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I have recently purchased a Celestron NXT130 and have the following questions regarding planet viewing. I have obseved the moon, Jupiter and Saturn using the 25mm lens ( with and without the Barlow) with good results. However, when I switch from the 25mm to the 9mm lens (with or without the Barlow), I either can no longer see the planet (Jupiter and Saturn) or cannot properly focus (moon). I can understand that the moon may be too close for the 9mm to be effective, but I am a bit stumped about the other planets.

Looking for advice.

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Can you post a quick photo of the focuser with 9mm in place, please.

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Posted (edited)

If you can't see them with a 9mm, you probably possibly aren't spot on with the scope positiong. This is one of the reasons why when people swop eps for a close look they tend to move down the eps mags rather than bigger jumps. I. E 25,-20-15-9 and not 25-9. Unless you have your finger over the lens or forgot to take the cap off, the target isn't magically vanishing.

 

Try your 25, then Barlow the 25 to 12.5 (assuming it's a x2). Can you see it then?

Edited by DeathWarpedUp

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Try getting the object dead centre in your FOV with the 25mm before swapping down to the 9mm. At that magnification, the slightest movement away from dead centre could lose the object for you. It might need you to nudge the 'scope around a bit to find the object. How accurately aligned is the finder?

Is your 'scope on a GOTO?

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I agree with the above. Moving from the 25mm to the 9mm will show a much smaller portion of sky so unless a target is centered before the eyepiece change, it might well "disappear" when you get to look through the 9mm eyepiece. Also, if the scope is not tracking accurately and the eyepiece change takes a little time, the target may have drifted out of the field of view before you get to put your eye to the 9mm eyepiece.

 

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Thanks for the feedback. It is a GOTO scope and I am putting the object dead center im the 25mm eyepiece before changing to the 9mm (30 seconds or less to complete each step). I am also going from "25mm" to "25 mm with 2x Barlow" to "9mm".  I do not have a 12.5 mm but purchasing one sounds like a good idea so the  steps are smaller. The scope is tracking so I don't think that is the issue. I am typically using  the Solar System Alignment to look at the planets, but I wonder if using SkyAlign or Two Star Alignment would be more accurate for using the 9mm.

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The odd thing is that a planet that is visible with the 25mm eyepiece should disappear when the 9mm eyepiece is used. It does not make sense because in your scope (a 130mm F/5 newtonian reflector I believe ?) the 9mm eyepiece should be entirely functional - the 72x that the eyepiece produces is hugely within the limits of the scope.

It's a puzzle :icon_scratch:

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Posted (edited)
31 minutes ago, MountainDog said:

Thanks for the feedback. It is a GOTO scope and I am putting the object dead center im the 25mm eyepiece before changing to the 9mm (30 seconds or less to complete each step). I am also going from "25mm" to "25 mm with 2x Barlow" to "9mm".  I do not have a 12.5 mm but purchasing one sounds like a good idea so the  steps are smaller. The scope is tracking so I don't think that is the issue. I am typically using  the Solar System Alignment to look at the planets, but I wonder if using SkyAlign or Two Star Alignment would be more accurate for using the 9mm.

The 12.5 is the barlowed 25 (25/2=12.5).

The 3 or 2 star alignment is probably better. I always used the 3. However many people prefer 2. I think the usual align targets are vega and arctacus (normally some of  the first visible in the sky). Just make sure the targets are fairly distanced from one another. If you want something between a 25 and 8 however go for an 15-18, as you have the 12 covered with the Barlow.

 

 

 

Edited by DeathWarpedUp

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Is there any chance that the 9mm lens is the problem? Are bad lenses common?

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Have you used the 9mm on the moon? It the image is clear, just much more magnified, then the lens is okay.

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You said that you cannot attain focus with the 9mm on the moon, but it seems to me that you absolutely should be able to. In fact, I think that should give a really nice view as if out of the window of the Apollo module!

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That is correct - I cannot attain focus on the moon with the 9mm. