Celestial hemisphere:  Northern  ·  Constellation: Canes Venatici (CVn)  ·  Contains:  M 3  ·  NGC 5272
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M3 - 20200716 - MAK90 at F5.4, altazastro
M3 - 20200716 - MAK90 at F5.4
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M3 - 20200716 - MAK90 at F5.4

Getting plate-solving status, please wait...
M3 - 20200716 - MAK90 at F5.4, altazastro
M3 - 20200716 - MAK90 at F5.4
Powered byPixInsight

M3 - 20200716 - MAK90 at F5.4

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Description

Through the use of a total extension of 31 mm the 0.5x focal reducer was able to obtain a focal ratio of about 5.4 with the MAK90 (focal length of approximately 485-490 mm) to achieve greater luminosity at the expense of some vignetting in the image.

I also tried to use the full spectrum available to the IMX385 sensor, which is particularly sensitive in the IR by forfeiting the usual IR-CUT filter.

Unfortunately both the meniscus lens and (probably more) the doublet used as focal reducer introduce a certain amount of CA that is exacerbated by the use of the full spectrum.

The picture is not bad, but some stars required extensive postprocessing to appear barely decent.

The lesson learned is that an IR-CUT filter is necessary.

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M3 - 20200716 - MAK90 at F5.4, altazastro