How to remove the coating from a lens?

[ArthurDent]

I have a candidate lens for uv and want to remove any coatings which might reduce uv transmission. Any suggestions as to abrasives I should use? How to apply them? How to keep the abraisive out of the lens? Other important considerations? Thanks for any suggestions.

[Birna Rørslett]

Use the lens for UV first. Removing coating(s) might damage the optical performance so always best to test beforehand. Don't expect superior UV response from most lenses, whether they have coating intact or not.  However, the target one aims for will dictate whether more humble optics can serve nonetheless.

[ArthurDent]

Thank you, I will certainly try that first.

[Seapy]

Having been there and done it...  I had a 100mm E lens, a very nice example, near new.  I understood it was a reasonable candidate, so I set to with Dremel and some car polish, the coating was very tough to remove and the lens lost it's sharpness, a lot of work to ruin the lens!

Apart from UV transmission, the biggest issue with UV is focus shift.  Depending on the lens, focus shift can be very significant.  You focus on the subject, then fit the UV pass filter, make the exposure.  The results will likely be oof.  If you lay a tape measure or ruler on  a desk, focus on say the 100mm mark, then photograph it from above at 45º, observe where the best sharpness occurs.  Refocus so that the 100mm mark is sharpest and observe the difference.  I used a rail, from memory at about 350mm subject to lens, with ~ 100mm lens, I found the offset was about 14mm but it varies lens to lens.

Initially I used a Metz 45CT with (most but NOT ALL) the yellow coating removed from the tube.  Later I constructed a Nichia 365nm UV lamp with a special focusing fluoride? lens, which works well. Less savage than the Metz.





I tried various lenses but the Micro Nikkor to me seemed as good as any I have, although I do now have an EL 105mm f/5.6 lens with a helicoid. I have yet to try that combination.

A couple of images taken with this setup, Rudbeckia in UV: D200UV with Micro Nikkor 55mm f/2.8.



Dandelion in UV.



Not forgetting IR, Rudbeckia, with my 720nm D200 and I think the Micro Nikkor 55mm f/2.8.



Last but not least, I rather like the induced fluorescence effect, gerbera daisy, visible spectrum D200 camera, illuminated with my Nichia 365nm lamp and I probably used the Micro Nikkor 55mm f/2.8.



Hope the above is some help, do NOT claim expertise, a lot of fumbling in the dark (literally!).  Much assistance from Klaus with the  filters and lighting and from Bjørn's website etc. to surmount the obstacles.

[Øivind Tøien]

The UVIVF of the daisy is excellent, very nice colors!

Do you recall what kind of WB/color correction that was used?
(We have a current discussion about possible needs to warm up UVIVF captures on the UV forum site).

[Seapy]

The UVIVF of the daisy is excellent, very nice colors!

Do you recall what kind of WB/color correction that was used?
(We have a current discussion about possible needs to warm up UVIVF captures on the UV forum site).

Thank you Øivind, I rather like them too, one of my favourite compositions!  They were processed in Lightroom so yes I have all the detail.

Rather than incur the wroth of the Northern Bears,    I will start another thread in the Processing section, I don't want to spend three weeks in the wilderness!  LOL

I am also a member of the UV group but it's so long since I partook I have probably lost the url and my password...

[Øivind Tøien]

I do not think the Northern Bear would mind, do whatever you find most suitable.

The UV forum site URL: http://www.ultravioletphotography.com

[Birna Rørslett]

Seapy: I can reset your password on UVP if you wish. Send me a PM and get the username and a temporary password in return.

[richardHaw]

ammonia and other chemicals will do that for you. easier for early Zeiss T coating since water is all it takes 

[Seapy]

Seapy: I can reset your password on UVP if you wish. Send me a PM and get the username and a temporary password in return.

Thank you Birna, I will check my little red book, I may still have them.  If so I will log in again.

[ArthurDent]

ammonia and other chemicals will do that for you. easier for early Zeiss T coating since water is all it takes 

Richard, Do you think ammonia would work on the Nikon 50mm f/1.8 ais? My plan would be to suspend it with the front of the lens pointed down and to use a q tip saturated with ammonia to remove the coating, then use kimwipes to remove any excess, unless there is a better way?

[Dr Klaus Schmitt]

I have a candidate lens for uv and want to remove any coatings which might reduce uv transmission. Any suggestions as to abrasives I should use? How to apply them? How to keep the abraisive out of the lens? Other important considerations? Thanks for any suggestions.

This is an urban myth basically, old and honestly forget about that. There are so many good candidates for UV photography which do not require any such ...

Have a look here on my Blog and you'll find plenty: http://photographyoftheinvisibleworld.blogspot.com/2011/01/uv-lenses-tested-good-for-uv.html

[Akira]

Apart from UV transmission, the biggest issue with UV is focus shift.  Depending on the lens, focus shift can be very significant.  You focus on the subject, then fit the UV pass filter, make the exposure.  The results will likely be oof.  If you lay a tape measure or ruler on  a desk, focus on say the 100mm mark, then photograph it from above at 45º, observe where the best sharpness occurs.  Refocus so that the 100mm mark is sharpest and observe the difference.  I used a rail, from memory at about 350mm subject to lens, with ~ 100mm lens, I found the offset was about 14mm but it varies lens to lens.

When I shot images in UV, I sometimes mounted a lens without helicoid.  Then I utilized the Arca-Swiss clamp/plate as a focusing rail, both for focusing in VIS and adjusting the focus shift for UV.

[ArthurDent]

This is an urban myth basically, old and honestly forget about that. There are so many good candidates for UV photography which do not require any such ...

Have a look here on my Blog and you'll find plenty: http://photographyoftheinvisibleworld.blogspot.com/2011/01/uv-lenses-tested-good-for-uv.html

Thank you. I’ve bookmarked your site, very informative! It would seem tto use an enlarging lens, I’d need to couple it to a bellows to get it to focus? So, I’d need rails, bellows and adapters at both ends? Any suggestions?

[richardHaw]

Richard, Do you think ammonia would work on the Nikon 50mm f/1.8 ais? My plan would be to suspend it with the front of the lens pointed down and to use a q tip saturated with ammonia to remove the coating, then use kimwipes to remove any excess, unless there is a better way?

not sure. the coatings on the series E lenses are easier to strip if you want to but I am not sure if you really want to do that. Minolta coatings are known to be soft so you may want to use their lenses instead. just sneeze in front of it and the coatings will fly away like dust 

soak it in strong concentrations of ammonia and citric acid and watch the thing go away after an hour or so. i would just keep the Ais. its too precious to be used for an experiment