60mm f3.5 C mount UV lenses on eBay

[Andy Perrin]

The filter slider is cool and definitely needed because without it the optical path is a different length, causing focus changes. But I am going to swap the filters out for a 330WB80 and maybe BG-38.

 

What’s wrong in UV-C? It’s designed for it!

 

David, did you see the hotspot?

[Mark Jones]

I've never seen a front element so deeply recessed. Looking forward to your photos debateman.

[dabateman]

First tests using Olympus EM5mK2 hand held macro. This was where I see the field of view is much narrower. Later I measured the lens to actually be 75mm

 

One to One images of flower on tripod more controlled.

 

Olympus 60mm F2.8 Lens (ISO 200, 1/200 F3.5):

 

KSS 60mm F3.5 lens (ISO 200 1/25, F5.6):

 

Full image comparison:

 

 

The clear filter allows UVB to transmit, interesting the coatings of the lens seem different than my UAT, these all shot with same white balance preset that I normally use for 313nm. Here is comparison using 313bp25 filter stacked with 330WB80 improved to eliminate the IR leak with two UVB lights:

 

The clear filter did not impact using Baader Venus filter at all. Here is images using the two UVB lights:

 

KSS with Clear filter in place with Baader Venus U (F4, ISO 200, 2.5 seconds)

 

KSS No filter in slot with Baader Venus U (F4, ISO 200, 2.5 seconds):

 

UAT with for comparison with Baader Venus U (F4.5, ISO 200, 1.3 seconds):

 

Using a Hallogen lamp, I wanted to test the IR blocking of the UV slide in filter:

 

Clear filter in KSS using Hallogen No other filters on the lens (F4, ISO 200, 1/320):

 

UV Filer in KSS using Hallogen (F4, ISO 1600, 60 seconds!):

 

 

Now for the UV-C images Using my super dangerous 254nm Light:

 

Comparison:

 

Close up of image used above for KSS lens (F4, 3.2 seconds, ISO 1600):

 

Close up of UVC filter used on UAT lens (F4.5, ISO 1600, 1.3 seconds):

 

Visual of flower:

[dabateman]

Forgot to mention, that the plane of focus in UVc is razor thin. I needed a macro rail to adjust the focus point. A hair either way and you're out of focus. I think that is why this lens has a baffle to restrict the light path. And why the aperture settings on mine at least are much greater. F4 is really f8 for a normal lens. Oddly doesn't focus well unless really close to the subject in the 254nm light. But should be happy to see any thing at 260nm with Em1.

I will need to clean the UV filter more carefully, as I see similar lube oil as was on my clear filter. This may be why so hazy.

I have not used the lens outside yet, so can't comment on hot spots.

 

I also have not used it correctly with the back imager yet. I think I have almost figured out a way to mount my camera to the back, using an old tmount adapter.

[dabateman]

Not Sure if these images will look better. Using just the UVC filter and a 254nm germicidal UV-C light.

 

1:1 Crop from UAT with UVC filter and 254nm light:

 

1:1 Crop from KSS with UVC filter and 254nm light:

[Andy Perrin]

Ok, the other two lenses look just as foggy with that filter. I think you are correct, whatever oil got on the filter is blurring the image. Mine has no oil on it.

 

Also, I don’t know that I trust these images are really 254nm even at such long times. I want to know if you see the same picture with the fluorescent screen.

[Andy Perrin]

I successfully replaced the filter with a 330WB80 (Omega) filter. It's a little loose because it's much thinner than the UV-C filter. The screwdriver needed is a 1.3mm hex, which I bought as part of this set.

 

Here is the UV-C filter. It appears to be a 253.7nm center wavelength, 25nm bandpass, 25mm filter.

 

The filter holder comes apart just as you'd expect.

 

I dropped in the Omega filter and screwed it back together.

 

 

I plan to replace the clear window with a visible light bandpass; currently it seems to let through everything.

[Andy Perrin]

It's not bad in close-ups and macro in UV-A. This is with the newly-replaced 330WB80 filter. All of these are fully processed images from RAW, shot wide open at F/3.5 (nominally, anyhow), ISO3200, 1/30". Shooting handheld (so please ignore blur). The colors have been left alone (aside from the initial white balance off some asphalt). Light provided by the sun only. No lens hood, and no sign of a hotspot either, after incorporating the Acktar yesterday. I would say this is a usable lens for close-up and macro work, but not outstanding on the Sony A7S; a micro-4/3 would fare better because you would be using only the center of the image circle.

 

 

 

 

[dabateman]

Andy,

I cleaned my UVc filter and now I see the hotspot in UVc. It only focuses with the lens in full macro mode. I was able to almost get an infocus shot today on camera. Really hard, with exposure f4, 50 second ISO1600.

