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Kershaw Type 250 Projection Lens
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PostPosted: Sun Nov 30, 2014 9:32 pm    Post subject: Kershaw Type 250 Projection Lens Reply with quote
It's a 4 inch / 102mm f 2.8 English lens, presumably of the Kershaw type? It's something I picked up today for next to nothing, so...shall I hack it onto the Sony? or is it a priceless bit of cinematographic history?





Ignore the dirty glass, it's cleaned up spotlessly.




PostPosted: Sun Nov 30, 2014 11:45 pm    Post subject: Reply with quote
I have a 4 inches f/2.8 Kershaw projection lens with the same helical mount but looking a little different (a more recent model, I think).
I've tested it on NEX (tape mounted) and came to the conclusion that it's not worth the effort of a better adapter. It has very low contrast (in spite of being coated), low resolution and disturbing flare. But, of course, that could be my lens only - yours could be a different beast. Test it and let us know.


PostPosted: Mon Dec 01, 2014 12:07 am    Post subject: Reply with quote
I've got a dead Minolta 135 and a big roll of Gaffer tape, the project is on! Laughing


PostPosted: Sun Oct 29, 2023 1:26 pm    Post subject: Reply with quote
dan_ wrote:
I have a 4 inches f/2.8 Kershaw projection lens with the same helical mount but looking a little different (a more recent model, I think).
I've tested it on NEX (tape mounted) and came to the conclusion that it's not worth the effort of a better adapter. It has very low contrast (in spite of being coated), low resolution and disturbing flare. But, of course, that could be my lens only - yours could be a different beast. Test it and let us know.


Perhaps yours was a different model. My sample of the silver helical barrel Kershaw 250 is not only one of the heaviest projector lenses I own at this focal length, but among the sharpest triplets * I've ever used. And it draws beautifully. The bubble is mild with this one, but it's absolutely comparable in sharpness to the Trioplan and certain recent Chinese copies of it. On 43MP full frame, it's not much less sharp in Zone C (corners) than the centre - at least Colorplan-level, maybe even better. Will test more rigorously.

* EDIT - correction - that's because it's not a triplet (see below).


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Last edited by 16:9 on Mon Oct 30, 2023 5:12 pm; edited 1 time in total


PostPosted: Sun Oct 29, 2023 10:02 pm    Post subject: Reply with quote
Lloydy wrote:
I've got a dead Minolta 135 and a big roll of Gaffer tape, the project is on! Laughing


I never did get around to bodging this lens onto my Sony, but I think I will having seen these pictures.


PostPosted: Sun Oct 29, 2023 10:08 pm    Post subject: Reply with quote
Here's another grab shot from the garden today, showing it's outer-circle performance . . .



All images full-frame, uncropped with basic colour correction. Out of camera, contrast is better than average for a lens of this type.
Performance is, as your might expect, better at 1m+ distances than close-up. These were shot at around 80cm.
It looks like samples after around 46xxx acquired a black paint job on the nose and inner barrel.
There was at least a 2-inch and 6-inch version, too: https://deltalenses.com/?s=kershaw+250


PostPosted: Mon Oct 30, 2023 11:05 am    Post subject: Reply with quote
As a pleasant bonus, the thread attaching the brass lens assembly to the outer barrel is 55 x 0.75mm – which is exactly the same as the one fitted to the Syoptic 52.5mm Magic Ring.


PostPosted: Mon Oct 30, 2023 2:03 pm    Post subject: Reply with quote
Show us a pic' of the setup, that Magic Ring looks interesting. does it fit onto a helicoid of some sort?


PostPosted: Mon Oct 30, 2023 5:09 pm    Post subject: Reply with quote
After writing a quick 'first-look' review for Delta, about how surprising this lens is, I found BosunHiggs' forum post on DPReview - in which he also wrote about how surprising it was. The biggest surprise is that it isn't a triplet: it's an unusual 'back-to-front' Ernostar four-element, very similar to the Pullin Pulnar 100/2.8 - even down to the timeframe and serials. This lens just keeps on surprising . . . will post a pic shortly, but at the bottom of this article, there's a pic of the Syoptic ring attached to the inner barrel of the Kershaw 250 102/2.8: http://16-9.net/adapting-slide-projector-lenses

Last edited by 16:9 on Mon Oct 30, 2023 5:11 pm; edited 1 time in total


PostPosted: Mon Oct 30, 2023 5:10 pm    Post subject: Reply with quote
16:9 wrote:
dan_ wrote:
I have a 4 inches f/2.8 Kershaw projection lens with the same helical mount but looking a little different (a more recent model, I think).
I've tested it on NEX (tape mounted) and came to the conclusion that it's not worth the effort of a better adapter. It has very low contrast (in spite of being coated), low resolution and disturbing flare. But, of course, that could be my lens only - yours could be a different beast. Test it and let us know.


Perhaps yours was a different model. My sample of the silver helical barrel Kershaw 250 is not only one of the heaviest projector lenses I own at this focal length, but among the sharpest triplets I've ever used. And it draws beautifully. The bubble is mild with this one, but it's absolutely comparable in sharpness to the Trioplan and certain recent Chinese copies of it. On 43MP full frame, it's not much less sharp in Zone C (corners) than the centre - at least Colorplan-level, maybe even better. Will test more rigorously.




Looks very promising! Great that you gave it a try!
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