Polariser using B/W film

[sp_key]

Hi all,

I'm thinking of trying my polariser on b/w film. Anyone has tried this on a DSLR? Any suggestions or tips?

Thanks

 

[Torus34]

Your questions are confusing. Polarizers have been used with b&w film almost since their inception. The one most often used is called a 'linear' polarizer. Its purpose is to reduce/eliminate reflections or to darken skies. Light from the sky differs in the degree of polarization depending on the relationship to the sun. It is most polarized at a point 90 degrees from the position of the sun. Therefore, the maximum sky-darkening effect will be found at that position.

In use, the filter [linear] is rotated until the desired effect [usually the maximum effect] is achieved.

Polarizers are used on DSLRs all the time. Usually, the 'circular' type is used so as not to interfere with the through-the-lens exposure metering function.

No one, to my knowledge, has successfully used b&w film in a DSLR. However, I can't speak for Mystery Scribe - he's capable of some pretty amazing stuff!

 

[sp_key]

Hi Torus,
thanks for you speedy reply - very explanative - and I apologise if my question confused you. I did not mean 'Has anyone tried to put a b/w film in his/her DSLR camera?'. What I meant is 'Has anyone tried to use a polariser for taking b/w photographs?'. Obviously I was unaware a polariser could be used successfully on b/w as I read that polarisers saturate colour that's where the confusion comes from my part comes. Also, I only have a film camera to experiment and I didb't want to waste film.

 

[Michael Humle]

Hey sp key, your question is a good one and many people are confused about the use of ploarizers! In this forum, NO question should require an apology! Ask away!!!

 

[Torus34]

sp key;

No apologies needed. Any confusion simply gave me an opportunity to be my pedantic self and prattle on for a while. [I was relatively sure you didn't mean putting b&w film in a DSLR, but couldn't resist 'funning' you a bit.]

You can get a linear polarizer relatively cheaply on ebay. Just remember that it will walk the dog for b&w film, but isn't so good for digital rigs. For film, polarizers will result in a small correction in exposure - usually about a stop.

And ask away whenever you hit an information wall.

 

[fightheheathens]

with B&W photos (at least film) a polarizer is going to darken skys.
back in the good olde days before people really knew how to make a good film, skys were completely blown out. This is mostly because a crap ton load of light comes in from the skys and if you wanted to not have black for your subject, you hada trade off and go with the blown out skys. Then some people got better at the whole film making process and learned that mostly blue light comes in from the skys so if you added some stuff into the film to absorb blue light, you could keep the skys from blowing out.


B&W film actually sees intensity of light and not color so if you can cut out certian light, say all blue light, anything that your eyes see as blue will look black on B&W film.
So what does a polarizer do? it lets in only certian wave lenghts of light. With out getting all technical, you end up cutting out a lot of blue light comming in from the sky. (thats what makes it look darker and bluer)
so whats that do to film? Since there is less blue light comming in, it looks darker. IF you add a red filter to that you can block out even more blue light. (red is at the other end of the light spectrum from blue) so if you use red plus polarizer you can almost block out all of the light comming in from the sky (but not clouds) so basically what you get is black skys.

as an example, the following picture was done with a polarizer and a red filter. i did do some burning of the sky when i printed, but to be honest, i didnt need to do much.

 

[Don Simon]

No one, to my knowledge, has successfully used b&w film in a DSLR. However, I can't speak for Mystery Scribe - he's capable of some pretty amazing stuff!

Now I'm almost tempted to donate my DSLR, just to see what it would look like hollowed out and with a 5x7 back stuck on it

 

[fmw]

sp Key, the polarizer will work the same way with b&w as it does with color. If you have Photoshop, however, there is a much better way. You can load up your colorphoto and choose image>adjustments>channel mixer. You can check the monochrome box and that will show you the image in black and white. It is still a color image, however and you can adjust things with the red, blue and green color sliders. As an example, decreasing blue or increasing red would darken the sky. The nice thing about doing it this way is that you can make infinitely fine adjustments and see the results as you work. It is far more precise than trying to nail it with filters at exposure time.

 

[Don Simon]

True, but using a polariser during exposure can also control reflections in glass, water etc.

 

[sp_key]

Thanks for your replies.

I enjoy Photoshop but coming from an audio background I'm trying to get things right from the source rather than spending more time in post trying to fix things. This way I can improve my photography while I can still improve my image processing skills afterwards.

So by the way, what's the difference between the polariser and the ND?

Thanks in advance

 

[Big Mike]

ND is just neutral density. It reduces the light getting in...without adding any color or effect. These are good for when you want a longer shutter speed than the light would other wise allow (shooting water falls etc.).

 

[Groupcaptainbonzo]

Now I may be wrong here but... As far as I am aware the Linear polariser is for manualy focusing cameras, and the circular is for auto focus.....
Therefore as long as you already have a polariser for your camera then it will work in mono (Black & White).
It will highten contrast and reduce reflections off surfaces just as in colour (Polychromatic). but obviously you will have taken the "Colour" out...

 

[fmw]

No, polarizers do not really affect contrast. They can reduce it a little by reducing the luminosity of sky light. They can increase it a little by reducing some contrast-robbing reflections. Contrast is affected primarily by the lighting, the subject and the lens.

Personally, I'm unclear about the use of circular polarizers. I discovered years ago that the linear ones filter polarized light more effectively and I've always used them - even with autofocus. Perhaps some cameras react differently than mine to the linear filters. I seem to remember that some metering designs were affected by linears also. I don't know the details. I've use linears successfully for many years.

 

[sp_key]

Hi again,

Something I 've found regarding the use of polarisers: http://www.ephotozine.com/equipment/buyersguide/fullbuyersguide.cfm?buyersguideid=25

" First thing you should know is that there are two varieties - linear and circular. Although they're both physically round, a linear variety can have an effect on the autofocus or metering accuracy of any camera that uses a semi-silvered mirror or prism to split the light entering the viewfinder. This is known as a beam splitter and is used by most modern SLRs to calculate exposure and focusing distance. As a rule use a circular filter if you have an autofocus camera or a manual focus model with a spot meter such as the Canon T90. "