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  #1  
Old 19th September 2014, 10:33 PM
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Reinhold Reinhold is offline
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Default Filter Spectral Graphs

For those folks who are uncertain which filter to use, here are spectral graphs for various filters.

A filters effect on the photographic negative depends heavily on the type of film you're shooting.
In other words... the emulsion's spectral sensitivity should be taken into consideration when selecting a filter, especially when using non-panchromatic films.

Consult your films data sheet for it's spectral response curve and compare it to each filters curve.

The heavy dark line is the filters transmission on a 360-750nm colored background.
Panchromatic films are more sensitive to the central portion of the graph.
It's here where most contrast filters are used (Yellow-green/ Orange/Red).

If you're shooting paper negatives, the Blue/Green part of the graph is most important.
Yellow/Orange/Red filters are nothing more than safe lights in this case.

The dashed line represents the spectral response for Ilford's Ortho Plus film.
This film can only see Blue/Green light... Yellow/Red filters are mostly useless.

The 380-520nm area defines the spectral response for typical wet plate (collodion) emulsions.
A Blue filter may make focusing easier by blocking out the distracting Yellow/Red component.

Reinhold
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File Type: pdf Yel-O-G-B-R.graphs. HZ.pdf (878.3 KB, 1692 views)
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  #2  
Old 8th December 2022, 09:14 PM
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Petrochemist Petrochemist is offline
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I know this is a very old thread, but my tuppenny's worth might be useful here

I work with spectra & have interests in ultra violet / infra red imaging, so have made use of equipment at work & the internet to build up quite a library of spectra for filters & even lenses.

The spectra I have are not as nicely presented as these (no colours overlaid) and generally lack spectral response for papers/negatives (for the time being at least blame my digital background).

The filters shown above are generally far from normal spectra for filters of these colours, yellow, orange & red filters being mainly longpass types that block shorter wavelengths almost entirely then go through a fairly rapid transition to transmit the vast majority of the longer wavelengths...

So I thought I'd share a resource I've found on archive.org. They have several copies of the 'Kodak Wratten handbook' which shows the spectra for just about all the filters in the extensive Wratten range. Many other filter manufacturers use the wratten numbers to identify filters so despite the age of the original works the information is still relevant.
I don't have a specific link to hand & being a newbie I may not be permitted to share one anyway (this is common on other forums) but the info above should make it easy to locate using archive.org's search function
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Old 11th April 2023, 01:59 PM
Mark J Mark J is offline
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Having a link to the Wratten filter book would be very useful. I have a copy of the book at work, but a pdf copy for use at home would be nice. i was looking for this only a week or two back, came up blank, but didn't try looking on archive websites.
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  #4  
Old 23rd May 2023, 08:25 PM
Mark J Mark J is offline
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Here are the Wratten 2 data.
There are one or two interesting ones from the older series missing - eg. the 13. I will try & get a paper scan of that one.

https://www.kodak.com/en/motion/page/wratten-2-filters
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Old 24th May 2023, 01:54 AM
Molli Molli is offline
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I hope the following files may be of use:


Kodak Reference Handbook via archive.org:

https://archive.org/download/KodakRe...ceHandbook.pdf

(Be aware, this file is almost 78mb in size)
Information about Filters starts on pdf page number 162 and runs through to 179.




The rescued files below come via 125px.com:

Transmission of Wratten Filters

https://125px.com/docs/unsorted/koda...%20filters.pdf



Kodak Filters (Kodak Data Sheet July 1999 B3AKIC)

https://125px.com/docs/techpubs/kodak/b3akic.pdf



Kodak News October 2015
Selected Kodak Filters Discontinued

https://125px.com/docs/motionpicture...0100215__Q.pdf
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Old 24th May 2023, 02:10 AM
Molli Molli is offline
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I hope the following files may be of use:


Kodak Reference Handbook via archive.org:

https://archive.org/download/KodakRe...ceHandbook.pdf

(Be aware, this file is almost 78mb in size)
Information about Filters starts on pdf page number 162 and runs through to 179.




The rescued files below come via 125px.com:

Transmission of Wratten Filters

https://125px.com/docs/unsorted/koda...%20filters.pdf



Kodak Filters (Kodak Data Sheet July 1999 B3AKIC)

https://125px.com/docs/techpubs/kodak/b3akic.pdf



Kodak News October 2015
Selected Kodak Filters Discontinued

https://125px.com/docs/motionpicture...0100215__Q.pdf
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  #7  
Old 27th May 2023, 06:55 PM
Mark J Mark J is offline
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Thanks, some nice info there.
That Kodak handbook has loads of interesting information it's like a short course in optics !
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  #8  
Old 27th May 2023, 10:02 PM
Molli Molli is offline
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Quote:
Originally Posted by Mark J View Post
Thanks, some nice info there.
That Kodak handbook has loads of interesting information it's like a short course in optics !
Kodak put out so many guides and reference booklets from the time the company started until they decided to more or less dump film and paper and "focus" on failing in the digital realm. They did have most of the pamphlets and all of their film and paper data sheets online, but a site revamp a couple of years ago either failed to move the files over and/or broke the links making everything impossible to find.

I can't recall who runs 125px.com - Tom Someone? - but they've done a fantastic job of saving so much information that Kodak once made freely and readily available.

archive.org is your best bet for the more vintage elements. If you use Eastman Kodak as your search term or even just Eastman Co. you'll find all of the old Kodakery booklets as well as every other edition of "How To Make Good Pictures".

To anyone who's muddled their way through all of the above (and survived) be aware that The Internet Archive is under serious threat by publishers who claim that they're in breach of copyright. Those books still in copyright are only available to borrow - not copy - just like any other library.
The Internet Archive is also responsible for The Wayback Machine. Its existence is pretty much the ONLY reason we haven't lost access to all of the amazingly knowledgeable, curious, inventive, creative and generous people who have shared their experience, experiments and insights with the world through blogs and forums. When the forums fold or the website creator dies, without the Internet Archives and the Wayback Machine, all of their knowledge dies with them.

Apologies, I know that probably wasn't where you were all expecting a discussion on the spectral response of camera filters to go, but I think it's important to keep all of this learning alive and accessible.
None of us here probably need much encouragement to appreciate history, and even less do we need encouragement to hoard treasures - but if you value education and the preservation and passing on of knowledge, and believe it should be accessible to everyone, please find ways to support those who do the preserving, educating and sharing.

(Too much? &#128578
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  #9  
Old 28th May 2023, 03:43 AM
MattKing MattKing is offline
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Quote:
Originally Posted by Molli View Post

I can't recall who runs 125px.com - Tom Someone? - but they've done a fantastic job of saving so much information that Kodak once made freely and readily available.
That is Tim Gray, whose in his day job apparently works for NASA!
If you are looking for stuff there, and can't find it in the section reserved for Kodak, it is worthwhile using the search tool, because he has quite a bit more Kodak related material that hasn't made its way to being catalogued under the Kodak heading.
There is also a bunch of non-Kodak stuff there.
By the way, there are also a number of internet orphans still around - parts of what was once part of the Eastman Kodak internet presence relating to various international subsidiaries - but for some reason show up and are still usable if you search for them.
The bankruptcy is what made so much of this nearly disappear.
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