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UltravioletPhotography

[Filter Test] 290BP10 UV-Pass


Andrea B.

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I thought I had posted this on NG, but couldn't find it to reference here. So maybe I didn't.

 

D300-broadband with no internal clear glass filter.

290BP10 UV-Pass filter.

Some UV lens, probably either the Ultra-Achro-Tak or the UV-Nikkor. Its written down somewhere but of course I cannot find those notes. (The EXIF is incorrect about the 58mm.) ((Bjørn will now remind me to chip my lenses. :D ))

 

A pair of grocery store Sunflowers in the sunlight.

 

Visible with Baader UVIR-Cut Filter

f/5.6 for 1/4000" @ Iso200

helianthusCultivarPair_VisSun043011wf_18070pn.jpg

 

UV with Baader-U UV-Pass Filter

f/5.6 for 1/2" @ Iso200

This photo is ever so slightly 'flat', I think, because I didn't use the UV-Flash.

helianthusCultivarPair_UVBaaderSun043011wf_18075pn.jpg

 

UV with 293BP10: the original converted to jpg, no edits, no attempt to white balance.

f/5.6 for 156" @ Iso200 with Incandescent WB

1sunflowerPairUV290Sun043011wf_18094orig.jpg

 

UV with 293BP10 Edit 1: tweak contrast.

2sunflowerPairUV290Sun043011wf_18094_contrast.jpg

 

UV with 293BP10 Edit 2: tweak B/W points, shadows.

3sunflowerPairUV290Sun043011wf_18094_BWPts.jpg

 

UV with 293BP10 Edit 3: boost saturation, play with colours a bit.

This revealed a light leak? I was holding the filter onto the lens by hand.

4sunflowerPairUV290Sun043011wf_18094_saturation.jpg

 

UV with 293BP10 Edit 4: deal with noise.

5sunflowerPairUV290Sun043011wf_18094_noise.jpg

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Another editing attempt of the 293BP10 photo in Photo Ninja .

Not so great.

 

helianthusCultivarPair_UV290Sun043011wf_18094origpn.jpg

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Thanks Andrea,

 

I remember seing these pictures long ago. Who manufactured your 290BP10 filter?

I am asking because I have just tested the 280BP10 filter from eBay (item number 150941002885).

Unfortunately, it leaks so much UV in 310-330 nm range that it is useless for any serious testing.

I can take pictures with it through one of my UV-capable enlarger lenses!

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I finally found the NG link: http://nikongear.com/live/index.php/topic/33120-uv-290nm-filter-experiment/

In that thread Klaus said that he thought the 293BP10 was an Omegafilter.

 

I also saw that I had used the UV-Nikkor to make the fotos. So I will amend the OP above to state that.

 

Unfortunately, I don't really have a way to test whether this filter leaks in the 310-330 range. If it does leak in the low 300s and the D300 exposure needed 2.6 minutes anyway, then that certainly indicates even more strongly that the D300 is not useful around 300nm. Remember the D300 had no clear glass internal filter.

 

Just in case anyone wants to see it stated --> hand-holding a filter to the lens is not good practice. :D :D

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Thanks Andrea, good info.

You say that the Nikon D300 camera, has no cover glass on the sensor ?

How are the micro-lenses & CFA protected ?

Col

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Protected from what ?? :D

 

We primarily need an internal clear filter over the sensor pack to maintain focus depth when not using Live View.

But I don't want to sound flippant. I do not recommend going without a clear filter because dust or pollen can get in there

and must be cleaned off -- thus creating a risk of scratching any coatings on the surface of the sensor pack.

 

The surface of the D300 sensor pack is smooth but has a slightly different feel from glass.

 

My original conversion of the D300 used LifePixel's Standard IR filter.

When I realized the D700 was a flop as a broadband,

I removed the D300's IR filter myself and started using it for UV/IR with external filters.

And subsequently never got around to sending the D300 in for "re-modification" to add a clear filter.

 

The D300 filterless sensor has always cleaned up nicely, but I am careful.

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Andrea said "Protected from what ?? :D"............from you :D

If the sensor is open to the elements the fine gold connections will be exposed & very vulnerable to shorting & breakage.

I can't imagine the micro-lenses are that easy to clean either ?

Col

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Colin, please do not jump into conclusions and re-read what Andrea says.

