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UltravioletPhotography

Anyone familiar with this filter?


JCDowdy

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Another strange one ?

Further down the listing it has "The ground and polished piece of optical glass that is used as a base for the filter coating. Schott B270, HB610 or RG610."

The filter ring thread spec is a strange one too, M46 x 1.86mm ??

Col

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enricosavazzi

I did not google around, but there seems to be something wrong with the filter size. An M46 filter ring is not wide enough to contain a standard 2" filter blank. These blanks are usually mounted in M48 rings.

 

The transmission spectrum visible in the picture of the data sheet seems similar to the Asahi Spectra XRR0340:

http://www.asahi-spectra.com/opticalfilters/uv_broad_bandpass_filter.html

 

See also http://savazzi.net/photography/uvpassfilters.html#asahispectra for samples with the XRR0340 filter.

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By dealing directly with the manufacturers and suppliers in China and keeping our overheads low in the UK we are at the forefront of the bargain price supply chain.

 

It had to happen that eventually there would be cheap Chinese knock-offs of the Baader Planetarium and other such filters.

But I see no mention at all of how the IR suppression is achieved. Are there dichroic coatings?

 

Buyer beware unless you have a way to verify the transmission.

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Well, knock-offs they might be, but cheap they are not. Hence an understandable wish of having better data on the filter spectral performance.
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Oh man did I ever misread the price !!!

It is indeed very expensive. Yarg!!!

£249 = US$381 = €318

 

These days the Baader U is running around $350 in the US.

I don't know how anyone is going to be able to afford this UV hobby anymore.

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enricosavazzi

It is indeed expensive enough to be a remounted Asahi Spectra filter.

 

The copper-color is a dielectric coating. The original Asahi Spectra XRR0340 is copper-colored on one side, black on the opposite side (which probably shows the color of the ionic substrate, very likely a U-340 or equivalent).

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The transmission data sheet in the accompanying images and the appearance of the filter are consistent with a UG-11 type dichroic red rejection filter. However, the filters of that type (DUG-11) that I have handled appear much redder, like the Asahi Spectra XRR0340.
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