Celestial hemisphere:  Northern  ·  Constellation: Cygnus (Cyg)  ·  Contains:  IC 1340  ·  NGC 6992  ·  NGC 6995  ·  Network nebula  ·  Veil nebula
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NGC6995 - 20101015 - ST80 at 40/200 - UHC, altazastro
NGC6995 - 20101015 - ST80 at 40/200 - UHC
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NGC6995 - 20101015 - ST80 at 40/200 - UHC

Getting plate-solving status, please wait...
NGC6995 - 20101015 - ST80 at 40/200 - UHC, altazastro
NGC6995 - 20101015 - ST80 at 40/200 - UHC
Powered byPixInsight

NGC6995 - 20101015 - ST80 at 40/200 - UHC

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Description

Test image taken between passing clouds and before the sky became really overcast.

The experiment consisted in stopping down the Skywatcher ST 80 to 40 mm of aperture, while at the same time reducing the focal length to 200 mm by using the 0.5x focal reducer.

In the end, because of the distance between focal reducer and sensor due also to the presence of filters in between, the effective focal length, according to plate solving, was 187 mm instead of 200 mm and hence the focal ratio 4.68 instead of 5.

Unfortunately, the optical train was not perfectly "on axis" and so there is pronounced coma on the left side, but the experiment had nevertheless a positive outcome, with rather little CA or spherical aberration.

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NGC6995 - 20101015 - ST80 at 40/200 - UHC, altazastro