Filter options for conversions & full spectrum

My mirrorless cameras that have been converted both have 'full spectrum' conversions theoretically allowing them to respond to UV, visible & IR. Which part(s) of the spectrum they end up recording will depend on which filter is fitted to the lens (as well as any absorption from the lens itself - many lenses block UV rather well).

Fortunately I have access to a high grade spectrometer at work so can measure the spectral transmission of filters (and some lenses) myself.
Here are some spectra of useful filters:
Typical IR filters (and a DIY option)

Some adjustable IR options

possible UV options

Options to restore normal use

For those not familiar with spectra, in each case the higher the line is at a given wavelength the more light will get through. If two filters are used together the combination will be the same as multiplying the fractions transmitted of individual filters.

Actual results from a given filter will of course be highly dependant on white balance & post processing, these are all taken via a #25 red filter which is effectively a 650nm.

Andrew Jordan - Infra red panning by Mike Kanssen, on Flickr

Infra red Photowalk by Mike Kanssen, on Flickr

Bee in infra red by Mike Kanssen, on Flickr

St Mary's entrance by Mike Kanssen, on Flickr

P1160561d by Mike Kanssen, on Flickr

P1160553 by Mike Kanssen, on Flickr

The last three using hue adjustment (a red/blue channel swap is more commonly done)

And a few images from oddball filters:
Variable ND filter (similar to a 850nm)
PK 28mm vari ND by Mike Kanssen, on Flickr

Unexposed & processed B&W film negative (Roughly 800nm equivalent)
IR via negative by Mike Kanssen, on Flickr

Through the magnetic part of a floppy disk (quite poor transmission)
IR via diskette by Mike Kanssen, on Flickr

without a filter (IR & visual both recorded the team outfits are visibly black & orange)
Full Spectrum grid by Mike Kanssen, on Flickr

via a Schott U330 filter (UV & some IR)
Crocuses by IR1 by Mike Kanssen, on Flickr

via a Schott BG3 filter (UV, blue & IR)
aP1040238 by Mike Kanssen, on Flickr

Has anyone had a satisfactory experience with a UV filter/lens combination yet? I've tried using a B+W UV pass filter and found it transmits more IR than UV with my informal testing/shooting.

There are some modern UV pass filters that have been coated to block IR transmission, sadly they are well out of my price range.
Converted cameras are usually more sensitive to IR than UV so even filters like the schott U340 that transmit more UV than IR show significant IR character.

It's definitely a challenge, if you're on a budget, but stacking a U330 & a bg39 should work, with the right lens & camera (my GF2 whilst full spectrum seems to give less UV than my full spectrum A7ii. I must have another serious try at UV this summer...

Lots of lenses attenuate heavily in the near UV. The Coastal Optical 60/4 does not.

Interesting, I’ve also been using a GF2 full spectrum conversion. I’m planning to upgrade to an E-M5 mkIII soon, maybe that will help.

Heh, that lens has been on my wish list for a while. Alas, it is currently out of my budget. Based on my research, it seems like there are a lot of older 35mm f/3.5 designs which were more able to transmit UV but I have yet to find one which works well for me. Thanks for the suggestion though!

It may be down to some conversion services describing a camera as full spectrum, when the internal cut filter is replaced with glass (IMO that's a 2 spectrum conversion as the glass absorbs UV). My GF2 was pre-converted so I don't know the details, while my A7ii had quartz used for the replacement to maximize UV.
The remainder of the sensor stack on MFT is also quite thick so this may be a factor.

When it comes to lenses all those designed for UV photography are many times my budget. The metal bodied 'El-Nikkor' enlarging lenses are highly recommended by Dr Klaus Schmitt (his website is great on UV photography). Another I've found to transmit reasonably well is a Fujian 35mm/1.7 lens (c-mount & quite affordable). Both of these reach around 50% transmission at 350nm & give some transmission at 325nm.

I have brought a few bare quartz elements & will eventually get round to trying these. UV transmission should be excellent, focus will doubtless vary with wavelength but for UV only a relatively narrow wavelength range is all I'll be able to get, so hopefully it won't be an issue.

