Planet transits in front of the sun is not so common. I had a great view of the Venus transit on 2004 June 08, and on 2012 June 06. I have also observed Mercury transits a few times. Last time was on 2016 May 09. Below are some photos from these occasions.
Venus is much larger and much easier to see. Mercury is tiny, and can be seen near the lower/right edge on the Mercury transit photos.
A comparison of the Venus transit of 2012, and the Mercury transit of 2016:
The first three are from the time of the Venus transit, the last three are from the time of the Mercury transit. Mercury is very tiny, and the sun stood low in the west. A lot of turbulence. Anyhow, one can find a small tiny Mercury at the bottom of the sun's disc. A sunspot in the middle of the sun can also be seen. The last image shows Mercury at the bottom right, close to the limb.
The Venus transit of June 8th 2004.:
This transit was the first one I had a chance to see. The weather was partly cloudy, but I managed to see it from my observatory. This exposure is with an ancient ST6 CCD camera on my 12" Meade telescope. The planet is big!
www.galaxies.se - Ivar Hamberg - Updated 2020, Sept 01