UV/Protective filters can cause reflections in the photos.

[Huss]

Working on a film project, I noticed that the images had what looked like a square reflection of a building's light opposite it at the bottom of the pic.
I had shot that set using a CV 40 1.4 SC, and a B+W F-Pro UV SC filter.

I just realized that perhaps it was the filter that was causing the issue? So I took a couple of quick shots of the scene on digital. One with the filter on, one with it off. With the filter on you can see the blue square reflection. With the filter removed - no reflection. So, if you have a light source within the frame in a night time shot, you can get reflections if you are using a filter. Of note, when I bought the B+W filter I thought it was the MRC (multi coated) version, but it is not. It is the SC version, so there is the possibility that this could be diminished or avoided by using the MRC version.
As I shot the project with the CV lens, I wanted to repeat using the same equipment and do not have a 43mm MRC filter to compare against.

 

[ray*j*gun]

Yep, I had this happen to me shooting a dinner in Wildwood NJ at night lit only with the neon window lights. I have since removed "clear" filters when shooting anything critical esp on film.

 

[BLKRCAT]

I've noticed this too.

 

[willie_901]

I never use filters unless there is no other choice... even though I know people have had lenses saved from impact damage by using filters.

Examples would be:

o windy, dusty conditions including blowing sand
o rain/mist/snow
o ND filters
o graduated ND filters
o polarizing filters
o color filters with B&W film

The fact is even high-quality filters degrade IQ and can produce reflection artifacts. The IQ degradation is usually trivial and easily remedied during post-production work.

As far as I know, reflection issues with filters depend on the type of camera one uses.

mirrorless >>DSLR >>>> film

I have no idea how digital M cameras compare.

Of course lens design and coatings play a major role as well.

I suppose if one really needs to use filters for aesthetic purposes the least risky (and most inconvenient) way is to use a 4 X 6 rectangular filter/holder system. I have used a 4 X 6, 3X, graduated, ND filter often and the ghosting in contre jour situations was similar to what I experienced without a filter.

 

[Huss]

As far as I know, reflection issues with filters depend on the type of camera one uses.

mirrorless >>DSLR >>>> film

I have no idea how digital M cameras compare.

Of course lens design and coatings play a major role as well.

I don't think the type of camera has anything to do with it, as the reflection is an optical artifact. I don't think the lens design and coatings has anything to do with it either as it is not a fault of the lens, but a direct result of reflections caused by the filter. The lens just picks that up as part of the image as it has no idea that it is not part of the image!
I first noticed it when I used that lens/filter combo on film, then reproduced it on digital as shown above using the same lens/filter combo. The camera was an M240.
With both the film and digital camera, the reflection disappeared when the filter was removed.

Lesson here is that if you are taking shots in low light conditions with light sources in the frame, remove the filter to make sure you do not get reflections.

 

[Huss]

I've noticed this too.

Do you remember what filter you used and if it was a multi coated or single coated one?

 

[BernardL]

I don't think the lens design and coatings has anything to do with it either as it is not a fault of the lens, but a direct result of reflections caused by the filter. The lens just picks that up as part of the image as it has no idea that it is not part of the image!

Don't agree. Plane-parallel glass plate alone cannot create such artifacts, like a diametrically opposed (wrt optical axis) ghost image of a bright light. Try with a filter, however poor quality, in front of just your eye.
It takes one reflection off one of the curved lens surfaces and a reflection off the filter.
Ghost being absent with lens alone does not prove that lens play no role in lens+filter ghost.

 

[BLKRCAT]

Do you remember what filter you used and if it was a multi coated or single coated one?

Single Coated.

B+w 010 UV Haze on a Nokton 50mm F1.1. Probably at F1.1 or 1.4

 

[Huss]

Don't agree. Plane-parallel glass plate alone cannot create such artifacts, like a diametrically opposed (wrt optical axis) ghost image of a bright light. Try with a filter, however poor quality, in front of just your eye.
It takes one reflection off one of the curved lens surfaces and a reflection off the filter.
Ghost being absent with lens alone does not prove that lens play no role in lens+filter ghost.

Your eye's lens is curved, it's not flat. And you can see the reflection in the filter.

The lens used was a CV 40 1.4. What in its lens design would cause the filter to cause a reflection seeing there is no reflection without the filter?

What lens design would not cause this reflection with a filter? And an example of this lens would be good as I have a whole sack load of lenses that I could use but I didn't because I saw the reflection with this CV lens, and wanted to know what caused it so I performed the test with this particular CV lens.

 

[Huss]

Single Coated.

B+w 010 UV Haze on a Nokton 50mm F1.1. Probably at F1.1 or 1.4

Thanks, just like mine. I think I have an MRC on my Planar 50 so I will see if that makes a difference when I get a chance.

 

[minnichphoto]

I get a filter reflection on my Hasselblad 60mm.

http://minnichphoto.tumblr.com/image/142808494690

http://minnichphoto.tumblr.com/image/141260060860

I have tried different filters and they behave slightly differently but mostly still get some degree of the round ghosting. I should probably go filter free.

 

[Huss]

I just always thought it was just a ploy by camera stores to sell you something you didn't need.

I live by the beach where there often is salty spray in the air, as well as sand.
Places like this it is helpful to have one.

 

[daveleo]

Don't agree. Plane-parallel glass plate alone cannot create such artifacts, like a diametrically opposed (wrt optical axis) ghost image of a bright light. Try with a filter, however poor quality, in front of just your eye.
It takes one reflection off one of the curved lens surfaces and a reflection off the filter.
Ghost being absent with lens alone does not prove that lens play no role in lens+filter ghost.

I agree with this assessment.
Some lenses are more prone to this effect than others (using the same filter), which tells me the lens plays an important role. My X100 was notorious for doing this with filters.
Also, very possibly the proximity of the digital sensor to the lens glass. In the cameras I've owned, the (APS) sensor is maybe 6mm closer than where the film plane would be.

 

[Huss]

Also, very possibly the proximity of the digital sensor to the lens glass. In the cameras I've owned, the (APS) sensor is maybe 6mm closer than where the film plane would be.

Exactly the same result whether I shot on film or on digital using the same lens.

Bottom line, this is a heads up for those who may be shooting in dim/dark conditions with light sources in the image. Simple solution is take off the filter which will remove the possibility of it happening.

 

[Huss]

I get a filter reflection on my Hasselblad 60mm.

http://minnichphoto.tumblr.com/image/142808494690

http://minnichphoto.tumblr.com/image/141260060860

I have tried different filters and they behave slightly differently but mostly still get some degree of the round ghosting. I should probably go filter free.

That actually looks like lens flare from the filter, not a reflection. You can see lens flare from the lens itself - the aperture shaped images - and flare from the filter - the circular images. I definitely would not use that filter on that lens.