Drop-in polarisers

Hi all. Friday afternoon obscure question about an obscure product.

 

Back when the 200 f/2 VRII was launched, I picked up one of the last mk1s, because the price difference was huge (£3000 vs £5000 at the time). Being a completist, I also picked up the drop-in polariser (C-PL3L). Possibly in the store, because the filter doesn't come out very cleanly, I managed to scuff the filter on the lens - I'm not sure I didn't do the same with the optical flat that normally sits there. Stupid design, it really shouldn't be necessary to apply force to a £300 filter at an exact angle in order to avoid damage. Partly because I've not dared look (but mostly because I use my 200 f/2 indoors), I've never actually tried to use the polariser since.

 

Anyhoo, fast forward. I was recently having a look at my filters, and indeed there was a big mark on the polariser. Reassuringly and to my surprise, a combination of rubbing it for about twenty minutes with a lint-free cloth, huffing a lot (which would have worked better if it hadn't been one of the hottest nights of the year in a room with no airflow) and swearing at it eventually seems to have removed the mark, I think. I've just picked up a lens pen, with which I might give it another go. I don't quite know how I could have put the kind of mark on it with the hard edge of a lens that would have come off with a cleaning cloth (unless I actually removed the optical coating, which is even scarier), but fingers crossed.

 

So question 1, which may be unanswerable: can I possibly have successfully removed a mark from the front of a new filter if the mark was applied with the hard edge of a lens? I don't understand how I could have succeeded (I only tried out of unusual optimism), although unless I've actually just removed the coating I guess I'll take the win.

 

While peering at the filter under a light, it seemed to have some "blotches" on it, as though it were wavy - or more specifically as though the polariser was made from a laminate that was delaminating, or there was a polarising layer between glass flats which was warping. That description sounds like the kind of cheap filters that people like Hoya warn you about when trying to get you to buy their solid lumps of glass, which is surprising for a Nikon product - but then I don't really associate Nikon with filter manufacture. I've not actually tested shooting through it to see whether it's okay, but I'm not sure how accurately I could test it. I don't think I was pressing hard enough on the filter as part of the cleaning process to cause any part of it to separate.

 

Question 2: Has anyone seen this kind of thing on a Nikon drop-in polariser? Should I worry? It's quite an expensive item to have iffy manufacture.

 

To an extent, if I've not used it since 2010, it probably doesn't matter. But I'd vaguely like to know whether it's now a tiny paperweight. I gather the 800mm takes the same drop-in, which might be of interest to me if I hire one in the future.

 

I've asked Nikon UK for their input, and they're going to check how the C-PL3L is manufactured and get back to me, but without seeing the filter there's not much they can do.

 

Any thoughts welcome.

I can't imagine which hard edge of the lens the filter could have come into contact with upon removing it from the lens - and doing so with sufficient force to leave a mark.

Properly applied optical coating adheres fairly well to glass and by itself is also fairly hard - I'd be surprised if you could be removed by simply rubbing it with a cloth. Some seem to frown upon breathing on it as they claim acids in the breath could eat into the coating - I am quite skeptical about that.

or more specifically as though the polariser was made from a laminate

Because that's what they indeed are - at least two "films" - one a linear polarizer and the other a quarter wave plate; one can't construct a polarizing filter out of glass alone.

Some CPL filters (B+W) appear blotchy - apparently an optical effect when viewing it under certain conditions.

I've not actually tested shooting through it to see whether it's okay, but I'm not sure how accurately I could test it.

You should shoot with it and simply look at the images to see if there is any ill effect.

I have to do the same with a Hoya variable ND filter (which AFAIK uses a polarizing element as well) as I recently discovered five "scratches" that run roughly parallel to each other starting at the corner and extending almost to the centerline of the the filter. Except they aren't scratches on either glass surface but apparently some issue with the films inside. Clearly visible with the eye but I am not sure whether or not there's an effect on actual images taken with it.

In order to even do damage to the filter’s glass surfaces in the first place, you really need to remove it at an angle as the filters are recessed in the holders. However, lifting straight up and then at an angle can make the glass surfaces rub against the lens barrel, but I am not sure why anyone would do that when changing these filters?

 

I have the Nikon C-PL1L and it the only concern I have about it (and the Nikon NC that always sits in the optical path when I do not use the polarizer) is the weather sealing.

 

Both my C-PL1L and Nikon CP-L II filters show something that looks like what Dieter described when looked from certain angles. I would not worry about it, but shoot some at F16 or 22 and see if you can see any of it in the photos. I cannot.

 

May I suggest you get a lens cleaning kit, or a least some optical cleaner from an optician? I got a small Rodenstock kit for free and I do not think that cleaning liquid does any harm to clean expensive optical surfaces. That sample has lasted me several years already so I would probably get another free sample when it eventually runs out.

