Oh man ! I have a lens that does this.

[Andrea B.]

The amazing Gamma Terragon 35/3.5.

 

This is even better than my unusual Heligon. Better than a lens baby.

I'm going to have fun with this one.

This is incredible !!!!

 

Pentax K5-broadband + BaaderU + Sunlight

f/3.5 for 1/2" @ ISO-160

I didn't do this. The lens did it. Wow! I live to find lenses like this !!

[1-2]iso160_20151504wf_140918pf.jpg]

 

 

Here is what the scene is "supposed" to look like at f/3.5.

Pentax K5-broadband + BaaderU + Kaligar 35/3.5 Sunlight

f/3.5 for 1/1.7" @ ISO-160

So boring!

[nfoto]

Built-in impressionist drawing. How cool is that

[OlDoinyo]

That is some of the wackiest distortion I have ever seen. Is it flare, CA, or something else?

[colinbm]

What...........what causes that to happen ?

[Andrea B.]

I think the aberration appears to be too extreme to be the well-known 'swirly bokeh' effect?

I wonder if there isn't perhaps a reversed element in the lens?

Would that cause such extreme coma - or whatever it this aberration is?

 

But if that is the case, then I don't want to fix it.

I'd rather use the lens for awhile as it is to make abstractions and impressions.

 

Something else I should perhaps look at is that the lens might not have the M42 flange focal distance that I thought it had? It is very difficult to focus this lens.

[colinbm]

Is it a dirty, leaky, stuck or bent aperture blade ?

Col

[Andrea B.]

No, everything looks very clean. The aperture blades move well, no sticking.

[colinbm]

Oh well, try a T2 mount adapter ??

[Alex H]

One of the lens elements is reversed. That is also the reason why flange distance is off.

I had the same effect with my Apo-Rodagon, that I bought from a reputable dealer. One of the inner menisci was reversed (which was not an easy thing to do to be honest).

[kds315]

Yep, lens is not correct, I agree with Alex. Someone most likely cleaned it and re-assembled it incorrectly.

I have the same lens, performs like a Kuri 35mm.

[baffe]

The Question is if a repair destroys the lens?

 

;-)

[Andrea B.]

Now that I have the new spanner wrenches I will carefully try to remove front and rear elements and see if I can find a reversed element. But I'm not touching any screws given the recent broken screw Novoflex disaster. (Sigh.)

 

Before checking for a reversed element however, I really really do want to make some photographs first. I enjoy abstractions and unusual lens effects. Some call it art. Some call it Instagram trash. ;) B)

[nfoto]

Surely you have these 35/3.5 items in the plenty. So keep it in its present state, please. Add a drop of epoxy glue to ensure you cannot open it up - ever.

[Andrea B.]

I hear ya !!!! :lol:

[igoriginal]

I'm obviously late to this thread (and apologies for "bumping" it, for those who have already moved past it), but I can confirm Klaus's and Alex's assessments that the optical configuration of the elements within this lens has been incorrectly re-assembled. I have the same exact lens, and have known about its UV suitability for quite a while. It is NOT "supposed" to behave like this. (Do note that I put "supposed" in quotations, to denote the fact that this can otherwise still be a desirable side-effect for creative photographic work. ;) )

 

Furthermore, this "effect" can be generated by deliberately messing around with the optical configuration of many other 35mm F/3.5 lenses of similar design. Additional and interesting "effects" can also be created by leaving out some elements in the optical formula, altogether. :-)

[lost cat]

This reminds me of the "swirly bookah" the Helios 44 is known for. I read of someone able to recreate that effect by reversing the front element,

 

http://www.verybiglobo.com/extremely-swirly-bokeh-short-tutorial/

 

The author claims this mod can be done to most lenses for a similar effect.

[igoriginal]

This reminds me of the "swirly bookah" the Helios 44 is known for. I read of someone able to recreate that effect by reversing the front element,

 

http://www.verybiglo...short-tutorial/

 

The author claims this mod can be done to most lenses for a similar effect.

 

Normally, however, the more pleasing of "swirly bokeh" is a product of a specific optical scheme / arrangement of the Petzval field curvature. (Thus, what made the original 'Petzval' lens so popular, among other reasons). This is based upon a two-doublet optical formula. Many 'Cine' lenses (for 8mm and 16mm movie-reel units) exhibit a similar "Petzval effect", because of being built with a similar optical configuration.

 

However, it seems that this effect can be somewhat "simulated" (though crudely, and not to as much of a magnitude or symmetry as a Petzval design), by messing around with other optical formulas, as you have already noted.

 

The one thing that makes an actual Petzval optical configuration so desirable, is that while the "swirly bokeh" along the edges of the frame is quite prominent at wide-open apertures, the center of the image can remain razor sharp. This is not the case, when "hacking" other lenses that are not of the same optical design (including the Gamma Terragon above). Thus, do note this caveat, because not all swirly-bokeh is created equal.

 

Hence, I am a bit wary of any claim of modding "most lenses for a similar effect." All is not equal in the land of field curvature. Far from it, in fact, and I am sure that our resident optics expert Alex H. can further confirm this.

[Alex H]

Modifying a lens like to achieve "swirly" bokeh will most probably result in the loss of sharpness due to increased spherical aberrations. There are plenty of lenses that show the same effect, be it of petzval-derived optical formula, or double-gauss (infamous Helios-40, etc).