How to mount a DE OUDE DELFT RAYXAR E65/0.75 Revisited

[Erik Lund]

Very nicely adapted all of them! And super images

[simsurace]

Do consider the weight first ....

Yes, it weighs roughly 1.5 kg.

[Bjørn Rørslett]

A few diagrams to help people understand why these specialist lenses exist in the first place, and why they are so heavy and rugged.

Basically they help transport the X-ray image into safe viewing positions. The final image can be recorded to [cine] film or TV media.



The first lens is the collimating lens and the second is the recording lens. Due to the construction and placement, there is no conjugate loss of light.

For X-ray screening, limiting the exposure to unhealthy radiation is a primary concern. Hence the use of ultrafast lenses in the imaging system.

[simsurace]

Interesting!
Do you have information about the refractive indices of the different elements inside the lens?

[Bjørn Rørslett]

Must be very high, if you look at the strong curvature and thickness of the elements Usual speed is f/0.75 or thereabouts.

These X-ray lenses were very expensive, but nothing compared of course to the total price of the X-ray device they were a part of !!



Copied from a post Klaus Schmidt made at forum.mflenses.com, original seen in Sidney E. Ray (2002): Applied photographic Optics. Focal Press, as noted by him.

[BEZ]

A simple diagram of the elements with measurements   ....internet folklore says if you remove the rear element you achieve focus at infinity.

 

[Bjørn Rørslett]

Interesting. The drawing indicates the rear lens cell actually comprises 2 groups. Although there is an air space indicated, this seems to be absent when you extract the entire rear cell as it comes off in one piece not two?

If the entire rear cell is removed, focus on a mirrorless camera can go to several meters, but quality is really bad.

It should be possible to make a dedicated digital setup for this lens for infinity photography by literally standing the lens directly onto a sensor. The cover glass of the sensor will act as the final air spacing.

I do notice the two lens diagrams are not identical. Are there several versions of this lens as well? (BEZ removed one of the diagrams because it might refer to another lens)

[simsurace]

Bez, where did you find the lower picture with the rays? Given enough sample rays, one could infer the refractive indices of all the elements.

[BEZ]

It should be possible to make a dedicated digital setup for this lens for infinity photography by literally standing the lens directly onto a sensor. The cover glass of the sensor will act as the final air spacing.

A digital version of this ....https://sites.google.com/site/francoisastrocat/

[BEZ]

Bez, where did you find the lower picture with the rays? Given enough sample rays, one could infer the refractive indices of all the elements.

Good luck with reading the text     .....http://plaza.rakuten.co.jp/utsurundesu/diary/200810040000/

Google gave the image as Rayxar 65mm f0.75 ....but on investigation (This guy's blog) I don't think it was correct. Interesting how close the Heligon is in design.

[Bjørn Rørslett]

A digital version of this ....https://sites.google.com/site/francoisastrocat/

Exactly what I had in mind.

The image circle is probably quite small, thus a m43 sensor should suffice.

[BEZ]

I do notice the two lens diagrams are not identical. Are there several versions of this lens as well?

I think my Japanese let me down (and Google)   ....the second diagram may of been a Heligon, so I have removed it to save confusion.

[BEZ]

Exactly what I had in mind.

The image circle is probably quite small, thus a m43 sensor should suffice.

It would seem relatively simple to achieve with a donor m43 camera?

[Bjørn Rørslett]

The problem is that the hosting camera has to be complete butchered and the shutter probably must go. Thus a model with electronic front shutter could be advantageous. The bits & pieces must be put into a light-tight box - probably easy . and the controls be available on the outside.

Apparently infinity focus is obtained with 4-5 mm of clearance to the rear element. Still I don't think there is room for a shutter curtain, but this can be investigated further.

A good project for a Nerd subgroup of NG?

[BEZ]

I forgot about the shutter ....it now seems trickier