Honestly, if a grey card is a matter to you, that means you think the actual reflective index is important and critical. Why risk to buy an informal piece of 18%-like grey card from a non-camera store? Knowing that even you think the color might look the same, they might have a different reflective index though. And if you think that's not too critical, then just save that whatever $5 or $30 and use no grey card la!  |