Kolari Vision Pro Slim Filter Review
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Kolari Vision Pro Slim Filter Review

We exclusively use Kolari Vision PRO SLIM filters for all our testing (and our own personal use as well) and decided that we like them so much we should write up a review about them.

Kolari vision’s PRO SLIM filters are Teflon coated with 6061 aircraft grade aluminum rings that provide a smooth putting on and taking off experience from the lens, or in our case, usually step up ring adapters.  Unlike many slim filters, Kolari Vision PRO Slim filters have a front thread, this and the slim feature of the filter allows us to add different filters or a polarizer, ND filter on top of the IR filter for different effects.  Kolari Vision Filters PRO SLIM filters are also anti reflective coated to cut down on flare and ghosting.

If you use a full spectrum camera, then having an excellent set of filters is mandatory, as you are always swapping filters often to get different infrared or color photography effects in your images.

Even for a regular IR converted camera, you can still use filters to change the look by using a different IR filter in front of your lens. As an example, if your camera is 720nm IR converted, you can still use the 850 IR filter in front of your lens, to give you a rich black and white IR conversion to your images.

We fully recommend that if you are interested in infrared, your best solution is always either a full spectrum or a two-spectrum converted camera.  What’s the difference? The full spectrum allows UV, color and IR light to hit the sensor.  The two-spectrum sensor allows only visible and IR light, and has a UV cut filter installed.  If you never plan on shooting UV, then doing the dual spectrum conversion is a logical option.  According to Kolari Vision, the dual spectrum conversion gives you the most accurate color imagery, because the combination of the UV cut filter that exists on the sensor and adding a hot mirror filter, gives you a response almost identical to that of a stock cut filter if you had never removed it from your camera. 

Figure 1 - Two Spectrum Sensor with a Hot Mirror gives you almost completely accurate color response
 

Meanwhile, full spectrum, the filter is simply a piece of optical glass, allow all possible light to reach your sensor and you are responsible for choosing a filter that allows you to choose what spectrum of light you wish to record.

Full or Two spectrum cameras are also uniquely suited for shooting color photography and also by switching filters be tuned to shooting astrophotography without the limitations of the hot mirror that usually exists in front of the sensor.  Shooting astrophotography means you usually want to have a high sensitivity to the h-Alpha band which exists at 656nm.  A normal camera has 2 to 3 EV less sensitivity in this region.  A full spectrum camera, with a Kolari Vision H-Alpha + Visible filter, is uniquely suited for astrophotography with a full spectrum camera.

Figure 2 - H-Alpha and Visible filter

Kolari Vision Hot Mirror Filter

This filter is necessary to shoot normal color photography if you have a full (or dual) spectrum converted camera.  All our cameras are full spectrum converted and use Kolari Vision hot mirror filters for color photography.

There are two types of IR/UV cut (or Hot mirror) filters that you need to be aware of.  There are some, like these that the filter is of a blue/green color that is usually called hot mirror filters.  There are others that are interference based, and usually, much cheaper than have a clear or silvery color to them.  While for normal lenses, the clear or silvery colored filters will work, they will not work with any focal length under around 24mm.  The hot mirror filters have no such limitation and will work no matter how wide your lens is.

Figure 3- Transmission of the Kolari Vision Hot Mirror filter

In actual use of this filter, we find that the transmission curve matches up well to Canon color, giving us an out of the camera experience even when using the camera’s AWB setting.  If you find the AWB a little off, as you can see the hot mirror filter tends to allow a little more UV than a standard camera’s low pass filter, you can stack a UV cut filter such as a Hoya UV + IR cut filter with your hot mirror filter (another reason to get the PRO SLIM filters is that you can easily stack this with an ultra-wide lens and still not cause any vignetting).

Figure 4 - Standard Hoya IR UV cut filter

If you merge the two transmissions, you’ll see that the combination will have a very sharp cut at 400nm, like a regular low pass filter on a camera that has not been modified.

Installing the Kolari Vision hot mirror filter in either a lens or using step up ring adapters, is smooth with little friction.  At times we find it difficult to catch the first thread and screw the adapter on, but once the thread catches, we have no problems.  By shining the filter against a strong light, you can see that it is very little in the way of reflections from the surface.

Looking closely at the glass we see no imperfections, measuring the glass thickness with a digital micrometer, we find the glass is exactly 1.80mm of thickness along the surface, taking random measurements along the filter.

Testing the filter for adding additional flare, if anything we find that the hot mirror filter in front of the lens has little effect on the flare in which we saw from using the 18-150mm EF-M as a test lens.  Slightly more contrast, and perhaps a little more brightness to the flare.  We can conclude that the addition of a front filter Kolari Vision SLIM PRO filter did little to increase the flare.

