Jump to content

SkySurveyBanner.jpg.21855908fce40597655603b6c9af720d.jpg

Which William Optics Refractor for Astrophotography


Recommended Posts

Hi all.

This will be my first post here.

I´m new to astrophotography, but have been around it for some time so I have an idea of what I´m going into.

Next up is finding the right equipment, have read the internet front and back. 

I´ve narrowed it to William Optics. Like them a lot. 

But witch one would be the best one? Go for higher aperture and less focal ratio or the other way around?

I´ve been looking at: 

GT102 - 102mm f/6.9 Apo 

GT - 81 FD / F5.9 

I´m willing to go up to 1600 USD for the telescope for now... So if you have an idea for another brand I up for all ideas!

For now I´ll be focusing on deep space stuff, the planets will wait for a bit.

I have an EQ6 Pro mount.

Hope you can help me... I´m lost :/

Link to comment
Share on other sites

Both are good but it may be better to pick the GTF-102 or GTF-81.

They have the flatener built in so you do not need to purchase one and then set all the distances.

The built in flatener does however extend the focal length so makes the scope slower - just be aware.

A smaller one is the Star-71, another WO scope.

Finally there is one by APM+TS it is an 81mm imaging scope that like the GTF-81 has built in flatener, however it is also a reducer and is a 6 element set up, triplet at the front and a 3 element reducer/flatener. I suspect they can gett he same 81mm objective and chopped up a GTF-81 and redid the bit at the rear to include a reducer and flatener.

This is the link I had: APM/TS-81

However cannot locate it easily on their site (APM) so I wonder if it has ceased.

May be worth an email asking.

Link to comment
Share on other sites

Thank you for your reply! You talked about slower scope... Is there a recommended speed for astrophotograpy... or a no go zone? 

The rule of thumb for astrophotography is: the faster the better, especially if you want to do deep sky imaging. For lunar and more so planetary 

photography you want larger f ratios. Hence I would choose the 102 f/6.9. It is middle of the road and can do both. With a reducer flattener you

can make it faster for deep sky if you wish and with a good Barlow lens you can get good planetary performance out of it.

Link to comment
Share on other sites

copy paste from blog

Doubling ISO from 800 to 1600 halves the max exposure time. Doubling the focal ratio from f/3.5 to f/7 quadruples (4x) the max exposure time

from what I was reading i'd say F3.5 to F8 max ?

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.