[lmd91343]

I am just starting UV photography. I have a full spectrum K-01 with UG-1 and Tiffen hot filters over the front of the lens.

I have four lenses that I intend to start with: Takumar Bayonet 135mm f2.5; Takumar Bayonet 28mm f2.8; Takumar Macro 50mm f4 1:1; and Optomax 35mm f3.5.

I am not even sure what is a good exposure. I don't know if the filters are working properly. It takes ISO 800 1/60 second at f4 during clear midday sun to get middle the bracketed of these exposures.

First the 50mm snaps.

Second the 35mm snaps

Last my handheld UV selfies with sunglasses

TIA

Attached Images

View Picture EXIF

File Date

 

View Picture EXIF

File Date

 

View Picture EXIF

File Date

 

View Picture EXIF

File Date

 

View Picture EXIF

File Date

 

View Picture EXIF

File Date

 

View Picture EXIF

File Date

 

View Picture EXIF

File Date

 

[Bob 256]

Some of these exposures look pretty good. Focusing seems to be more of an issue which is not unexpected with UV since the infinity end of most lenses won't focus infinity due to the shorter FL presented by UV light (you can't get the lens close enough to the sensor). Some of those, however look reasonably well focused. One way to check the UV characteristics is to set up a series of LEDs of varying wavelengths. Nowadays, you can get LEDs with wavelengths all the way from infrared, through the visible spectrum, and into the UV end of it. If you set up a row of these (maybe 10-15 different ones) and place a diffuser in front (like frosted plastic), and take some shots at different exposures, you can tell the range of wavelengths that are getting recorded. The other way might be to shoot a spectrum produced by a prism or diffraction grating which breaks the light up. The latter is a little iffy because the light source must contain UV or it won't be in the spectrum. Most incandescent sources should work into the near UV range but they will not produce much deeper into the UV range. Anyway - just food for thought. Your photos are looking good so far.

Keep in mind that a true UV photo will be monochromatic (B&W) since there are no colors involved and the colors shown by your K-01 are due to differences in transmission through the Bayer filter which produces "pseudo" colorization.

[Medex]

Pictures with sunglasses look to me more like infrared but not UV. Normally sunglasses should block UV light, or am I wrong? They should be dark/black in UV light pictures?
To be sure about UV transmission of the lens try sun protection cream on the face and look if you will get darker areas where you applied it. As I know, most normal lenses do not transmit UV light due to coatings.
Next thing is your Tiffen filter on the lens. What exactly it is? What transmission properties it has? You say "hot filter". Do you mean it has Hot mirror properties? If yes, then you block whole UV spectrum.

[milligan22963]

When messing with UV light, I found my normal glasses would look like sun glasses given all of the coatings on them specifically for that. It might be the sunglasses in question do not have any coatings which may indicate a need for different sunglasses if that was what you wanted . I picked up a filter from: https://kolarivision.com/getting-started-uv-photography/ to get me started. I have not been able to get some of the same results as shown on that page but still it is interesting to explore. I also picked up a UV light at a local discount store to increase the amount of UV light.Hyper Tough 24" Fluorescent Black Light, 17 Watts and 31" Mountable Fixture - Walmart.com when looked at in live view, it came across as a light sabre from star wars which was kind of interesting looking also.

[lmd91343]

I tried the sunblock test and it failed. Obviously the sunblock is old and bad or one of the filters are bad.

I tried shining a 395nm flashlight at the unfiltered camera and it appeared as a specular white spot. I took unfiltered snaps and they all looked like images produced by other full spectrum cameras.

As for the Tiffen Hot Mirror filter, its specs indicate that it passes UV. Maybe mine is a counterfeit. A $70 counterfeit?

The UG1 might also be bad. It is opaque to visible light. But how to test it??

[Bob 256]

I tried the sunblock test and it failed. Obviously the sunblock is old and bad or one of the filters are bad.

