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Anti-Reflective Coated Filters
Kolari Vision offer these coating on conversions for an extra $100. When I first got one of these conversions I tried to test it against non-coated conversions. Although I was sure something good was happening I failed to measure exactly what benefit they give. Since I still have both a normal conversion and an 'Anti-Reflective' (AR) one (of the same camera type) the lens scores I have made here could help to show some interesting results in the coatings.
The AR coated filter I have is an internal 720nm wavelength. The other is a full spectrum conversion, so here I used an external Hoya r72 filter to match the results. I also ran the tests on the internal 720mn AR conversion with the external Hoya r72 filter on as well, to see what using both would do.
A reminder of the scores: (0=Terrible - 10=Perfect). Here are the results on the brand new Samyang 24/2.8 (native Sony FE) lens...
Initial Results
The first set of results came out pretty consistent throughout the apertures, confirming the lens characteristics remain intact and suggesting that the tests are meaningful and repeatable. The offset between the main two (green and blue) suggest that the AR coating does have an effect. Adding an external filter (of the same wavelength) as well reduced the effectiveness of the internal coatings, but not completely. This is not quite what I expected, I had hoped the results would improve further, but this is interesting none the less. OK, all we need now is to see each lens perform in the same order, so let's run this test on another lens and see what we get...
Repetition
Great! Just as the first test the three results are showing up consistently and in the same order. Again the AR coatings are making an improvement and if you add another filter in front of the lens that improvement is diminished. I do wonder what would happen if we added AR coated external filters as well. Perhaps then the results would improve further.
So far we have tested one 'Acceptable' lens and one 'Poor' one. For my third test I will try one very good performing lens, to challenge the results. This should be interesting because there will be little room for improvement. If we see the AR coating get any worse then the tests will look to be less conclusive...
Three For Three
Ok, wow!... I'm quite excited by the consistent-ness on display here. You can just see the green line showing above the red and the blue one below. With almost no improvement to be made there is still some movement and in the same directions as the other two results. I will continue to test more lenses, but so far this is looking quite promising.
Conclusion
Now, I should point out that there could be another explanation for these results. It is possible that the improvements are coming from the filter simply being internal (behind the lens). I will try to devise some more tests that might shed light on this soon, but I may need some more hardware to continue.
I would like to run the tests again with external 830nm filters on both cameras. I have this, I just need the time to make the tests.
It would also be nice if I could get some internal 720nm & 830nm IR filters for the Sony camera.