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2 minutes ago, wiskerke said:

 

Not so fast, IS/VR may cause some of it as well.

 

 

wim

 

 


OK.  I actually didn’t read that link yet. I was using the basic logical principle that if a hypothesis can be proved wrong in one case, then that disproves the hypothesis but yes there may well be multiple causes for this effect (and I did qualify what I said with single cause). 😀

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3 hours ago, MDM said:


OK.  I actually didn’t read that link yet. I was using the basic logical principle that if a hypothesis can be proved wrong in one case, then that disproves the hypothesis but yes there may well be multiple causes for this effect (and I did qualify what I said with single cause). 😀

 

Yes Ockham's razor and all that.

 

wim

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On 13/08/2020 at 03:21, MDM said:


Depending on the volcano and the type of activity, you might need more than a protective lens filter. 

 

Nicaraguan volcanos tend to be more decorative than dangerous, but do put out lots of dust and sulfurous fumes.

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Looking thorough the various images of the phenomenum, it appears that the seperation between the finges gets wider the further in front or behind of the point of focus the area of the image is. As the point of focus the fringe spacing becomes so small it disappears. Long focal length mirror lens bokeh (and other lenses) show the same effect as shown admirably here. https://c1.staticflickr.com/5/4077/5394380056_55d1a78863_b.jpg

 

It suggests there's some non-uniformity in some filters (micro-waviness in the polishing or coating, or maybe the UV filtering bit is a polymer laminate with oriented polymer chain molecules)? Polarisers often have a sandwiched plastic film inside. No idea about UV filters.

 

Mark

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One thing strikes me about this effect, as someone who wears sunglasses a lot (I’m on meds that make me more susceptible to cataracts) the artefacts seen here seem vaguely reminiscent of some of the patterns you occasionally see on tempered glass when looking through polarised lenses. The fact that rotating the filter can influence the impact would seem to indicate that some sort of polarisation effect could be at play. I haven’t had chance to read any of the linked articles or research the issue in any way shape or form but it may be a possibility (or maybe not) 🤔

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2 hours ago, wiskerke said:

 

Yes Ockham's razor and all that.

 

wim


Having had a look at the Klaus Shuler bokeh site, I think I will continue my unwritten philosophy of concentrating on the subject and not worry too much about the bokeh. That guy is obsessed by bokeh. 
 

 

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2 hours ago, MizBrown said:

Nicaraguan volcanos tend to be more decorative than dangerous, but do put out lots of dust and sulfurous fumes


That is what I meant 😀. Sulfurous fumes are not good for the lungs and nor is the ash or secondary dust. 

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13 minutes ago, MDM said:


That is what I meant 😀. Sulfurous fumes are not good for the lungs and nor is the ash or secondary dust. 

And how do you make it to screw a lens protective filter in your face mask to avoid them?? Can't figure it out! 😁

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All I can say is, the filter that the retailer send me for free with my lens was this:
Green.L UV Series 77mm dHD Digital RoHS standards
You can read in the filter box: Reduce brillant light scaterring. More brillant, less flare
They forget to add: "bokeh fantasy lines included" 🙄
Price in Chinese pages: around 6€

 

The good filter I bought, put on the lens and have never take it apart since then (2014) is:
B+W XS-PRO NANO MRC UV-HAZE 77mm (ref. 1066125)
I think one of the best filters I could find/afford for that lens.
Price: between 50-90€ (it cost me 70€)

 

The lens was a brand new AF-S Nikkor 300mm f/4D IF-ED.
I used it, as most of the time, with a Kenko Teleplus Pro 300 AF 1.4X DGX, and a Nikon D90…so effective focal length is 630mm aprox.

 

With the cheap filter, used a couple of days waiting for the good one, many images show the lines. They appeared in out of focus areas, especially with variated patterns (branches, leaves, moving water surface…). The lines are most prominent in the background, and less in the foreground. Plain backgrounds like blue or gold skies doesn’t show any lines. 

 

With the expensive, and IMHO very good filter, no lines nor other side effects, in all kind of situations.

