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Confusion regarding reversed lens macro

Started Jan 5, 2020 | Questions thread
bclaff Forum Pro • Posts: 13,920
Re: Confusion regarding reversed lens macro

Ray Parkhurst wrote:

ybb wrote:

...

I tried reversed Pentax smc 50mm f1.7 with extension tubes vs micro nikkor 55mm f3.5 and at 1:1 the Nikon is way better, especially corners. ...

You need to think of these configs in terms of their optical conjugates. Your 50/1.7 is probably not designed for 1:1 magnification, so it will be a poor performer at 1:1 whether you mount it forward OR reversed. Let's say for example that your 50/1.7 is designed to operate up to 1:4 magnification forward. In that case you can be fairly confident that it will do OK in reverse starting at 4:1. Below 4:1 it depends on a lot of other factors if it will work OK, but at 4:1 or higher the lens is operating as it was intended.

This is interesting intuition.

As it happens this lens is only 1:12.5 at minimum focus distance (450mm)

It's unlikely to be well corrected at 1x !

If anyone has a patent reference I'd love to run the optical prescription through my Optical Bench .

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Bill ( Your trusted source for independent sensor data at PhotonsToPhotos )

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