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Rangefinder 50mm with most uniform bokeh (and a big front?)
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PostPosted: Thu Oct 03, 2019 12:40 am    Post subject: Rangefinder 50mm with most uniform bokeh (and a big front?) Reply with quote

Hey guys, I'm looking for a 50mm (45-60 range) rangefinder lens that would have the most uniform bokeh.

There is this effect that people refer to as "cat's eye bokeh" or "bokeh lemons", I also saw people call it "bokeh vignetting".

Essentially the front element of the lens is big enough to not cause vignetting of the image itself, but small enough to cause vignetting in bokeh, and sort of "cut off" specular highlights (bokeh balls).

This results in a certain effect that combined with field curvature creates a bokeh "swirl".

Field curvature, that also is sometimes referred to as "undercorrected petzval" is another effect that causes bokeh balls closer to the edge of the projected circle (and the frame) to distort and compress along the radial axis of the image circle.

I'm looking for a lens that does not have these effects, or has them well corrected.

I know that stopping down really helps to reduce it – because your entrance pupil gets smaller in correlation to the front element. There is this discussion I found that has a lot on the topic https://photo.stackexchange.com/questions/52126/what-is-the-cause-of-this-non-uniform-bokeh-effect

I am looking to adapt this lens to panasonic s1H, that's why I'm looking for a rangefidner lens to keep the setup compact, but if anyone knows of an SLR lens that fits the description please let me know.

So if the lens is slow-ish, like 50 2 or 50 2.8 I'm more then fine with it, even if it's a 50 3.5.

Another option is to get a very fast lens, like 1.2 that has a lot of aperture blades, and just stop it down to 2.4 or 4, but the aperture count has to be like 10+ to keep the bokeh round.



I would appreciate any suggestions on the lens, I am also interested in longer focal lengths to make a set, something like 50, 80, 115, etc.

Thank you for your advice!


PostPosted: Thu Oct 03, 2019 9:11 am    Post subject: Reply with quote

I cant think of any lens that fits all of the requirements. Isn't the quest for round bokeh balls in the edges a new thing? The first time I read about it was in a Sony G master lens release, possibly the 85mm 1.4.

This is the opposite of compact but maybe adapted medium format glass can accomplish the task. I just looked through my images and found that even a Mamiya 645 80mm 2.8 has the effect to a degree.

It will be interesting to see if the forum can find something!


PostPosted: Thu Oct 03, 2019 10:35 am    Post subject: Reply with quote

Have you tried the Canon LTM 50mm f1.4 - sometimes referred to as the Japanese Summilux.
I am not sure if it will meet your requirements, but there are plenty of images on Flickr to peruse
Tom


PostPosted: Thu Oct 03, 2019 10:43 am    Post subject: Re: Rangefinder 50mm with most uniform bokeh (and a big fron Reply with quote

redimp wrote:
Hey guys, I'm looking for a 50mm (45-60 range) rangefinder lens that would have the most uniform bokeh.


Some of my old Soviet lenses would suit this Wink

My Jupiter-8 is a 50mm f/2 with 9 blades, my Industar-26m is a 50mm f/2.8 with 10 blades, both take 40.5mm filters.

For reference:
My Jupiter-9 is an 85mm f/2 with 15 blades and a 49mm filter thread.
My Jupiter-11 is a 135mm f/4 with 12 blades, this also takes a 40.5mm filter.

When bought, these old 39mm screw-mount (LTM) lenses were almost "10-a-penny" ... with the advent of mirrorless digital cameras and adaptors prices have risen!

Good luck Smile

Afterthought : I'm not familiar with many SLR lenses that would fit your specifications, other than my Zeiss Triotar 135mm f/4 with it's 15-blade diaphragm or the Tamron 135/225mm "Twin-Tele" (early f/4.5-7.7 version) with it's 13-blade aperture, but other early lenses with pre-set apertures, often with a T-2 interchangeable mount, may suit your purposes, as the non-auto apertures in these lenses often had more than the "usual" 5-6 blades in an auto-aperture lens.


Last edited by kypfer on Thu Oct 03, 2019 11:01 am; edited 1 time in total


PostPosted: Thu Oct 03, 2019 10:48 am    Post subject: Reply with quote

I think it's a tough task if you limit yourself by rangefinder lenses.
Voigtlander 50/1.2 maybe will do at F2.8-F4.

Keep in mind that roundness of OOF highlights is highly dependant on focus distance.
At MFD even a lot of non-curved blades wont give a perfectly circular bokeh-balls, while at longer distances one sometimes can get away with just six highly curved ones.

One alternative would be getting a rangefinder 35 and crop to 50.


PostPosted: Thu Oct 03, 2019 11:25 am    Post subject: Reply with quote

Modern large aperture 50ties are solving this 'problem' by using a larger image circle than necessary for 35mm format. Essentially the lenses are medium format. One reason why they are so big.


PostPosted: Sat Oct 05, 2019 1:37 pm    Post subject: Reply with quote

The Konica AR 50mm 1:1.4 has a relatively large front element. The difference is visible, but not overwhelming at all:
http://www.artaphot.ch/systemuebergreifend/objektive/479-standard-lens-bokeh-ii

If you want a smooth background blur, choosing a longer focal length is much more useful than trying different lenses with the same focal length:
http://forum.mflenses.com/bokeh-background-blur-and-focal-length-t80917.html



Stephan


PostPosted: Sat Oct 05, 2019 2:04 pm    Post subject: Reply with quote

I recall th cat's eye in most of my fast lenses (1.4-2.0). But, I've got the komura 100 1.8 ,soft wide open (but very good for portraits) and round bubbles on the edges just like in the middle . I don't remember other vintage lens ,but I've seen some trioplan pics on the net, that might be worth to look for. The komura is multiblades, of course the bubbles will be circular just like all of the other lenses with lots of blades , but wide open, I'm not sure that all work the same. I've got the 35mm konura mutiblades also, but I would need to check if it performs the same. I'm not sure if there is a komura 50-60 mm besides de Zenza Bronica ,but that would be interesting to see some pics of it. Of course, modern lenses won't show cat eyes wo in fast aperture (at least, most of them)


PostPosted: Sat Oct 05, 2019 8:58 pm    Post subject: Re: Rangefinder 50mm with most uniform bokeh (and a big fron Reply with quote

redimp wrote:


Another option is to get a very fast lens, like 1.2 that has a lot of aperture blades, and just stop it down to 2.4 or 4, but the aperture count has to be like 10+ to keep the bokeh round.

The Jupiter-3 has 13 blades, and the 3+ too.

More modern, the Voigtlander 1.5/50 is very well regarded and has 10 blades. The newer 1.2 has 12, but is larger and heavier.

Probably outside of your anticipated price-range, but the APO Summicron-50 is quite well corrected for most aberrations.