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The $4.5K Fuji XT-1 Forensics Package Doesn’t Really Create UV Photos

UV photography has many obstacles. Ultraviolet light, or light from 200nm – 400nm in wavelength, is notoriously difficult to image with normal camera equipment. A normal digital camera will record images in the visible light spectrum, or 400nm – 700nm in wavelength. To unlock sensitivity to those shorter wavelengths, a camera has to be physically modified to allow passage of light below 400nm.

We over at Kolari Vision achieve this by performing a full-spectrum conversion service to your camera’s sensor. This modification gives most cameras the needed sensitivity to see UV light, but this is only half the battle. We then have to filter out visible and infrared light or else any UV light coming through the lens will be drowned out by the much more plentiful visible and IR light, and the ultraviolet signal we are looking for will be lost.

This is where a UV bandpass filter comes in. A proper UV pass filter will allow ultraviolet light to pass through to the sensor while blocking all visible and infrared light that may contaminate an otherwise purely UV image. The trouble is, UV light is so easily blocked by most camera optics that even small visible or IR light leaks will overpower the UV light and create a mostly visible or IR image instead.

This is also why it’s important to make sure that you are using a lens with high UV transmission, as most lenses block too much UV and end up allowing IR and Visible light to trickle in and take over the exposure.

The Fuji X-T1 Forensics Bundle

We noticed that the Fuji X-T1 forensics bundle included an old B+W 403 UV bandpass filter in their kit built for UV and IR forensic photography. Knowing the limitations of these style UV filters, we set out to test it and see if it actually works for UV photography.

How can you tell if your UV filter is working properly?

A spectrometer will tell you the exact transmission profile of your filter by plotting a graph visualizing just how much light is managing to pass through and at which wavelengths. Another much easier way to verify if your UV filter is doing the job or not is to know what you’re looking for and check the images. We’re going to demonstrate the latter DIY method here with a set of filters to compare.

For this test, we’ll be comparing our Kolari Vision UV Bandpass Filter to another popular UV passing filter, the B+W 403 Ultraviolet. Alongside these two, we’ll also be testing our 720nm Infrared filter as a control to demonstrate what an intentionally infrared image is supposed to look like.

Test number one will be shot with a Canon 50mm f/1.8 II lens on a Full-Spectrum Sony a6400. Test number two was shot with the Fujifilm 60mm f/2.4 Macro lens (also part of the Fuji Forensics bundle) on a Full-Spectrum Fuji X-T2.

Test #1: Snapshots of our parking lot in strong sunlight

Kolari IR 720nm
B+W 403 Ultraviolet
Kolari UV Bandpass

We can immediately see a clear difference between all 3 filters, and that the B+W 403 is performing much more like a near-infrared filter than a UV Pass filter. Leaves and foliage are usually highly IR reflective leading to bright if not completely white vegetation in infrared images. While producing some different coloration, the 720nm and B+W 403 both prominently display this property.

Our UV pass filter, on the other hand, creates very dark if not black foliage. We can also see that the most UV reflective object in the frame is the siding of our building. This is likely due to a UV reflective treatment to the siding to protect from long term sun damage. To Fuji’s credit, the 60mm F/2.4 Macro is actually a good lens for UV photography.

Test #2: Sunscreen Lotion

Kolari IR 720nm
B+W 403 Ultraviolet
Kolari UV Bandpass

As of late, filming in UV has been a favorite method for companies to advertise the effectiveness of their sunscreen lotion, so we’re using that method in reverse here. If the sunscreen is absorbing UV light, it should appear very dark or black. Though the lotion does glisten brightly from certain angles, our filter is the only one showing UV absorption while the B+W 403 is once again performing more like an infrared filter.

Interestingly, the lotion seems almost transparent when viewed through the B+W 403 Ultraviolet. On another side note, the healing wound on my thumb contrasts much more strongly with the surrounding skin with the Kolari UV Bandpass than it does with the B+W UV or the 720nm IR filters. These characteristics are all very strong indicators of whether or not an image is composed of purely UV light or if it is contaminated with other, undesired wavelengths.

