Dealing with reflection between lens and filter?

[jvuokko]

Recently I have been using some quite dark filter. Deep reds, very dense ND filters (between densities 1.5 ... 4.0). All are made from gelatin.


The problem is that sometimes the lenses barrel and markings will reflect from the filter to the image. This happens with wide field lenses, like 90mm, 75mm and 65mm in 4x5" size.

The most problematic is my 75mm super-angulon, Linhof Technica-labeled and has shiny metallic barrel. From lenses with black paint finish, only the white markings will cause reflections.


I guess that the main cause is the small gap between the front of lens and the filter itself. I have tried to close that gap with black paper but that doesn't help much. Perhaps it allowed still too much light to enter to the front of the lens via corners etc.


Is there any commonly known solutions for this?

[Gem Singer]

Are you using a lens hood?

[jp]

You can tape the filter to the back of the lens.

Otherwise, you're going to need some sort of hood/compendium to keep the stray light off the filter/lens.

[vinny]

darken light lettering and chrome with a black dry erase marker.
as Gem said, use a compendium shade if you aren't already.

[Mark Woods]

On film cameras, there often is a gap between the outside edge of the lens and the inside edge of the matte box. The gap is covered with a "doughnut" made of about 1/2" black foam the slips over the lens barrel and extends beyond the edge of the matte box. Simple, cheap, and can be made for different lenses.

[Brian Ellis]

Multi-coated filters don't help?

I don't recall experiencing this problem with my Technikas and filters. I did use a Linhof compendium shade for a while but it was a pain to put on and take off so I didn't actually use it much. I also tried an Ebony "flag" gizmo on Ebony cameras but all that really did was keep direct sunlight off the lens. And finally I used the Lee filter system which includes a bellows and a filter in front (similar to the Linhof compendium shade but easier to put on and take off). It too was something of a pain.

I mention all these systems just because you might want to try one of them. I wasn't wild about any of them. In fact with filters I quit even screwing them on the lens, I just started holding them in front of the lens by hand and that seemed to work fine.

I hope this doesn't sound like I cared so little about my photography that I didn't want to go to any trouble. That wasn't the case, I just didn't find the problem for me to be worth these solutions. But maybe one would work for you.

[Mark Woods]

One can also put the filter behind the lens. Sinars have this capability, but one could put something together to do this on any camera.

[E. von Hoegh]

A multicoated filter will minimise reflections. You could cut a ring of black felt to place on the front ring of the lens, that should eliminate all reflections.

[Paul Fitzgerald]

" You could cut a ring of black felt to place on the front ring of the lens, that should eliminate all reflections. "

so would a black paper ring, easier to cut and use.

[jvuokko]

I have ordinary Toyo compendium in my Toyo monorail cameras. But for very wide angle lenses, it cannot be extended much, thus light can easily reach lenses front from gap between gelatin filter and the lens.

Here's example with longer lens, the compendium works quite well:

94537


With my 4x5 field, it's different story. Currently I have compendium, but it's attached to the filter holder. All the filters will be in direct light.
Usually it's enough if I just shade them with my hand or darkslide, but when using really dense filters the reflections become problem.

All filter systems with compendium that I have seen has this problem. The filters aren't covered by the hood. No matter if it's Lee system or Cokin.

Here's compendium attached to the filter holder. The gap is huge:

94538

[Peter Yeti]

With that set up it might help to put the dark cloth over the camera and compendium to shade the filter holder. But placing the filter behind the rear lens element might be the best solution.

[lenser]

One of the best 'behind the lens' systems I ever saw was from Calumet. It's a combination of their Gel filter frames and a metal frame that mounted to the rear of the lens board via some adhesive tabs. The frame could be extended rearward to accommodate longer optics. I've seen quite a few of these come up on the bay and sometimes the cardboard frames as well. The latter would be easy enough to fabricate oneself. As others have said, behind the lens would pretty much remove reflections from the equation although using multiples would effectively create "air glass" surfaces that could create multiple images of light sources in the photo.

