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Can you help me identify these things that came with my telescope??


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Hi guys,
 
I'm hoping for some help here.
 
I purchased a used Celestron Astromaster 130 which came with a few extras:
 
2x Barlow
3x Barlow
Moon filter
Lens cleaning equipment.
 
However, there appears to be some kind of laser pointer.

post-37995-0-02764200-1407173206_thumb.j

The 3x Barlow (below) doesn't seem to have any lens, it is just a tube. I'm assuming that it is no good.

post-37995-0-39639300-1407173304_thumb.j

All the rest of the equipment seems fine but any wisdom that you have on these two objects would be greatly appreciated. 

Thanks

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The second piece does seem to say: 3x Achromatic Barlow, and as such i'm guessing it should have a lens in the smaller end. It could have been a 3x barlow at some stage and the previous owner removed the lens to convert it into an extension tube which is obviously needed for the scope to get into focus (usually when attaching a camera). The first part (as already said) is a laser collimator. 

Edited by LukeSkywatcher
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The first item is a laser collimator. This is used to help you align the mirrors to the focuser. The second item is labelled x3 barlow. if it doesn't have a lens in the bottom of the tube then it is a broken x3 barlow. it probably won't help you achieve prime focus with a dslr because the problem is usually not being able to get the camera close enough to the point of focus, not the other way around.

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It really is your choice. You can get a dual axis motor (controls both the up/down "DECLINATION", and left/right movement "RIGHT ASSENTION"), or you could get a single axis motor (RA). Most people would opt for the single RA axis motor so they can track objects. These motors are not too expensive and can be retrofitted simply using a screwdriver.

I personally probably wouldnt bother with either. Once the Dec axis is set to your co-ordinates (degrees north of the equator), its a simple case slowly turning the RA slo-mo knob to track objects.

 "it probably won't help you achieve prime focus with a dslr because the problem is usually not being able to get the camera close enough to the point of focus, not the other way around".

Indeed, you are correct. An extension tube would take a camera further away from prime focus. Achieving focus in the 130 seems to be a problem for many who get into imaging. 

Probably best just to bin it...............(the 3x barlow bit) that might have been converted for something else.

Edited by LukeSkywatcher
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Er, at the risk of being swatted by the far more experienced peeps above, item #2 could well be a perfectly good 3X Barlow.

Simply unscrew the lens bit from your 2X and add it to the 3X.

As I understand things, Barlow focal lengths are defined by the length of the extension tube in "Barlows" before light is resolved by the EP.

The important bit of your 3X Barlow tube would be twice as long as your 2X Barlow tube. ie 2 Barlow lengths where 1 = 2x, 2 = 3x, 3 = 4x.......

I'll now go shake out the woodlice.

Rich

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Er, at the risk of being swatted by the far more experienced peeps above, item #2 could well be a perfectly good 3X Barlow.

Simply unscrew the lens bit from your 2X and add it to the 3X.

As I understand things, Barlow focal lengths are defined by the length of the extension tube in "Barlows" before light is resolved by the EP.

The important bit of your 3X Barlow tube would be twice as long as your 2X Barlow tube. ie 2 Barlow lengths where 1 = 2x, 2 = 3x, 3 = 4x.......

I'll now go shake out the woodlice.

Rich

Not sure about the math, but the idea of unscrewing the lens from the 2x and attaching it to the 3x could actually work (assuming they are both either 1.25 or 2 inch).

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Rich is correct, using progressively longer spacers between the eyepiece and the Barlow lens will increase the effect of the Barlow. Swapping the actual Barlow lens is an inexpensive means of doing this. A zoom eyepiece works on this principle, as you twist the barrel the Barlow lens slides up or down to vary the magnification.  :smiley:

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Thanks Paul,

Do you recommend getting a motor for the mount? 

I have to say that at someone who has the exact same telescope as you, but with the motor drive I love the scope.  I do, however, find that the motor drive gets in the way for everything other than astrophotography!!  I want to be able to slew the scope around in any direction (once aligned) but I find that when the motor drive is attached it knocks against the fine adjustment arms of the EQ mount.  I've removed mine and having just bought myself a GoTo mount, I don't think I'll be putting it back on for a while!!

I got in touch with Celestron and they confirmed that the Astromaster 130 tube is compatible with the GT and SLT mounts of their NexStar range.  As such, I've just purchased at 90 GT from eBay for £130 and will be using that for my 130 tube.  The 90 refractor will then probably be relegated to the EQ mount or donated to my local Astro Society (surprisingly, it's cheaper to buy the scope and mount as a package than the mount as a single item).  I know that the NexStar mounts eat their way though batteries in short order, so I've also ordered myself the 7mah Power Tank to keep everything running smoothly (and charge my iPhone whilst I'm sitting in a field!!).

In summary; don't bother with the motor drive, enjoy the scope, and FLO do a good deal on their power tanks - buy one!!

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