Jump to content

Sketches

Focal reducer.


Recommended Posts

So with the help of this wonderful forum and its excellent posters, I have now focused and come to a decision: I intend to order the Celestron Evolution 9.25 telescope:  https://www.firstlightoptics.com/nexstar-evolution-telescopes/celestron-nexstar-evolution-925-telescope.html

?

I still have so many questions and they appear to be beginner ones, so I am posting in this section.

Next question is regarding focal reducers, which I read are not just for imaging, but can help with visual too. So, should I order, when I order the telescope, one of these: https://www.firstlightoptics.com/reducersflatteners/celestron-f63-focal-reducer.html

It reduces the F10 native to the scope, down to F 6.3, which sounds like it could be useful. I am unsure if I should be bothering so any advice would be greatly appreciated.

I am sorry but there are going to be so many more beginner questions from me. I apologise if I should be posting elsewhere now. ?

 

Link to comment
Share on other sites

The use of focal reducers are of use is for astrophotography, as they reduce exposure times by 1/3rd. You can use them visually too, but I would think about it for a later purchase and concentrate on other accessories first, as astrophotography is a steep learning curve.

Link to comment
Share on other sites

5 hours ago, Philip R said:

The use of focal reducers are of use is for astrophotography, as they reduce exposure times by 1/3rd. You can use them visually too, but I would think about it for a later purchase and concentrate on other accessories first, as astrophotography is a steep learning curve.

Totally depending on the reducer... In this case the reducer shortens the exposure times with T:(f1:f2)² , which means for example a 100 second exposure will be reduced to 40 seconds. The main difference of a reducer for visual is of course the wider field of view and the dimmer objects being better recognizeable.

Link to comment
Share on other sites

Thank you for the answers. ?

It is indeed the wider field of view that I was thinking of getting it for, just how much of a difference to the view, visually, be going from F10 to F6.3? I still find it hard to visualise the change if F number.

Link to comment
Share on other sites

18 hours ago, Greymouser said:

So with the help of this wonderful forum and its excellent posters, I have now focused and come to a decision: I intend to order the Celestron Evolution 9.25 telescope:  https://www.firstlightoptics.com/nexstar-evolution-telescopes/celestron-nexstar-evolution-925-telescope.html

WOW!! ?  They sure are expensive in the UK.  That works out to $3035 USD.  They're only $2199 here in the US.  It must the 20% VAT and 20% import duties at work.

A fellow at a local star party had the 8" EdgeHD on this mount and was controlling it via a tablet.  The views were amazing through a 10mm Delos, and the ease of control via the tablet was pretty slick.

The focal reducer is a great way to get to lower powers without investing in a 2" visual back, 2" diagonal, and 2" wide field eyepieces.

  • Like 1
Link to comment
Share on other sites

The maximum field of view is limited by the baffle tube that goes through the centre of the mirror and your eyepiece so the reducer may only give you smaller brighter view of the same thing, not that that's a bad thing.

Some folk use a visual back with 2" eye pieces to obtain the maximum usable FOV.

Dave

Louis beat me to it :grin:

Edited by Davey-T
Link to comment
Share on other sites

1 hour ago, Greymouser said:

Yes I would like to avoid getting another visual back for it. Not least because it will involve buying a new set of eyepieces... ?

You wouldn't need to buy a new set of eyepieces. The diagonal will come with a 2" to 1.25" reducer so you can continue using the same eyepieces and just add some extra 2" ones if/when you want them. 

  • Like 1
Link to comment
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
 Share

×
×
  • 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.