Just catching up on this thread. Honestly, I've had issues with many 95mm filters causing measurable softness at the 600mm end. Unfortunately, some mid-range options just arent as good as expected because they lack the optical planarity required for long focal lengths. Before providing more data, what kind of lighting do you usually work in? High-contrast backlit scenes will really show the flaws in cheaper coatings. At 600mm, any deviation in the glass surface gets magnified. If the light transmission is below 98 percent, you're going to lose that biting sharpness this lens is known for. To balance cost and performance:

• Hoya 95mm NXT Plus UV Filter
• B+W 95mm Basic UV Haze MRC Filter I was kinda disappointed with the coating durability on some other budget brands lately. Stick with those two if you want to keep your costs down without turning your expensive lens into a blurry mess.

That lens is absolutely amazing! I have been shooting Z glass since launch and the 180-600mm is a total standout for wildlife work. Before recommending a specific piece of glass to protect that 95mm front element, I need to clarify a few technical points to ensure we maintain peak image quality:

• What is your approximate budget range for this accessory?
• Are you planning to shoot in high-glare environments or harsh conditions like salt spray where specific coatings are a must? Methodically choosing the right glass is vital because cheap filters will definitely soften your images at 600mm. Tbh, it would be a shame to degrade such a fantastic lens with the wrong choice!

Building on the earlier suggestion about the 600mm softness, I would suggest being extremely cautious about the mechanical construction of whatever glass you put in front of that lens. People always talk about the glass quality, but the frame tension matters just as much for long-term reliability. If the retaining ring is even slightly over-tightened during manufacturing, it puts mechanical stress on the element. This causes what we call pinching, which basically ruins the wavefront error and makes your sharp 600mm shots look like they were taken through a screen door. Make sure to check the parallelism specs if you can find them. At these focal lengths, if the two sides of the filter glass aren't perfectly parallel, you're introducing a slight prism effect that can actually mess with the phase-detect AF accuracy. I'd also be careful with those ultra-slim filters. They're great for wide angles to avoid vignetting, but on a big telephoto, they sometimes use thinner glass that's way more prone to flexing under temperature changes. Honestly, unless you're in a high-risk environment with salt spray or blowing sand, just using the lens hood is usually the safest bet for maintaining the best possible IQ.

I uses Chiaro Pro 95mm 99-UVBTS Brass UV Filter, everything is ok.

TIL! Thanks for sharing