Cumulus Support

In another thread I suggested a Polarising filter make a difference to deepen the blue of the sky and increase the contrast with the clouds. Generally giving a more punchy and accurate image?

Well I've just popped round to a neighbour who has a Logitech QuickCam Pro 9000 HD Webcam. We have just pointed it at a double glazed window and take the follow two images. Both have been cropped to focus on the sky region.

Picture Four - a snap of a region of the northern sky with my camera Poleriser hand held in front of the lens

Picture Three - is the same region of sky without the filter .

A noticeable improvement though not tremendous. I think it depends on the angle of the sun. Worthwhile though IMO, particularly with the additional function of keeping wet off the webcam. The webcam itself does have a front window in front of the lens and it looks like the front could be waterproof but I'm not going to risk it!

I've decided to buy a polarising filter from Amazon UK. I have Amazon Prime so it will arrive tomorrow http://www.amazon.co.uk/gp/product/B000 ... ss_product

I already have a small plastic box that will take the webcam perfectly (with enough room for a small heater resistor - though the webcam may produce enough heat itself to stop the window misting up).

The sky really does need something done! The attached image shows a recent webcam image with cloud and bits of blue sky but this is lost in the image I'm looking forward to trying a polarising filter.

A polarising filter will need turning to get the best effect as the light changes.

The images look to be just under exposed 0.5 stop which would improve the sky colour and contrast in the cloud anyway.

RCE wrote:A polarising filter will need turning to get the best effect as the light changes..

Now that might be a problem. As the camera is fixed I would hope there was a 'sweet' spot' that you could set the polariser to that would suit most occasions.

geoffw wrote:

RCE wrote:A polarising filter will need turning to get the best effect as the light changes..

Now that might be a problem. As the camera is fixed I would hope there was a 'sweet' spot' that you could set the polariser to that would suit most occasions.

Yes, that's what I'm hoping. I don't really want to add a motor drive to the filter

Maximum sky polarisation occurs at roughly 90 degrees to the Suns position, if you use a linear polariser that the optimum angle to the horizon will change as the Sun moves if the camera is in a fixed position.

A circular polariser may be a better bet as it is angle independent, though I don't think the effect is as pronounced. Still a fixed linear filter will be an improvement over no filter at all.

mcrossley wrote:Maximum sky polarisation occurs at roughly 90 degrees to the Suns position, if you use a linear polariser that the optimum angle to the horizon will change as the Sun moves if the camera is in a fixed position.

A circular polariser may be a better bet as it is angle independent, though I don't think the effect is as pronounced. Still a fixed linear filter will be an improvement over no filter at all.

Thanks for that info Mark I've bought a circular polarising filter, so we'll see how well it works.

Just received to circular polarising filter and propped it in front of the webcam - a definite improvement, the clouds are showing now

I've just a quick test of removing the IR blocking filter from a webcam abd attaching a fisheye lens. The image quality isn't too good, but it is currently shooting through double gazing. Howve to the eye the sky is a pretty uniform haze with the odd faint contrail. The IR image is a bit different though!

http://87.194.103.60:8888

After quite a while now with the circular polarising filter on the webcam I can definitely say that it's a great success - it brings out the blue sky well.

looks good Gina - even to a colourblind male like myself!!

Yep looks great but...


Where have the cows gone?!?

hills wrote:Where have the cows gone?!?

They're in the next field (to the left of the frame). I expect they'll be back soon - they have access to both fields

The cows are back