Filter Transmission

A look at each filter’s spectral response curve as measured by our spectrometer shows the underlying reasons why both of the UV pass filters are producing such different results. Our UV Bandpass filter on the left is blocking enough infrared light to prevent contamination of the image. Due to the much higher sensitivity most sensors have to visible and IR light compared to UV, the out of band signal needs to be blocked VERY strongly. We found during development that even 0.1% transmission peaks could wash out the UV signal.

As you can see from the graph, the B+W 403 Ultraviolet is letting in so much infrared light alongside the UV that it is almost completely overpowering the exposure, leading to what is essentially a near-infrared image. The only way the B+W 403 could be used on its own to create a purely ultraviolet image is in a controlled environment with no infrared light present, or to use it with UV film with no IR sensitivity, AKA how it was initially designed to be used.

Combining this filter with another hot mirror style filter to block the IR signal and allow UV can also work, and we hope this is the recommendation Fuji provided their clients, however nothing provided in the Forensics bundle can be used in combination to make this UV filter work properly. Both the B+W UV/IR Cut MRC 486M filter, and the new Tiffen T1 filter provided in some bundles, block UV light.

See below for some comments on the B+W UV/IR Cut MRC 486M filter provided with the Fuji Forensics kit. Using this type of dual-pass UV filter on a digital full spectrum camera will simply not work for UV photography alone. We shutter to think about how much evidence may have been shot with the B+W 403 and interpreted as a UV signal, when really what was being captured was infrared.

Our 39mm UV Bandpass filter will however work with this forensics kit perfectly and can rescue the Fuji kit. Alternatively, you can order our forensics package designed from the ground up by experts in multi spectral imaging.

B+W UV/IR Cut MRC 486M

One minor point on the B+W UV/IR cut filter included with the Fuji Forensics kit. While some hot mirrors can be used in combination with an old-style UV filter to isolate the UV signal, this one cannot. It is an aggressive UV cut filter that blocks the UV signal, while at the same time not blocking enough IR. We’ve tested this filter against our own hot mirror filter, and show that it lets in much more IR light, and produces worse color accuracy when used on a full spectrum camera. Fuji provides two of these filters for their Forensics kit to use with the included lenses to restore normal color for regular photography, where it simply isn’t the best filter for this application. It is also an interference-based filter, which can change transmission at different light angles, causing a color shift towards the edge of the frame with wide-angle lenses.

Normal camera
Full spectrum camera with Kolari Hot Mirror
Full spectrum camera with B+W 486 UVIR Cut filter

If you look at the transmission curve, the B+W 486 filter lets in much more IR light than any normal camera sensor filter. Fuji has started offering the Tiffen T1 IR filter in some bundles which cuts out more IR light, this combined with the B+W 486 should improve color accuracy but we have not tested it ourselves.


About the author: Pat Nadolski is a photographer and technician at Kolari Vision, an infrared camera conversion business based in New Jersey. The opinions expressed in this article are solely those of the author. Kolari Vision recently announced the Kolari IR ND filter, which it believes to be the best on the market. You can learn more about the company’s service’s on its website. This article was also published here.

Kolari Vision Unveils High-End Drop-In Filters for Canon’s RF-to-EF Adapter

Kolari Vision has just unveiled a line-up of high-end, ultra-rugged drop-in filters for Canon’s special EF-to-RF mount adapter with a built-in filter slot. According to Kolari, not only are these the first third-party drop-in filters actually shipping to consumers, they’re also some of the most durable and high-quality filters money can buy.

While Kolari is first to market, they are not the first to announce a third-party option for Canon full-frame mirrorless users. That distinction goes to Breakthrough Photography, who unveiled their drop-in filters at the beginning of August.