I tried shining a 395nm flashlight at the unfiltered camera and it appeared as a specular white spot. I took unfiltered snaps and they all looked like images produced by other full spectrum cameras.

As for the Tiffen Hot Mirror filter, its specs indicate that it passes UV. Maybe mine is a counterfeit. A $70 counterfeit?

The UG1 might also be bad. It is opaque to visible light. But how to test it??

The UG1 is a filter which passes UV light but it also passes infrared light, hence the need for a "hot mirror" or a filter which should block infrared light and just allow UV to pass to the camera (the camera sensor is also sensitive to infrared light and you'd be recording a UV/IR image if the infrared is not blocked).

Here's the passband for a typical UV filter showing the infrared issue (see attached image along with a typical IR cutoff filter passband).

You can test your UV filter by shining your UV flashlight through it and see if a florescent material (like florescent orange or yellow) will give off visible light. It should allow the invisible UV light to pass and produce a bright florescence. Your eyeglasses would be expected to appear clear since normal glass is stated as being opaque to UV but that only applies further down in the UV spectrum and normal glass (especially plastic lenses which are used in a lot of sunglasses) is fairly transparent to UV in the 370-400nm range (UV A). UV B & C which is responsible for tanning and skin cancer has shorter wavelengths and is well blocked by regular glass. Tinted glass in cars is less transparent to UV as you might note in your photos. You can test your glasses the same way with the UV flashlight and see how much they dim the florescence when you put them in the UV light path. You can also test the sunblock by smearing a thin film of it on a piece of glass or transparent plastic and doing the same.

Note the shown curves would show results further to the left in the UV but the light source used for testing these filters was lacking in that range so the curves fade to noise.

[lmd91343]

I took two photos of my 395nm light with my Optomax 35mm lens with the UV band pass and hot mirror filters attached in a darkened room. Both had settings of f3.5, 1/10 second, and ISO 100. The Full Spectrum K-01 showed a large blob of specular white. The unconverted K3 III showed a tiny violet dot. This indicates to me that the camera, lens, and filters operate correctly. I have posted a picture below.

Attached Images

View Picture EXIF

File Date

 

[Pufferchung]

You might want to set your K01’s in-camera white balance. If that doesn’t work, then you could try to use another uv + IR filter stack. From your pictures, I think your UV filter and IR filter might not be thick enough.
My first full spectrum is K01, I bought it from an eBay seller from HK, but it only worked for a year (sticky shutter).
So I bought a new KP and converted to full spectrum. I now use my full spectrum KP for UV and UV “Bee Vision” photography.
For UV photography, I recommended 2mm thick Hoya U-340 filter + 2mm thick Schott S8612 filter stack.
Your Optomax 35/3.5 is a good UV lens. You could post your pictures @ ultravioletphotography.com.

[lmd91343]

You might want to set your K01’s in-camera white balance. If that doesn’t work, then you could try to use another uv + IR filter stack. From your pictures, I think your UV filter and IR filter might not be thick enough.
My first full spectrum is K01, I bought it from an eBay seller from HK, but it only worked for a year (sticky shutter).
So I bought a new KP and converted to full spectrum. I now use my full spectrum KP for UV and UV “Bee Vision” photography.
For UV photography, I recommended 2mm thick Hoya U-340 filter + 2mm thick Schott S8612 filter stack.
Your Optomax 35/3.5 is a good UV lens. You could post your pictures @ ultravioletphotography.com.

Thank you,
I will try adjusting the WB then the other filters.

The Tiffen Hot filter is not thick enough?

[Pufferchung]

Thank you,

I will try adjusting the WB then the other filters.

Here is a link on how to adjust in camera WB...a little bit complicated. <> Sticky :: White Balance in UV/IR Photography <> - STICKIES, References & Lists - UltravioletPhotography

The Tiffen Hot filter is not thick enough?

I don't have Tiffen Hot mirror filter so I don't know...but from your picture, looks like your camera picked up a lot of IR...so that means your Tiffen hot mirror filter is not thick enough (or just not good enough).