Yes with Em1 and with the handheld back imager, I see the exact same thing.

Really cool. I will have to look into how you got rid of the hotspot.

 

Also I only see stuff with 254nm light. I tried my 302nm light and didn't work. So the filter spec you found is real.

[Andy Perrin]

I'm unsurprised that 302nm didn't work -- fluorescent screens are picky, so they would have suited the filter to the screen. I found similar things with my old SWIR fluorescent screen setup. Cool that the 254nm you were picking up was real! I want to see your images using the fluorescent screen and the clean filter now. I wonder why on earth they didn't fix the damn hotspot themselves? I mean, yes, it's only a real issue when the light source is in front of the camera, and you can always put your light in the right place to get rid of it, but it's not a hard problem to coat the barrel in something UV-absorbing and matte.

[Mark Jones]

nice flower shots!

[dabateman]

Andy,

Sorry the UV filter only works with a 254nm light source. Its too dark under any other light.

The imager actually works even with a 313nm UVB light source, using the clear filter and 313 or BaaderU. You should still be able to use it with your 330WB80. It takes a single Cr123 battery.

[Andy Perrin]

Update to add: I'm totally wrong about the screen -- I tested it just now and it works fine with the 330WB80 too, so apparently the filter wavelength must have been chosen for some other reason (maybe having to do with fingerprint reflectance).

 

[Andy Perrin]

Update - I just discovered that my RAFCAMERA 52-34.5mm will just fit the eyepiece of the imager.

[Mark Jones]

Not too big a fan of that green and black color palette. looks like the matrix. I realize it's scientific usefullness, but still not a fan.

[Andy Perrin]

Not too big a fan of that green and black color palette. looks like the matrix. I realize it's scientific usefullness, but still not a fan.

 

Haha, just make it monochrome/grayscale, then. We have the technology! The thing is, in UV-C you won’t see any false color anyway apparently, so the screen is not an issue. Just grayscale it. For UV-A, you should use the lens directly on the camera like I did with the flower photos. The only point of the image above was to show the fluorescent screen works fine in UV-A, which I was not expecting.

[dabateman]

Actually,I like that its green our cameras have more green photosites, so will be great when I couple a camera to the back.

Also more calming then the red IR vision I have seen. Blue would be bad.

But maybe just reminds me of really old computer monitors.

 

[Mark Jones]

" I measured the aperture and its the same, almost 2 stops slower than marked.

This is also why F4 is the sharpest setting on my lens. Its really about F8."

 

so any idea why the lens manufacturer did this? or maybe the company modified it for the figerprint viewer application?

 

Seems very restrictive to have a f/4 lens whos' aperture is permanently set to f/8 or smaller. when you opened it up did you see any mechanism for restoring the entier aperture range?

[Andy Perrin]

Seems very restrictive to have a f/4 lens whos' aperture is permanently set to f/8 or smaller. when you opened it up did you see any mechanism for restoring the entier aperture range?

I do not think mine has this restriction. Did you see the flower photos? Those were all the way open, and I wasn't particularly close to the flower. You can see how blurry the background is! No way is that "F/8". Also, my lens is marked F/3.5, not F/4. Maybe we should post photos of our lenses. They may not be the same.

[Mark Jones]

when your lens is all the way open are the aperture blades still visible through the lens?

[Andy Perrin]

Yeah, so I guess it's not quite all the way. But not obscuring half the aperture! I suppose it might be the difference between F3.5 and F4.

 

--

Edit:

Okay, measured from this photo, using the wide part of the hexagon, I'm seeing 50% of the entrance pupil, wide open, so I guess exactly half. I get F/3.96 from that, assuming correct focal length of 60mm.

[Mark Jones]

I've never seen a lens that does not open up all the way. Even a half stop difference is uncalled for. Wonder why this lens has this problem?

[Andy Perrin]

Even a half stop difference is uncalled for. Wonder why this lens has this problem?

Because they can get away with it, since they are selling to the police? Why are you so into running this lens down? You seem really aggrieved! You don't even own it.

 

It seems to work well enough for the purpose I want it for.

[Andy Perrin]

Ok, I'm wrong again - it IS opening all the way. This is viewed from the rear.

[dabateman]

Well almost. See that black disc in the wide open photo, that seems to be limiting the maximum aperture.

When I had mine apart, I didn't see a way to increase it. So I left the disc in.

Anyway, focusing in UVC, what the lens is designed for is really hard. So that extra depth of field is needed.

 

However, the rear phosphor makes focusing easier. I was able to rig my GM5 to it and get some great monochrome images. My filter is exactly the same as Andy's. When I mounted it to my UAT today, focusing was very hard and it doesn't offer much for a wider field. So I have decided to keep this my UVC imager.