[catastrophe]

Hi,

Anyone know what may be causing this weird banding issue when using a B+W 10 stop ND filter? It happens randomly but once it does, it seems to occur every shot even though I ensure the lens and filter is clean. I'm using a Pentax 15mm. Sometimes it's subtle but sometimes it's so horrible that it destroys the image...

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[crewl1]

All these shots are pointed at the sun so perhaps it is weird flare behavior.
Do you get the banding when the sun is behind?
Try another filter. I have not used a B&W filter but based on how much they cost I would think this should not occur.
Are there counterfeit B&W filters?
Edit:http://mainlinephoto.wordpress.com/2009/04/16/how-to-tell-the-difference-bet...ke-bw-filters/

[Franc]

did you cover the eye piece? It leaks light taking long exposure shots that causing banding.

[Islejones]

Eye piece cover was my first thought too.
I dont think that the filter is a variable one, i got those issues with a cheap variable ND filter.

Regards,
Islejones

[Joojoo2010]

Yes looks like light is leaking from someplace.

+1 viewfinder is not covered and light leak from there

[Na Horuk]

I thought of the ND filter first. Cheap ND filters or knockoffs can cause all sorts of odd behaviours, especially with such wide angle lenses and in bright light
But the light leak idea is good, too. Next time you notice this, try covering the viewfinder. If that doesnt help, return the ND filter and get a different brand.
With filters you should be careful, because if you buy online there is a chance you are getting a fake. You should only buy filters from brick and mortar stores, or very reputable online stores (ones that a lot of people use, that you can call up, who have an office you can visit..)

[interested_observer]

I had experienced some light leakage, somewhat similar from memory. The images are on my PC with all the storage.

This thread supports the light entry via the viewfinder - leaking around the mirror being up and down to the sensor. This does make sense in terms that the light is always banding across the long side of the frame, and it does take on the appearance of the edge of the mirror.

• https://www.pentaxforums.com/forums/120-general-technical-troubleshooting/18...r-issue-2.html

There were a couple more posts across the web on this. But, I did come across a couple of other interesting items.

• The Lee variable ND (since it is made out of two polarizers) that when turned determine the amount of light - at times produces an "X" pattern (based on the relative positions of each of the polarizers relative to the sun in the frame.
• The other item that I found very interesting is that with a couple of types of ND filters - Black Glass (of which the 10-stop B+W is this type) acts on waterfalls a bit differently that other types of filters. Color casting across the different makes of ND filters, along with the supporting the viewfinder light leaking issue.
  • "The Ultimate Guide To Neutral Density Filters" by Peter Hill | Redbubble

[catastrophe]

Thanks guys for the help. It's a multi-coated BW filter so it's really likely it's caused by light leakage from the viewfinder instead of a low quality filter. Will try long exposures again with the eye piece and hopefully there's no problem....

[MadMathMind]

Your top image is without the filter, right? The same banding issue is in both your beach photos, so it's definitely not the filter.

[catastrophe]

They are all with filters, with exposures of longer than 10 secs.

[TaoMaas]

I think it's light-leak from the viewfinder. Post your results when you test it. Folks are curious. Thanks!

[mikeSF]

not to pile on, but those look just like viewfinder leaks to me. I cant say how many of those covers i have lost, but the number equals how many ive purchased, lol.

[littledrawe]

cant say how many of those covers i have lost, but the number equals how many ive purchased,

Sounds like something Confucious would say...

[Spodeworld]

I wish I saw this before I left for vacation in Hawaii. We're finishing up now and I noticed terrible sky banding on long exposures of waterfalls using an nd filter. Too late for this trip unfortunately. I doubt I will forget to cover the viewfinder again.

[tibbitts]

It's irritating that Pentax cameras don't feature the built-in finder blinds that even mid-level 35mm cameras from the 1970s offered. Having some little plastic accessory that you have to fit over the viewfinder is no substitute for a simple lever you flip open and closed.