Steve Curran Wonders About UV for Leica 100-400mm lens

Posted Jul. 24th, 2017 by Daniel J. Cox

Hi Dan,

I’ve been reading your articles on the Leica 100-400mm lens over the past few days. Super informative by the way!

I recently picked one up and decided on put a UV filter on it for protection. I noticed one of your comments saying that you always use UV filters for protection, but after some tests you performed, you may not be using one for the 100-400. You said to stay tuned for your results, but I can’t find the post of that anywhere.

The filter I am using is a ProMaster Professional HGX Prime UV filter. It’s one of the more expensive ones, rivaling the top Hoya and B+H filters in price.

Not sure if you have any experience with the ProMaster HGX filters, but what are your thoughts on using one on the 100-400? I’m a bit of a pixel peeper, and I’m noticing that getting tack sharp images at longer focal lengths with this lens is proving to be challenging to say the least. Close focusing is superb. Not sure if it’s the filter causing an issue, the lens is defective, or my technique is at fault?

Appreciate any input you have, and thanks in advance!


Steve, not sure what you are referring to as far as me stating I might decide not to use a UV protector for the 100-400mm. If I wrote that, I must have been thinking I didn’t want any additional glass and that comment most likely was referring to the prototype 100-400mm I first used. Either way, I did decide to use a UV filter and have had one on for the past year and a half. My current favorite UV filters are the Hoya HD3’s. I get mine at Bozeman Camera here in my hometown of Bozeman, Montana. You can reach them at (406) 586-8300 or on the web at Bozeman Camera.

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There are 4 comments on this post…
  1. John O'ConnellOn May. 15th, 2018

    I would like to relate my recent experience with UV filters, have had the Olympus 40- 150mm f2.8 since it came on the market, always had a Heliopan UV filter on it, some months ago it wouldn’t focus sharply, especially at the longer focal lengths, tried it on my Pen F, still the same, sent it back to Olympus. Exactly the same problem. returned it, forgot to remove the filter. Came back with a note saying, do not use with this UV filter! tried it on both bodies, worked perfectly without. I put a clear filter on, no problems.
    The only conclusion I reached was that the last firmware update had something to do with it, talked to Oly, but they couldn’t shed any light on it. So if anyone experiences similar problems be aware.

    • Portrait of Daniel J. Cox

      Daniel J. CoxOn May. 15th, 2018

      Very curious. Never heard of this one. Thanks for sharing.

  2. Steve CurranOn Sep. 12th, 2017

    Thanks for the response Dan. Much appreciated.

    Down here in Australia, I can’t get the HD3 filters. Camera stores only seem to stock Hoya HD UV filters. Would you recommend these?


    • Portrait of Daniel J. Cox

      Daniel J. CoxOn Sep. 13th, 2017

      These basic HD filters were what I started with. They will be fine. Not sure what the number 3 adds to the filter but it is there newest version. That said, I recall the benefit of the regular HD so they should work great for you.

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