The dreaded black hole & window shopping, a theory

[Rusty]

This may be another one of my silly ideas,probably born dead because of my lack of knowledge about the behavior of light and optics
I have no means to test the idea at the moment, but hope somebody will try it out .....
Everybody knows the "black hole " problem when photographing shiny bugs, when the objective is reflected back by the shiny surface of the beetle

Ever tried looking into a shop window when it is brighter outside than inside? all you see is a reflection of the outside world
Even if the shop sells massive microscope objectives and there is one parked just behind the glass, you will never see it
If you cannot see it, you cannot reflect it back to be recorded on the image the guy in the shop is taking of you through this massive objective

So...given that, all we need is a little" shop window" between the bug and objective and a darker environment around the objective ,like the inside of the shop
Like this



Could this be a simple solution to a sticky problem?
_________________
Daniel

[ChrisR]

I daresay Rik will answer you, but in the meantime, where's your illumination?

[Planapo]

That's one cool beetle that is!
I hypothesize he must be feeding exclusively on m&ms.

--Betty

[Rusty]

[Bob^3]

Daniel,

The biggest issue I can see with this concept is that if standard glass sheet were used (say without anti-reflective coating), the amount of light that would bounce off of it toward the subject would be relatively low compared with the light illuminating the subject directly from the source (but this would depend on precisely how the source light was directed at the glass and subject).

One way to enhance the "fill light" effect would be to use a partially silvered mirror for the glass plate (at least in the portion that the lens looks through). This would act like beam splitter and have the effect of a neutral density filter on the lens, which will reduce the amount of light reaching the sensor thus requiring longer exposures.

If you used a large mirror as shown and only the center portion was partially silvered, I think this could work. However, there might be serious problems with flare and ghosting due to light reflecting between the mirror and the lens elements or sensor---tilting the mirror could help with this issue.

This is the concept is what Charles successfully tested a while back using a cube beam splitter in front of the lens. If memory serves, someone also suggested a half sliverd mirror.
_________________
Bob in Orange County, CA

[Bob^3]

[Craig Gerard]

Daniel,

Thoughts regarding the characteristics of light are good thoughts.

I expect you would find the book 'Light - Science and Magic' to be a valuable asset. I'm looking at Diagram 6.2 page 131 Third Edition.
http://www.focalpress.com/books/photography/light_science_and_magic.aspx?cat=98&sub=114

I like your analogy. It is similar, in some respects, to a one-way mirror.

[Bob^3]

[ChrisR]

[Blame]

I am not sure your beetle idea will fly.

Problem 1 is that the sheet of glass looks like invading the beetle's personal space. The idea might not fly but the beetle will!

Problem 2 is more basic. Your window is not stopping the image of your camera being reflected by the beetle. All it does is add a hopefully larger reflection to mask it. You are replacing a dim reflection of the camera with a bright reflection of the beetle. You will get a beetle reflected in a beetle reflected in.... well you get the idea. Just like a hall of mirrors.

Problem 3 is how are you going to get the camera relatively dark? you would need to put the camera in a black box, with a window.

Finally why bother when there is already an easy answer? Use a polarized filter on both lens and a flash. Angle them at 90 degrees. There will be no reflection. The beetle will photograph as if it was not shiny.

[Blame]

Oh, I think I should warn you not to eat the beetle.

It is probably loaded with artificial colors, flavors & preservatives.

[Rusty]

Blame wrote:

[Harold Gough]

[Craig Gerard]

Here is some more food for thought.

Lieberkühn Reflector

http://www.alanwood.net/photography/olympus/lieberkuhn-reflectors.html


Craig
_________________
To use a classic quote from 'Antz' - "I almost know exactly what I'm doing!"

[Blame]

Craig

A good way of using microscope lighting for macro photography. Could be very easy to setup.

Interesting. but shouldn't it be a new thread?