1. ## question about calculation of close up magnification

Close up of the word "FIFTY" on a 50cents coin.

Reverse mount 58mm lens onto Sony DSC 707 at full optical 48.5mm zoom or 190mm in 135 film format.

Calculation of the magnification factor for a 135 format film camera,

focal length of lens mounted to camera / focal length of the lens thats reverse mounted.

So in this case, should it be 190 / 58 or 48.5 / 58?

I am thinking it cant be 190 / 58 = 3.2x mag factor.

It looks more like 48.5 / 58 = 0.8x mag factor (which in this case reduction factor).

Pls help.

Thanks.

2. ## Re: question about calculation of close up magnification

anyone? pls help.

3. ## Re: question about calculation of close up magnification

just found out, the 707 sensor size is 8.8mm x 6.6 mm.

the length of the wording is about 11mm

so the converter factor is 8.8 / 11 = 0.8x.

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