Raynox dcr150 custom tube lens

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leanderborg220
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Joined: Tue Sep 29, 2020 7:53 am

Raynox dcr150 custom tube lens

Post by leanderborg220 »

Hello,
I'm in the process of building a custom tube lens for a Raynox dcr-150 coupled to a Mitutoyo mplan 10x objective lens. I will be using aluminum tubing and a lathe for machining these fittings. Can you please indicate to me the optimum distances for this setup. (please refer to the attached diagram)
Attachments
tubelense.png

Adalbert
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Re: Raynox dcr150 custom tube lens

Post by Adalbert »

Hi,

Approximately A=20cm and B=5cm.

But I change A (using helicoid), so that the camera with DCR is focused to infinity.

My setup:
https://www.photomacrography.net/forum/ ... +on+Harley

Best,
ADi

Pau
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Re: Raynox dcr150 custom tube lens

Post by Pau »

Just to point that the term tube lens in our context refers to the lens itself (in your case the Raynox) and not to the tube that contains it.

A is the distance that focus the tube lens alone (without objective) to infinite. With low magnification infinite objectives you can play with it to some extent but as NA increases this distance becomes more and more critical

B is much more variable without affecting focus, magnification or resolution, this is the function of the infinite space design where you can put flat optical elements like filters avoiding inducing aberrations. Of course there can be a sweet spot for a given combination of tube lens, objective and sensor size, for example in order to avoid vignette
Pau

leanderborg220
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Re: Raynox dcr150 custom tube lens

Post by leanderborg220 »

Adalbert wrote:
Wed Jan 06, 2021 3:53 am
Hi,

Approximately A=20cm and B=5cm.

But I change A (using helicoid), so that the camera with DCR is focused to infinity.

My setup:
https://www.photomacrography.net/forum/ ... +on+Harley

Best,
ADi
Thanks Adalbert,
So distance B 5cm can be fixed.
Instead of using a helicoid for distance A, I had the intension of machining 2 tubes sliding inside each other like a helicoid.
If I make it 20cm and have +/- 2cm for fine adjustment, would that be enough ?
and would you recommend that I mount the raynox150 reversed or not ?

Adalbert
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Re: Raynox dcr150 custom tube lens

Post by Adalbert »

Hello,
Yes, Raynox DCR reverse.
+/-2cm means between 18cm and 22cm will be good enough.
But if you can do more, then you would be flexible and ready for experiments :-)
Best,
ADi

JKT
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Re: Raynox dcr150 custom tube lens

Post by JKT »

leanderborg220 wrote:
Wed Jan 06, 2021 4:28 am
Instead of using a helicoid for distance A, I had the intension of machining 2 tubes sliding inside each other like a helicoid.
If I make it 20cm and have +/- 2cm for fine adjustment, would that be enough ?
and would you recommend that I mount the raynox150 reversed or not ?
I would think that instead of sliding, it would make sense to use outside thread on one and inside thread on the other. Then you could use a simple locking ring to lock thinks together at any length within your adjustment range.

Lou Jost
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Re: Raynox dcr150 custom tube lens

Post by Lou Jost »

We need to know the size of your sensor to give you advice. The advice given above may not be correct for you. There is a tradeoff between center resolution and edge resolution; an arrangement that is best for center resolution is a good choice for smaller sensor like APS, but an arrangement that favors even resolution across the sensor (at the expense of central resolution) is better for larger sensors.

leanderborg220
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Joined: Tue Sep 29, 2020 7:53 am

Re: Raynox dcr150 custom tube lens

Post by leanderborg220 »

JKT wrote:
Wed Jan 06, 2021 9:48 am
leanderborg220 wrote:
Wed Jan 06, 2021 4:28 am
Instead of using a helicoid for distance A, I had the intension of machining 2 tubes sliding inside each other like a helicoid.
If I make it 20cm and have +/- 2cm for fine adjustment, would that be enough ?
and would you recommend that I mount the raynox150 reversed or not ?
I would think that instead of sliding, it would make sense to use outside thread on one and inside thread on the other. Then you could use a simple locking ring to lock thinks together at any length within your adjustment range.
I already thought about something like that. good idea. thanks for sharing.