My lens has a tendency to hold on to filters - even when the latch is in the release position, the filters get hooked on something in the lens. A small amount (having done it more often while cleaning I now know how much - but didn't the first time I removed the filter) of jiggling is required, and then the lens suddenly releases the filter. While the exterior of the lens is fairly smooth, the edge of the slot into which filters are inserted is sharp and slightly raised. If you're jiggling and pulling on the filter, especially if you're not used to it, and the filter suddenly comes free, it's quite easy for the sharp lip to come in contact with the optical surface - nothing keeps the filter in line as it comes out, and being off by a couple of mm is enough; I'm not that accurate when trying to jiggle something by a tiny release knob, at least when I don't know I have to be.

 

Hopefully Nikon fixed the sharp lip, or the tendency of the filter to bind, or the ability of the filter to exit the lens at an angle, on the VR II version and the 800mm, which take the same filter. I'm aware of it (even after eight years) and was careful this time, but I can see how I had a problem before.

 

The blotches might be what I'm seeing. I think I can get a slight reflection off something inside the filter which seems wavy, but I admit that it seems okay looking through it. I just worried that if there's supposed to be a film sandwiched between layers of glass, the sandwich may be loose. I guess I'll have to experiment, I just don't know that I'll be able to tell if the effect is subtle.

 

I've just picked up some more cleaning cloths, some lens pens (I'll check I've blown off any residual carbon) and a better blower. Having said all that, I actually do have some cleaning fluid - I've just never used it, and forgot (d'oh). I'll have another go with better tools, but I think it's now serviceable after just the use of elbow grease.

 

Fingers crossed all is well. If not, I'll have to drop it with Nikon. The other filter that might end up in there (in the place of the flat) is a strong nebula filter for astrophotography - but I may be better with my AI-S 200mm/4 for that, since I'm not sure my cheap astro tracker will like a 200/2.

 

On that note, I see Fuji have a 200/2 now, and it's s lot lighter than the Nikkor, much as the Sony 400 f/2.8 is lighter than the SLR versions. The mirrorless guys are catching up with the big exotics...

I looked at my filters and lens (a 300/2,8 VR) and the edges of the lens barrel are rubberised. There is no friction when inserting or removing the filters, apart for the last millimeters when putting the polarizer in place. However that is just enough to hold it in place, should you turn the lens upside down before locking it in place.

 

The lens’s slot has two metal clips that help guide (and probably fix) the filter holder. If I look down into the slot, the clips are out of sight. Perhaps one or both have gotten loose or damaged/bent on your lens?

Thanks, Heimbrandt - I'll shine a light in the slot and see what I can see. Maybe my lens needs a trip to Nikon. There's certainly no rubberized edge on the older 200mm (the filter edge grinds on metal the whole way out), but then it's a (slightly) different polariser drop-in than the 300mm.

It's possible - I know because I've done it - to scuff a filter on relatively soft aluminium, in such a way that a streak of 'ali' is left on the glass. Hard rubbing can sometimes remove the deposited metal leaving the glass pretty well unharmed. Hopefully, that's what's happened to your filter.

 

In any case, there's little more you can do about it. Just shoot some with and without test shots, and be happy if you can't see any difference. I strongly suspect that's going to turn out to be the case.

 

Either way, enough rubbing with a cloth already! If you must scrub at a lens or filter, at least use a fresh lens tissue, and not a potentially grit-harbouring old cloth. The fabric might be microfibre and safe, but the muck it picks up isn't!

:-) Don't worry, Joe - new lens cloths. And I've ordered a bunch more on the basis that I have no way to clean them that won't cover them with lint.

 

I had a pad of "lens tissues" (apparently slightly rough tissue paper); I tried one, it shed dust over the filter that took me another five minutes to dislodge, I decided not to try again. Better products may exist. :-)

 

I'll try to test - I was just worried it would take a while for me to notice a problem. If there's a post from me on here in the next couple of weeks that contains a lot of swearing, the polariser is trashed. Fingers crossed.

Andrew, I use PEC pads and Eclipse or Zeiss fluid for my general optical cleaning. Lens cloths, the micro fiber type, worry me once they have been used so they are not something I carry. I don't generally touch the optical surfaces of my lenses more than 2 times a year unless I am in the desert where it gets dusty.

I may use a lens pen but only 3 - 4 time before I pitch it. You can't really clean a lens pens very well but they are inexpensive and work

on some of tougher area of my lens and sensors. Sorry for your polarizer problems. Rodeo's explanation about the aluminum make perfect sense to me.

Good hunting.

I clean infrequently as well - hence forgetting that I had cleaning fluid. I did find alarmingly low contrast on my 70-200 recently, caused by having the cap in my pocket and it transferring tissue fluff to the front filter - but generally I only huff, brush lightly, and remove any splodges gently. The marked polariser was an exception, but fingers crossed it's okay.

 

I think the last time I had a serious clean to do was when I was taking a fish-eye off the camera and mistakenly thought I'd already replaced its cap. Pressing a convex element into your palm is a spectacular way to grease up a lens.

I am glad that I can't afford such a problem.

I am glad that I can't afford such a problem.

 

Yes. I realise this thread could do with a "first world problems" tag.