Re: [Leica] Copy Stand Lighting Question

[csocolow <csocolow@microserve.net>]

Richard Clompus wrote:
> 
> Dear Fellow LUGnuts,
> 
> I will be photographing ophthalmic lenses and glasses for use in my
> lectures.  I will be ordering a small table top copy stand from Delta 1 that
> has white plexiglass so it looks like a seamless background.  I want to have
> the glasses and lenses "float in air" without any background detail.  I
> thought I'd lay them on the white curved plexiglass or on a clear plexiglass
> plate suspended over the white plexiglass curved background.
> 
> The hard part for me is the lighting.  Should I get a light tent to go over
> it and try to use one flash outside the tent - or try to use two strobes
> (one on either side) for shadow free lighting?  This type of high precision
> photography is new to me.  I'll have a Leica R8 and a 60/2.8 or 100/2.8 Apo
> Leica macro lenses.
> 
> Can anyone offer some suggestions for me?  I have some books on photographic
> lighting and illustration but they don't cover this topic very well.
> 
> Thanks for your suggestions.
> 
> Happy shooting,
> 
> Richard Clompus, OD
> West Chester, PA soon to be Roanoke, VA (Leica and Zeiss Information capital
> of the world) <bg>

Richard,

Several considerations. I think first of all that you'll have to run
some sort of light source behind the white plexi that the product is
placed on. If I were setting up the shot I would spot meter the
background with a flashmeter and then base my product exposure at 1.5-2
stops brighter so that you have a good clean white. For example, if the
background metered f16 I'd shoot it at f8.5 or f8.0. In order to light
the product I might construct a light tent out of Roscolux diffusion
material or something similar. I might make a cone with the opening at
the top for the lens to fit in. You do have to be careful because you
will get a reflection of the opening somewhere on a reflective
subject.One of the other issues is that you have roughly the same lens
to subject distance so that you're not stuck with a cone that is too
short or too long. I'd probably run two stobes roughly on either side.
You'll have to judge placement based on some tests. You might want to
bias the ratios toward one light or the other so that there is a hint of
directionality. I would probably place a grey card in the subject
position and using a spotmeter, again I would adjust exposure so that it
was properly illuminated by the tent at the aforementioned desired
exposure of f8.5 or f8.0

Another possibility, and one that I've used when photographing highly
reflective glazed ceramic artwork, is to place a large white card with a
hole in it on the front of the lens. Using a lens shade to avoid flare
(and hold the card on the lens) you direct your lights into the card so
that what the subject sees and shows is a clean even reflection of the
card. This then becomes the illumination on the subject and also
represents a nice clean even highlight. You can still backlight the
plexi at the same ratios as I described earlier and this backlight
source will add to the light coming off the card onto the subject. Try
to use as large a card as possible so that you don't see its edges
reflected in your subject.
                                 __________
                                 [ Camera ]
                                     [ ]
                             ________   _______   card


				     0^0           	         subject
                    Light _________________________Light	 plexi


				    [___]	   backlight

Each light to the side of the subject would be aimed at the white card
with no light spilling on the subject. Email if you don't understand or
if you have further questions.
 
Carl Socolow

http://members.tripod.com/SocPhoto/