Rainbow help

[JP Bruce]

With the monsoons starting here I get to see lots of rainbows. I have yet to be happy with an image of them. All images I take seem to be washed out. The problem is the image will look divided by the rainbow, with part looking exposed well and the rest looking underexposed. Any thoughts or suggestions? Would prefer to get it right in the camera than play with it in PS.
Thanks for any help.

[Alfred Forns]

HI Bruce I think Roman is going to give you the best suggestions He will be looking in !!

Off the top of my head I would try to do it PS maybe even with dual conversion then adjustment layers. Not sure if there is a way to do so like an HDR ? Will be interested in seeing how this develops.

[Roman Kurywczak]

Hi JP,
I do not know why this phenomena happens but many times above the rainbow will be darker while below it appears light. I would expose for the lighter area and let the darker area fall where it may. I always use a circular polariser when photographing rainbows.......This does 2 things......takes away much of the glare that some objects have during that time as the sun does tend to get intense..........and allows you to adjust the intensity of the rainbow. You will actually see the intensity through the viewfinder as you rotate the filter! 90% of the time this is all that is neded and most of the time the filter is at it's maximum intensity....but just back off a hair to not make the sky too dark. Angle to the sun............and amount of moisture in the air all also come into play but I have always had the best results with the polariser. An alternative that may work in certain situations it to use the Grad ND filter, soft stop, upside down from what we normally use..........darker area on the FG with the lighter/clear pointing up. You can probably use both together to achieve some dramatic results.........just remember to do you exposure check with both on. Easiest way in the field.......check the difference between the lighter and darker area with a meter reading.........if within 3 stops......apply the filter and expose for the darker area reading. Over 3 stops........(Unless you are me who carries 5 stops of Grad)........do a HDR.
This should work most of the time.
Roman

[Alfred Forns]

Thanks Roman !!! I knew you would come up with great help !!!

[JP Bruce]

Thanks for the information. Gives me good ideas to work with. Now all I need is for the weather to cooperate.

[Linda Dulak]

<I do not know why this phenomena happens but many times above the rainbow will be darker while below it appears light.>

There is a very good reason for this to happen and it's the physice of light reflecting through the raindrop.. If you have a double rainbow, the area between the rainbow will be darker than the area outside that arc. As the light is reflected through the raindrop to produce a rainbow, there is a lack of light being reflected back out of the raindrop in that area above the original rainbow and then if the light is strong enough, you will get a second rainbow with the sequence of colors reversed from that of the first one. Take a good look the next time you see a double rainbow. And if you look carefully, the sky will be lighter on the outside of the second rainbow.

Linda

[Roger Clark]

Hmm, this is odd. I was sure I responded to this thread and it shows up in my subscribed threads because I responded, but I do not see my post. So here goes again.

Rainbows are polarized. The angle of polarization changes with the direction along the rainbow, pointing to the direction opposite the sun (that's the center of the arc of the rainbow). So if you are using a wide angle lens, then a polarizer will reduce some part of the rainbow. If using a longer focal length, the polarizer works great to enhance the rainbow by reducing the intensity of scattered light around the rainbow.

Roger