Upgrading Focuser For Refractor Telescope

[Refractordude]

Besides smooth focusing, what other advantages are there in upgrading from a stock focuser? I googled/binged this question. However, could not find much info on a focuser's effect on magnification, image, color etc. Thanks to you all.

[notFritzArgelander]

Besides smooth focusing, what other advantages are there in upgrading from a stock focuser? I googled/binged this question. However, could not find much info on a focuser's effect on magnification, image, color etc. Thanks to you all.

That's because there is none. It's purely mechanical and has no optical effects. The only thing a focuser does is achieve good / optimal focus. Some stock focusers don't do that job so well.

[Bigzmey]

In addition to the main function - smooth focusing, other things to consider:

Dual speed focusing - micro wheel helps with precision.

Focuser travel - with stock focusers, in particular on fast achro, you may run in to issues that you can't achieve focus with particular EP. diagonal or barlow, because there is not enough focuser travel.

Payload - ability to hold focus with heavy attachments like glass grenades, binoviewers, filter wheels, cameras, etc.

Collimation - some of stock focusers are too clumsy or poorly designed, that even with all the adjustments there is a play in the draw tube which will affect scope collimation and in the result image quality.

I could keep going. Unless you have a premium scope with a good focuser already in place, upgrading stock focusers is a good move.

[Ozypic]

Ah hocus pocus ,its all just smoke and mirrors ... you have to be a magician to work out focus. I want a focuser that says in a big loud voice " STOP you fool " before you go past that perfect focus point . I do often wonder just how central my view is down the tube, as the focuser does have an amazing amount of slop in it. My son bought me an electric focuser for my birthday a few weeks ago and I havent had a clear or available night to try it. I expect the best thing will be not having to touch the scope .... we will see . Phill

[notFritzArgelander]

Ah hocus pocus ,its all just smoke and mirrors ... you have to be a magician to work out focus. I want a focuser that says in a big loud voice " STOP you fool " before you go past that perfect focus point . I do often wonder just how central my view is down the tube, as the focuser does have an amazing amount of slop in it. My son bought me an electric focuser for my birthday a few weeks ago and I havent had a clear or available night to try it. I expect the best thing will be not having to touch the scope .... we will see . Phill

I have happy memories from 50 years ago with a motorized focuser on a professional 16" Cassegrain. That was deluxe! My fat fingers can press a button better than they can turn a knob, that's for sure. Hope you enjoy yours.

[Ylem]

:sly: "STOP you fool"
Sounds like the Mr T focuser :cool:

[Refractordude]

What upgrade budget focuser would you use for a Meade LX70 f/8 achro refractor? The stock focuser is kinda sloppy. At high power I have to use a 3 inch aperture mask to get star rings. Thinking a focuser upgrade might change things.

[bladekeeper]

What upgrade budget focuser would you use for a Meade LX70 f/8 achro refractor? The stock focuser is kinda sloppy. At high power I have to use a 3 inch aperture mask to get star rings. Thinking a focuser upgrade might change things.

I've had good luck with this one: https://agenaastro.com/gso-crayford-foc ... -86mm.html

[notFritzArgelander]

What upgrade budget focuser would you use for a Meade LX70 f/8 achro refractor? The stock focuser is kinda sloppy. At high power I have to use a 3 inch aperture mask to get star rings. Thinking a focuser upgrade might change things.

In the early 2000s I had the Orion version of the same scope. I found that mine arrived out of collimation and I had to collimate it. It had a collimatable lens cell. The focuser was OK. I don't know about the Meade version. The tube and mechanics might be a little different. I'd check collimation first.

I've had good luck with this one: https://agenaastro.com/gso-crayford-foc ... -86mm.html

Yes. That's the one to use as a focuser upgrade.

[Lady Fraktor]

A new/ better focuser to get rid of the JOC/ Synta rack and pinion is always a great upgrade.
One I have always recommended as being in the top three ways to get better results from your refractor.
Do not forget to make sure it is aligned well with the telescope tube.

[notFritzArgelander]

The fact the OP has out of round Airy disks that are fixed by an aperture mask worries me though. It might not be the focuser but a miscollimated objective lens.

[Lady Fraktor]

I missed a post somewhere then.
I would be checking the lens out if that was the situation.

[notFritzArgelander]

I missed a post somewhere then.
I would be checking the lens out if that was the situation.

I'm getting some differences of opinion on whether the Meade has a collimatable lens cell or not. The discontinued Orion did and the Celestron version does.

https://www.cloudynights.com/topic/6090 ... refractor/

So the OP needs to check for push-pull screws on the lens cell, I think.

[Lady Fraktor]

From the look of the dewshield on the lens cell I would suspect it does not have adjusters, I also looked at the manual and there is no mention of adjusting the collimation in it.

[notFritzArgelander]

Glad you found that. I didn't.

[yobbo89]

A more rigid focuser will remove focuser slop if you have some play and being able to collimated the focuser is a plus

[Refractordude]

I can not collimate the lens cell. I do get a perfect diffraction star test front and back focus. Thanks for all the responses.

[Refractordude]

Will try the GSO focuser. If things don't work out, can I use this GSO focuser as an upgrade for a Skywatcher Proed 120mm f7.5?

[Lady Fraktor]

If the focuser to tube adapter is the same size it will fit, another adapter may be needed.
I think Astro Agena has a chart of which ones fit which tubes. You can also email them if you cannot find the information on site.

[pakarinen]

If the focuser to tube adapter is the same size it will fit, another adapter may be needed.
I think Astro Agena has a chart of which ones fit which tubes. You can also email them if you cannot find the information on site.

https://agenaastro.com/articles/gso-cra ... ility.html