Blown Color Channels

[spfanatic]

Miriam's post (http://www.pixel-shooter.com/forum/showthread.php?t=6739) got me thinking more about the difficulty I sometimes have with intense colors blowing out - particularly pinks, red, and yellows (flower colors!). She said she used a magenta filter to help her capture the colors of the cactus flower. I have done a bit of research on this now and 2 threads which explain this technique are here (http://forums.dpreview.com/forums/read.asp?forum=1021&message=17142860)and here (http://www.luminous-landscape.com/forum/lofiversion/index.php/t10937.html). Both are interesting, but quite complex threads, but I encourage you to take a peek even if you think this isn't a problem for you or even if you don't think you will use this technique. I learned a lot!

[Lisa]

Wow, what a difference! Honestly, I've never noticed my greens being blown out nearly as much as other colors. Since most flowers are the colors you mentioned, that's what I aim to shoot and that's why I tend to see those as the problem areas. I should probably pay more attention to the greens as well.

It appears that this filter may be something to look into. Thank you for the links as well as Miriam's thread.

[Kevin]

I haven't had a chance to read through the links but will. I usually run across blown reds or yellows when shooting flowers in bright sun. I'll adjust my exposure to limit the blow out and can usually pull detail out further in the RAW file. But it would be nice if there's another alternative. Doing what I do typically ends up with a darker than desired background.

[beaucamera]

Thanks, Pam.
These are interesting reads for all of us.

Are you using the Magenta CC40M filter?
Just wondering if you (or anyone else) has personal experience in its use.

Virginia
aka beaucamera

[spfanatic]

Yes, this certainly is something to think about....
Thanks, Pam.
Are you using the Magenta CC40M filter?
Just wondering if you (or anyone else) has personal experience in its use.
Virginia
aka beaucamera
No, I haven't tried this yet, but I hope to. Miriam is the only one I know who has used this.

[MiriamJ]

Pam,

Excellent links. Julia Borg's initial post is a little confusing here (http://forums.dpreview.com/forums/read.asp?forum=1021&message=17142860), but less so when you also read TOF guy's questions here (http://forums.dpreview.com/forums/read.asp?forum=1021&message=17143435), and her response here (http://forums.dpreview.com/forums/read.asp?forum=1021&message=17147529).

I'll try to post identical photos showing green foliage and a red apple taken with and without the filter, along with histograms, so you can see the effect of the filter on both greens and reds in nature. I tried yesterday to get a closeup of a branch, but couldn't because our desert winds were blowing too much.

Virginia, can I answer any questions regarding the use of the filter?

[beaucamera]

Pam,

Excellent links. Julia Borg's initial post is a little confusing here (http://forums.dpreview.com/forums/read.asp?forum=1021&message=17142860), but less so when you also read TOF guy's questions here (http://forums.dpreview.com/forums/read.asp?forum=1021&message=17143435), and her response here (http://forums.dpreview.com/forums/read.asp?forum=1021&message=17147529).

I'll try to post identical photos showing green foliage and a red apple taken with and without the filter, along with histograms, so you can see the effect of the filter on both greens and reds in nature. I tried yesterday to get a closeup of a branch, but couldn't because our desert winds were blowing too much.

Virginia, can I answer any questions regarding the use of the filter?

Yes, Miriam you can.
Could you show us a picture of the filter?
Does it come in different sizes?
I'd like to know more and am looking forward to seeing your pics.

Virginia
aka beaucamera

[MiriamJ]

Virginia, I'll do better than that, I'll just point you at the kit I purchased. You can double-click the photo for a better view here (http://www.bhphotovideo.com/c/product/186726-REG/LEE_Filters__Gel_Snap_3x3_4x4_Filter.html). Here's the less expensive one without the cardboard adapters LEE Filters Gel Snap (4x4" Filter Holder) for Lenses up to 82mm (http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=getItemDetail&Q=&sku=162544&is=REG)

The square thing on the bottom left is one of the cardboard adapters thrown in so that you can use the 3"X3" filters with the holder. Do yourself a favor and buy the cheaper one without the adapters and just use the 4"X4" filters. The 3"X3" filters slide around in the adapter and has to be repositioned from time to time.

The holder, being shown held by the hand along with a representative filter, (not included), is hinged along one side. You just open it, lay the filter in it and snap it closed. The two verticle lines are very heavy duty rubber bands that will fit any lens up to 82mm diameter or an external flash. It looks like the rubber bands are very durable and shouldn't wear out quickly.

I've been told the inexpensive Lee polyester filters work well. Here's a link: LEE Filters 4x4" - Magenta - CC40M - Color Compensating Polyester Filter (http://www.bhphotovideo.com/c/product/102489-REG/LEE_Filters_M40_4x4_Magenta_.html)

Added info: I had previously bought the 3"X3" Lee polyester filter, and had taken a fall and broken it. (very minor scrape for me, camera, lens and filter holder are fine). What was left of the filter was enough to use it, but it didn't hold very well in the holder, so I went to buy a 4"X4" Lee polyester filter from BHPhotoVideo. I saw a 4"X4" frame as an accessory, so it looks to me like you need to buy that, too. As I'm writing this BHPhotoVideo is not taking phone calls for about 12 more hours, so I can't ask.

If anyone reading this knows anything about this, could they jump in? Thanks!

Now to get some photos! :)

[MiriamJ]

Added 6/7/2007 @ 6:33 P.M. This works only if you are using a pre-set white balance. If you auto white-balance with the filter it corrects and cancels itself out.

I took 2 pictures, one with the CC40M filter, and one without. On the one without the filter I increased the shutter speed 2/3 ev to make up for the removal of the filter.

I also took shots of a white balance card to correctly white balance the photos.

Before white balancing the photos, the green channel on the photo with the filter was offset to the left. After white balancing the photos the color channels were aligned on both photos. However, the photo without the filter had much more clipping.

Here's the photo without the filter after white balancing.
http://farm2.static.flickr.com/1416/535285037_0265903d96_o.jpg

Here's the photo with the filter after white balancing
http://farm2.static.flickr.com/1327/535168356_8eee720c2b_o.jpg

Here's a histogram of the photo without the filter after white balancing. Note the excessive clipping.
http://farm2.static.flickr.com/1303/535362863_85078242dc_o.jpg

Here's a histogram of the photo with the filter after white balancing.
http://farm2.static.flickr.com/1224/535362857_38d139041f_o.jpg

If you download the pictures and switch back and forth from one photo to the other, the one without the filter might look better at first, because it's a bit brighter, but closer inspection shows detail missing in the unfiltered photo. At least that's what it looks like to me. (Look at the bubbles on the Pepsi bottle).

[beaucamera]

Miriam, thanks for posting all this info and your test shots!
You are the best!

:cheer: :cheer: :cheer:

Sorry for the late reply.
I've been busy...computer issues.
This time my hubby's! shocked;

Virginia
aka beaucamera

[MiriamJ]

Miriam, thanks for posting all this info and your test shots!
You are the best!

:cheer: :cheer: :cheer:

Sorry for the late reply.
I've been busy...computer issues.
This time my hubby's! shocked;

Virginia
aka beaucamera
Thanks, Virginia! Happy to help!:) :) :)
Hope Hubby got his computer working again.

[MiriamJ]

BTW, I know the photo with the filter looks a bit faded. Here's what it looks like after a very slight saturation and a levels adjustment.
http://farm2.static.flickr.com/1362/538341799_66fc017928_o.jpg