Zenithstar 61 focusing and thermometer

[Lachlan]

Hey everyone, 

I know the William Optics zenithstar 61 comes with an inbuilt thermometer, but is there some kind of general rule I can follow so that I can use the thermometer to know when I should refocus? 

Also, since the body of the OTA is not carbon fibre, has anyone had any major issues with the scope badly shifting focus?

thanks 

[Adam J]

On 20/11/2018 at 03:49, Lachlan said:

Hey everyone, 

I know the William Optics zenithstar 61 comes with an inbuilt thermometer, but is there some kind of general rule I can follow so that I can use the thermometer to know when I should refocus? 

Also, since the body of the OTA is not carbon fibre, has anyone had any major issues with the scope badly shifting focus?

thanks 

Just had a discussion on this in respect to the 130PDS. I would think that the ZS61 being both slower in F-ratio and of a much shorter tube would need a much larger shift in temperature to require refocus more than 10 degrees c I expect. Its unlikely that you will see that kind of temperature drop / rise over the course of an imaging session...or at least in the UK it is. As such really....the temperature gauge on a ZS61 at least is a marketing gimmick. 

[Davey-T]

Don't know about temperature fluctuation in Oz but I've never had to refocus my WOZ61 during an imaging session.

Dave

[Ruud]

here is a video of this scope

No focusing issues, but also buying the field flattener is a good idea.

[ollypenrice]

I'm an anti-gadget astrophotographer. It would do no harm to build up an idea of how temperature change affected focus but but instinct tells me that creating a hard and fast link between focal distance and temperature will never work. I certainly wouldn't trust it. There are variables everywhere.

Olly

[david_taurus83]

The thermometer in my GT71 actually fell out! I haven't put it back in ?