Lens Use Guide for Macro Photography

Started May 10, 2020 | Discussions thread
bclaff Forum Pro • Posts: 11,800
Re: Shutter speed and focal length and magnification

Tech Head wrote:

...

I plan to add sufficient tube length to make it about 1x magnification at 175mm. So, a lot of extension tubes.

If you already have at least one tube then you can measure the focal length of the lens at closest focus. It could be around 130mm.
At 0.2x you need 0.8x more so that would be 0.8 * 130mm = 104mm of extension.

The reason I’m doing this is to get greater working distance at 1:1 magnification and because adding extra glass with a close up lens might reduce optical quality.

...

You can lose optical quality with extension tubes too.
Moving the lens so far away from the designed image plane has consequences.

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

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