SkyWatcher 180mm Mak first light

[Bigzmey]

@WilliamPaolini @notFritzArgelander

Long acclimation is certainly an effective way to deal with the issue. I would rather do that or insulation than forcing outside air with fans.

Bill, not to change your ways but for the sake of better understanding. I think long insulated dew shield should slow down cooling of the corrector plate and for the mirror one could make insulating layer with holes for visual back and focuser. I am already using insulated dew shield and will try insulated back if I see the need for it.

[John Baars]

Congratulations on the VROD!

[notFritzArgelander]

@WilliamPaolini @notFritzArgelander

Long acclimation is certainly an effective way to deal with the issue. I would rather do that or insulation than forcing outside air with fans.
........

I view forcing air into the OTA as introducing undesirable dust. IOW with something akin to horror.

[John Baars]

(...) So the back of the SCT OTA is very sensitive to unavoidable body heat (i.e., face or any contact with un-gloved hands) when the outdoor temps are very low. So I know folks in certain environments where the insulation does a pretty good job, and does no good for others.(...)

True.
Oddly enough, I have had anomalous experiences with rear insulation of a Maksutov. This was admittedly on a 5.5 inch Maksutov. The same experiences on a 4 inch. Similar experiences were reported by a fellow forum member on the Dutch forum who used a 7 inch Maksutov.
The bottom line was that complete rear insulation distorted the star image as if it were pinched. Even after more than two hours of cooling. Only when the backside was left free of insulation did an Airy disk with round diffraction rings form. Apparently radiation from the back of the Maksutov, but probably the warm convection current from body and head around the back, and subsequently the internal radiation to the main mirror was just enough to form a stable star-image. Behavior that actually needs more investigation.

[Bigzmey]

@WilliamPaolini @notFritzArgelander

Long acclimation is certainly an effective way to deal with the issue. I would rather do that or insulation than forcing outside air with fans.
........

I view forcing air into the OTA as introducing undesirable dust. IOW with something akin to horror.

Ikr? Just the thought sends shivers down my spine. Dust, spores, moisture and what not.

[kt4hx]

Nicely done Andrey, and sounds like you have a keeper there. Also, congrats on the VROD.

[Bigzmey]

Nicely done Andrey, and sounds like you have a keeper there. Also, congrats on the VROD.

Thanks Alan!

[John Donne]

This is a very nice report Andrey.
Congratulations on the VROD

[Bigzmey]

This is a very nice report Andrey.
Congratulations on the VROD

Thanks Mark!

[WilliamPaolini]

@WilliamPaolini @notFritzArgelander

Long acclimation is certainly an effective way to deal with the issue. I would rather do that or insulation than forcing outside air with fans.

Bill, not to change your ways but for the sake of better understanding. I think long insulated dew shield should slow down cooling of the corrector plate and for the mirror one could make insulating layer with holes for visual back and focuser. I am already using insulated dew shield and will try insulated back if I see the need for it.

I very much agree. But all those actions will simply slow the rate of cooling. And any temp variations within the OTA will be minimized, but not eliminated. And of course the more radical the temp delta between the instrument and the outside air sometimes slow cooling will not be slow enough. Best solution IMO is the pipe dream, i.e., that the designer of the instrument actually builds it for proper acclimation profile instead of leaving it for ATMers to dream up different ways to mitigate the issues engineering never addressed. SCTs have a lot to love with their minimal form factor, but operationally they just do not perform up to what I need them to in my environment. I guess I should move to a less radical environment, but so far I much prefer the grandkids over the telescopes