Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
12-03-2015, 03:21 AM   #1
Senior Member




Join Date: Jun 2014
Posts: 144
From failure to measure

I had a misshot and took picture of my red socks. The problem is that they are brown or black (really dark) in the picture. I blame the lightning as I can do that thing with only one lamp.

I have socks in my feet but in my hand I have light sensor system called camera. Can I use it to create some kind info of CRI or spectrogram of the lighting? I tried white paper, but quickly brutalizing some .tiffs with matlab didn't give anything useful.

12-03-2015, 03:40 AM   #2
Senior Member




Join Date: May 2013
Location: France, Annoisin-chatelans
Photos: Albums
Posts: 100
check the white balance setting in the camera and use the histogram to get a good exposure.
12-03-2015, 04:20 AM   #3
Pentaxian
LensBeginner's Avatar

Join Date: Sep 2014
Photos: Albums
Posts: 2,490
As for the exposure bit, you could use a gray card, or you could do it by eye, or using the back of your hand (if caucasian it'll be 1 stop lighter, on average).
As I believe you already know, the meter of your camera meters for middle gray, so it will underexpose a mainly light scene (snow), and overexpose a mainly dark scene (the classic black cat).
12-03-2015, 05:16 AM   #4
Site Supporter
Alex645's Avatar

Join Date: May 2015
Location: Kaneohe, HI
Photos: Albums
Posts: 1,140
If color accuracy is the issue, know that with even the correct white balance, you're not going to get perfect color if the light source doesn't have a full spectrum. And as mentioned above, using a gray card is really helpful if you have software like Photoshop. If you can't use your flash, and your WB white balance settings match the light source, then your light levels or ISO is probably just too low. Are you shooting RAW or jpeg?

12-04-2015, 04:40 AM   #5
Senior Member




Join Date: Jun 2014
Posts: 144
Original Poster
Color accuracy isn't the real problem yet at least. In my tests I've set white balance to daylight. This gives wrong colors but it's always the same way wrong and matches best my house lighting. I use too expensive 965 fluorescent light in my house.

My studying of color started with poor CFL (CRI 82) and then I've tested some colorcharts and white paper under different light. I've placed them on grey target so that about 75% of picture is grey. Sun hasn't shined so I haven't been able to go out and take a good reference. And I know that I can't see object if there isn't color emitted from light source which the object reflects. I wont give in just yet. I have some ideas how I might be able to do this.

However I think I'm not able to get the light info and CRI value from light with camera that easily as it isn't designed for measurement device even it would be nice information to know how bad light really is.

And I'm shooting raw always as I want to do something with the data which my camera gives me
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, dslr, photography, picture, socks
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
How to measure the filter thread size? jt_cph_dk Troubleshooting and Beginner Help 4 05-18-2013 09:42 AM
how to measure flash power? adwb Flashes, Lighting, and Studio 5 05-27-2012 07:11 PM
Where to measure canon fd flange focal distance? ripit Pentax SLR Lens Discussion 2 01-22-2012 09:29 AM
? how to measure distance from camera to subject... dcmsox2004 Pentax DSLR Discussion 12 10-22-2010 06:40 PM
How to measure heat leakage from a building. jms698 General Talk 12 06-08-2009 02:20 PM



All times are GMT -7. The time now is 08:48 AM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top