60mm f3.5 C mount UV lenses on eBay

[OlDoinyo]

It is wonderful that we have broken the 300 barrier at last, and maybe even 200! At 185 nm, I expect you would need to work in a vacuum. I knew some who worked in a chemistry lab with a 190-nm laser, and everything had to be in vacuum. Evidently air gets really opaque down there, which is why that sub-band is called "vacuum UV."

[Andy Perrin]

That is quite interesting. You have got to fix that hotspot. It’s honestly not that hard. Get either the Semple paint and paint a piece of paper, or get the Acktar sample size (despite the high price per piece, one piece has lasted me for years now...) and cut a strip of black material that is the right length and width to go in the barrel. Then you simply let the paper’s natural springiness hold it in place. No worries about paint in the barrel getting on the lens.

 

Clark, regarding vacuums...at close range I bet enough light will still get through for imaging. Lasers have the issue that they are very intense, and as a result if they heat the air enough then the change in refractive index from the hot air makes the beam jiggle. This won’t be a factor for imaging with an ordinary lamp.

[dabateman]

It is wonderful that we have broken the 300 barrier at last, and maybe even 200! At 185 nm, I expect you would need to work in a vacuum. I knew some who worked in a chemistry lab with a 190-nm laser, and everything had to be in vacuum. Evidently air gets really opaque down there, which is why that sub-band is called "vacuum UV."

I am at close distance. But maybe the haze I saw was not all hot spot but was air.

I will have to play more.

 

Andy,

I painted a sheet in August. Still haven't gotten around to taping it into the lens.

This may motivate me.

[Andy Perrin]

Mine is not taped. It holds itself in there!

 

Regarding atmospheric absorption, it seems it is not a factor. These people are using 185nm light for modifying plastic surfaces and they report,

Innovative pretreatment by UVC light (185 nm) and by radio-frequency (RF) plasma at atmospheric pressure to functionalize the Nylon surface, increasing its bondability toward TiO2, is reported in this study. In the case of UVC light pretreatment in air, the molar absorption coefficient of O2/N2 at 185 nm is very low and the air in the chamber absorbs very little light from the UVC source before reaching the Nylon sample.

 

Incidentally, considering the use they are making of this 185nm light, you might want to consider damage to your equipment...

[KhanhDam]

I just won this auction for $400 usd.  this video shows some sort of adapter tube to fit a point and shoot camera on it. Looks like they are using a canon G5, which is pretty old tech.  what kind of camera+macro lens combo are you using with this setup?

 

[Andy Perrin]

I have one of these KSS lenses. You got a nice deal! If you just want to use the lens for UV-A shooting, it unscrews from the image intensifier  and I can attach it to my Sony cameras with a C-Mount adaptor. The UV-C filter needs to be replaced with a 25mm dichroic UV-A filter but this is easily done. It does not have threads for front mounting a filter. Also there is a strong hotspot if you don’t flock the inside of the lens with something UV-black due to reflections. 
 

If you want to do UV-C imaging, I was able to attach the eyepiece of the image intensifier to my camera with a 52mm-34.5mm step ring. 
 

Use a camera with a small sensor size. APS-C or smaller. 
 

Do not forget the precautions for UV-C light. 

[KhanhDam]

1 hour ago, Andy Perrin said:

25mm dichroic UV-A filter but this is easily done. It does not have threads for front mounting a filter. Also there is a strong hotspot if you don’t flock the inside of the lens with something UV-black due to reflections. 

thank you, does one have to disassemble the lens to flock it? or just do the front portion of the lens up to the first quartz element? if you can post photo of how you did yours that would be great. 

I'll probably just start out with UV-A. can you recommend where to get a 25mm dichroic UV-A filter from? I own the 2" verison of this: Baader U-Venus-Filter (350nm) - Filters (baader-planetarium.com), looks like they make a 1.25" one, but that is too big and they are pricy. 
would a chepaer z1b work 1PCS 25*2.0mm ZWB1 UG11 UV Via Glass Lens Filter For 302nm 312nm Lamp| | - AliExpress ? with a IR block filter?

[Andy Perrin]

I just did the front element. It was very quick and easy. I think if you start at the beginning of this thread you will see the pictures I already uploaded! 

 

Unfortunately you can't use absorption glass because there is no way to stack filters. Again, READ THIS THREAD. I already showed a lot of the process for you, including how I loaded the filter in there.

Quote

where to get a 25mm dichroic UV-A filter from

That is somewhat harder. Possibly Thorlabs would have something, or if you can find an Omega 330WB80, that is what I used.

