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Barbados Aug 15, 2002 8:07 PM

Polarizing Filter, What went wrong?

It was a bright sunny day. Brilliant blue sky. The colour is too saturated, dark and intense. What did I do wrong? How can I obtain a more light, sky blue color next time?

Canon D 60, 28-125 f/3.5-5.6 IS, Program AE, shutter speed, 1/125, ISO 100, Polarizing Filter 81 A

NHL Aug 15, 2002 8:41 PM

This is normal with a polarizer, just don't dial in as much angle and the sky won't darken as much... Just like Photoshop, don't go overboard, or you'll get an outlandish effect which some photographers put to good use BTW. Normally lights come from all directions, including reflections and scatters... What a polarizer does is it cut down all the light except for the ones that aligned on certain axis depending on how you line up the two elements in the polarizer. At the maximum setting only the light straight ahead is allowed to passed through and hence your camera is looking into the end of the universe without any back scattering from the sun... If you had some clouds in the background, it would have popped right up against the darker sky!

It's a good shot though and I think you can undo most of it in Photoshop with the level and saturation adjustments...

[Edited on 8-15-2002 by NHL]

Also notice the angle of the sun is very critical! In my example the left side sky is bluer than the right side because of the wide field of view. However all the water reflections are cut off which is also another popular use for a polarizer...

[Edited on 8-16-2002 by NHL]

NHL Aug 16, 2002 6:54 AM

BTW for those lucky D7i, or the D7 owners that just have upgraded, check out your real-time histogram... Not only Minolta has provided you with real filter thread but watch those pixel density shift as the polarizer is adjusted! Rather unique and powerful instrument wouldn't you think?

KCan Aug 16, 2002 10:12 PM

I love the shot , I like the level of saturation and contrast , just rite my taste , a bit more luminance and it's perfect ( for me)

You are rite, I don't know how many cam offer the real time histogram , but it's a terrific pre-shot real time analyzer , one more step making the manual shooter "smarter" even without many years of experience .
I am still learning to benefit from that feature.

I took the liberty to past your pic through ACDSee with just one operation: Auto-level , and it's perfect for me

The dark blue sky just dramatize more the loneliness of the stump in the darkness of universe ...

[Edited on 8-17-2002 by KCan]

Barbados Aug 16, 2002 11:05 PM

Edited Photo
Thank you KCan. I used "auto levels" in Photoshop and agree. It does improve the color balance. I'm just learning all that can be done digitally.

BTW, my images are copyright. Please either credit me as artist, or link to my galleries :

[Edited on 8-17-2002 by Barbados]

KCan Aug 17, 2002 1:11 AM

No problem, I deleted the pic in my gallery

NHL Aug 17, 2002 6:22 AM



Just like Photoshop, don't go overboard...
You can move the two left & right triangles below the level histogram in Adobe and control the 'dramatic' effect, moving the middle one will set the overall white level... In your case there's no pixel in the 220 to 255 range, and In my opinion you can safely move the right triangle all the way to the 190 point, then play around with the middle triangle. Add some color, then increase the hue/saturation and you have a wall hanger for sure!

For the lucky few folks with real-time histogram:
o Twisting the polarizer shift the histogram density Left/Right
o Adjusting the contrast spread the histogram curve out...(or squash it down)
... combined with the color saturation, and you all have a 'mini-lab' there with the tiny EVF !!!
While at it, how about a USM screen Minolta for the next upgrade? hard(+) and soft(-) doesn't mean anything to anyone....

[Edited on 8-17-2002 by NHL]

ashenfie Aug 17, 2002 8:52 AM

The effect of the polarization filter has drawbacks in the effect does not loo natural. The filter has the most effect at midday with the sun at 90 degree to the camera. If you change the angle/time you can get an effect more to your liking.

These filter a great, but need some care in use.

[email protected] Aug 21, 2002 9:33 AM

Rule of thumb when using polarizer Filter
On the sunny day with the sun behind your back, to maximize the effect of the pol-filter, using your hand with your thumb point at the sun and your index finger pointing at other direction in a 90 degree angle with your thumb, that where your picture should be, compose your shot, pre-focus, turn the pol-filter until you see the maximum effect of the result, then shoot.
You never go wrong with this, I recommend you use manual focus and manual exposure exposure if you can or use AE lock if you have this feature when you compose the shot. Filter factor should be automatically compensated via TTL metering, if you use handheld meter, besure to compensate for it base on your filter instructions. Cheers

[Edited on 8-21-2002 by [email protected]]

[Edited on 8-21-2002 by [email protected]]

sever Oct 27, 2002 2:44 AM

Using a Polarizing Filter
Well, you could just say this is the effect you were going for. :)

Assuming it wasn't, though, you should be aware of how to properly use this filter. From now on you can use the "thumb rule" to figure out what the sky will look like through a polarizing filter. To do this, simply point your index finger at the sun (without looking directly at it!), and then pop your thumb up 90 degrees. Now, if you rotate your thumb around your index finger, keeping that index pointed directly at the sun the whole time, you'll sweep out a 180 degree arc in the sky. If you point your camera anywhere along that arc and take a picture with your polarizer oriented correctly (either vertically or horizontally, I forget which), you'll get the most saturation.

So what? The point is, if you know you're going to be taking a wide angle shot that includes that arc, and you want a less dramatic gradient, then just turn your polarizer 30 or 45, or even 60 degrees off. In water, you'll get some reflections you wouldn't otherwise get, but that's the price you pay. The other alternative is to buy a graduated polarizing filter. That way, you can polarize the "off 90 degree" half of a shot while leaving the 90 degree part, which would normally be deeply saturated, unpolarized. This would have worked for this image you posted.

The only trick there is, finding one. I haven't seen a graduated polarizing filter being sold though I know they exist. I think a lot of people probably do this by using the huge square filter mounts, and then they just slide the polarizer filter in halfway.


Nov 6, 2002 11:21 AM

exposure and polarizer
it's a great shot in terms of composition.
however, the pic is underexposed and shows that the polarizer was not compensated for.

looking at the pic, i'm guessing that you placed the camera on either matrix averaging mode and set the exposure meter emphasis on the sky. this tends to make everything else darker and averages the exposure on everything. better shot would have been to either spot meter or center-weight meter the darker rocks first and then polarize in the sky without killing too much of the water action.

such is the case with the stump. excellent shot. exposure seems to indicate that emphasis was either spot/center-weighted metering was on the stump.

it's best to try to resolve exposure problems when taking the pic first before getting it back to the pc and tinkering with it.

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