Haven’t used the lens without filter. Maybe i would find it is better without it! ;)

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14 minutes ago, shearwater said:

And how do you make it to screw a lens protective filter in your face mask to avoid them?? Can't figure it out! 😁

 

It was my understated sense of humour. I meant a respirator. I have been around a few active volcanoes in my previous life as a geologist. Some are very benign and some are very dangerous. 

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39 minutes ago, MDM said:


That is what I meant 😀. Sulfurous fumes are not good for the lungs and nor is the ash or secondary dust. 

 

Masaya Volcano has a ten minute maximum stay per car or truck and requires that vehicles be backed into the spaces so if the volcano acts up, the visitors can get out fast.  It's a regional park volcano occasionally dumps rocks -- one landed on the roof of a tourist's rental car.

 

I have photographed Momotombo after it went active for the first time since the early 20th Century, but from a distance.

 

 

 

 

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10 minutes ago, MizBrown said:

 

Masaya Volcano has a ten minute maximum stay per car or truck and requires that vehicles be backed into the spaces so if the volcano acts up, the visitors can get out fast.  It's a regional park volcano occasionally dumps rocks -- one landed on the roof of a tourist's rental car.

 

I have photographed Momotombo after it went active for the first time since the early 20th Century, but from a distance.
 

 

 

Sounds fascinating if dangerous. The explosive ones are the most dangerous and can be unpredictable as we saw in New Zealand last year. I've been to Chile but never to Central America. Maybe one day. So many amazing places 

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2 minutes ago, MDM said:

 

Sounds fascinating if dangerous. The explosive ones are the most dangerous and can be unpredictable as we saw in New Zealand last year. I've been to Chile but never to Central America. Maybe one day. So many amazing places 

 

I met a Swedish family on one flight back to the US who came to Nicaragua every December and who always visited Volcan Masaya.  People can drive up to overlook Santiago Crater.  Costa Rica and Guatamela also have volcano tourism, not sure who lets the tourists drive up the closest to active volcanos.

 

Momotomobo is near Leon (it destroyed Leon Viejo).  Best viewing is from Puerto Momotombo on Lake Managua.   This is with the 200mm end of a Sony 55-200mm lens for their APSC cameras.   From Puerto Momotombo at dusk.  peak-of-volcan-momotombo-showing-recent-

 

 

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9 hours ago, MDM said:

 

It was my understated sense of humour. I meant a respirator. I have been around a few active volcanoes in my previous life as a geologist. Some are very benign and some are very dangerous. 

Yes, I understood. I only was trying to make a (bad) joke...but english is not my mother tonge...and spanish humor is different, and writing is less expresive...so it could sounds rude. Far away from my intentions. Sorry about that.

Never been near an active volcano...it sounds to be a heartbeating experience 😲

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1 hour ago, Sally R said:

 

That's very interesting Shearwater and good to know. In your case, the higher quality filter seems to eliminate the problem. I think I will go without a filter on my telephoto lens for a while and rely on the hood to protect it. If I do ever get another UV filter in the future, I'll keep in mind the B+W one you mention there. I'm very much looking forward to taking wildlife images without the annoying lines from now on 🙂

 

B+W, is a very reputade german brand. One of the best filters you can get. Quality and pricy. I have no shares of them ;)

I do also use Hoya filters, the pro series (they have many different qualities). Good price-quality ratio.

Great to know that you will get rid of the annoying lines. Enjoy it! :)

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17 minutes ago, shearwater said:

Yes, I understood. I only was trying to make a (bad) joke...but english is not my mother tonge...and spanish humor is different, and writing is less expresive...so it could sounds rude. Far away from my intentions. Sorry about that.

Never been near an active volcano...it sounds to be a heartbeating experience 😲

 

 

No pass nada hombre. 😀

I didn’t take your comment in any strange way at all. It can be hard enough to communicate in one’s native language on forums never mind in a second language. 
 

And if you have been to El Hierro and La Palma you have not just been near but effectively on active volcanoes. El Hierro is a series of very young volcanoes and could erupt in any one of several places including underwater. The whole of southern La Palma (Cumbre Viejo) is essentially a giant active stratovolcano. Similarly with Tenerife. The last eruption on La Palma in 1971 formed the Teneguia cone in the far south. Many people don’t realise what they are walking or living on. Fortunately they have extensive monitoring systems in place to warn of impending eruptions. 