Finally got that wish to have a dedicated IR thread! Great to see you over here, wow your posts in this thread are full of interesting response curves and samples, It's going to take me some time to look into them more deeply and absorb all that information.

Thanks for posting those curves, there's so little good info like that available. I'd really like to see the response curves of some of the raw filters I have and some of the combos I've been trying out as a result of those candy pink threads over in the dpreview forums. Clearly the cutoffs of some filters aren't what's advertised, and it'd be nice see what they really are. It's especially interesting to see the curves for materials we might even have thought of as IR filters!

Love this shot Mike!

I only recently got my conversion to 590 back from Kolari and the weather here hasn't been all that great.

Thanks Gary.
590nm is my favorite filter, and would be the conversion I'd have gone with if full spectrum wasn't available.
It's capable of giving reasonable monochrome when the lights good, and you can add an external filter if you want to play with more restrictive conversions. In addition there's lots it can do with false colour as you've already found out :)

Trying to repost transmission data I determined years ago (from another IR forum): sadly the BBcode for tables doesn't work here (yet). It's nearly unreadable without this but comma separated variable might work for some of you (it can be imported to most spreadsheet packages):

I've built up a collection of spectra for quite a range of filters & may as well share the data here.
To Begin with IR filters, normal Photography (& astronomy) filters, related technical glasses & IR blocking filters.
All IR filters I tested other than the 850nm were from Rocolax (Cheap).
Where I have several sizes these were measured separately & are show to give an idea of batch/test variation.

A yes entry in Web data means I've not checked it myself just found the data on the web, otherwise they are my measurements of filters I have available.
? means that value not measured.

