DIY Add on diopter

Started Oct 26, 2013 | Discussions thread
Stephen Barrett
Contributing MemberPosts: 580Gear list
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Re: DIY Add on diopter
In reply to dicklaxt, Oct 28, 2013

I think you can have some fun with your diy closeup lens. It is about 4 times stronger than your Raynox 250, which is 8 diopters. You get the most magnification when using full optical zoom of your SX50. The magnification is approximately the ratio of the camera's focal length to the closeup-lens' focal length. So for full optical zoom, you will get 215 mm / 30 mm ~ 7 x magnification, which is huge. If you take a photo of something 1/2 mm high, the image on the sensor will be 7 times that, or about 3.5 mm high. The sensor height is only about 4.5 mm, so you will nearly fill the picture height. The "macro" setting on the SX50 has only about 0.2 magnification up close to the lens. (Macro has traditionally meant a magnification of 1 for SLRs but, if you take into account the crop factor of small-sensor cameras, the effective magnification is around 1, so they call the setting "macro". That would make the "effective magnification" of your home-made lens approximately 40x ! )

The drawback to having so much power is that the depth-of-field is very small - I would guess ~ 1/10 mm at full zoom. The EXIF data on your bubble picture says 36.54 mm, so you can get about 6X more magnification than that.

My experience has been that even the Raynox 250 is so strong that I use it mostly indoors on a tripod , but other people post really good pictures in this forum, taken hand-held, but usually with much less than full zoom. For flowers and insects outside, I most often use my home-made 600 mm closeup lens (made from the front lens of a cheap telescope). Canon makes a 500 mm (2 diopter) lens, which is just a little stronger. Besides greater depth-of-field, another advantage of weaker closeup lenses is that the working distance (equal to the focal length of the closeup lens) is larger, so it is easier to avoid casting a shadow on your subject and to avoid scaring away insects.

Anyway, I hope you play around with your home-made lens and show us some spectacular pictures.

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