 

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1 minute ago, MDM said:

 

 

No pass nada hombre. 😀

I didn’t take your comment in any strange way at all. It can be hard enough to communicate in one’s native language on forums never mind in a second language. 
 

And if you have been to El Hierro and La Palma you have not just been near but effectively on active volcanoes. El Hierro is a series of very young volcanoes and could erupt in any one of several places including underwater. The whole of southern La Palma (Cumbre Viejo) is essentially a giant active stratovolcano. Similarly with Tenerife. The last eruption was on La Palma 1971 formed the Teneguia cone in the far south. Many people don’t realise what they are walking or living on. Fortunately they have extensive monitoring systems in place to warn of impending eruptions. 

 

Thanks, MDM :)

Yes, you are completely right. El Hierro and La Palma are two "floating", and by now asleep, volcanoes in the Atlantic sea. I really meant an active in the moment volcano.  Actually, as you mentioned, there was an underwater eruption near the south cape of El Hierro in october 2011. Diving tourism dissapeared. I went there one year later (nov2012) and as far as I was told the underwater life hadn't recovered completely at that time. Nor even diving tourism. Don't think it has fully recover.

I remember a volcanoes documentary taking about a possible future eruption in west La Palma, that could badly destroy east coast of America by its provoked tsunami. Terrifying.

 

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9 minutes ago, shearwater said:

Thanks, MDM :)

Yes, you are completely right. El Hierro and La Palma are two "floating", and by now asleep, volcanoes in the Atlantic sea. I really meant an active in the moment volcano.  Actually, as you mentioned, there was an underwater eruption near the south cape of El Hierro in october 2011. Diving tourism dissapeared. I went there one year later (nov2012) and as far as I was told the underwater life hadn't recovered completely at that time. Nor even diving tourism. Don't think it has fully recover.

I remember a volcanoes documentary taking about a possible future eruption in west La Palma, that could badly destroy east coast of America by its provoked tsunami. Terrifying.

 

 

Yes it shows how important exact language can be. If you ever want to see an erupting volcano then pay a visit to Stromboli, one of the Aeolian Islands in the Mediterranean north of Sicily. 

 

I know the documentary you are talking about. It was way too sensationalist and caused a lot of unnecessary fear. The BBC should be ashamed of itself for that one. The idea that the Cumbre Viejo of La Palma is on the verge of collapse is vastly exaggerated. The evidence used has been strongly refuted since the documentary was made in fact. That said, mega-collapses of volcanoes can and do happen but are very very rare.

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On nisen bokeh, Roger Cicala (of LensRentals) four years ago said this, and I tend to agree by now, even without having seen the why of the effect caused by some filters:

 

Cicala:
Dec 12, 2016
https://www.dpreview.com/forums/thread/4090070?page=2

 

One thing I would like to point out is we tend to over-generalize in this type of discussion somewhat. Nisen Bokeh can have a lot of causes.

Some are correctible: bad filter, a bit of oily film on the lens, etc.

Some are inherent to lens design: such as lenses with overcorrected spherical aberration, etc.

Some are for a bad copy of the lens with a decentered or tilted element.

Often it will only affect foreground or background bokeh.

The IS unit is a lens element and in certain positions could play a role, at least in theory. This will often be very random, only if the IS unit is in a certain (usually maximum correcting) position which will vary shot to shot or even among some of several shots in a burst.

Focusing distance also plays a role, with it being more apparent at some distances than others.

With ANY zoom lens, however awesome the zoom is, there will be certain focal lengths at which it is more likely appear or be more noticeable than other distances. And, of course, now we have the dual feature of focusing distance and zoom focal length coming into play.

So it isn't surprising to me that we see it in some shots and not others. If I had a lens that others all raved about showing Nisen bokeh, I'd be concerned something was wrong. If I sometimes saw it, and others sometimes saw it, I'd be trying to narrow down the conditions in which it occurred so I could avoid them when possible. Although that's a lot of work to do, so knowing myself I'd probably just accept the randomness of it.

