Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_2018_sp_banner.thumb.jpg.a4fa178de7d36660e48f7eb1205319eb.jpg

R26 oldtimer

Newtonian and focal reducer

Recommended Posts

Hello everyone!

I have a sw 130p f/5 that I use for eaa with a diy Effio-a camera (same as revolution imager2). I was thinking of getting a 0.5 reducer to use with that setup in order to speed things up to f/2.5 but was wondering if the focal reducer will induce any annoying ca. What do you think?

Share this post


Link to post
Share on other sites
1 hour ago, shirva said:

https://www.firstlightoptics.com/coma-correctors/skywatcher-coma-corrector.html

Haven't got one but had seen this for sale from FLO

How would a coma corrector or otherwise focal reducer affect focus position? Normally barlows will push focus outwards and reducers pull focus further in. So unless the reducer is designed not to do that it might cause issues achieving prime focus for some scopes?

Share this post


Link to post
Share on other sites
53 minutes ago, pipnina said:

How would a coma corrector or otherwise focal reducer affect focus position? Normally barlows will push focus outwards and reducers pull focus further in. So unless the reducer is designed not to do that it might cause issues achieving prime focus for some scopes?

As in my reply I haven't got one,, but I take it skywatcher make them for a reason and FLO sell them,,, there is a description on Flo's link

Share this post


Link to post
Share on other sites

Inwards travel is an issue, but at this point I was more sceptical about introducing color abberation, as the 0.5 reducer is aggressive and not of the best quality, although the small sensor is forgiving. 

Share this post


Link to post
Share on other sites

Pretty sure when I tried to use a high powered reducer on my Newtonian, I had trouble focusing and stars around the edges were more like streaks.

I  can use a x0.7 reducer fine though, with a small chip gpcamv2.

Share this post


Link to post
Share on other sites

I have just found this thread as I am doing some research on the exact same thing. Having just purchased an ASI224MC and 0.5x reducer, I have a 130PDS and a 200p that I am looking to do this with.
From what little research I have done so far it seems to be that smaller chipped sensors do not suffer so much with issues such as coma etc... to the same degree that a larger sized sensor would.
The other interesting thing to note is that a 0.5x reducer can be used as a 0.6x or 0.7x etc... depending on the distance from the sensor, this should allow for better tuning.
As far as using the SW Coma corrector, this I cannot comment on. The issue you may have here is that the SW CC already has a focal reducer built in.
If Coma is a problem then I have the Baader MPCC Corrector that I can test this with and may be a better option (although only rated down to f/4).

I will be following this with interest

 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

×

Important Information

By using this site, you agree to our Terms of Use.