Judging criteria

The optimal characteristics of these 5 criteria are described below.

Sencha, normal steam (Futsu or Futsumushi Sencha):

Leaf Shape - Long, thin and round needle shape, smooth surface, uniform in size and shape.  It should contain little powder, stems, large, flat or broken leaves.

Leaf Color – Deep green or fresh green with a shiny smooth surface. 

Liquor Color – Clear and light yellow with a green hue expressing thickness and strength.

Aroma – Refreshing smell of young tips, also expressing a sweet, cool and fresh aroma.

Taste – Has an overall balanced taste and umami and leaves a refreshing aftertaste.

Sencha, deep steam (Fukamushi):

Leaf Shape – Similar to normal steam.  Deep steaming tends to produce a lot of powder but it should not be an unusually large amount.

Leaf Color – More yellow or yellowish green and deeply vivid in color than sencha.

Liquor Color – Deep green with thickness and strength.

Aroma – Similar to the normal steam.

Taste – Strong umami and sweetness with good aftertaste.  Should not taste under steamed.

What do these all mean?  The characteristics of good tea are described mostly in subjective terms, such as long thin needle shape?  How long and thin does it have to be?

This will grow on you with experience and continuous study of tea.  

One advice I would like to give:
If you can afford to buy some expensive tea, buy the best grade, the middle grade and low grade tea in the same category.  And compare the differences.  It's best if a store carries contest winning grade, because they are guaranteed good grade by judges.  Also, there are quite noticeable regional differences.  Shizuoka and Uji generally have completely different profile that they aim at.

Here is a practice you can do by looking at the following photographs of tea.
(clink on the images to enlarge)

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