Observing

If you hadnīt used optics, Venus would have been noticeable only like a black point, which rolled over the sun disc. If you had at your disposition a larger telescope, you would see the following details in the beginning and in the end:

Part of sunlights can disperse in Venus atmosphere before total dip planet across disc of our star and illuminate it. Due to this effect came into being the belief, that the Venus has an atmosphere. 

It could seem to be something as a black drop after the second and before the third contact. This drop is an optical delusion, which arises from oscillation in the Earthīs atmosphere and bow effects in the telescope.

You can see on the Sun these details except planet transit too:

Edge darkle - is caused by high temperature on the Sun. We observe colder layers of atmosphere near the limb, whereas we can see in the centre deeper and too warmer.

Granulation - granuls are due to cycling convection sun material. Colder material from the circumference falls inside and comes up warmer, which cools off and it will fall again to the middle.

Sun spots - generally they agglomerate into groups.They originate in disturbanceīs places of the sun magnetic field, when retardion of substanceīs convection takes place on the Sun. New spots are produced in these very areas. For example they are big as the Earth. Their warmness is 1500°C less than the temperature of the surrounding gas. Actually they are red. It seems to be black because of hot surroundings.
the Sun

DONīT LOOK STRAIGHT AT THE SUN THROUGH THE TELESCOPE! YOU CAN GO BLIND INSTANTLY!

USE RATHER EFFICIENT FILTER OR SCREEN ON THE PAPER BEHIND TELESCOPE. If you observe Sun only by eyes use special glasses for sighting Sun eclipse, floppy or welding glass (no. 14) etc.