Filter, web-data, 300nm, 350nm, 400nm, 500nm, 600nm, 700nm, 750nm, 800nm, 900nm, 1000nm, 1100nm, notes
650nm IR filter, no, 0, 0, 0, 0, 0, 91%, 91%, 91%, 91%, 91%, 91%, sharp transition 50% @~650nm
Another 650nm, no, 0, 0, 0, 0, 0.7%, 91%, 91%, 91%, 91%, 91%, ?, 10% @ 638nm
680mn IR filter, no, 0, 0, 0, 0, 0.01%, 85%, 88%, 89%, 90%, 90%, ?, 10% @~665nm
Another 680nm, no, 0, 0, 0, 0, 0, 84%, 87%, 88%, 89%, 89%, 89%, sharp transition 50% @~675nm, 69% @ 680nm
720nm IR filter, no, 0, 0, 0, 0, 0.04%, 53%, 89%, 89%, 89%, 89%, ?, 10% @ 680nm
850nm IR filter, no, 0, 0, 0, 0, 0, 0.1%, 0.5%, 9%, 90%, 90%, ?, Different supplier
950nm IR filter, no, 0, 0, 0, 0, 0, 0, 0, 0.4%, 20%, 58%, 76%, slow transition '~40%@950nm'
Another 950nm, no, 0, 0, 0, 0, 0, 0, 0, 0.2%, 14%, 51%, 71%, 33% at 950nm
SuperBlue (Public Labs), YES, 90%, 98.5%, 95%, 5%, 0%, 30%, 98.5%, 99%, 98.7%, 94%, ?, Values from 'Public Labs website. (max transmission very high)
SuperBlue (Life Pixel), YES, 83%, 91%, 88%, 3%, 0%, 25%, 91%, 91%, 91%, ?, ?, more believable values from Life pixels website
Hoya Yellow K2, no, 0, 0, 0.1%, 87%, 97%, 96%, 96%, 96%, 95%, 94%, 94%, Effectively ~485nm IR
Hoya Orange O(G), no, 0, 0, 0, 0.02%, 97%, 96%, 96%, 95%, 94%, 94%, 94%, ~530nm IR Sharp 20% @ 530, 50% @537
Orange 23A filter, no, 0, ?, 0.15%, 0.03%, 92%, 92%, 92%, 92%, 92%, 92%, ?
Red 25A filter, no, 0, ?, 0, 0.01%, 0.4%, 92%, 92%, 92%, 92%, 92%, ?
Hoya 85B 'Warming' filter, no, 0, 0.6%, 4%, 34%, 77%, 77%, 68%, 69%, 87%, 92%, 92%, slow transition with peaks 50% @ 541, 20% @ 435
Hoya Green X1 filter, no, 0, 0, 0.9%, 43%, 18%, 3%, 5%, 5%, 8%, 14%, 23%, Max 60% @533nm 20% @ 471 & 595nm
Cokin Blue A020 (+2 80A), no, 0, 0.7%, 34%, 43%, 13%, 89%, 92%, 92%, 91%, 92%, 92%, 50% @ 665nm 20% @ 375, 550, & 635nm
Cokin Polarising, no, 0, 23%, 34%, 37%, 40%, 44%, 50%, 56%, 73%, 77%, 77%, 20% @ 342nm, many bumps v limited polarization in IR
Hoya Skylight 1A, no, 0, 0, 80%, 84%, 91%, 93%, 92%, 92%, 93%, 93%, 93%, 1% @ 352nm
Didyminium filter 'Red Enhanser', no, 0, 0-95%, 60-95%, 60-95%, 10-96%, ~95%, 35-96%, 20-96%, ~90%, ~90%, ?, Reduces Sodium light Multiple sharp bands
Green 58 filter, no, 0.01%, ?, 0.03%, 35%, 8%, 0.5%, 0.5%, 0.5%, 1%, 2%, ?,
Blue 82A filter, no, ?, ?, 91%, 76%, 33%, 40%, ?, 38%, 42%, 50%, ?,
Light Green No 11 Filter, no, 0, ?, 0.1%, 70%, 72%, 65%, ?, 86%, 87%, 88%, ?,
Schott RG9, no, 0, 0, 0, 0, 0, 0, 82%, 88%, 80%, 59%, ?, Transmits ~720+nm
Schott RG695, no, 0, 0, 0, 0, 0, 66%, 98%, 98%, 97%, 97%, ?, Transmits ~695+nm
Schott OG590, no, 0, 0, 0, 0, 80%, 98%, 97%, 96%, 95%, 94%, ?, Transmits ~590+nm
Schott OG550, no, 0, 0, 0, 0, 91%, 91%, 91%, 91%, 91%, 91%, ?, Transmits ~550+nm V sharp
Schott BG3, no, 77%, 90%, 83%, 0.14%, 0.01%, 11%, 87%, 90%, 88%, 77%, ?, Similar to Super blue
Schott GG495, no, 0, 0, 0, 73%, 99%, 98%, 97%, 96%, 94%, 94%, ?, Transmits ~495+nm
Schott BG12, no, 0.02%, 58%, 80%, 15%, 1%, 8%, 10%, 9%, 11%, 17%, ?, Transmits ~330-500nm
Schott BG24a, YES, 90%, 91%, 89%, 24%, 6%, 85%, 89%, 87%, 83%, 80%, ?,
Schott BG39, no, ?, 59%, 79%, 88%, 52%, 1%, 0.03%, 0, ?, 0, ?, Transmits mainly 350-600nm
Schott BG40, YES, 0, 76%, 88%, 91%, 71%, 10%, 2%, 0.4%, 0.2%, 0.9%, ?, Transmits 320+ with minimal IR
Schott IRC-09, no, 0, 0, 88%, 94%, 93%, 0.7%, 0.2%, 0.3%, 0.3%, 0.5%, ?, Transmits ~390-650nm Hot mirror option
Schott BG18, no, 0, 40%, 70%, 91%, 50%, 1%, 0.1%, 0.01%, 0, 0.01%, ?, Transmits ~330-700nm Hot mirror option
Schott BG38, no, 0, 81%, 88%, 90%, 75%, 22%, 9%, 4%, 2%, 3%, ?, Hot mirror option
Baader UV/IR cut, YES, 0, 0, ~97%, ~97%, ~97%, ~97%, 0, 0, 0, 0, 0, V steep cut off & square profile ~50% @420&680nm ~1% @400& 700 (MAY vary with angle?)
Neewer UV/IR cut held flat as possible, no, 0, 0, 88%, 88%, 94%, 2.4%, 1%, 0.1%, 0.03%, 0, 0, Steep cut transmission varies with angle
Neewer UV/IR as above tilted ~30°, no, 0, 0, 84%, 93%, 93%, 1%, 0.2%, 0%, 0.03%, 0.2%, 6.6%, This shows transmission varies with angle
Sigma SD14 Internal Cut Filter, no, 0, 0, 0, 91%, 93.5%, 0.25%, 0, 0, 0, 0, 0.1%, The camera's easily removable hot mirror/dust protector
Copper sulphate solution (5mm at 50% saturation), YES, >50%, >75%, >80%, >80%, >50%, <0.1%, <0.1%, <0.1%, <0.1%, <0.1%, <0.1%, UV Pass IR block Actual transmission depends on pathlength & conc.