 

 

Then there is this image of a (probably cheap) UV filter:

UV filters test - supplement - Introduction

translated https://www.lenstip.com/120.1-article-UV_filters_test_-_supplement_Introduction.html

from a well known Polish photography site https://www.optyczne.pl/

 

It's been disputed what we're seeing here, but whatever it is, it's totally not even:

  From https://www.lensrentals.com/blog/2017/06/the-comprehensive-ranking-of-the-major-uv-filters-on-the-market/

  Brandon Dube - Chris Jankowski 3 years ago

  In the second link (120...) they claim they've captured interference fringes. They most assuredly have not -- there is no type of interferometer (Fizeau, white light, michelson, lateral shearing, etc) that produces such sharp fringes with that large of a spacing.

  Their spectral transmission charts are difficult to comprehend, as is their notation for extinction coefficient. IMO.

 

wim

 

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On 15/08/2020 at 16:31, wiskerke said:

Then there is this image of a (probably cheap) UV filter:

UV filters test - supplement - Introduction

translated https://www.lenstip.com/120.1-article-UV_filters_test_-_supplement_Introduction.html

from a well known Polish photography site https://www.optyczne.pl/

 

It's been disputed what we're seeing here, but whatever it is, it's totally not even:

  From https://www.lensrentals.com/blog/2017/06/the-comprehensive-ranking-of-the-major-uv-filters-on-the-market/

  Brandon Dube - Chris Jankowski 3 years ago

  In the second link (120...) they claim they've captured interference fringes. They most assuredly have not -- there is no type of interferometer (Fizeau, white light, michelson, lateral shearing, etc) that produces such sharp fringes with that large of a spacing.

  Their spectral transmission charts are difficult to comprehend, as is their notation for extinction coefficient. IMO.

 

Assuming you are referring to the interferogram shown, I agree it is unusual and couldn't be caused by simple optical non-flatness or variations in thickness for exactly the reason you say. But if the UV filter is made from polymer film sandwiched in adhesive between two glass flat sheets, and the polymer is also optically active then I think it's possible to get all sorts of wierd effects. I remember being involved in some work on polarizing filters in the coherent light path of an interferometer and we saw all sorts of effects. If I recall correctly the problem we had was that some of the interference coherence was disrupted within the plastic film and the effect was temperature sensitive. It might be interesting to know how the filter concerned was made. Multilayer vacuum deposited coating or sandwiched polymer?

 

Mark

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9 hours ago, M.Chapman said:

 

Assuming you are referring to the interferogram shown, I agree it is unusual and couldn't be caused by simple optical non-flatness or variations in thickness for exactly the reason you say. But if the UV filter is made from polymer film sandwiched in adhesive between two glass flat sheets, and the polymer is also optically active then I think it's possible to get all sorts of wierd effects. I remember being involved in some work on polarizing filters in the coherent light path of an interferometer and we saw all sorts of effects. If I recall correctly the problem we had was that some of the interference coherence was disrupted within the plastic film and the effect was temperature sensitive. It might be interesting to know how the filter concerned was made. Multilayer vacuum deposited coating or sandwiched polymer?

 

Mark

 

Which would mean we should be able to see it with a pola filter and polarized light.

 

wim

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Gee, I would have guessed it was caused by Cosmic rays being blasted at us from one of the moons of Jupiter by an alien race in order to make us all crazy and therefore a cinch to conquer when they finally show up.  Their evil plan seems to be working so far.  I would suggest tin foil hats for everyone and the camera/lens.😁

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4 hours ago, Johnnie5 said:

Gee, I would have guessed it was caused by Cosmic rays being blasted at us from one of the moons of Jupiter by an alien race in order to make us all crazy and therefore a cinch to conquer when they finally show up.  Their evil plan seems to be working so far.  I would suggest tin foil hats for everyone and the camera/lens.😁

 

Haha!

Maybe they're from the same people that brought us these:

Mad Ad Men: X-Ray vision

Or they're from the Twilight Zone....

 

wim

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