 55mm shots. You have to try harder to get visible spikes at 50mm, no matter what the aperture looks like.

One lens you might try at 50mm is the Pentax-M 50mm f4 macro, because it has a 5-blade aperture, excellent coatings and few elements. It produces a 10-point star when you get one, and is pretty flare-resistant. Pentax has a lot of older lenses wider than 50mm, like the M28/2.8. Still have to look for your shot at 28mm, but inexpensive fun.

So my question is, why my two most spiky lenses are the Minolta MD 50/1.7 and MD 45/2? Is there anything special with the optical formula allowing such spikes, and are there any similar K-mount or M42 lenses?

[bdery]

So my question is, why my two most spiky lenses are the Minolta MD 50/1.7 and MD 45/2? Is there anything special with the optical formula allowing such spikes, and are there any similar K-mount or M42 lenses?

Shape of the aperture, number of aperture blades, light paths inside the lens relative to the blades, etc. Knowing how the aperture is designed will help, but apart from that it's a case by case basis.

[butangmucat]

Shape of the aperture, number of aperture blades, light paths inside the lens relative to the blades, etc. Knowing how the aperture is designed will help, but apart from that it's a case by case basis.

The MD 50/1.7 uses straight 6-blade diaphragm and MD 45/2 uses straight 5-blade ones. Except these I don't know much about these lenses, except they are decently sharp and are prone to flare from time to time.

[Na Horuk]

Yeah, aperture shape is definitely important, but its complicated because these are not simple optical designs. For odd starbursts you usually want a lens with straight blades and possibly older lens coatings with missing lens hood. Some lenses get odd special flares appearing because of internal reflections (shiny inner body, shiny aperture blades) or light leaks (often the fault of adapters)
The Volna you showed has an aperture shape similar to Pentax M 50mm f1.7. It is a little star-shaped, but only when stopped down a little. Here is an example: Cosmic fly by Stolpulus II - Photo 10557733 / 500px
This doesn't necessarily mean crazy starbursts, though.

One thing you could try to get consistent starbursts is a crosshatch filter. Some filters will make starbursts more interesting, but these filters can also become annoying real quick. Here are some of my examples of using an old manual lens with a crosshatch filter:
https://500px.com/photo/61862005
https://500px.com/photo/60424950
With the filter you have advantage that you can rotate it, and there are filters with different effects

[butangmucat]

When you use a longer lens, the points of light which make the spikes obvious get bigger. Go out at dusk in an urban environment with an 18-55 and you can see the difference pretty quickly between 18mm and 55mm shots. You have to try harder to get visible spikes at 50mm, no matter what the aperture looks like.

One lens you might try at 50mm is the Pentax-M 50mm f4 macro, because it has a 5-blade aperture, excellent coatings and few elements. It produces a 10-point star when you get one, and is pretty flare-resistant. Pentax has a lot of older lenses wider than 50mm, like the M28/2.8. Still have to look for your shot at 28mm, but inexpensive fun.

What about SMCA 50/2.8? I am eyeballing this now.

[butangmucat]

So I bought a FA43 from someone on eBay who was trying to switch system after two days of consideration.



The diffraction spike does look pretty beautiful.



However the coating on the Volna is not very well, and it seems to have more glare or ghosting.

[bdery]

Just for fun, here's a recent shot with the DA21...