White Balance 18% Grey Vs White

I have always read that 18% gray was the way to go. I guess you could try a bunch of different colors and see which one works best for you.I have seen some nice pics with a black background.
John1

Are you post processing a RAW file? If so, what does the processing software expect to see in order to set/adjust the white balance? My software has a gray point setting for this, so I use an 18% gray card as the background when taking a photo. If needed, then I can just pick any point (or 3 or 5 with my software) on the background to adjust the white balance.

If you are using a grey card you can trust, such as a true grey reference or 18% grey card, then once you perform MWB you should shoot the reference and take a close look at the output image. When you mouse around the image, you will see the pixel XY location and RGB values in the lower left corner of the page. Those values may vary a bit due to exposure, but all 3 RGB values should be the same (or at least very close). If so, then your MWB is successful. If not, you should do MWB and check again. I like to assess the consistency of a grey card or true grey reference by doing MWB many times in succession, at different areas of the card/ref. If I see a change in the color each time I do MWB, then the reference is not adequate. One way you can mitigate this problem is by de-focusing either high or low so that there is no "detail" to be seen during MWB process. Often this can "fix" a poor WB reference so that you get a more consistent and accurate WB. In the end, if all else fails and your shot of the WB reference shows a color shift, you can compensate with the WB shift function in EOS Utility. I don't know the corresponding function in Pentax but there should be some way to do a WB shift. Once you do the shift, shoot the reference again. It should now come out with equal RGB values. If not, make further changes to the WB shift until you achieve equal RGB in the output image.

Ray, thanks for the tips. I will give them a shot .

BadDog, why don't I shoot in Raw. Simply because I don't know too much about it.. I will review your link. Live is a pre shot software.

ngs428,

Fair enough. When I first started taking coin photos I also didn't know much about RAW files or processing them either. When I finally decided to investigate the RAW format, I didn't think processing a RAW file was any more or less difficult than processing a JPG (I use GIMP to process JPGs). You may have a similar opinion (or not)

Here's a link that discusses the RAW file format. If you take a look at it, you may find that you want to at least experiment with post processing a RAW file.

I would think that your CANON camera has a setting that would let you save the photo as a JPEG, a RAW or both at once. Canon should have included a utility that lets you post process a RAW file. The final step in processing the RAW file is to save it as either a JPG or TIFF file. The RAW file itself isn't changed.

As Ray says, some folks prefer JPG postprocessing and some prefer RAW post processing, if you give each a try then you can make your own informed decision.

Well, 4/255 is ~1.5%, not too bad.

If the coins look different when using the two methods, it's likely your white index card is not really "white". A lot of "bright white" paper has a bluish tone. Best way to tell is to do the WB using the trusted grey card, and then shoot the white card to see how far off it is from true grey.

@ngs428 Which photo is truer to the actual coin in hand view?

I think they both look good but each highlights slightly different aspects of the coins detail.