Which Circular polarizer

Don Kondra

Greetings,

I'm prepping to shoot a grandfather clock with glass sides, front and top in the near future.

Basic set up is paper backdrop and strobes in softboxes.

I understand a polarizing filter will help with reflections in the glass.

Would appreciate recommendations on brands, etc...

TIA,

Cheers, Don

ziggy53

Don Kondra wrote:

Greetings,

I'm prepping to shoot a grandfather clock with glass sides, front and top in the near future.

Basic set up is paper backdrop and strobes in softboxes.

I understand a polarizing filter will help with reflections in the glass.

Would appreciate recommendations on brands, etc...

TIA,

Cheers, Don

Don,

A polarizing filter can indeed reduce reflections, but you need a polarized light source for it to work properly. The sun is a popular source of polarized light. In order to polarize electronic flash I believe you will have to also add a polarizing filter in front of the flash itself. Then you would adjust the angle of the polarizing filter on the camera lens to an angle which will cancel the reflections of the polarized light.

This is a quote from "The Hasselblad manual" by By Ernst Wildi, Edition: 6, pages 261 and 262:

"Using Polarizing Filters over Light Sources

You can polarize light from tungsten lights or electronic flash by placing a polarizing filter over the light source. the polarizing filter on the camera lens then eliminates all reflections, at all angles, from all materials. This procedure is necessary to eliminate reflections on bare metal. It is also a superb approach for copying.

To be effective, the polarized light must illuminate the picture or document from an angle of between 30and 40 degrees. You then turn the polarizing filter on the camera by visually examining the image on the focusing screen."

Don Kondra

Thanks Ziggy,

My research is contradictory. Some say you need a polarizing gel over a reflector on the strobe, some say the light coming out of a softbox is polarized.

I'm going to try a Hoya Pro CL for ~$100 and I've ordered the $12 ebay version. Again reports are the $12 version works but there has to be a difference, perhaps similar to standard lens compared to high grade lens? We'll see.

I also remember talking to a friend who is a professional photographer about polarizing issues. At the time I wasn't paying close enough attention but he had found a common lighting shade that can be adapted to a strobe to polarize the light. I'll check that out and continue to search for a supplier of polarizing gels.

Cheers, Don

ziggy53

Don Kondra wrote:

...

My research is contradictory. Some say you need a polarizing gel over a reflector on the strobe, some say the light coming out of a softbox is polarized.

...

No, a softbox does not polarize light. Just using a polarizing filter on a lens will give some benefit regarding reflections, but for control you need a polarized light source and polarizing filter.

In the case of the softbox you really need the polarizing material over the final diffusion panel for best results.

Don Kondra wrote:

...

I'm going to try a Hoya Pro CL for ~$100 and I've ordered the $12 ebay version. Again reports are the $12 version works but there has to be a difference, perhaps similar to standard lens compared to high grade lens? We'll see.

...

It can't hurt to try.

Don Kondra wrote:

...

I also remember talking to a friend who is a professional photographer about polarizing issues. At the time I wasn't paying close enough attention but he had found a common lighting shade that can be adapted to a strobe to polarize the light. I'll check that out and continue to search for a supplier of polarizing gels.

Cheers, Don

I believe that some of the CRT/monitor shades used polarizing material and there are (relatively) cheap sources of polarizing sheets, sometimes "seconds" from sunglass manufacture, that are appropriate for the task.

Check out these links:

http://www.bhphotovideo.com/bnh/controller/home?O=search&A=search&Q=&sb=bs%2Cupper(ds)&sq=asc&sortDrop=Brand%3A+A+to+Z&ac=&bsi=&bhs=t&ci=1329&shs=&at=Type_Polarizer&basicSubmit=Submit+Query

http://www.polarization.com/shop/catalog/

In 1975 I bought some material from Edmund Scientific, but I haven't checked there recently:

pathfinder

Ziggy,

You still have and can find your receipts for 1975??

Toshido

From the little of high school science class i remember on the subject.

Sun is not polarized, reflections are to a degree. Which is why polarized sunglasses work on glares but does not cancel out all light.

An experiment based on that to try to partially polarize the light source would be to reflect the light. not sure if or how much it would work of course.

ziggy53

pathfinder wrote:

Ziggy,

You still have and can find your receipts for 1975??

To be honest, my father was going through some stuff at his house and came upon the original package, which is how I store the polarizing sheets. The receipt was still inside. It's just odd that his discovery and this thread coincide.

I'm not sure why the sheets were at his house. I had been looking for them a few months ago and couldn't find them at my house, so I thought I had lost them.

ziggy53

Toshido wrote:

...

Sun is not polarized, reflections are to a degree. Which is why polarized sunglasses work on glares but does not cancel out all light.

...

That's true that the direct light from the Sun is not polarized when it comes to the Earth, but our atmosphere has a polarizing effect. That's why a polarizing filter can darken the sky. Diffusion can scatter the light again so that what hits the Earth's surface may not be tremendously polarized.

Reflections from metals and water can indeed polarize the light, which is why a polarizing filter works so well to reduce glare from those objects. Controlling the angle of polarization is not as easy with reflection, so that polarization films and screens are the most common materials to polarize light for photographic and scientific applications.