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Isco-Goettingen 5.6/50: sharply bokehsquarious
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PostPosted: Sun Oct 30, 2022 8:16 pm    Post subject: Isco-Goettingen 5.6/50: sharply bokehsquarious Reply with quote
With a nice enlager lens Steinheil-V-Cassarit 3.5/50 I have not caught a very special bokeh, in spite of its triangular aperture. The whole other story was a supersharp and slow Isco-Goettingen Iscorit 5.6/75. It has a square diaphragm, and this makes it clearly seen.

I had lastly a nice occasion to get a shorter Isco lens, 5.6/50, in a similar plastic barrel, with three aperture positions which are f5.6, f8 and f11. Due to a more compressed DOF it might not show the same strongly "pixelated" bokeh as its longer relative. Meanwhile it shares the same character, as for sharpness, colours plasticity when editing, and overall pleasing IQ.

The lens was put on a Chinese helicoid and then to a Sony Nex. Colours and contrasts were readjusted in most cases.


#1 Slight square bokeh effect


#2 Well pronounced squares in OOF, WO


#3 Sharpness WO


#4 Sharpness with short distance bokeh, WO


#5 Sharpness with long distance bokeh, f8


#6 How the bokeh changes at various apertures: WO (f5.6)


#7 At f8


#8 At F11


#9 MFD on helicoid


#10 Round objects in background, no square bokeh


PostPosted: Sun Oct 30, 2022 9:51 pm    Post subject: Re: Isco-Goettingen 5.6/50: sharply bokehsquarious Reply with quote
alex ph wrote:
With a nice enlager lens Steinheil-V-Cassarit 3.5/50 I have not caught a very special bokeh, in spite of its triangular aperture. The whole other story was a supersharp and slow Isco-Goettingen Iscorit 5.6/75. It has a square diaphragm, and this makes it clearly seen.

I had lastly a nice occasion to get a shorter Isco lens, 5.6/50, in a similar plastic barrel, with three aperture positions which are f5.6, f8 and f11. Due to a more compressed DOF it might not show the same strongly "pixelated" bokeh as its longer relative. Meanwhile it shares the same character, as for sharpness, colours plasticity when editing, and overall pleasing IQ.

The lens was put on a Chinese helicoid and then to a Sony Nex. Colours and contrasts were readjusted in most cases.




Nice shots - thanks for sharing! I've been wondering about those Iscorit enlarging lenses a couple of times, but not seen any samples. I like lenses with square apertures (I use Meopta Belars for the most part, but there are several out there... I recently found a Will Wetzlar Wilon lens which has a beautiful rounded square aperture shape for example) - it's a lot of fun to experiment with those.


PostPosted: Mon Oct 31, 2022 6:51 am    Post subject: Reply with quote
For those interested, the same effect can be had from cheap fixed-lens cameras with inbuilt Schneider/Isco lenses. I can't remember the same (some wordplay like Isconar) nor the exact speed (45/2.8?), but I was given a camera like that a while ago, broken, and salvaged the lens to use on Nex. Worked nicely, including manual aperture control, and had the same bokeh. And can probably be bought used for less than a fiver.


PostPosted: Thu Nov 03, 2022 8:51 pm    Post subject: Reply with quote
Thank you fellows!

Yes, an absolute fun to use these "strange" lenses.

Kathala, do you have some samples to show from your f2.8 adaptation? The square bokeh must be well seen already at f4.


PostPosted: Thu Nov 03, 2022 8:56 pm    Post subject: Reply with quote
A couple more shots, with contrasts pushed further this time.

#1


#2


#3


PostPosted: Fri Nov 04, 2022 6:47 pm    Post subject: Reply with quote
Great find - thanks for sharing - this looks like an interesting lens. Can you post, or send me, a picture of both lenses for the Delta catalogue? I hadn't come across them before, even though you posted some great pictures with the 75mm back in 2020 . . .


PostPosted: Fri Nov 04, 2022 10:38 pm    Post subject: Reply with quote
alex ph wrote:
A couple more shots, with contrasts pushed further this time.

#1




This looks very good - great clarity! Do you feel like it holds up at full res or do you start to see the image quality waning?


Here's a shot of the very rounded squares of the "Will-Wetzlar Wilon 75 mm f/4.5" in action:

Graspin' color… by simple.joy, on Flickr

vs. the regular squares of the "Meopta Belar 75 mm f/4.5"
Usually that's how well I fit in... by simple.joy, on Flickr

Both are stacked shots, which helps in terms of detail and sharpness. I wouldn't say either of those lenses is exceptional in terms of image quality. I absolutely love the shape of the Wilon aperture though, and while I wouldn't say that about the Belar's squares, I can't dispute its effectiveness!

As kathala suggested, I'm sure an f/2.8 or faster lens with square aperture is preferable overall because it can be used in more cases. I've seen some modified square-aperture Helios lenses out there, but I can't comment on their quality.


PostPosted: Sat Nov 05, 2022 5:07 pm    Post subject: Reply with quote
16:9 I'll make a shot of both and will post in the respective threads. This way the images will be present in both sites.

