Astrologers work with different tools, but they all use aspects and certainly they use aspects within the tighter orbs. There is no doubt about the effects of aspect combinations. They symbolize interaction between positions in the sky above. There is an aspect when there is a meaningful distance between objects in the chart. There are different kind of aspects. There are major aspects (the so called Ptolemaic aspects) and there are minor aspects. There are soft aspects and hard aspects. Let me give you a list:
MAJOR ASPECTS
0 degree Conjunction
60 degrees Sextile
90 degrees Square
120 degrees Trine
180 degrees Opposition
MINOR ASPECTS
30 degrees Semi sextile
36 degrees Semi quintile
40 degrees Novile
45 degrees Semi square
51.4 d Septile
67.5 d Semi sesquisquare
72 degrees Quintile
80 degrees Binovile
135 d Sesquisquare
150 d Inconjunct
157.5 d Sesquisquare + semi square
160 d Quatronovile
I use tight orbs, no more than 5 degrees and no more than 2 for midpoints and minor aspects in the natal chart. Considering the minor aspects, the orb for midpoints and the fact that if you want sharp hours of birth, it is also worthwhile to use sharp orbs.
Extend the orb only if there is an object between the two other objects in a -too- large orb! (There is mostly also a midpoint combination then).
Using larger orbs, will turn the chart of the hour of birth into the chart of the day, week or even the month of birth…