Relay lens choice

This problem suggests that you need a corrective lens between the two lenses to correct the focus....I would suggest some service that could map and specify a lens that performed this function....

https://www.dxomark.com/glossary/vignetting/

On the other hand it could be corrected after the fact with some software program perhaps...

https://expertphotography.com/vignetting-types-tips/

Or perhaps you could just make the second lens a bit larger...

https://sot.com.sg/vignetting-factors/

https://www.dpreview.com/forums/thread/4671253

This should be possible without any corrective lens. Some lenses are better than others with regard to vigetting, I just need to find the right one.

I don't understand the problem here, but, this might help. Are you aware that you can now get "prototype" 3D printed metal parts? This would enable you to couple any two optically suitable lenses at any required separation.

Lens couplers are available, the distance between the lenses should not be critical.

If you have access to Python, this may help.

My understanding is that you want to focus the screen of some device like an image intensifier on the sensor of a camera. I have some questions:

We have a couple of pairs lenses here, RICOH 25mm F1.4 or FUJINON HF16HA-1B 16mm F1.4. We've tried coupling them but they suffer from vignetting, the image gets much darker towards the edge.

Are you coupling the RICOH to RICOH and FUJINON to FUJINON, or one of each?

The image area is an 18mm diameter circle.

Is this the image size you are trying to focus on the camera sensor? What magnification do you want (camera image size / source image size)?

Vignetting is due to the optical path of a light ray hitting the edge of the camera encountering an obstacle on it's path from the source image.

Vignetting can be minimized by increasing the focal length and by stopping down the f/stop.

"Increasing the numerical f-stop number

Natural vignetting or cos4θ roll-off can be avoided if the lens is stepped down by two f-stops that increase the numerical f-stop number.

Using a longer focal length

Vignetting can also be caused in cases like lower f/#s (ratio of the focal length to the aperture size), short focal length lenses, or lenses where higher resolutions need to be achieved at a lower cost. Mechanical vignetting is the only type that can be eliminated by using a camera technique (using a longer focal length)."

https://www.e-consystems.com/blog/camera/technology/what-is-lens-vignetting-and-how-to-eliminate-it-in-embedded-cameras/

We are not mixing lens types, we tried those pairs because we had them available. The input image is an 18mm diameter circle, the output will, I assume, be coupled to a CCD camera but we have no knowledge of the specific type. The magnification through the lens pair, i would expect to be 1:1. The lenses we have are f1.4.

We can try different lenses but they are likely to be £500 each or more so I am trying to gather as much info as I can before going down that route.

Which f/1.4 moderately sized prime lenses do not vignette on Full-Frame?

https://www.dpreview.com/forums/post/64556314

Lens vignetting comparison...they have done the testing for you ....

https://www.the-digital-picture.com/Reviews/Lens-Vignetting-Test-Results.aspx?FLI=0&API=0&FLIComp=0&APIComp=0&LensComp=769&CameraComp=453&Lens=1059&Go.x=8&Go.y=17

That's really useful, thanks for that.

I think we've pretty much decided that we will have to use F mount lenses. It's overkill on the aperture size but we know that it works.

https://www.edmundoptics.com/knowledge-center/application-notes/imaging/lens-mounts/

https://www.simtrum.com/WebShop/ProductList5.aspx?pid=1832

That is pretty much the same as we are making.

https://www.photonics.com/Articles/Image_Intensification_The_Technology_of_Night/a25144#:~:text=An%20image%2Dintensifier%20system%20works,image%20for%20viewing%20through%20an

https://www.l3harris.com/all-capabilities/enhanced-night-vision-goggle-binocular-envg-b

Vignetting is when the light path is blocked around the periphery by the lens stop. I'm thinking that using the smaller f/1.4 lens (16mm dia.) on the end towards the light source and the larger (25mm dia.) f/1.4 lens at the camera sensor end might be less likely to vignette. And if the lens stop is adjustable, I think it should be wide open.

https://photographylife.com/what-is-vignetting

I realise that this is out of time, but, these lens adapters might help with future projects:-

https://www.aliexpress.com/item/32594292002.html?spm=a2g0o.pay_result.pcSmartCardPaySuccess.4.41093474tChH3X&gps-id=pcSmartCardPaySuccess&pvid=713f788d-601d-4eea-8edf-d2ac28cdd30a&_t=gps-id:pcSmartCardPaySuccess,pvid:713f788d-601d-4eea-8edf-d2ac28cdd30a,tpp_buckets:668%232846%238113%231998&pdp_npi=4%40dis%21GBP%2117.34%2114.40%21%21%2121.08%2117.50%21%40211b618e17144026388902864ee0e1%2112000016578247131%21rec%21GB%212719264949%21&utparam-url=scene%3ApcSmartCardPaySuccess%7Cquery_from%3A

18 adapters (9 each way) for under $20 seems like a real bargain.