But speaking with Kolari Vision owner Ilija Melentijevic, he tells PetaPixel that there are several important reasons why you might want to consider their options, and not just because you can buy them right now (Breakthough’s filters don’t ship until September 25th).

According to Melentijevic, there are five main reasons the Kolari filters stand out:

  1. Ours is CNC machines aluminum
  2. We use a gorilla glass substrate for the ND filters, the only one of its type.
  3. We’re aiming for the top with our ND filters in general, and have the data to show our 10 Stop is flatter than anything else on the market, even Breakthrough. We’re investing aggressively and won’t stop until we have the best filter in every category.
  4. We offer more options for multi spectral. Breakthrough is offering one 720 filter, we will be offering a series designed for full spectrum cameras including 590, 665, 720, ultraviolet, and our IRChrome. This will open up UV and IR to lenses for which no filter currently exists.
  5. Maybe most distinctly, we are launching in parallel here a clip filter system for the RF mount that can be used in tandem with the drop in, or alone with native lenses, offering potentially two spots behind the lens to put filters for extra combination options.

Alongside these filters, the company is planning to introduce some specially modified and calibrated unfiltered versions of the Canon EOS R5 and EOS R6, where they put the IR filtration into the clip filter instead of modifying the sensor. This allows for a user-interchangeable OLPF system like some RED cameras have and some Sigma DSLRs had in the past.

A chart comparing the transmission of the various 10-stop ND filters on the market. Credit: Kolari Vision

As of this writing, you can already order Neutral Density, Infrared, Ultraviolet, IR/UV Cut, and IRchrome filters, with a Circular Polarizer and Variable ND filter listed as “Coming Soon.” In terms of pricing, the filters range from $100 for the various IR filters and the IR/UV Cut filter, to $150 for that 10-stop ND filter, all the way up to $300 for the UV bandpass filter.

To learn more about any of these drop-in filter options—and their clip-in counterparts—or if you want to order your own, head over to the company’s website.

Teardown Reveals ‘Overheating Timer’ Chip Inside the Canon EOS R6

Here at Kolari Vision, we love tearing into the newest camera gears to learn how they work and if they can be modded for infrared photography, full spectrum photography, or other things. We’ve been really excited about the R5/R6 release, and had plans to add some cooling mods and overhaul it into a proper video camera.

Reports from EOSHD that Canon uses an overheat timer rather than actual temperature readings left us a bit disappointed, and calls into question whether physically cooling down the camera can actually give any more shooting time.

Andrew Reid was able to bypass this timer by using a screw to override the safety shutoff switch in the battery door compartment and do a hard shutdown during recording, but this seems to corrupt video files. “Math Class” on Baidu recently showed that removing the clock battery can also bypass this timer. A firmware update by Canon on the R5 has also recently extended the shooting length by a seemingly arbitrary time, showing that software can absolutely affects shutdown times.

These data so far suggest that the camera keeps internal time, keeps time when the camera is off, and uses these values to influence if shooting can resume. A hard shutdown corrupts some data being written, preventing a time limit from being established. The clock battery removal suggests that without a clock keeping time while the camera is off, there is no way to establish a countdown timer, and the camera defaults to zero on the shooting time.

With this knowledge, we wanted to investigate how the camera functions without a clock battery, could we identify a physical clock chip on the board, and is there a more advanced modification that could be made to interrupt the clock timer communication without affecting date/time settings. Right now we only have the R6 to work with, but we suspect the R5 works similarly. If anyone has an R5, please contact us.

So first, let’s start with the clock battery. It can be found on the back of the main circuit board.

The first thing we wanted to check was, how does missing the battery affect general performance? The clock is of course reset, but on other Canon cameras it has prevented saving shooting settings and custom settings, which would be deal breaker.

So we set some custom menus, changed some shooting values, and some menu settings, and then proceeded to remove the clock battery. Leaving the board completely powered off without any battery source for about 30 minutes, we re-assembled the camera sans battery and checked it out. We received the expected prompt for time/date, but were pleasantly surprised to find the rest of our settings were still there. Nice!