I bought a Kyoei/Kurbayashi (clone) UV lens from an eBay seller. The lens came with two filters for UV photography. One is ZWB1 2mm (Chinese made UV pass filter) and BG39 2.3mm (Chinese made IR filter).
When I compare the Schott S8612 IR 2mm filter with Chinese BG39 IR 2.3mm filter that I have, I could see the Chinese BG39 2.3 mm filter is not as "blue" as Schott S8612 2mm filter.

If you don't want to spend too much money on a Schott filter, Chinese BG39 2.3mm would works too.

[lmd91343]

I don't have Tiffen Hot mirror filter so I don't know...but from your picture, looks like your camera picked up a lot of IR...so that means your Tiffen hot mirror filter is not thick enough (or just not good enough).

I bought a Kyoei/Kurbayashi (clone) UV lens from an eBay seller. The lens came with two filters for UV photography. One is ZWB1 2mm (Chinese made UV pass filter) and BG39 2.3mm (Chinese made IR filter).
When I compare the Schott S8612 IR 2mm filter with Chinese BG39 IR 2.3mm filter that I have, I could see the Chinese BG39 2.3 mm filter is not as "blue" as Schott S8612 2mm filter.

If you don't want to spend too much money on a Schott filter, Chinese BG39 2.3mm would works too.

I got a Schott BG39 3.1mm thick filter to replace the Tiffen Hot filter and it works! The results look just like other UV photos. You were right on. I tried the sunblock test and it was good.

As an added bonus I found that the old 50mm f4 Takumar 1:1 macro makes a good UV lens. It is much sharper than the Optomax. I'll try the K-mount Takumar Bayonet lenses tommorow.

[Pufferchung]

I got a Schott BG39 3.1mm thick filter to replace the Tiffen Hot filter and it works! The results look just like other UV photos. You were right on. I tried the sunblock test and it was good.

As an added bonus I found that the old 50mm f4 Takumar 1:1 macro makes a good UV lens. It is much sharper than the Optomax. I'll try the K-mount Takumar Bayonet lenses tommorow.

That's wonderful! Glad the filter works!
For most of my UV works, I use Sigma 50mm f2.8 DG Macro (AF lens), Sigma 70mm DG macro f2.8 (AF lens) and Pentax DA 35mm AL f2.4 (AF lens)....plus a few other older MF lenses.
I didn't know 50 mm f4 Takumar macro is a good UV lens, that's wonderful. I'll see if I could find one on Ebay, thank you!

[lmd91343]

Get the oldest, the one that extends to 1:1.

[lmd91343]

Thank you everyone.

I now have a great kit with a filter stack of a 2.0mm thick ZWB2 and a 3.1mm Schott BG-39.

My four lenses are: Takumar 50mm f4 macro 1:1 (oldest model, no coatings); 35mm Optomax; 28mm Takumar Bayonet (no coatings); 135mm Takumar Bayonet (no coatings)

I judged the lenses on four tests: sharpness with high contrast objects (sunlit white on black); tone difference between petals on my BoP flowers; darkness of sunblock patch on my arm. All test were performed with the filter stack on and the same custom set white balance.

Lens. ---------- Sharpness. -- Sunblock. -- Petal color.
Tak 50 macro. ------- 9. ------------ 8. ----------- 8
Optomax. ------------- 6. ----------- 8.5. --------- 9
Tak Bayonet 28. --- 7.5. ----------- 7. ----------- 7
Tak Bayonet 135. --- 7 ------------- 6. ----------- 6

These tests were highly subjective. I had no measuring device to compare one against the other, only my memory as I chimped on the K-01 viewscreen. I am particularly wary of the 135mm results, because of using it at its closest focus. I would have no qualms about using the Takumar 50mm macro for most everything, unless I needed more FOV or slightly more discernment in UV only tones. The Takumar 50mm 1:1 macro is that much better than the others.