UG11, YES, 87%, 90%, 1%, 0, 0, 20%, 10%, 3%, 1%, 3%, UV pass with IR leakage
U330, no, 88%, 88%, 20%, 0.1%, 0, 45%, 43%, 28%, 26%, 33% , >10% throughout 240-404nm >70% throughout 260-290nm UV pass with IR leakage
U340, no, 73%, 78%, 0.2%, 0, 0, 1.4%, 0.5%, 0.02%, 0, 0, >10% throughout 70-380nm >70% throughout 300-355nm UV pass with IR leakage
U360, YES, 0.3%, 35%, 0.2%, 0, 0, 0.2%, 10%, 1.5%, 2%, 2%, >10% throughout 307-394 max 68% @363nm UV pass with IR leakage

Variable ND at darkest, no, 0, 0, 0, 0, 0, 0, 1.5%, 20%, 73%, 79%, 79%, 1% @730nm & 50% @ 843nm close to 860nm filter
Variable ND at palest, no, 0, 0, 12%, 43%, 47%, 48%, 50%, 57%, 76%, 79%, 79% , 1% @ 393nm about half stop more IR than visual
Variable IR darkest, no, 0, 0, 0, 0, 0.05%, 0.2%, 0.5%, 16%, 68%, 75%, 75%, 1% @ 759nm & 50% @ 856mn again close to 860nm
Variable IR palest, no, 0, 0, 0.3%, 0.04%, 16%, 46%, 48%, 48%, 71%, 75%, 76%, 1% @ 562nm & 50% @ 816mn red with relative enhanced IR
Variable IR intermediate setting, no, 0, 0, 0, 0.01%, 6%, 16%, 18%, 22%, 70%, 75%, 76%, 1% @ 575nm, 50% @ 851mn gives a stepped spectra unlike other filters
Variable control on these basically effects brightness of visual portion

Shade 8 welding glass (~10 stop), no, <0.03%, <0.03%, <0.03%, <0.03%, <0.05%, <0.03%, <0.03%, <0.02%, <0.02%, max 0.1% ~ 560nm
'Minus Green' Gel, no, 0, 60%, 68%, 52%, 70%, 90%, 90%, 90%, 90%, 90%, Transmission starts ~330nm reduces colour cast of welding glass

Floppy Disc material, non 0.003%, 0, 0, 0, 0.09%, 0.9%, 1.6%, 2.1%, 2.6%, 2.9%, 3%, poor transmission but works as IR filter
Unexposed but developed colour negative, no, 0.02%, 0.004%, 0.3%, 0.5%, 2.2%, 0.1%, 0.9%, 24%, 77%, 82%, 83%, Remarkably good DIY IR! 50% ~828nm
Exposed & developed colour negative, no, 0.04%, 0.16%, 3.3%, 18%, 46%, 42%, 53%, 74%, 85%, 87%, 88%, 50% ~740nm
The exposed negative might work as a high colour IR filter by itself, and could potentially be used with unexposed negative for a DIY an IR graduated filter

Note the IR portion of many normal blue & green has been found to vary widely. I now have three X1 filters, one with practically no IR transmission, one with lots of IR & a third that is intermediate.
Red orange & yellow filters are typically long pass types with good IR transmission.

That worked well. Thanks.

Thanks for the information! I created the spreadsheet.

Glad it's looking useful 😀
A few extras now added to the bottom