leanderborg220
Posts: 29
Joined: Tue Sep 29, 2020 7:53 am

Re: Raynox dcr150 custom tube lens

Post by leanderborg220 »

Lou Jost wrote:
Wed Jan 06, 2021 10:48 am
We need to know the size of your sensor to give you advice. The advice given above may not be correct for you. There is a tradeoff between center resolution and edge resolution; an arrangement that is best for center resolution is a good choice for smaller sensor like APS, but an arrangement that favors even resolution across the sensor (at the expense of central resolution) is better for larger sensors.
the sensor is an aps-c sensor of a sony alfa

JKT
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Re: Raynox dcr150 custom tube lens

Post by JKT »

Adalbert wrote:
Wed Jan 06, 2021 5:24 am
Yes, Raynox DCR reverse.
+/-2cm means between 18cm and 22cm will be good enough.
I'm not entirely sure about that. I'm using it in forward position and the distance from sensor to the rear flange of Raynox is 210.6 mm. There is some uncertainty in that, but that shouldn't be more than 1mm. There might also be some sample variation. In any case that would suggest that the optimal distance in reverse to the front of Raynox (now closer to sensor) is closer to 18 cm ... assuming the distance between focal planes is not too large. I would suggest testing before doing the machining. As I understand it, there is no use in putting the lens too far away, but putting it too close can sometimes help. So you should have enough adjustment in that direction.

Lou Jost
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Re: Raynox dcr150 custom tube lens

Post by Lou Jost »

In that case, Robert O'Toole's very careful tests apply. You should use his numbers.

https://www.closeuphotography.com/raynox-tube-lens

For full frame the set-up needs to be quite different if edges are important.

JKT
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Re: Raynox dcr150 custom tube lens

Post by JKT »

Unfortunately that article doesn't give the distance from Raynox to sensor in the nominal position.

A quick measurement gives 202.8 mm. The Raynox was much shorter (15.5 mm) than I recalled. So It should be sufficient to use 205 mm as maximum length with reversed DCR-150.

Enoplometopus
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Re: Raynox dcr150 custom tube lens

Post by Enoplometopus »

Instead of creating a fixed tube for the tube lens, I am using a bellows system. This gives me perfect flexibility in terms of magnification or finding the sweet spot of the objective. The distance of 210 mm given for the Mitutoyo M Plan Apos is necessary for getting the exact nominal magnification stated on the objective, but it does not necessarily give you the best performance in terms of sharpness. When using a bellows system, you are free to experiment and have something like a zoom objective. And some bellows systems allow for a quick an easy change of objectives, like Novoflex Balpro 1.
Best regards,

Daniel Knop/Enoplometopus
www.knop.de

leanderborg220
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Re: Raynox dcr150 custom tube lens

Post by leanderborg220 »

Thanks for all the feedback guys.
So, I will be mounting the raynox reversed
I will try to machine this thing with the flexibility of having distance between frontside of raynox and sensor that can be adjustable from let say 230mm to 140mm.
And a fixed 50mm from backside of raynox to backside of objective. Is that right?

I will paint these machined tubes insides with this special non-reflective paint. https://www.ko-pro.black/product/musou-black-paint

Keep you posted with the design and results :D

leanderborg220
Posts: 29
Joined: Tue Sep 29, 2020 7:53 am

Re: Raynox dcr150 custom tube lens

Post by leanderborg220 »

had some free time to do a rough sketch :-k
the purple thing in the middle is the raynox
blue aluminum tube slides in green one and will be secured with Allen screws from the sides that will lock it in place
Attachments
sketch_cross section.png
sketch.png

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