Simple.joy thank you! I'd say the full-res looks as good as the resized version, to my eye. But I mostly use Sony Nex with enlarger lenses, so still need to check with Sony FF.

Your close ups and macros bring the full value of the lenses character. I agree, the Wilon is a pure festivity. But I also like the straight squares of Belar which you put into a thoughtful composition (and clear opposition) between the round and the square. A nice inventive job!


PostPosted: Mon Nov 07, 2022 1:43 pm    Post subject: Reply with quote
Like 1 Like 1


PostPosted: Wed Nov 09, 2022 9:24 am    Post subject: Reply with quote
Pictures of the lens, including it together with a longer sibling, Isco-Goettingen Iscorit 5.6/75 which is just a tad larger. In both the square diaphragm is visible aready wide open, i.e. at f5.6.

#1


#2


#3


#4


PostPosted: Thu Nov 10, 2022 9:30 am    Post subject: Reply with quote
alex ph wrote:

Kathala, do you have some samples to show from your f2.8 adaptation? The square bokeh must be well seen already at f4.

Yes, thanks to the magic of huge hard drives, I found some tests I did with the lens.
Turns out, it is a 45 mm f/2.8 Color Isconar.
Centre performance is quite acceptable, but corners are smeared. The lens is compact, but the resulting setup with an adapter less so. Therefore, and in light of other lenses I already own, I decided not to pursue it.

Bokeh open:
#1


Bokeh stopped down a bit
#2


1:1 bokeh detail of above
#3


1:1 centre crop (42 MPix)
#4


ditto right bottom corner
#5


PostPosted: Thu Nov 10, 2022 9:18 pm    Post subject: Reply with quote
kathala wrote:
alex ph wrote:

Kathala, do you have some samples to show from your f2.8 adaptation? The square bokeh must be well seen already at f4.

Yes, thanks to the magic of huge hard drives, I found some tests I did with the lens.
Turns out, it is a 45 mm f/2.8 Color Isconar.
Centre performance is quite acceptable, but corners are smeared. The lens is compact, but the resulting setup with an adapter less so. Therefore, and in light of other lenses I already own, I decided not to pursue it.

Bokeh stopped down a bit
#2



Looks really interesting - thanks for showing that unique look!

Today got a chance to try the Will Wetzlar Wilon 75 mm f/4.5 mentioned before again for a couple of shots and while it can't be used for such interesting pixelated effects with its rounded squre aperture it was very interesting to see what it can do and what lighting situations tend to work best.

You‘ll shine among the squares by simple.joy, on Flickr

Square root by simple.joy, on Flickr

Geometric growth by simple.joy, on Flickr

Low-res backgrounds by simple.joy, on Flickr


PostPosted: Fri Nov 11, 2022 12:32 am    Post subject: Reply with quote
I love the pixelated look of the bokeh! Can you show us a photo of the lens on the camera? I would love to try this on a Sony FF camera. How did you adapt the lens?


PostPosted: Fri Nov 11, 2022 8:46 am    Post subject: Reply with quote
[quote="mr_tibbs2004"]Can you show us a photo of the lens on the camera? I would love to try this on a Sony FF camera. How did you adapt the lens?[/quote]
I did use it on a FF Nex, but I have no photo of the setup Sad. I'm not even sure the lens is still around...
Coming from Leica M, I have been using the Nex system with an M mount helicoid adapter which sits on the camera permanently. So to adapt old lenses, I just need an M39-M adapter as a base, plus a washer or two as needed, and a hot glue gun Smile
Focus is then doable with the helicoid alone; I'm not sure anymore whether the Isconar was salvagable with its focus helicoid.
The bokeh is rather special indeed, but also a bit of a one-trick pony. You can also see how much I had to defocus the image to obtain this level of bokeh - that would equal a flower close-up shot.


PostPosted: Sat Nov 12, 2022 12:26 am    Post subject: Reply with quote
Kathala, simple.joy, congrats for the expressive and joyful pics! Nice examples of square bokeh.

Kathala, your approach sounds pretty easy and efficient. I wonder if all Isconars on lower-grade fixed lens cameras had a square diaphragm. There is a large variety of cameras. And as long as the leaf shutter does not let look behind it, before you have the camera in your hands, it's impossible to detect the right one.


PostPosted: Sat Nov 12, 2022 8:13 am    Post subject: Reply with quote
alex ph wrote:
Kathala, your approach sounds pretty easy and efficient. I wonder if all Isconars on lower-grade fixed lens cameras had a square diaphragm. There is a large variety of cameras. And as long as the leaf shutter does not let look behind it, before you have the camera in your hands, it's impossible to detect the right one.

Indeed the approach has worked well for me for a decade already Smile
Not wishing to sound mean, but the build quality of the lens implies to me that cheapness was paramount, so choosing one (aperture) design for all lenses seems likely. At the time these cameras were made, f/2.8 appears to already have been the cheap option, and, judging from image quality, was not chosen for ultimate resolution either. In any case, the most expensive thing about buying such cameras today should be the postage, so I'd just give it a try and chase one down on ebay.
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