Real-World Test: Reducing Mount Adapter Internal Reflections with FINESHUT KIWAMI

Hi, I'm Teppei from the new-products team at ANSOKEN.

Our ultra-low-reflection material for the inside of optical equipment, FINESHUT KIWAMI, had just gone on general sale when we wrote this test. It turns a cutting-edge material into a sticker you simply cut and apply, so anyone can treat internal reflections. Let's try it right away on an inexpensive mount adapter.

The camera is a Fujifilm X-H1. Through an MD-FX mount adapter bought for about 4,000 yen, we mounted a Minolta MD 50mm f/1.7.

Why an MD lens? Because it was cheap. I mean, because of its rendering, of course.

The Minolta MD 50mm f/1.7 and the MD-FX mount adapter

Being an inexpensive adapter, its internal anti-reflection treatment is basic. It looks like lathe-cut baffle grooves with a black anodized finish, and as you can see, it is quite glossy. Black anodizing generally has a total reflectance of around 4 to 5% in the visible range (and it gets much worse in the near-infrared: see Black Anodizing Reflects Near-Infrared Light).

Inside the adapter, from the lens side (left) and the camera side (right)

We applied FINESHUT KIWAMI to the wall on the camera side, which is about 6.5 mm wide. To compare the effect with and without it in the same shoot, we covered only half of the circumference.

This is the result. The lined side is, of course, on the right. It clearly suppresses the reflection. Now let's go out and shoot.

Comparison test outdoors

It was 9:30 in the morning. Fine weather, but still cold, around 5°C. The sun was strong, which made it perfect for this test.

The first thing we wanted to check: does light actually reach that inner wall of the mount adapter, and if so, how?

Yes, a direct hit!

With the MD 50mm on the adapter and the lens pointed at a certain angle away from the sun, a strong spot of light landed on the wall. This photo is wide open; stopping down only changes the size of the spot, and it lands in the same place.

This area is only about 10 mm in front of the sensor, so it matters, and the reflection was stronger than we expected. We expected it to have a big effect on image quality. (Results will differ from lens to lens.)

So how much does the sticker reduce the reflection of this spot of light?

Left: untreated. Right: lined with FINESHUT KIWAMI.

Left is untreated, right is with the sticker. What do you think? The reflection is greatly reduced.

FINESHUT KIWAMI has a total reflectance below 1% (about 0.7% at 550 nm). At the time of this test it was our best material; today, FINESHUT KIWAMI XX goes down to about 0.5%.

Next, we compared real photos.

Here is how we shot them. First, we found the angle at which light hits the inner wall, and aimed so that it landed on the untreated half. When you look through the viewfinder, you can tell, because the flare makes the whole image noticeably brighter. That is when we pressed the shutter.

Then we rotated the camera 180° around the lens barrel and took the same composition again. The opposite half of the adapter is the lined half, so the light now lands there, and we can compare image quality.

Left: untreated. Right: after the anti-reflection treatment (the right photo was taken with the camera upside down, and is rotated 180° here for comparison).

Left is untreated, right is after the anti-reflection treatment. The difference is hard to see in a thumbnail, so please view the images at full size. The flare in the lower left is reduced, and the contrast is better.

By the way, inexpensive adapters, including this one, often have silver screw heads exposed on the inner wall, but they were not the cause of this flare.

For photographers who aim higher

Thank you for following this long test. To be honest, cases where our anti-reflection sticker makes such a clear improvement are probably rare. Even in the case above, properly shading the lens with a hood actually improves flare more.

We are confident that the anti-reflection performance of our material is excellent, even compared with manufacturers' own treatments. But manufacturers also do what they can within their budgets, so the overall improvement in optical performance will be small.

Excellent optical products, however, gain their obvious advantage by stacking up 10 or 20 small improvements. We also supply optical parts such as light-shielding rings and aperture blades, and the attention to detail of optical manufacturers is remarkable.

(For example, our light-shielding rings: to reduce reflections from the cut edge of a black PET film only 50 microns thick, we deliver them with the edge cut at 45°. The image on the left below is an illustration.)

FINESHUT KIWAMI is a product for exactly those small improvements. We hope it interests photographers who are always aiming higher.

Material used in this article

The anti-reflection sticker applied inside the mount adapter is FINESHUT KIWAMI. Its visible reflectance is about 0.7% (at 550 nm), and it sticks on with the tape on the back. It can also line lens hoods and the inside of lens barrels. If you want it cut to a specific shape, you can order online through our Laser Cut Service.

Feel free to ask us about internal reflections around cameras and lenses. Tell us the shape and dimensions of the area you want to treat, and we will suggest a suitable material and cutting method.

Originally published in Japanese on March 15, 2019. Translated into English in October 2026.

Related: Which Materials Reflect Infrared? · What Is Reflectance? The Science Behind True Blackness