Small tube lens

Saul · Post by **Saul** » Mon May 04, 2020 8:30 pm

Anybody knows small size (25 - 33mm diameter), 100-150mm FL tube lens ?
Lots of candidates on the Surplusshed, but their search results look strange, no way to take a look at the item (except very few of them)

Thanks,

Chris S. · Post by **Chris S.** » Mon May 04, 2020 10:44 pm

Perhaps either AC254-100-A-ML, AC254-125-A-ML, or AC254-150-A-ML, here: Thorlabs Ø1" Mounted Achromatic Doublets, AR Coated: 400 - 700 nm. I haven't tried any lens of this type, but have a vague memory that others may have?

--Chris S.

Saul · Post by **Saul** » Mon May 04, 2020 11:37 pm

Chris S. wrote:Perhaps either AC254-100-A-ML, AC254-125-A-ML, or AC254-150-A-ML, here: Thorlabs Ø1" Mounted Achromatic Doublets, AR Coated: 400 - 700 nm. I haven't tried any lens of this type, but have a vague memory that others may have?

--Chris S.

Thanks Chris ! AC254-100 is on a way , but only B (close to infrared) version . Any idea, how it will affect picture ?

Charles Krebs · Post by **Charles Krebs** » Tue May 05, 2020 12:39 am

Saul,

They show the "A" coating as in stock. Why not get the "A"?

I once ordered a "B" coated Thorlab condenser lens by accident, and it was unsuitable for use in the visible wavelengths.

Saul · Post by **Saul** » Tue May 05, 2020 12:48 am

Charles Krebs wrote:Saul,

They show the "A" coating as in stock. Why not get the "A"?

I once ordered a "B" coated Thorlab condenser lens by accident, and it was unsuitable for use in the visible wavelengths.

It was ebay listing, cheap price , 100mm, just for proof of concept, how it will cover crop sensor. It was unsuitable at all ? Was it 100mm ? Or it was completely different TL ?

Charles Krebs · Post by **Charles Krebs** » Tue May 05, 2020 3:17 am

To check for coverage it will be fine.

But the "B" coating reflects too high a percentage of light wavelengths up to about 500nm (see chart and spreadsheet here: https://www.thorlabs.com/newgrouppage9. ... p_id=12767 )

I think you will find it does not give good color for imaging or light transmission, The one I accidentally ordered was a short focal length aspheric condenser lens to be used in a Koehler lighting system.

Ichthyophthirius · Post by **Ichthyophthirius** » Tue May 05, 2020 5:44 am

Hi,

0.5x focal reducers used for telescopes have a focal length of about 100 mm. Might be worth a try, especially if you have one already.

https://agenaastro.com/articles/guides/ ... guide.html

Not easy to find the focal lengths but this company actually lists them on their pages:

https://agenaastro.com/gso-1-25-0-5x-focal-reducer.html

Regards, Ichty

Macro_Cosmos · Post by **Macro_Cosmos** » Tue May 05, 2020 8:36 am

I would try achromatic doublets from either Thorlabs or Edmund Optics.
The 25mm/1in versions are very easy to integrate into an SM1 (lens tubes with 1in dia) system. Mitutoyo M Plans actually screw right into the SM1 tubes, though I always recommend adapting it instead. Thorlabs does offer an SM1-M26x0.706 adaptor.

Smokedaddy · Post by **Smokedaddy** » Tue May 05, 2020 12:28 pm

Saul, I have a GSO 1.25" 0.5x Focal Reducer if you want to try it.

-JW:

Saul · Post by **Saul** » Wed May 06, 2020 12:08 pm

Thank you all for advises !

Smokedaddy wrote:Saul, I have a GSO 1.25" 0.5x Focal Reducer if you want to try it.

-JW:

Thanks, James ! Let's wait a little bit, 2 TLs on the way (different brands), let's see results.

Smokedaddy · Post by **Smokedaddy** » Wed May 06, 2020 12:59 pm

Saul wrote:Thanks, James ! Let's wait a little bit, 2 TLs on the way (different brands), let's see results.

If I can test the GSO for you on my end and have the necessary components, I'm more than willing, you have my email.

Regards,
-JW: