Tux4711 Posted September 1 Share #1 Posted September 1 Advertisement (gone after registration) Hello, I use my M 240 with a UV/IR cut filter. I bought this filter when I was still shooting with the M8. After switching to the M 240, I simply left the filter on the lenses for protection. My lay understanding is that the external filter was necessary for the M8, because the sensor lacked a corresponding filter—whether for design reasons or to improve image quality. The M 240 however does not require an external filter, as the sensor is equipped accordingly. Now I wondered whether the extra UV/IR cut filter could affect the image quality in any way. In simple tests, I noticed no difference with or without the filter. Nevertheless, the filter is somehow an additional, quasi-unnecessary layer through which the light must pass to reach the sensor. Does anyone have any experience with this or knowledge about that issue? Link to post Share on other sites More sharing options...
Advertisement Posted September 1 Posted September 1 Hi Tux4711, Take a look here UV/IR Cut Filter on M 240. I'm sure you'll find what you were looking for!
jankap Posted September 1 Share #2 Posted September 1 Just try it. A sunny scene and one exposure with filter and one without. 2 Link to post Share on other sites More sharing options...
darylgo Posted September 1 Share #3 Posted September 1 I used them with all my lenses without any difference from a standard protection filter or without a filter except when shooting into the sun. The sun turns into a non circular blob, and will be more rounded without the filter. The UV/IR will remove the excess IR that all M digital sensors are unable to filter due to the thin filtration in the filter stack of the sensor. In practical terms it makes very little difference if any. 1 Link to post Share on other sites More sharing options...
lct Posted September 1 Share #4 Posted September 1 Got a bit of cyan shift with IR-cut filters on Elmarit 21/2.8 asph and Skopar 21/4 so i quit using those filters on the M240 but i did not try them with other lenses. • M240 + Elmarit 21/2.8 asph, f/2.8, w/o IR-cut filter • M240 + Elmarit 21/2.8 asph, f/2.8, with IR-cut filter 2 Link to post Share on other sites More sharing options...
adan Posted September 2 Share #5 Posted September 2 Exactly. Leica ceased the firmware compensation and support for cyan stains/shift caused by IR filters, when the M9 replaced the M8. Replaced it with the compensation for "Italian flag syndrome" - differential cyan and red shifts due to the slight asymmetry inherent in the Bayer RGGB color filter pattern, especially on full-sized sensors. 1 Link to post Share on other sites More sharing options...
Tux4711 Posted September 2 Author Share #6 Posted September 2 Thank you very much for your helpful answers. I had actually expected that the answer to my question would be that the external filter plays no role at all. I am surprised that it can indeed have an impact, even if this is certainly rather marginal in practice. As recommended, I will experiment from time to time in different situations. Link to post Share on other sites More sharing options...
jaapv Posted September 13 Share #7 Posted September 13 Advertisement (gone after registration) However, when I still used the M240, I had various shoots at noon in the tropics which were totally spoilt by IR contamination and had a non-correctable yellow cast as a result; they had to be converted to B&W. After the M8 this camera is the most IR-sensitive M. In normal circumstances OK, but for instance portraits under IR-rich light will produce purple skin blotches. I would recommend to consider the use of IR cut filters under such conditions. 1 Link to post Share on other sites More sharing options...
frame-it Posted September 13 Share #8 Posted September 13 On 9/2/2025 at 12:05 AM, darylgo said: The UV/IR will remove the excess IR that all M digital sensors are unable to filter due to the thin filtration in the filter stack of the sensor. does it really? i have one on my 90APO and one on my 50lux [since the day i bought them], just for dust protection, and those 2 lenses perform exceptionally on my infrared 850nm converted cameras 1 Link to post Share on other sites More sharing options...
jaapv Posted September 15 Share #9 Posted September 15 Which filter type do you have? If you have? We are talking about IR cut filters here, like B+W 486, not the black IR pass ones like 093 or plain UV filters. Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/424000-uvir-cut-filter-on-m-240/?do=findComment&comment=5863651'>More sharing options...
Tux4711 Posted September 19 Author Share #10 Posted September 19 (edited) Am 15.9.2025 um 11:05 schrieb jaapv: Which filter type do you have? If you have? We are talking about IR cut filters here, like B+W 486, not the black IR pass ones like 093 or plain UV filters. Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! I use (or have used) the B+W 486 filter. Thank you for the figure. What exactly can I see on these curves? Sorry, if the answer is obvious, but I have no idea how to interpret such a chart. Edited September 19 by Tux4711 Link to post Share on other sites More sharing options...
jaapv Posted September 19 Share #11 Posted September 19 You can see that all light outside the visible spectrum (300-700 nm) gets blocked 100%. IR converted cameras need an IR pass filter ( 092/093 for instance) to perform like IR cameras. Otherwise they will work perfectly as normal cameras when combined with a 486 filter. 1 Link to post Share on other sites More sharing options...
jaapv Posted September 19 Share #12 Posted September 19 M8 Hektor 135, 093 filter minimal processing. Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! 2 Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/424000-uvir-cut-filter-on-m-240/?do=findComment&comment=5865492'>More sharing options...
Tux4711 Posted September 19 Author Share #13 Posted September 19 Thank you, interesting photo 🙂 Link to post Share on other sites More sharing options...
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