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Beam Splitter Glass

 
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Author Previous TopicReplies: 10 / Views: 5,075Next Topic  
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 Posted 02/07/2015  8:51 pm Show Profile   Bookmark this topic Add jprine to your friends list Get a Link to this Message
Beam splitter glass is real expensive. Found this on ebay. It has a 70% light transmission and looks like I can adjust the angle pretty easily. Would this work better than the plate glass I am using now? I do not know diddly about this stuff but really want to improve my attempts at axial shooting. Need some expert help! Thanks.

http://www.ebay.com/itm/R810-10-iPa...em4abf309a42
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 Posted 02/08/2015  02:42 am  Show Profile   Bookmark this reply Add austrokiwi to your friends list Get a Link to this Reply
It is expensive!!
If you are going to go for axial lighting you will find a proper 50/50 beam splitter will be simple to use; in the set and forget manner. I haven't used teleprompter glass and I suspect it might not have the optical qualities needed. Even so heres a cheaper version:

http://www.ebay.co.uk/itm/LCD4Video...em1e907a65b7

I use an old 50/50 edmunds optical beam splitter, it cost me US$60.00 on ebay some years ago...but I have not seen another for sale since then. Edmunds produces much more modern beam splitters. Those modern beam splitters include an anti reflective coating on one side and the glass is optically correct. Every so often my beam splitter has annoying reflections so an anti reflective coating on the camera side of the glass does appeal to me. The Edmunds beam splitting glass is only slightly more expensive than the item you posted:

http://www.edmundoptics.eu/optics/b...tters/46583/

{ I hope the link shows you the US price; last year that sized beam splitter was only US$135.00 In January Edmunds had run out of that size and the new stock is more expensive.}

SuperDave had mentioned, in another thread, his belief that you only need a circular light of 53mm in diameter for most coins. That doesn't suit my way of working, but it may well suit your needs if thats the case you could look at a smaller sized beam splitter from Edmunds.....but it would make the construction of the beam splitter mount a little different. My issue with a small round light is it seems to add unnecessary setting up of the light for each shot. I often move the coin around to centre it and a small light source would have to be adjusted nearly every time I moved the coin( Usually Silver dollar sized sometimes larger).


The link I have already posted should take you to a 127 X 178mm 50/50 beam splitter. However you could get a 60 X85MM example under US$70.00 :

http://www.edmundoptics.com/optics/...tters/64408/


I would imagine that to effectively use such a small beam splitter you would have to construct a mount of the usual size suspending the Beam splitter in the right position using some "cross members"( Can't think of a better word right now) if you made the mount to that beam splitters size I can imagine difficulties getting coins into place and the space would be too small to get your hand in easily.
Edited by austrokiwi
02/08/2015 03:02 am
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 Posted 02/08/2015  09:24 am  Show Profile   Bookmark this reply Add rmpsrpms to your friends list Get a Link to this Reply
I have been experimenting with microscope vertical illuminators recently. Bausch and Lomb made an excellent one for use with Stereo microscopes, and it is not difficult to adapt to camera use. If you are interested in doing true coaxial illumination, you might want to give one a try. They have 50-50 beam splitters and all the anti-reflective mechanisms. Here's an example

http://www.ebay.com/itm/VINTAGE-BAU...em462f95862e
Contact me for photographic equipment or visit my home page at:
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 Posted 02/08/2015  10:13 am  Show Profile   Bookmark this reply Add SsuperDdave to your friends list Get a Link to this Reply
It kind of stands to reason that if your illuminated subject is only 40mm in diameter, there's no need to throw a 12" square beam of light on it.

70/30 Beamsplitter (yes, it's "teleprompter glass") isn't a bunch brighter than regular glass - which reflects 20-25% - but far better chromatically. When the time comes, I'm just going to attach a strong alligator clip to a Jansjo and use that to hold the corner of a piece of glass.
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 Posted 02/08/2015  12:30 pm  Show Profile   Bookmark this reply Add jprine to your friends list Get a Link to this Reply
astrokiwi-I cheked edmunds and the 127 x 178mm is affordable, but I am concerned that that size would be to small to work with. They have it in 254 x 356 but that is nearly $500. That is a little out of my range. Has anyone had any luck with 127 x 178 (5 x 7)?
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 Posted 02/08/2015  1:19 pm  Show Profile   Bookmark this reply Add austrokiwi to your friends list Get a Link to this Reply
MIne is 127 X 178mm I find it perfectly adequate that said Its the first beam splitter I have used......before that I used to lean some picture glass on some stacked books.... so perhaps anything was an improvement LOL. Heres a photo of it before I taped it up with black insulation tape( I've posted this photo before). To make the mount I found some kids Protractor sets being sold cheaply Two sets gave me the sides and of course they were already at 45 degrees. I used the rulers that came in the sets as bracing. I have since cut those rulers square with the sides...I first used superglue and silicon sealant but I later changed to epoxy resin ( much stronger)

Edited by austrokiwi
02/08/2015 1:22 pm
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 Posted 02/08/2015  1:35 pm  Show Profile   Bookmark this reply Add BStrauss3 to your friends list Get a Link to this Reply
These people: http://www.telepromptermirror.com/ have diy plans and sell custom cuts by the sq inch. They also have pre-fab units. Somebody posted their info recently here on CCF but didn't include the link.
-----Burton
46 year / Life ANA member (joined 12/1/1973)
Life member: Numismatics International, CONECA
Member: TNA, FtWCC, NETCC
Owned by four cats and a wife of 35 years (joined 1983)
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 Posted 02/08/2015  7:08 pm  Show Profile   Bookmark this reply Add jprine to your friends list Get a Link to this Reply
astrokiwi-I have a piece of 5x7 plate I will try to play with tonight and see how it works for me.

It appears that 50/50 beam splitter is optimal. Behind that would 60/40 or 70/30 be next? (I am assuming 60/40).
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 Posted 02/08/2015  10:43 pm  Show Profile   Bookmark this reply Add rmpsrpms to your friends list Get a Link to this Reply
50/50 is indeed optimal. With 50/50, about 25% of your illumination is effectively getting to the sensor. With 40/60, it is 24%, and with 30/70 it is 21%.
Contact me for photographic equipment or visit my home page at:
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 Posted 02/09/2015  7:41 pm  Show Profile   Bookmark this reply Add jprine to your friends list Get a Link to this Reply
Tried shooting with a piece of 5x7 plate tonight. I was able to get the same results although it was a little more difficult manipulating the coin, but not so much that it doesn't impact the difference in price between the 5x7 and larger beam splitter. So, I have a little more to think about before I jump. Anyway, here is the results from tonight's work.


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 Posted 02/22/2015  6:43 pm  Show Profile   Bookmark this reply Add BStrauss3 to your friends list Get a Link to this Reply
Using a couple of small test pieces I had TelePrompterMirror.com cut for me of both 60/40 and 70/30, I've executed a few test images.

The first subject is a yellow toned Sac

What I don't know is how much is due to the poor quality of the 'comparable' photo using off-axis LED lights (three strips from Ikea):

For now, this is just a lash up... notice the bottom shadow line? - that's the piece of dental floss holding the mirror at the 45 degree angle...
-----Burton
46 year / Life ANA member (joined 12/1/1973)
Life member: Numismatics International, CONECA
Member: TNA, FtWCC, NETCC
Owned by four cats and a wife of 35 years (joined 1983)
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