[KhanhDam]

Thanks I found some Omega 330WB80 25mm on ebay for about $40. very excited to get and use this lens. 

[dabateman]

If its like our lenses,  it has a 37mm filter thread. You can use a UVA filter screwed into the front of the lens with the clear filter you see in the back lens slider. Or just remove the slider and screw your filters to the front. But the optics might expect a back filter.

I can't remember how deep the holder is, but you might be able to stack filters if you play with best combinations,  like 2mm S8612,  tape thin spacer, 1mm or 1.5mm zwb1 or U340.

I did end up double side taping in a thin piece of paper painted with Semple black 2.0 for my lens.

 

Be super careful with the included lights, they will be germacidal UVC light sources. 

[Andy Perrin]

Dabateman I couldn’t see front threads on mine?

[dabateman]

2 hours ago, Andy Perrin said:

Dabateman I couldn’t see front threads on mine?

I see them in your photo you posted here:

 

You also say they are

On 7/29/2019 at 1:03 PM, Andy Perrin said:

Dabateman: I measured the filter thread diameter with calipers, and it seems to be 36.5mm.

 

Mine is 37mm. The Resolve lens is supposed to be 30.5mm or 34mm depending on the manual I find.

[Andy Perrin]

I'm wrong, I think I remembered the conclusion which was "I can't put anything on the front" but not the reason for it, which was probably "no step ring of the right size."

[KhanhDam]

Well the batteries are corroded in good can’t even wrench them out

filter looks like a mirror

 

cant figure how to remove the lens either.?!?   Is trying to fix the imager worth it?   Thinking of soaking the bottom 1/2” in vinegar for a day or longer

[dabateman]

The 254bp25 filter looks good.

To remove the lens, slide the filter fully out. Then turn the lens out. Its C-mount, so it will just unscrew from the base. The filter slider is part of the lens, it ends at that silver part you can see at the base.

 

[KhanhDam]

removed the back panel where the on/off switch is located and that revelas the other battery terminals. i could probably hammer or drill out the batteries, but I'm gonna let it soak in viengar overnight and try to ease them out in the morning.  Got lens removed! actually used the filter holder to torque it off. 

[lonesome_dave]

Khanh I hope you get your Sirchie imager working. The issues with this lens have been covered well by the other posters. I can only add that all of the Sirchie 60mm quartz lenses (KSS100a) that I've owned had 30.5 MM front filter threads. I was able to get the smaller Baader-U into a spare 30.5 filter ring and was happy with the results using it on front. I had removed the filter insert portion of the lens and reinstalled the C-mount flange on the remaining lens body. This was the only way I could get to infinity focus on my full spectrum Sony A6000 with a C-mount adapter.

 

Trying to mount the 254nm filter on the front threads of this modified lens and using it with the Sirchie imager was not satisfactory however for reasons I never figured out. The resulting images were fogged. So if you want to do UVC you should leave the lens as is and use the filter slider.

I'll try to put a post together next weekend on the uses I've found for the Sirchie imager itself independent of the lens we are talking about in this thread.

 

[Andy Perrin]

Used with a small enough sensor, I think it is not a bad lens. The imager has been handy (using 330WB80 filter) for checking sunscreen application. 

[KhanhDam]

On 8/29/2022 at 12:42 AM, lonesome_dave said:

.I'll try to put a post together next weekend on the uses I've found for the Sirchie imager itself independent of the lens we are talking about in this thread.

 

That would be awesome    I would love to learn the full potential of this kit

[Lou Jost]

On 7/23/2019 at 9:16 AM, JMC said:

EDIT: 13th September 2019. These lenses apparently aren't original Resolve Optics 60mm ones. They were reverse engineered by another company.

 

Currently on ebay there is a company selling second hand forensics imagers called Sirchie Krimesite cameras. As far as I can tell, they are using the 60mm f3.5 Resolve Optics UV lens shown here;

 

https://www.resolveo...-forensic-lens/

 

The ebay link is here;

 

https://www.ebay.co....~0AAOSwHcNc-TVG

 

They have a variety for sale, including full forensics setups, but the one in the link above is cheaper than a full setup and includes the filter holder (which some of the others don't have).

 

I spoke briefly with Resolve Optics earlier, and asked about a new price for one of their lenses. They did not want to give that info out, however when I asked if it was more than £1000, the answer was, "oooh yes".

 

I have no affiliation with the ebay company selling these, however I have bought one myself (which I wont see until November when I next see my family in the US). They accepted an offer of $700 for one.

 

I'm sharing in case it is of interest.

