Hoya ProND 1000 purple/green rings

[aaron l]

<p>Has anyone used the Hoya ProND1000 filter? I just received mine and found it's showing green and purple rings in the image around light sources. I can see it even just looking through the filter not on the camera. This is supposed to be a single piece of glass but the pattern looks like moire. Has anyone else used or seen this? I need a 10 stop filter but am at a loss for something that actually works. I currently have a Hoya400ND and it's pretty good, though it adds a little green cast. I need a darker filter, though.<br>

Is there any way to post pictures to show this problem anymore?</p><div></div>

[aaron l]

<p>Here's another sample.</p><div></div>

[lex_jenkins]

<p>A reviewer noted a similar problem with ghosting in <a href="http://www.the-digital-picture.com/Reviews/10-Stop-Neutral-Density-Filter.aspx"><strong>this review</strong></a>. Try repeating the tests with the viewfinder eyepiece blocked. See if that clears up any artifacts that might be due to internal reflections or light entering the eyepiece during long exposures.</p>

[CvhKaar]

<p>Question, is this just for this ( kind of) lightsources ?<br>

(& What ty of lamps are in this fixture.?)<br>

They do not look like old fashioned lightbulbs to me, and it may be that the filter shows the composition of the light better than you can see with human eyes ....</p>

[kari_oinonen]

<p>Aaron, is the first photo cropped from the image center?<br>

Can you make another test with a different lens?</p>

[phule]

<p>[[and it may be that the filter shows the composition of the light better than you can see with human eyes ....]]</p>

<p>An outside, daylight, test is a good idea. </p>

[rodeo_joe1]

<p>No way that defocussed light entering through the eyepiece could cause interference rings; and how would such light get past the mirror in its up position anyway? However it is a good idea to use an eyepiece blind with strong ND filters if you're relying on the camera metering.</p>

<p>All I can say is that I've seen no such problem with my 10 stop no-brand ND. It might not be quite neutral grey, but at least the colour shift isn't striped!</p>

<p>I suggest you throw that filter back at the supplier for an exchange or refund Aaron.</p>

<p>Edit: I think the quest for a high density filter with no colour cast or shift is pretty much a fool's errand. That's what shooting RAW or setting a custom WB are for. And you only need to add a 0.3D (1 stop ND) filter to your ND400 to bring it up to 800x, which is then within 1/3rd of a stop of an ND 1000.</p>

<p>Further edit: The Hoya ProND range uses a thin-film dichroic metallic coating to produce the ND effect. That explains everything.</p>

[lex_jenkins]

<p>Regarding blocking the eyepiece, I was only passing along Hoya's own suggestion. I'm skeptical about that particular cause/effect too - an unblocked eyepiece usually only affects metering in some cameras (I have to use the eyepiece blind on my D2H with the IR filter setup I've described for accurate exposures). The reviewer in that article I linked to mentioned some problem with the same Hoya, but didn't provide any sample illustrations of the problem he experienced.</p>

<p>I'm wondering whether the effect might be minimized by using another lens. When combined with filters, some lenses seem more vulnerable than others to producing reflection artifacts, hot spots (with IR) and other oddities.</p>

[aaron l]

<p>I could actually see this effect just by looking into the filter with my eyes. It wasn't the lens at all.<br>

So you think it's the dichroic coating that causes this? These are CF bulbs but they're in a glass globe. I looked directly into a bare CF bulb and could see the same thing. I don't see this effect with a tungsten bulb or on a cloudy day. It must be the CF spectrum with the coating. I just don't want to go on an expensive trip only to come back with irreparable issues.Looks like the filter is going back.<br>

You're right, Rodeo Joe. I've needed an ND 0.3 or 0.6 for a while, so maybe that'll be a better combination.</p>

[rodeo_joe1]

<p>Difficult to believe that Hoya could get it so wrong with this filter design. Taking Aaron's experience and those of the reviewer linked above, this filter appears to be a complete donkey of a product. Shame, because in theory the metallic film approach should be the ideal solution.</p>

<p>I have two thin-film ND filters, one made by Bolex and another made by Sony and both perform superbly. Unfortunately they're only in small diameter fittings and in low densities; one being 4x and the other being 8x. Maybe this technology has exceeded its limitations in going to a 1000x attenuation factor. After all it relies on the metallised film remaining thin.</p>

[randy_cooprider1]

Newtons rings caused by separated elements.

[aaron l]

<p>I'm wondering if it's a single error or an endemic problem. Either way, I need to get something I know works, so it's back to the ND400 and another 0.9 filter. Oh well. I'll avoid metalized filters from now on.</p>

[CvhKaar]

<blockquote>

<p>Newtons rings caused by separated elements</p>

</blockquote>

<p>MM Not likely when the filter is indeed created from 1 piece of glass..<br>

Interbal reflections within the lens system and/or sensor reflections would be possible though, if within the lens system itself then the pattern would be differend depending on the lens used.</p>

[mike_halliwell]

<blockquote>

<blockquote>

<p>Newtons rings caused by separated elements</p>

</blockquote>

<p>MM Not likely when the filter is indeed created from 1 piece of glass..</p>

 

</blockquote>

<p>Maybe the evaporated-on metallic coating is 'lifting' by a few microns? As both are, in-effect, transparent, and they are semi-touching, I guess you could make Newton's Rings.</p>

<p>If the OP can see interference rings by eye, it's just a filter fault, no lenses, no internal camera reflection etc etc.</p>

[tom_mann1]

<p>MH: <em>"Maybe the evaporated-on metallic coating is 'lifting' by a few microns? As both are, in-effect, transparent, and they are semi-touching, I guess you could make Newton's Rings...."</em><br>

<em> </em><br>

I think we can eliminate that possibility. Evaporated metal coatings as thin as the ones used in such filters simply don't have the structural integrity to lift off and stay in one piece. Think of a piece of metal whose thickness is a tiny fraction of the thickness of gold leaf.</p>

<p>However, it's possible that the applied metalization was not of uniform thickness and we are seeing a bit of interference between reflections from the front and back of the metal coating. The extremely high loss tangent (epsilon double prime) of the metal would make any such interferences very, very broad (in wavelength), but I suppose it could happen. Problems with non-uniform coatings are not all that uncommon, so one could have slipped through their QC checks.</p>

<p>Tom M</p>

 

[mike_halliwell]

<p>Tom, good info, many thanks! Never really thought just <em>how</em> thin they'd be.</p>

<p>Someone told me that green laser pointers show through thin gold leaf OK....mind you that is pretty intense light..:-)</p>

<p>CFL lights are renowned for sometimes producing green > magenta 'stripes' on CCDs, can something similar be happening visually with the 2 distinct wavelength peaks?</p>

<p>EDIT. The fact a 'continuous source', like a Tungsten bulb or daylight seems OK, seems to be conclusive.</p>

<p> </p>