Kolari Vision IR Filters

When we do our testing and our own shooting with infrared, we use Kolari Vision’s SLIM PRO infrared filters.  We find that Kolari has the best and widest selection of IR filters from the incredible IR Chrome, NDVI standard IR wavelengths, and UV.  Kolari Vision calls these filters;

  • IR Chrome – mimics the effect of Kodak Aerochrome IR film and requires no channel swaps in post-processing for the effect. A brilliant filter.
  • False floor filmic (550nm).  Before Kolari Vision came up with the IR Chrome filter, this filter was the closet that they could come up to Kodak Aerochrome IR film.
  • Ultra Color (590nm) – Leaves are a golden color, skies are bright blue and is the most vibrant of the normal IR filters
  • Extra Color (665nm) – Somewhat in between the 720 and 550nm, leaves are a pale yellow and skies are brighter blue than with the 720nm.
  • Normal IR (720nm) – this is the standard IR filter that is most commonly used today because Hoya made one of the original R72 filters of this wavelength.
  • Deep black and white (850nm) – this filter is used to produce strong contrast black and white IR images.

As with the Hot Mirror PRO SLIM filter, the PRO SLIM IR filters have Teflon coated threads on a brass coated ring.  Taking off and putting on the filter onto either a lens or a step up ring is smooth and friction free.

We randomly tested the thickness of the various filters and found them to be;

  • Kolari Vision IR SLIM PRO 590nm – 2.00mm
  • Kolari Vision IR SLIM PRO 720nm – 2.07mm
  • Kolari Vision IR SLIM PRO 590nm – 1.99mm

All the filters had a uniform thickness.

All in all, we find the glass to be a consistent thickness for all the filters.

This, if we compare to a cheap Chinese, made IR filter that we bought from eBay shows a slight difference in thickness during random spot checking between 2.08mm and 2.07mm.

Note the variations of the thickness of the filter which could potentially have an effect on your actual images.  If anything, it demonstrates itself to be a lower quality filter.

All the IR filters are similar (with the exception of the IR Chrome filter) where they allow certain light wavelengths to pass.  The wavelength mentioned with the lens is the lowest wavelength that the filter will pass before it starts to sharply block the light.  Everything above that amount will be let through.

Hot Mirror Testing

In this segment, we’re going to check the difference between a standard hot mirror filter from Kolari Vision and the PRO SLIM version.

For this first example, you can clearly see the difference in the amount of light being reflected off the filters.

The non AR coated Hot mirror filter is to the left, while the PRO SLIM filter is to the right.

In this test, we are looking for reflections caused by the bright LED’s reflecting off the filter, on the left you can not see any reflections at all.  We carefully looked at the full image for any signs of reflections and couldn’t find anything.  However, on the non-coated Hot mirror, you can clearly see reflections.

IR Filter Testing and Comparisons

Testing a few IR filters we have for reflections, we tested the Kolari Vision 720nm, a cheap Chinese filter and an expensive B+W 099.  As you can see below the Kolari Vision PRO SLIM 720nm (far left) has the least amount of reflections. If you look carefully, you’ll see very slight reflections, however for all practical purposes, there is none.

The B+W 099 (far right) and the Chinese filter (middle) is uncoated, and it shows in this reflection test, as both of them showed far more reflections, with the cheap Chinese filter the worst.

I also found interesting the difference in contrast.  The camera, in this case, is set to full manual, and you can see a difference in contrast and clarity between the Kolari Vision 720nm and the Chinese filter.  There’s an understandable slight difference in exposure and clarity with the B+W filter because it’s actually 695nm, allowing a light bit more visible light to reach the sensor than the other two filters.  That shows clearly here by the exposure difference.

You can also see a dramatic difference of flare around these LEDs in the image.  The Kolari Vision 720nm, you can clearly see the circuit board black outline around each LED, while the other two it’s far more indistinguishable because of the flare around each LED.

Conclusion

While there are many filter options for normal standard IR of around 720nm.  You have Hoya, B+W, Tiffen and many others such as Chinese based filters.  Then, you have Kolari Vision, which offers the most complete range of IR and Hot mirror filters available in the market today.  You can get the more economical standard filters or the PRO SLIM filters.  We highly recommend the PRO SLIM family of filters, because of the choice, consistency, and quality of both the filter itself, the filter ring and threads.  Using the thin filters allows us to have stacking options that simply other IR filters do not have, without causing vignetting.

Kolari Vision filters are also very high quality from the filter ring to the glass itself, and with the coatings, there is little any additional flare that would be normally caused by the filter.

There really is no one else that has the breadth and quality that Kolari Vision does when it comes to UV, Chrome, or IR filters.

Disclaimer:

Kolari Vision is one of our exclusive vendors, and we get a commission for each sale made via links from our website.  However, even with that, Kolari Vision has long been our personal preferred source for anything Infrared conversions and filters from July 2013.  They have converted 4 different cameras for us over the years, and, we have purchased quite a few different hot mirror and IR filters as well. So, while we are an affiliate of theirs, we are also a long-time customer of theirs as well.

 

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