Manor courtyard in Svaty Jur

[Unscenerie]

Upscale hotel and dining on a hill to vineyards.

 

Sony A7 + Soligor 35/3.5

 

1: IR 

2 and 3: UV with UVROptics NIR blocker + ZWB1 4mm from UVROptics

3: darktable, white-balanced on lit wall

 

This is my first time posting pictures with a 4mm thick ZWB1 I received from UVROptics. 

My impression is that the combination of NIR blocker (3.00mm thick) + ZWB1 (4mm) does a good job of blocking wavelengths other than UV, and the exposure time seems comparable to a Chinese equivalent. I feel like there's an extra glow to the new picture. I am getting to like this new setup. I might wanna rear-mount the filters to combat vignetting.

 

1.

 

2.

 

3.

[ulf]

Rear mounting filters changes the optical path length making the lens focus beyond infinity. 

That that can be compensated by placing the lens further out.

A rear mounted filter stack of 7mm total thickness will need a substantial shift of some mm. 

[nfoto]

A good approximation is focus plane is displaced 1/3 of the filter thickness.

[colinbm]

I like these.
The IR one, the arch on the left has changed the IR colour of the bushes behind it ?

[Unscenerie]

It's important to know that rear mounting filters needs to be compensated with extra space. I'll keep it in mind.

 

@colinbm The IR one, the arch on the left is a window with a reflection of foliage. The window is see-through with the naked eye.

 

 

[Unscenerie]

I'm excited to have an IR blocker (NIR blocker from UVROptics) that can potentially let me see deeper (into the UV-B maybe?). I've only had experience with TSN575 as an IR blocker, and I enjoyed it, but my next question with be, will the pictures look different?

[Andy Perrin]

Ulf found that the NIR blocker from UVROptics was not especially great compared to known alternatives like S8612 2mm. It will definitely NOT let you see UV-B. If you read the existing threads on UV-B then you will see that to get there requires a monochrome sensor and a lot of filtration designed for UV-B specifically.
 

This filter will let you see UV-A in combination with a UV-pass filter. If you are interested in UV-B, start by getting a debayered camera!

[ulf]

The penalty for using a filter like the TSN575 is minors as all sensors have more sensitivity close to visual, most lenses drop in transmission and sunlight contains less and less light into UV, starting already at 400nm.

A filter stack with UG11 2mm and BG39 2mm will give a slightly deeper filter transmission with the Soligor, but I would not expect a dramatic difference in the images.

 

To get a filter with a deeper UV reach that also attenuates the upper UV-A and the IR-peak near 700nm, I have found that the ZWB1, 8mm works well.

However the images were impossible to WB when taken with any accidental deeper reaching lens like Focotar-2 50mm. 

Only with my deep UV-reaching simple FS lenses and my UV-Nikkor 105mm that was possible.

[Jorge Garcia]

A monochrome astronomical camera (whithout any internal filter) can be used instead of a debayered sensor?

[Andy Perrin]

Jorge- yes that’s true. You also (as Ulf just alluded) need a lens that passes UV-B, which none of our accidental UV lenses do. You need a quartz or quartz-fluorite lens. If image quality is not a concern, a quartz singlet would work. 

[Unscenerie]

Oops, UV-B is harder to reach than I thought.

 

A filter stack with UG11 2mm and BG39 2mm would probably give a shorter exposure time compared to NIR blocker 3mm + ZWB1 4mm, and perhaps the false colors might not differ so much as I would've imagined.

 

 

 

[Andy Perrin]

UV-B is quite hard to reach. The 340nm range of UV-A is probably the practical minimum for those of of us with Bayer filters and glass lenses. Lukas’s photos from UV-B have shown small differences but not too much to get excited about. The primary reason to seek shorter wavelengths than UV-A would seem to be the increased resolution and surface detail that becomes possible with good quality lenses, since the diffraction is lessened. Jonathan has taken advantage of this for his microscope. 

[lukaszgryglicki]

Also note that many NIR blockers can also block UV-B itself (at least its. lower range) my UV-B stack has no NIR blocker, it just uses brute force to stack 3 filters that pass in UV-B. reas around 340 or 330 can use NIR blocker imho, but starting from 300-310 down NIR blockers also block there... and in 250-260 they block everthing :(

 

[Unscenerie]

I've been aware of the ZWB1 8mm topic, but I thought the glass was too thick for optimal results - and here I am, equipped with a 7mm-thick UV-pass stack trying to get good results... 

 

Interesting comments, everyone.

[lukaszgryglicki]

I have 8mm ZWB1 - I can do some tests if needed, just LMK what do you need.

I think it leaks IR when pushed to the UV-B area.

 

[ulf]

11 hours ago, lukaszgryglicki said:

I have 8mm ZWB1 - I can do some tests if needed, just LMK what do you need.

I think it leaks IR when pushed to the UV-B area.

 

It will likely leak too much when stacked further with an UV-B only-pass filter.

In my setup it worked well only with my deep reaching lenses that gave a wide enough range of false colours to make it possible to do a good WB.

(UV-Nikkor and single element FS DIY-lenses)

 

The main interesting feature of the ZWB1, 8mm is that blocks the upper UV-A wavelengths well.

That is something few other filters do.

If the  upper UV-A wavelengths are not cut away they will dominate the image regardless of how it is WB.

 

An alternative to the ZWB1, 8mm is a stack of two UG11, 4mm or a single UG11, 8mm, but they will be very expensive if at all possible to find.

The UG11 alternative has a bit better OD than the ZWB1, 8mm.

 

[lukaszgryglicki]

Yes it cuts a lot of UV-A because output image mostly have red, then green (color looks orange) and blue is almost pure noiuse - very low levels.

 

[ulf]

You can say the it is the complement (opposite) to the not anymore available dichroic SEU filter series.