PDA

View Full Version : Question...ripped right from my myspace


Sprockett
12-09-2006, 04:07 AM
Just recently got Photoshop CS2 - amazing program. I love the fact that it will actually accept RAW image files (PS7 didn't). That definitely creates more tweaking possibilities, and an overall better possible picture quality. I'm really interested in learning more about how to effectively make an HDR composition, so if anyone has any idea how to do that I would greatly appreciate the input.

I'm mainly confused on two parts to this process: the different stop exposures, and the PS curve tool.


I need a little bit of explanation on this.


Hypothetical example:


Let's say I'm taking a picture of something stationary, and want to turn it into an HDR composition. If it was metered at f/4.0 and 1/50, would I need to do the following (if something else, please correct me):


for a -1 stop picture, leave at f/4.0 but change to 1/100

for a -2 stop picture, leave at f/4.0, but change to 1/200

for a +0 picture, leave at f/4.0, 1/50

for a +1 stop picture, leave at f/4.0, but change to 1/25

for a +2 stop picture, leave at f/4.0, but change to 1/13



I guess the formula is that a +1 stop is where you are allowing twice as much light than a balanced +0 photo. So, if I kept the f-stop the same, I should have to double the exposure time, correct? a -1 stop is where you allow 1/2 as much light that a balanced +0 photo, so leaving the f-stop alone and cutting the exposure time in half should do that, right?

With an HDR photo you need to take a series of photos of the same thing, with the same f-stop, at different exposure settings...namely with a -2 stop, -1 stop, +0 stop, +1 stop, and +2 stop (and further out than that if necessary). I'm just having trouble figureing out exactly what I should do to the +0 shutter time to create those other stop values.

The curve tool is something I'm just going to have to search around and learn on my own I think. I'm pretty sure this is impossible to teach someone else unless you're here with me.

95VicChik
12-09-2006, 10:32 AM
you are correct hun


when doing HDR, never change the iso or the apeture, because that will call for a completely different setup all together...

shutter speed is the key to HDR...good luck! i love doing hdr's, i'd like to see the pic when u are done

if you want more info regarding, i found a pretty good webpage that gives a good description and an how to in CS2...just in case u had any questions regarding it!

HDR composition (http://www.cambridgeincolour.com/tutorials/high-dynamic-range.htm)

PS curve tool is a little tricky to explain over the internet, it's soo much easier to just show...definitely play with it and you will be able to understand more about it...but i will try my best -

http://www.jeffwignall.com/images/389_Curves_Dialog,PS.jpg

Basically here it goes, to lighten an image you drag the center point of the diagonal line to the left. To darken an image you drag the center point of the diagonal line to the right. Just like in the Levels tool you are moving the neutral gray point to a position that allows for more or less pixels to represent the lighter or darker part of the image. To increase contrast you drag the end points of the diagonal line horizontally towards the center (losing shadow and highlight information). To decrease contrast you drag the end points of the diagonal line vertically towards the center (reducing the dynamic range so blacks are not really black and whites are not really white). To get the best of both worlds, they say make an S like shape...looks kind of like this -

http://www.nikonians.org/html/resources/software/Adobe_digital_workflow/images-2/67-6_ps-curves-sin.jpg

The trick here is to increase contrast without losing detail and also to be able to decrease contrast without losing the dynamic range. By introducing an S shaped curve into the equation it is possible to increase contrast in one area while decreasing it in another.

I hope this helps, i know it's not the best description...but definitely play with it, it will make your pics look so much more natural compared to using levels :)

candymanjl
12-09-2006, 01:04 PM
on my camera I just set it to auto bracket :D basically it just figures out the shutter speed for you, and you set how big a difference you want up to +- 2 stops. I haven't played around with it that much really, one day I should just to be able to do it, lots of photochoppin to make it look good.

I have CS2, got it mainly to take RAW files right into it since that's all they really added with the new version. 99% of the time I don't like the results when compared to using Canon's RAW software. I haven't played with it a ton, but by default the pictures are cold and really processed looking. the canon software is much warmer and natural looking. usually I'll convert to JPG from canon's software then go into photoshop. photoshop does give you more RAW options and a couple times I liked those results better, but it's pretty rare.

Sprockett
12-10-2006, 07:36 AM
I lost my canaon RAW software :(


95VicChik, thank you...you explained it in simple terms that I could understand.

candymanjl
12-12-2006, 02:38 PM
go here and select your camera and you should be able to download the current version of the software.

http://www.usa.canon.com/consumer/controller?act=DownloadIndexAct

that link lets me select all the software and drivers for what came with my Canon 20D, worst case I can upload the software somewhere so you can get it.

95VicChik
12-12-2006, 06:08 PM
also check adobes website for updated raw softrware, for the CS2 software...


i know when 20d's first came out, photoshop CS couldn't read there raw format...the only way to get it was through there website :)

just make sure you keep on top of your software updates..it will save you a lot of time and aggrivation ;)