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White Balance 18% Grey Vs White

 
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Author Previous TopicReplies: 15 / Views: 1,754Next Topic  
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 Posted 06/27/2018  11:45 pm Show Profile   Bookmark this topic Add ngs428 to your friends list Get a Link to this Message
I have 18% grey cards and white cards. I have tried both for setting whitebalance. Is there a better one to use. I am on the $400 setup.

I seem to get a hint more yellow in the shot when using the white card.
Edited by ngs428
06/27/2018 11:52 pm
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 Posted 06/28/2018  04:44 am  Show Profile   Bookmark this reply Add John1 to your friends list Get a Link to this Reply
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
( I'm no pro, it's just my humble opinion )
Searched 6.5 +/- Million Cents Since 1971
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 Posted 06/28/2018  07:15 am  Show Profile   Bookmark this reply Add rmpsrpms to your friends list Get a Link to this Reply
I make disks that have true grey on one side and velvet black on the other. These work great for white balance, then placing the coin on a background that "disappears" so no circle cropping is necessary.Plus the disk makes it easier to move the coin around.
Contact me for photographic equipment or visit my home page at:
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 Posted 06/28/2018  07:20 am  Show Profile   Bookmark this reply Add BadDog to your friends list Get a Link to this Reply

Quote:
I have 18% grey cards and white cards. I have tried both for setting white balance. Is there a better one to use.


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.
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 Posted 06/28/2018  10:24 am  Show Profile   Bookmark this reply Add ngs428 to your friends list Get a Link to this Reply
Ray, that does sound good, but all of what I am shooting is in a slab.

BadDog, I am shooting to jpg with my Canon T2i. I set the white balance before my coin shot using the white card or 18% grey card. So the question is, what does the Canon live view software expect to see when I am setting white balance?
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 Posted 06/28/2018  1:59 pm  Show Profile   Bookmark this reply Add rmpsrpms to your friends list Get a Link to this Reply
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.
Contact me for photographic equipment or visit my home page at:
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 Posted 06/28/2018  3:39 pm  Show Profile   Bookmark this reply Add BadDog to your friends list Get a Link to this Reply
ngs428,

Here's a link to a discussion about white balance that you may find useful.

I'm wondering why you aren't shooting to a RAW file? If you haven't tried saving the photo in RAW and then processing the image, then I'd recommend you try it. Your ability to tweak the image (including white balance) is usually much greater when working with a RAW file image. As Ray said, you can easily move around an image and see how consistent the RGB values are and make adjustments if needed (or go back and make adjustments to the white balance settings in the camera until you get consistent values).

Since I use a Pentax camera and not a Canon, I don't use the Live View software, but my understanding was that Live View was pre-shot software and not post processing software. Am I mistaken in that?
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 Posted 06/28/2018  4:54 pm  Show Profile   Bookmark this reply Add ngs428 to your friends list Get a Link to this Reply
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.
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 Posted 06/28/2018  5:23 pm  Show Profile   Bookmark this reply Add rmpsrpms to your friends list Get a Link to this Reply
I've gone back and forth with RAW format over the years. Many folks swear by it, but the only advantage I ever found is if I output the file to TIFF rather than jpg, and that is not very practical. The advantage of RAW is that it can allow you to recapture shadow details that might be lost by poor jpg transfers. It can't help you if the image is over-exposed. So I've learned how to adjust the lighting, exposure, and jpg transfer parameters to ensure the full dynamic range is captured by the jpgs coming out of the camera.
Contact me for photographic equipment or visit my home page at:
http://macrocoins.com
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 Posted 06/28/2018  5:54 pm  Show Profile   Bookmark this reply Add BadDog to your friends list Get a Link to this Reply

Quote:
why don't I shoot in Raw. Simply because I don't know too much about it.


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.




Edited by BadDog
06/28/2018 6:03 pm
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 Posted 06/29/2018  1:41 pm  Show Profile   Bookmark this reply Add ngs428 to your friends list Get a Link to this Reply
My white index card and my 18% grey card both produced RGB values within 4 of each other at a few random points within where the coin would be placed. Not sure how close it has to be, but you stated very close Ray.

My grey card seemed to not produce as consistent RGB values as my white index card. But yes, the resulting untouched images of coins do look different between the 2 cards.
Edited by ngs428
06/29/2018 1:46 pm
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 Posted 06/30/2018  12:04 am  Show Profile   Bookmark this reply Add rmpsrpms to your friends list Get a Link to this Reply
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.
Contact me for photographic equipment or visit my home page at:
http://macrocoins.com
Valued Member
United States
359 Posts
 Posted 07/01/2018  09:04 am  Show Profile   Bookmark this reply Add ngs428 to your friends list Get a Link to this Reply
The white index card may not be white. The 18% grey shot below is better in my opinion. Here is a sample shot:

18% grey



White Index Card

Edited by ngs428
07/01/2018 09:27 am
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 Posted 07/01/2018  09:17 am  Show Profile   Bookmark this reply Add jafo50 to your friends list Get a Link to this Reply
@ngs428 Which photo is truer to the actual coin in hand view?
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 Posted 07/01/2018  09:30 am  Show Profile   Bookmark this reply Add ngs428 to your friends list Get a Link to this Reply
@jafo50

I just re-uploaded the 18% grey image. It is a better representation of the coin in hand. Just comes to show how critical white balance is. These images have no post processing (other than crop and black background).
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 Posted 09/18/2018  1:52 pm  Show Profile   Bookmark this reply Add Dar to your friends list Get a Link to this Reply
I think they both look good but each highlights slightly different aspects of the coins detail.
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