 

"Clear glass internal filter" is just a piece of "glass" (often N-BK7 or fused silica) that is used to replace the "internal cut filter" for full-spectrum converted cameras. Noone touched the sensor cover glass in her D300, which is part of the "sensor pack".

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Unfortunately, I don't really have a way to test whether this filter leaks in the 310-330 range. If it does leak in the low 300s and the D300 exposure needed 2.6 minutes anyway, then that certainly indicates even more strongly that the D300 is not useful around 300nm. Remember the D300 had no clear glass internal filter.

 

In my case, the exposures were just few seconds for the 280BP10 mounted directly in front of the sensor and pointed at the horizon, which included some clear sky and soem trees. When I added an enlarger lens on top of that, the exposure reached about 20-30 seconds for the same view (sky plus trees). I will redo the test this weekend much more carefully and with more appropriate test subject, so please do not read too much into what I just said.

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I should have been a bit clearer about the top of the sensor pack not showing the 'raw' parts after internal filters are removed. The sensor pack is protected, but I was never sure whether there was a kind of glass fused to the top of the sensor pack or whether there was perhaps some kind of "coating" fused to it. As mentioned the D300 sensor top feels smooth but also feels a tad more 'draggy' than glass. (IIRC, it's been awhile.)

 

I have looked through some patent descriptions and some sensor diagrams, but did not find mention of glass fused to top of the sensor pack. When you have the sensor board out of the camera and look from the side, some layering is apparent from a side view.

 

 

Andrea said "Protected from what ?? :lol:"............from you ;)

I have to laugh!! You know, I was very bold for awhile about opening up my cameras and removing internal filters and trying other filters. There is nothing magic about opening up a DSLR and unseating/reseating ribbon cables and other connectors as long as one takes due care to work on an anti-static mat with a wrist strap. And keep track of where all the parts fit.

 

Somewhere I mention that I put the old 1.25" Baader Venus filter into the D300 with no trimming or cutting. It worked quite well except, of course, for the obvious flaw of that old Venus - it bleeds IR all over the place. I was always going to purchase a proper Baader-U in the 1.25" size and dedicate the D300 permanently to UV. Never got around to it.

 

However, my camera modification career was abandoned when I blew a board in TWO D7000s in a row. :lol: :P :D The repairs were about $160(US) each so it wasn't too bad. But I was very embarrassed!

 

Dust issues are a hazard in DIY. And there certainly could be problems with getting the sensor board out of alignment which would create focus issues on the image plane. So I've abandoned DIY broadband modification altogether.

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The "cover glass" is typically bonded to the package that houses the actual sensor and not to the sensor surface. It is very thin and therefore somewhat fragile. Its purpose is to protect the fragile bond wires and sensor surface from physical damage as well as dust and moisture. Typical cut-off is around 300nm for the cover glass.
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Well that pretty much seals the fate of using our DSLRs below 300nm !!!!

And pretty much explains the difficulty I had in getting that Sunflower shot with that 290BP10.

Good to know.

 

And sad to know. Unless someone is bold enough to try to remove that 'cover glass' and replace it with something more UV transmittable.

 

I wonder how the MaxMax guy is reaching the Bayer filter to leach out the dyes? Maybe he has figured out how to get rid of the 'cover glass'?? Maybe the dyes don't need to be leached out at all for better UV transmission??? Maybe just getting rid of the cover glass would do it????

 

Hmmmm........maybe I'll haul out the retired D300 for another look inside.

 

ADDED LATER: I need to add a few of these new facts to the Sticky in the section about camera modification. Thanks Alex and Shane for providing UVP with some facts. :lol: :lol: ;) :D I'm a good student, ya know !!

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"De-Bayering" a camera requires removal of the cover glass but it is very risky. If the glass breaks it can damage bond wires and sensor surface.

 

Making a monochrome sensor from a "Bayer" sensor requires removal of the Bayer dyes and the microlenses. Most methods seem to involve mechanical "abrasion". There are rumours of plasma etching but I have a hard time believing them as I have plasma etched semiconductors before for reverse engineering and it is fraught with problems if you need to keep the chip alive. I know of one dangerous chemical that would likely do the job in several seconds but it is explosive and must be performed under strictly controlled conditions.

 

Saw some recent information that someone has success debayering Nikons using hydrocarbon solvents.

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Well nevermind then. I will simply have to force myself to be content with a 300nm limit. :D

 

I added some remarks to the Camera and Modification sections of the Sticky.

(And did a little tidying up.)

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