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UltravioletPhotography

[Filter Test SEU Gen2 #9B] Longpass Stack Results


Andrea B.

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[update 2018.07.25. Added the (obvious) statements that no Visible or Infrared light is passed by the SEU Gen2 filter beyond 410 nm.]


[Filter Test SEU Gen2 #1] Introduction to the SEU Gen2

[Filter Test SEU Gen2 #2] White Balance, Raw Histogram & Andrea's "White Signature"

[Filter Test SEU Gen2 #3] Filter Speed & A Windy Bull's-eye

[Filter Test SEU Gen2 #4] Dealing with the Usual Dichroic Effects

[Filter Test SEU Gen2 #5] Landscape Interlude

[Filter Test SEU Gen2 #6] Monochrome Museum Comparison

[Filter Test SEU Gen2 #7] Measured Filter Transmission

[Filter Test SEU Gen2 #8] Dichroic Reflection Detour

[Filter Test SEU Gen2 #9A] Longpass Stack Wandering Discussion. See #9B for results.

[Filter Test SEU Gen2 #9B] Longpass Stack Results

[Filter Test SEU Gen2 #10] What good is a filter test without a Rudbeckia?

[Filter Test SEU Gen2 #11] A Fascinating New Rudbeckian View

[Filter Test SEU Gen2 #12] Summary


 

Longpass Stack Results

 

Gear: D610 + UV-Nikkor 105/4.5 + SEU Gen2 + Sunlight

 

The first UV-only photo made with the SEU Gen2 was given an exposure which centered the brightness histogram. Each subsequent stacked filter photo was made at the same exposure.

 

Added 2018.07.27: All 12 photos shown in the three composites are straight out of the camera and are meant to show that either there was an image formed or there was not an image formed.

 

SEU Gen2 + Schott GG Longpass Filter (2.0mm): Composite_1

f/8 for 1/15" @ ISO-400

 

UPDATE 31 October 2018: I was too hasty with my original comment. I did not pay attention to the GG400 tolerances as given by the Schott data sheet. So I've crossed out the old comment and replaced it with a correct comment. Thanks to interested readers for pointing this out to me. I value that kind of feedback.

 

The SEU Gen2 transmission chart indicates some potential violet light passed between 400-406nm. We see this also in transmission charts for the BaaderU or for Hoya U-360 glass, for example. So this is no surprise. But the tolerances of the GG400 filter glass as given by Schott are not tight enough to say with certainty that the violet light affects an SEU Gen2 photograph (or BaaderU or U-360 stack photographs). There can be up to a 6 nm variance in the cut-on wavelength of GG400 glass. In retospect, I should have probably not shown this photo set because I do not have an actual measured transmission for my particular GG400 filter.

 

The SEU Gen2 transmission chart indicates some violet light is passed. That is evident here in the GG395 and GG400 photos. As shown in the SEU Gen2 transmission chart on the product page the violet light is between 400-406 nm. Many UV-pass filters pass are suspected of passing small amounts of violet light [just past 400nm]. I do not have a longpass filter between 400 nm and 420 nm to show that by 410 nm there is no violet light passed.

longpassComposite1.jpg

 

 

SEU Gen2 + Schott GG Longpass Filter (2.0mm): Composite_2

f/8 for 1/15" @ ISO-400

There is no Visible or Infrared Light leakage.

longpassComposite2.jpg

 

 

SEU Gen2 + Schott RG Longpass Filter (2.0mm): Composite_3

f/4.5 for 1/40" @ ISO-400

There is no Visible or Infrared Light leakage.

longpassComosite3.jpg

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