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Focal reducer flattener for 80ED
Here are some pictures taken with 80ED and 5D with and without a 42mm dia FL 325mm binocular objective as as focal reducer flattener. The lens was 75 mm in front of the focal plane of the camera. Curved side towards 80ED objective. The reduction works out to be a factor of 0.78 and the field was also much flatter although some vignetting was present due to the lens only having a usable aperture of 40mm. It looks like it is well worthwhile using focal reducers flatteners with the 80ED.
pic1 80ED ie 600mm @ F7.5 FOV 3.44X2.29 deg
pic2 80ED with FRed. 468mm @ F5.85 FOV 4.41X2.94 deg
pic3 Both pics stacked with Registar
A 50mm dia lens of 325mm FL should show no vignetting.
I have a reducer on order from Hutech which should have no vignetting.
For 20D etc sized sensors a 40mm diameter lens works very well.
Bert
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