We also found that the camera keeps time as long as the main battery is in place, even when turned off.

Next up, could we trace out where the battery leads connect to. Visually checking, the leads from the battery immediately go down into the board to a middle layer, so we could not visually trace them out. Oh well, we have a multimeter!

Running a continuity check from the leads, I was able to trace the right lead to the common ground right away. The left positive lead was a bit harder, but the trace must come out somewhere, so I went around testing components throughout the board on both sides. A bit tedious, but I was able to identify only one chip that the battery feeds into.

We needed a microscope to read the chip, but were able to identify it as the RX8130 Real Time Clock, complete with a 59 page documentation PDF. Bingo. This is what keeps time.

The wiring diagram for the RX8130 looks like this (see below). I was able to identify the clock battery feeds into pin 10 through a 470 ohm resister. Pin 7 also connects to ground. Interestingly, pin 6, 2, and 3 either connect to nothing, or connect to something directly going down under the board. We need to remove the chip to see more definitively, but potentially they are not used.

Pin 4 from the documentation is used for the frequency out, and this connects to a 6 pin chip immediately to the right that reads only pQ on it, hopefully someone has more insight on this chip. Pin 5 leads elsewhere on the board we can’t identify. Pins 1 connects to a distant BGA mounted chip with what looks like a smoothing capacitor connection to ground. Pins 8 and 9 also connect elsewhere we can’t trace yet and also feature smoothing capacitors.

So far, that’s all the progress we made. We like to be transparent in what our mods do, so we decided to open up our research here as we go.

Based on this chip’s documentation, our basic understanding is that this chip receives power from the main board first, and if there is no power there, it draws power from the backup button cell battery. The chip is able to keep time, and can output time data, as well as other stored data, there is some room for general bit storage. The chip is also able to send interrupt and data signals back out, but so far it doesn’t look like those pins are necessarily being used. Canon may not be using the internal interrupt and timer functions, and may be doing that elsewhere using this chip as only a timekeeper.

Our next plan is to verify this with an R5, and pop the chip out and see if we can measure any signals on a scope during the actual overheat event. In the meantime, from how the settings storage is handled, it looks like we should be able to just remove the clock battery, or put the clock battery on a separate toggle switch. Also, we can of course bypass the hard reset screw approach Andrew Reid did, and just put a hard switch on the power leads to the main board. We can even control these switch with a microcontroller and force a hard reset through software if needed, say something like, after you hit record the camera cycles a hard shutdown after 15 minutes, or cycles an ordered shutdown paired with a clock reset as a coordinated event.

We also want to check how the camera behaves if there is no clock power even when the camera is on. I suspect a hard error, but who knows! BUT WE NEED AN R5 to start. Please, internet. If you have one you can loan or sell us, we’ll share what we find publicly and give you first access to our Frankenstein bypassed ultimate R5 mod.

One final important comment: While it seems definitive that Canon is using a timer circuit to shut down the R5 in overheating, we can only speculate as to why for now. It is possible that it’s there to “cripple” the camera, but it’s still very possible that there are some overheating concerns for this weather sealed body, and they are shutting down based on a timer schedule for now for longevity.

I would approach any of these bypass strategies with extreme caution, as they will probably not only void your warranty, but potentially fry your camera from extended shooting. We still plan to open up the R5 and add a heatsink that’s thermally fused to the overheating chips and card slots, and attach this heatsink to an aluminum cage for dissipation, as well an active fan. In this cooled context, we expect to keep the R5 very cool for extended shooting, but it would require the timer shutdown to be bypassed.

So let us know what you think and if you have any chip insight! What would you like us to try next?


About the author: Ilija Melentijevic is a scientist/photographer and owner of Kolari Vision, an infrared camera conversion business based in New Jersey. The opinions expressed in this article are solely those of the author. You can learn more about the company’s service’s on its website. This article was also published here.