 

I guess I just won the eBay lottery, because I bought an original Resolve Optics 60mm f/3.5  (with filters) for $150. I just got it home yesterday. Early visual tests show that it does well at infinity. It came with an Andover Optics  253.7nm filter (whose retail price is double the price I paid for the filter + lens) and a "hot mirror" clear bluish filter. Resolve Optics literature says that it can be focused in visual light through the clear filter and will still be in focus when switched to the UV-C filter. Quite a nice feature. I've requested more technical information from them.

 

The filters have the same oil problem as the clones mentioned above.

 

I'll do some tests and report the results on this thread, if that is alright. Seems like a logical place.

 

 

 

 

[Lou Jost]

I have just received some information from Resolve Optics about this lens.

 

Maximum magnification 0.8 (1:1.25)

FOV 8.3 degrees at max m, 16.6 degrees at infinity

Image circle 17.5mm diameter

Special coatings for 99% transmission per surface over the design wavelengths of 230nm to 500nm.

Peak transmission at 230nm and 300nm.

Distortion less than 0.1%

Image resolution at 32 cycles/mm MTF on axis >60%, 0.7 field >40%, corner >20%

Vignetting < 22% in corners

Flange distance 17.53mm in air

Lens mounting thread 1" - 32 UN-2A

Filters (internal) 25mm +/- 0.25mm, 3.5-5mm thick (spacers are available)

Lens barrel rotatable to put markings in best location.

Weight 500gms

 

In addition they talk about their filter system, and their language implies that the clear filter is to be used for help in framing the subject. They do NOT say that you can focus with this and then change to the UV filters and shoot. So this is a lens that is not fully corrected for color aberrations and is best used with monochromatic sources. My tests confirm that there is a significant focus shift from 254nm to visible light.

 

Some commenters about the Sirchie lens say they had trouble getting infinity focus. My lens focuses at and beyond infinity in visible light with no problems, but only if the filters are in place. Note that I used a spacer between the lens C-mount and the camera C-mount, and this should have made it even harder to focus at infinity, but I could still do it. The lens was fairly sharp at infinity.

 

There don't seem to be any floating elements, making it likely that there is some optimum magnification. Judging from their product specifications I would expect it to be optimized for the highest magnifications rather than for infinity.

 

 

 

 

 

 

[Lou Jost]

I should add that the lens is much sharper at f/4 than at f/3.5.  f/5.6 doesn't look much different than f/4. Tomorrow I will carefully find the optimum aperture at macro distances (and at infinity if weather allows).

[lonesome_dave]

On 11/9/2023 at 4:36 PM, Lou Jost said:

Some commenters about the Sirchie lens say they had trouble getting infinity focus. My lens focuses at and beyond infinity in visible light with no problems, but only if the filters are in place. Note that I used a spacer between the lens C-mount and the camera C-mount, and this should have made it even harder to focus at infinity, but I could still do it. The lens was fairly sharp at infinity.

 

The reason I couldn't get to infinity focus with the straight Sirchie quartz 60mm f/3.5 is the large filter slider flange combined with the short exposure of C-mount threads made it impossible to mount directly into the C-mount adapters I have for the Sony. A 5mm C-mount extender was needed to reach the threads.

 

It was still very usable for macro work which is what the lens was intended for but at f/4 the farthest focus was about 2 meters.

I modified one of them by removing the filter slider flange and remounting the C-mount thread flange onto the lens. By also leaving out the tension plate the threads extended out far enough to directly mount into the C-mount adapter. Infinity focus was then achieved at max aperture.

 

Here's a couple pics of all the different types of Sirchie quartz lenses I have. At top is the KSS100b with 37mm front filter threads, next the KSS100a with 30.5mm front filter threads, and on bottom a modified KSS100a with filter flange removed. On the right is the filter slide assembly with the standard clear and 254nm bandpass filters. At bottom right is the little 25mm f/2.8 Sirchie quartz lens they use on their Scan & Find version of the UV imager. It has a 25.4mm front filter thread. I have a 25.4-30.5mm adapter on this one.

 

 

Lou, if you could post a pic of your Resolve Optics lens it might be interesting to see the differences.

[Andy Perrin]

I think I recall my copy of the KSS100b lens didn’t have infinity focus either but it worked fine for macro. With the filter replaced with a 330WB80, chromatic aberration was acceptable. This is one of my favorite UV lenses for macro work. 

[Lou Jost]

Here is my lens. Looks very similar to the Sirchie version. The filter thread is 30.5mm and I've added rings to get a 52mm front filter thread.