Concave Lens of more than >100mm in Diameter ???

[JA]

Hi folks,

I'm looking for a Concave or BiConcave lens in glass / optical glass... of more than 100mm in diameter, perhaps something in the 110/120 to 150mm range would be great or anything close please advise others too.-300 to -400mm focal length range (but interested in anything at this point). With or without coating. If you have one you'd like to offload please PM or if you have a link to a suggestion where I can get one that would also be great.

I've tried Surplus Shed and no luck. eBay has them at exactly 100mm, but unfortunately I need slightly larger.

Any help appreciated. Thanks in advance.

Best
JA

[Baza]

Have you tried cloudynights

[JA]

Thanks for the excellent suggestion Baza:thumbsup:

Best
JA

[JA]

Bump- still looking for a large 100mm plus concave lens. Preferably up to 150 to 160mm with 300/ 400 to 500mm or so focal length. Anything close is of interest.

Thanks and best
JA

[skysurfer]

https://www.surplusshed.com/

[JA]

Thanks sky surfer. I tried them a few weeks ago with no luck, but as you've reminded me I'll try again just in case.

Best
JA

[JA]

Bump-

No luck so far from SS or other and still looking for a large 100mm plus concave lens. Preferably up to 150 to 160mm with 300/ 400 to 500mm or so focal length. Anything close is of interest.

Thanks and best
JA

[Wavytone]

Have you tried putting a wanted ad on astromart for a refractor objective, poor or broken condition ? The negative element from one fits your description...

[JA]

Thanks Nick,
I have a few wanted ads for it, but I've yet to try there. Fingers crossed

Thanks and Best
JA

[Wavytone]

There’s another way. See alibaba... and contact a lens manufacturer in China for a quote to make a few.

Does it have to be glass ? Cast plastic ? How good does the surface have to be ? Scratches ?

https://m.alibaba.com/product/60291599893/BK7-convex-and-concave-lens-negative.html?s=p&spm=a2706.7843667.1998817009.28.732 c2c6bHbRpAV

For example at $US30 apiece and minimum qty of 5 off, it would cost $150. Though the quality will be like that for cheap magnifying glasses.

A single lens to high optical precision will cost about $1000 though for 1 piece.

Part of the reason for the minimum order qty is that the Chinese factories are using fully automated grinding and polishing machines that work in batches and the min qty will be 1 batch.

[JA]

Thanks again Nick for an excellent suggestion^ .
I already have submitted some quotes and waiting to hear back.

Best
JA