Astromaster 130EQ

[BenSwales]

Hi all,

I have been recommended to visit here, and hope I'm posting in the right part of the forum!

I have an Astromaster 130eq telescope (which I am aware isn't a particularly great telescope for astrophotography). I also have a Canon Eos 550d camera, and a t-adapter so it fits in the eyepiece, which is fine. When I have tried using it, I haven't been able to achieve focus, which I have found out is a fairly common problem with this telescope. 

Is there anyway that I will be able to get focus, such as with a barlow lens?

Thanks,

Ben

[astrofox]

depends on several things. I assume you cant rack the focusser in far enough. Thats the usual problem. Can you screw the T mount directly on the focusser without using an 2"- 11/4" adaptor. Some scopes can do that and decrease the focal distance. Finally you could try a barlow though this will lengthen the apparant focal length of the scope.

[AstroTux]

I have an AstroMaster 130EQ and a Canon 450D with T-ring and adaptor. I cannot get prime focus unless I use a Barlow - a Revelation 2.5x. It's a problem that I have run into before using a modified SPC900 web-cam with a focal reducer, as can be seen in this post http://stargazerslounge.com/topic/174689-custom-made-webcam-adaptor/ .

The solution appears to be that you either have to move the primary mirror up the 'scope ( something I don't want to do as it will upset the visual side of things ), shift the camera sensor closer to the focusser ( easily done with a modded web-cam but not so easy with a DSLR ) or use a Barlow.

The Barlow effectively increases the focal length of the scope and pushes the prime focus point a little further back, so this is probably the best option for a quick fix.

A quick word of warning though - my 2x Barlow is not sufficient so I have to use the 2.5x, but you may be luckier and be able to use a 2x.

BTW: welcome to Stargazers Lounge

Hope this helps,

Alan

[BenSwales]

Thanks for your quick reply. Yes, that is my problem. I have just tried that, and unfortunately it doesn't quite fit. Yes, that's what I was thinking, so I'll probably have a look into a barlow soon, thanks.

[BenSwales]

Thank you very much Alan! 

Hadn't refreshed the page, so didn't see your post when I last posted.

Yes I read the same thing about moving the mirror, which is why I came here, as that's not something I want to mess with. 

Thanks for the word of warning, I'll have a look into a 2.5x one then I reckon, to be on the safe side.

Thanks!

[c3po]

I have an AstroMaster 130EQ and a Canon 450D with T-ring and adaptor. I cannot get prime focus unless I use a Barlow - a Revelation 2.5x.......

The solution appears to be that you either have to move the primary mirror up the 'scope ( something I don't want to do as it will upset the visual side of things ), shift the camera sensor closer to the focusser ( easily done with a modded web-cam but not so easy with a DSLR ) or use a Barlow.

The Barlow effectively increases the focal length of the scope and pushes the prime focus point a little further back, so this is probably the best option for a quick fix.

Sorry to jump on the thread and chuck in a hijack, but I too have ambitious plans with my 130eq and Alan's stepper motor driver board.

I'm interested as to the pitfalls of moving the primary up the scope to achieve prime focus. The way I understand it is that it makes the scope faster? If so what detriment to the visual side does that cause? I have a Tal 2x Barlow to fall back onto if moving the primary affects it detrimentally for visual work, but the Barlow would slow the scope to about F10, which isn't great for DSO AP.

[AstroTux]

The main problem I can think of is that some of my eyepieces may not focus if I move the primary mirror up the tube.

When I first got my 'scope, my 40mm Meade 4000 would achieve focus ( just ) at almost the full length of the focuser away from the tube. When I came to collimate the 'scope I discovered that someone ( or something ) had positioned the secondary further up the tube, away from the primary it than should be. I moved the secondary back to its correct position under the focuser and achieved good collimation, but then my 40mm eyepiece would not focus. Moving the secondary closer to the primary had moved the prime focus position further away from the secondary. To correct this I had to buy a 1.25" extension solely for use with the 40mm EP.

I think if you were to move the primary up the 'scope this would have a very similar effect and could affect the focus position of most eyepieces - to say nothing of the fact that you may be losing light gathering abilities by positioning the primary too close to the secondary thus placing it well inside the light cone of the primary.

Whilst I can see the benefits of moving the primary up the tube for imaging purposes, I am mainly a visual observer and inveterate tinkerer . I'm afraid it's not for me.

Alan

[twin-kle1007]

This is a tricky set up.  I had a 130eq and had the same problem.  I can't remember exactly how I managed to achieve focus but I did get there.  Play around with a barlow attached.  Also there are a couple of parts (eye piece area) that actually screw completely off, allowing your DLSR to get closer the action, that might just get you into focus.  The DSLR wont be secure though.  I remember using a couple of elastic bands to hold it in place.  One of the great things about being an Amateur Astronomer is that you experiment until you find a way.  Good luck.