Custom made IR-block filters for C920 case
In addition to Logitech C920 case since now I have also custom made IR blocking filters. These are high quality thin (0.2mm) optical glass filters that blocks all IR light. Picture quality is as good as original filter sourced from Logitech lens assembly, well quality is good enough but filtering range is not that good. First batch mistake – working on improvements.
What is it
In case you missed blog post about custom Logitech C920 case this IR filter is to be used with it. After modification original lens assembly must be removed. IR block filter gets removed as well. Because original filter is not large enough it is impossible to attach it to aluminium case, so I have designed and ordered custom IR-blocking filters. I am offering these in addition to kit already available.
Mounting options
Filter is designed to be mounted on aluminium case itself, so image sensor and lens are untouched.
There are two options to mount:
Filter dimensions and mounting options
- Closer to lens – better option because dust settled on IR filter will be invisible in final image.
- Closer to image sensor -there some lenses (mostly cheap ones) that protrude further to sensor and can collide to IR filter.
How to mount
There are multiple mounting options, I used “3M 300LSE Double Sided Transparent Adhesive Tape for Cell Phone LCD Repair”. It is very thin and narrow. Also filter can be glued to case. Most of glues meant for glass/metal will work, just don’t use “super glue” (glue based on cyanoacrylate) or other that leaves residue when evaporating.
Update 2014-10-24
After some analysis of existing camera hot mirror / low pass filters (which should have been done before ordering filters) noticed that filter is beyond visible range above 50nm. See chart below. Anyway this filter looks like hoya filter.
Compare light transfer curves
I am also working on IR high pass (for filtering out visible light and passing through IR) and green (for laser) filters. If you are interested in in some other specific ones, leave a note.
Update 2014-10-26 -various filters mounted on camera
No Filter
Original C920 filter IR-cut
IR-700-cut custom made filter
Green-pass
Green-pass + IR-cut
IR-pass
UV-pass + IR-cut
Update 2014-10-29 – measured filters
C920 original filter compared to IR-700. About 50nm of IR is allowed to pass to sensor.
Update 2014-12-03 – received IR650
Received new filters that perform like original C920.
Here is sample picture
Compare new filter against no filter. Results are perfect!
Hmm… looks like expectations were to high and IR range is not blocked well enough. Logitech C920 still has reddish tint. Next week I am arranging lab time to measure spectral response and post results.
Looking forward to this filter.
And looking forward to the result, hope u share your output original and filtered image.
Hi Khairi, that’s my intention. I would like to measure and share analysis of these filters.
Preliminary data show that I have specified slightly wrong transmission curve. These filters cut light above 700nm (T50%=698nm), and curve is very steep. So range between roughly 650nm and 700nm still gets passed and most modern cameras have soft transition in this region. Though it is perfect to have these filters in addition, they pass to much of IR.
Anyway extensive tests will be done next week.
Here is approximate transfer curve:
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any news about ir ?
thank you !
Hi Oleg, waiting for them to to be manufactured. I think it will take 3-4 weeks to receive.
Received new batch of IR650 filters. These filters are like original C920 but made according to my specifications. These are designed to be used with C920 aluminium enclosure and gives best performance.
nice! can i have 6 ? :)
Sure. Check your email for details.
From now on, filters can be acquired on ebay: http://www.ebay.com/itm/151504338358
Also there is possibility to make your own custom filter of any required specifications (IR high pass, green, UV pass, etc.).
I ordered two cases and IR filters and I am very happy with the quality and design. I am interested in other filter as well. Do you have any plan to make a dual filter switch like this http://www.globalsources.com/si/AS/Shenzhen-Nordson/6008835324099/pdtl/IR-CUT-Filter-switch/1063298279.htm or even a rotate-able multi filter switch with a motor.
Hi Masoud, glad to hear. I have plans of adding filter like this to freshly designed camera. At the moment I am not sure of some details, but in any way this feature is planned. C920 camera has no control circuitry so switching filter can not be used.
Where can I buy a filter? eBay says the auction has closed.
Dear Doug, I have ordered new batch of these filters. Expecting to receive them in a 2-3 weeks.
Dear Doug, filters are available again. Please check ebay listings.
hi, i have c920 and i want to use it in night vision project with IR illimunator, what this filter for? is it for both using in day and night?
Hi Serkan,
* IR LOW PASS filter is used if you need to see only visible light with correct colors
* IR HIGH PASS filter is used if you need to see only infrared light.
If you don’t use any filters camera sensitivity should be highest (what is usually done in most surveillance cameras)
—
BR,
Saulius
Hi Saulius, I am at university doing an experiment using a logitech c920. We are attempting to create a light spectrometer and so we need to perform a test to find the spectral response of the camera.
If you are willing to tell us how you tested your c920 and produced the graph above, it would allow us to compare your results to our own future results.
Many thanks
Simon
Hi Simon,
I used laboratory grade spectrometer to measure filter transmission response. It has nothing related to camera response characteristics.
—
BR,
Saulius