Not as sharp as it looks!

Photo of the week #16: A macro shot of the necklace that Geoff gave me for Valentine's Day. I took this shot using my 50 mm lens reverse mounted onto my 55-250 mm lens (at 250 mm). This technique is great in that it allows you to take photos at a very high magnification (5:1 in this case, which is much higher than the 1:1 magnification that I get using my macro lens). It is however very difficult to focus when using a reverse mounted lens since the depth of field is extremely shallow: