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Forums > Back > next PZ lens test report: Sigma AF 150mm f/2.8 EX HSM DG APO macro OS (EOS)
#60
Ooops,

The current Imatest target is reflective while encoders base is transluctive.

Target has dark and white areas.The targhet is with high contrast. While most optical encoders are transluctive – metal grid over glas or trans[perant plastic.

Back illuminating is not an option. Since another side effects will occures – scattering, refraction etc. The encoder manufactures do a lot of trics to acheve resonacble sharp images. remember the encoder head is looking for 0 and 1 while we must look for nuaces of light

SinCos encoder is exection of 0s rule, but high end manufacures guaranties 1% THD by perfectly aligned encoder
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next PZ lens test report: Sigma AF 150mm f/2.8 EX HSM DG APO macro OS (EOS) - by miro - 08-10-2011, 08:47 AM

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