The last few nights I have been doing a side by side comparison of
double stars with a TeleVue NP 101 and my new TEC 140. A couple
of examples are 36 Andromeda and Delta Cygnus. 36 Andromeda, @ 1.0 sec, mag 6.1/6.8 is cleanly split with the TEC, but it is a figure eight in the TeleVue. The companion of Delta Cygnus @ 2.5 sec, mag 2.9/6.3 is a grey dot on the difraction ring in the TeleVue, and
appears to be about twice as far away from the primary in the TEC. I
seem to prefere the view through the TeleVue, even though the TEC
has better resolution. The TeleVue has a textbook diffraction pattern,
with a sharply defined central disk with a faint ring. With the TEC, I
don't see the sharply defined disc, and I have not seen a good
difraction ring yet. The smaller aperature with the larger difraction
image is more estheticaly pleasing to my eye. These results don't make me disapointed with the TEC, it just illustrates to me that a 4 inch APO is a great choice for a scope. I am waiting to see what the TEC will do with the planets, I expect it to show more detail than the TeleVue.
double stars with a TeleVue NP 101 and my new TEC 140. A couple
of examples are 36 Andromeda and Delta Cygnus. 36 Andromeda, @ 1.0 sec, mag 6.1/6.8 is cleanly split with the TEC, but it is a figure eight in the TeleVue. The companion of Delta Cygnus @ 2.5 sec, mag 2.9/6.3 is a grey dot on the difraction ring in the TeleVue, and
appears to be about twice as far away from the primary in the TEC. I
seem to prefere the view through the TeleVue, even though the TEC
has better resolution. The TeleVue has a textbook diffraction pattern,
with a sharply defined central disk with a faint ring. With the TEC, I
don't see the sharply defined disc, and I have not seen a good
difraction ring yet. The smaller aperature with the larger difraction
image is more estheticaly pleasing to my eye. These results don't make me disapointed with the TEC, it just illustrates to me that a 4 inch APO is a great choice for a scope. I am waiting to see what the TEC will do with the planets, I expect it to show more detail than the TeleVue.
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