[Mark Woods]

Multi coated lenses do not cut down on reflections, the affect contrast and color rendition. As I said, the foam doughnut is the go to item in the film industry.

[vinny]

Multi coated lenses do not cut down on reflections, the affect contrast and color rendition. As I said, the foam doughnut is the go to item in the film industry.
Mark, they're typically cut from neoprene.

[vinny]

I have ordinary Toyo compendium in my Toyo monorail cameras. But for very wide angle lenses, it cannot be extended much, thus light can easily reach lenses front from gap between gelatin filter and the lens.

Here's example with longer lens, the compendium works quite well:

94537


With my 4x5 field, it's different story. Currently I have compendium, but it's attached to the filter holder. All the filters will be in direct light.
Usually it's enough if I just shade them with my hand or darkslide, but when using really dense filters the reflections become problem.

All filter systems with compendium that I have seen has this problem. The filters aren't covered by the hood. No matter if it's Lee system or Cokin.

Here's compendium attached to the filter holder. The gap is huge:

94538

the other thing I used to do with motion picture camera mat boxes/filter holders was attach a flap of black felt in front of the filter slot that laid back towards the camera to cover that open area. Keeps out dust and extraneous light perfectly.

[Mark Woods]

Vinny, you're right. I never made them, only used them. They did look like a wet suit though. Also, the black felt you're talking about, my AC used steering wheel covers with elastic. Worked really well.

[jvuokko]

I have used some Q&D solutions to cover the filter slot over the years.
I used these because I have been worried about possible flare caused by light entering filter(s) thru the slot. For some reason, I haven't ever seen any picture of similar setups. In the books etc. the filters are always at least under the incident light from the sky.


With really dense filters, my Q&D solutions really doesn't work. Perhaps better than none, but there's still reflections occasionally.

I have used these among the other. Perhaps I should attach densiest filter only behind of the lens or use some DIY hood that would be light tight from the lens board to the compendium hood. This would make lens operating quite difficult though.

94552
94553

[Struan Gray]

Cromatek used to sell a filter holder and hood combination which housed the filters in a sealed box. They come up quite regularly on eBay.co.uk.

There's a neat homebrew solution here: http://jorgesantosphoto.wordpress.com/2012/10/07/filter-holders-for-the-nikon-14-24-f2-8/

[vinny]

Cromatek used to sell a filter holder and hood combination which housed the filters in a sealed box. They come up quite regularly on eBay.co.uk.

There's a neat homebrew solution here: http://jorgesantosphoto.wordpress.com/2012/10/07/filter-holders-for-the-nikon-14-24-f2-8/
still looks like there's nothing keeping light from striking the back side of the filter though.

[lenser]

still looks like there's nothing keeping light from striking the back side of the filter though.

So assuming that the light is coming from overhead, what's wrong with just rotating the opening to the horizontal position to cancel most of that problem?!

[Mark Woods]

If you're getting kick back flares, images, etc., from the lens, put the filter at an angle to the kick doesn't go right back into the lens and over the image. I've done that also. Those solutions don't really have that capability.

[vinny]

So assuming that the light is coming from overhead, what's wrong with just rotating the opening to the horizontal position to cancel most of that problem?!

nothing, unless you're using a grad filter or if shooting a side-lit scene where there are clouds overhead. Avoiding extraneous light is a good thing:)

[Mark Woods]

By solutions, I meant the matte boxes.

[Struan Gray]

still looks like there's nothing keeping light from striking the back side of the filter though.

Sure. I just like the idea of elastic on the back and a drawcord on the front. Extending the idea to cover the whole shebang is left as an exercise for the reader :-)



If you're getting kick back flares, images, etc., from the lens, put the filter at an angle to the kick doesn't go right back into the lens and over the image. I've done that also. Those solutions don't really have that capability.

This often done with filters in laboratory optics setups. They tend to be flat to a fraction of a wavelength, and if you mount them parallel you can get some disturbing multiple reflections and/or interference effects.