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T-Rex on ALEXA


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#1 Reg Voges

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Posted 26 February 2011 - 10:25 AM

I would like to know if anyone has experience using the P+S Technik T-Rex borescope lens system on the Alexa. We are using it to shoot macro shots of fish in a fish tank and shooting through the glass.
My concern is all that glass in front of the sensor and what the effect will be besides a loss of light. I have heard of ghosting when using the Alexa with big zoom lenses or many filters - any chance that something similar may happen with the T-Rex. And are there perhaps better alternatives - eg the Excellence Optex system?

Any insight will be greatly appreciated.
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#2 Alfeo Dixon

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Posted 28 February 2011 - 07:57 PM

I would like to know if anyone has experience using the P+S Technik T-Rex borescope lens system on the Alexa. We are using it to shoot macro shots of fish in a fish tank and shooting through the glass.
My concern is all that glass in front of the sensor and what the effect will be besides a loss of light. I have heard of ghosting when using the Alexa with big zoom lenses or many filters - any chance that something similar may happen with the T-Rex. And are there perhaps better alternatives - eg the Excellence Optex system?

Any insight will be greatly appreciated.

Reg,

You should be fine, I'm not sure about the ghosting issues stated. But if you have a concern, call Frank at CPT in Atlanta, Wolfgang Rossell invented the T-Rex and was the prior owner of CPT. http://www.c-p-t.net.../specialty.html

-Alfeo
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#3 Oliver Temmler

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Posted 02 March 2011 - 03:23 AM

Hi Reg,

ghosting occurs when the filters in a matte box are tilted towards eachother/not parallel. It doesn't matter which camera you stick into that matte box though. Works with digital cameras, 35mm cameras and even if you look through the matte box with your own eyes. Tried it.

Kind regards
Oliver
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#4 Reg Voges

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Posted 02 March 2011 - 10:36 AM

Thanks for the advice.

We ended up using an Optex lens system because there was no need for the T-Rex's image rotation or 3-axis function. The DOP only needed a straight borescope and the Optex was quite cheaper to rent. But we tested both lens systems and they performed equally well. There was no difference in light loss (both were T5.6) and the only difference was the light flaring quality of the Optex which the DOP preferred.

We also used 3 filters and did not experience any ghosting or aberrations. I think you are right about the tilted filters Oliver and I will definitely try that next time I do a gear check.

I can really recommend both these lens systems now for the Alexa.

Reg Voges
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Cape Town
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