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Shane

The ICF Database - Not all ICF are created equally

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Although the subject title is pretty obvious, the following two ICF (Internal Cut Filter) spectra illustrate the extreme variation that can occur between models.

I would like to create a database of ICF spectra for the various makes and models but this would require a collection of ICF which would obviously be a difficult and expensive undertaking. However, if anyone has an unwanted, damaged or broken ICF, that they would like to "donate" to the project I would be grateful. Please contact me via email if you can help.

Thanks.

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Shane

www.beyondvisible.com

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Guest kds315

© astrosurf.org given in Angstroms (divide by 10 to get nm)

nikon.png

canon.png

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Guest kds315

As measured today:

- Nikon D70 ICF (violet)

- Makario ext. ICF (turquiose)

- Schott BG40 (white)

Cut-on for the last two is about 320nm, Nikon is ca. 335nm

I prefer to use the BG40 since it damps NIR very well but allows UV to pass.

Also useful to be used with a normal UV transmissive, absorbing filter like

Schott UG1 for instance to suppress NIR leakage.

post-92-129983468926_thumb.jpg

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Thanks for posting these Klaus. I actually have a D70 ICF here (courtesy of Bob) but you beat me to the posting. I have often wondered if the D70 curve posted on astrosurf was correct as I would have expected more of a sharp cut-off at the red end, however your spectrum appears very similar. It would also appear that the Makario ICF is a pretty good match at both ends considering the cut-off for the modified D70 sensor appears to be around 320nm.


Shane

www.beyondvisible.com

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I have ICF from D40X. Interested? Send me yours adress!

And

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Guest kds315

Most welcome Shane. I have made tests using the Makario filter and

indeed it works pretty well and allows to use a mod. camera as if it

were an "off the shelf" one. It is a bit on the cold side (as is the BG40)

but a simple WB adjustment makes it work perfectly.

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It is a bit on the cold side (as is the BG40) but a simple WB adjustment makes it work perfectly

To be expected from the additional UV but it is good to know that it is easily compensated for with WB adjustment.


Shane

www.beyondvisible.com

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From the D200 ICF it is obvious why this must be modified for UV photography. I would really like to compare these ICF transmission spectra with the Nikon D40 if anyone has one.

post-558-129983470305_thumb.jpg


Shane

www.beyondvisible.com

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Guest kds315

Well that surely explains a lot. Thanks Shane.

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Thanks to Andrea, Bob Friedman and Andrew (Poland) for contributing their ICFs for the project.


Shane

www.beyondvisible.com

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Guest kds315

Since you have the ICF on Adrew, how does the one of his D40 look like?

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Since you have the ICF on Adrew, how does the one of his D40 look like?

I just received the D40X ICF yesterday and will try to run it in the next week or so when time permits. It would be nice to be able to compare it to the D40 if anyone has one. Also looking for Fuji, Canon and Pentax ICF.

I would imagine there are a lot of ICFs from DSLR conversions that are sitting around "collecting dust". They will probably never go back into the camera unless it was self-converted.  After all, if it costs around $400 to get the camera converted, who is likely to spend that again to get it converted back, especially if the camera is showing signs of age.


Shane

www.beyondvisible.com

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Guest Trainwreck

I have the ICF from a D100.

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Nikon D70 Custom ICF for Full Spectrum UV through IR. This appears to be a Schott Borofloat glass which has a slightly higher UV cut-off than the Schott WG280.

post-558-129983472131_thumb.jpg


Shane

www.beyondvisible.com

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Guest kds315

The one I have usaed for my D70 has >90% at 270nm. I find that one shown cuts off a bitg too much of useful response.

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The one I have usaed for my D70 has >90% at 270nm.

Assuming that the sensor can really be effective at that wavelength then I agree. I would at least go for the Schott WG280.


Shane

www.beyondvisible.com

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Guest brianc1959

Assuming that the sensor can really be effective at that wavelength then I agree. I would at least go for the Schott WG280.

Personally, I can't understand why fused silica isn't the standard material for this purpose.  Surely the amount of money saved by using an inferior material is minimal.

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Personally, I can't understand why fused silica isn't the standard material for this purpose.  Surely the amount of money saved by using an inferior material is minimal.

I agree, but for one particular company, who also makes filters, perhaps it is simpler and cheaper just to deal with one supplier i.e. Schott.


Shane

www.beyondvisible.com

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Guest kds315

I asked the company who did my conversion(s) and they recommended that 270nm filter glass (WGxx most likely). Fused silica they did not offer since I asked them for that of course. Maybe it is indeed a supplier issue, since they might get their stuff from an optics wholesaler....Doesn't matter since there is no useful response anyway.

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Guest Vivek

If these (WG270, fused silica, etc) are not coated on both side of the plate, wouldn't it be better not to use them as a cover glass?

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Guest kds315

Who said these were not coated? Mine is...

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Guest Vivek

I didn't say that these filters are uncoated.  Good to know yours is.

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