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Okaya Highkor 40mm f1.8 lens
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PostPosted: Sat Sep 02, 2023 3:39 am    Post subject: Reply with quote
Very impressive.


PostPosted: Sat Sep 02, 2023 7:49 am    Post subject: Reply with quote


PostPosted: Sat Sep 02, 2023 9:26 am    Post subject: Reply with quote
calvin83 wrote:
Ernst Dinkla wrote:
1" - 25,4mm C-mount thread has a pitch 1/32" if I recall it correctly. This kind of shutter rear thread is 25mm 0,5mm pitch. The difference may be enough to create issues.

There is exact adapter available. Click here to see on Ebay


And a wider range: https://customphototools.com/enlarger-lens-adapters/

Never used them though. I usually 3D print a piece that has a 25mm hole and covers the rear and edge of the salvaged lens and fasten it with the original retaining ring. M39 thread added on the design where a 39mm-M42 thread sleeve is turned on with some glue.


PostPosted: Sat Sep 02, 2023 1:13 pm    Post subject: Reply with quote
Nice shots everyone! I want in on this Smile


PostPosted: Tue Feb 27, 2024 2:29 am    Post subject: Reply with quote
Hello. Very nice result. Is this in apsc?
I did conversion to e-mount and i use my A7. There's vignet if i use full frame format


PostPosted: Tue Feb 27, 2024 4:15 am    Post subject: Reply with quote
br.sigit wrote:
Hello. Very nice result. Is this in apsc?
I did conversion to e-mount and i use my A7. There's vignet if i use full frame format


Yes, a small amount and somewhat dependent on focus distance.


PostPosted: Tue Feb 27, 2024 9:06 pm    Post subject: Reply with quote
br.sigit wrote:
Hello. Very nice result. Is this in apsc?
I did conversion to e-mount and i use my A7. There's vignet if i use full frame format


I don't think the vignetting is significant (with the 40 mm f/1.8 on a Canon EOS R5, in my case) at infinity, but perhaps I'm not the best to judge that, as I'll certainly won't use that lens to take landscape shots. I would expect it to have a significant amount of distortion. Made a quick testshot today and stopped down (to around f/11) it's not even as bad in terms of corner performance, as I would have expected though...

Anyways, here's what I use (and love) it for:

Is there a point to all this noise? by simple.joy, on Flickr

You think that makes you an artist? by simple.joy, on Flickr

Free Redical by simple.joy, on Flickr

C what I did there? by simple.joy, on Flickr

Interconnected by simple.joy, on Flickr







PostPosted: Wed Feb 28, 2024 12:02 am    Post subject: Reply with quote
Like 1


PostPosted: Thu Jul 25, 2024 12:11 pm    Post subject: Re: Okaya Highkor 40mm f1.8 lens Reply with quote
[quote="kymarto"][quote="nightstreet"]
kymarto wrote:
The lens, I am told, screws directly into a C mount to M42 adapter ring, and that can be screwed directly into a 12-19mm M42 helicoid. Even if that is not the case, you can use the retaining ring that holds it on the camera body to secure it to a M42 flat ring. Disabling the shutter is a bit more of an issue, but if you are interested I can describe what I did.


I would love to hear how you disabled the shutter on the Highkor 40/1.8.

I have taken the lens apart to this point. It doesn’t look like a straight forward issue to jam the shutter open. After cocking the shutter by twisting the shaft shown below I can hold the shutter open in Bulb mode by moving the other lever forward but I don’t see a quick way to jam the lever in that position. I guess I would need to glue something in that outside channel.

I would love to remove the shutter blades but they are very close to the aperture blades. Even with the aperture open I worry that ripping the blades out with force may damage the mounting point of the aperture blades even when they are tucked away.

Dismantling the lens further seems like the best option but that looks like it has to happen from the rear of the lens and it means I need to take the aperture blades out first which is never much fun. Any advice would be appreciated.
Thanks
Karen

Back of the lens


Front of the lens


PostPosted: Thu Jul 25, 2024 4:51 pm    Post subject: Re: Okaya Highkor 40mm f1.8 lens Reply with quote
[quote="kmcsmart"][quote="kymarto"]
nightstreet wrote:
kymarto wrote:
The lens, I am told, screws directly into a C mount to M42 adapter ring, and that can be screwed directly into a 12-19mm M42 helicoid. Even if that is not the case, you can use the retaining ring that holds it on the camera body to secure it to a M42 flat ring. Disabling the shutter is a bit more of an issue, but if you are interested I can describe what I did.


I would love to hear how you disabled the shutter on the Highkor 40/1.8.

I have taken the lens apart to this point. It doesn’t look like a straight forward issue to jam the shutter open. After cocking the shutter by twisting the shaft shown below I can hold the shutter open in Bulb mode by moving the other lever forward but I don’t see a quick way to jam the lever in that position. I guess I would need to glue something in that outside channel.

I would love to remove the shutter blades but they are very close to the aperture blades. Even with the aperture open I worry that ripping the blades out with force may damage the mounting point of the aperture blades even when they are tucked away.

Dismantling the lens further seems like the best option but that looks like it has to happen from the rear of the lens and it means I need to take the aperture blades out first which is never much fun. Any advice would be appreciated.
Thanks
Karen

Back of the lens


Front of the lens


I wedged a small piece of wood to hold the shutter blades open, then put a dab of glue to secure it further. It appears you have a bigger issue with the rear element. I hope it cleans well.


PostPosted: Thu Jul 25, 2024 5:21 pm    Post subject: Re: Okaya Highkor 40mm f1.8 lens Reply with quote
woodrim wrote:

I wedged a small piece of wood to hold the shutter blades open, then put a dab of glue to secure it further. It appears you have a bigger issue with the rear element. I hope it cleans well.


Glad to know that gluing a piece of wood in place holds well. I was worried that a wedge might work its way loose over time . The rear element is actually in pristine shape. I had to drop acetone on the lens retention ring to get it to move and I took that picture as soon as I got the lens out of the camera before I cleaned it up. The camera I bought was in rough shape but the lens elements are surprisingly clean. It’s always so nice when that happens. Buying the camera was a bit of a gamble but also very cheap.


PostPosted: Thu Jul 25, 2024 8:11 pm    Post subject: Re: Okaya Highkor 40mm f1.8 lens Reply with quote
kmcsmart wrote:
woodrim wrote:

I wedged a small piece of wood to hold the shutter blades open, then put a dab of glue to secure it further. It appears you have a bigger issue with the rear element. I hope it cleans well.


Glad to know that gluing a piece of wood in place holds well. I was worried that a wedge might work its way loose over time . The rear element is actually in pristine shape. I had to drop acetone on the lens retention ring to get it to move and I took that picture as soon as I got the lens out of the camera before I cleaned it up. The camera I bought was in rough shape but the lens elements are surprisingly clean. It’s always so nice when that happens. Buying the camera was a bit of a gamble but also very cheap.


To be clear, I wedged the wood in place; a tiny piece. The glue was only a safeguard. I do not know what camera you are using. Mine is Sony mirrorless. I use a shallow focusing helicoid as my adapter. It requires the C-Mount to M42 ring also. The helicoid provides for a better focusing range. Love the lens.
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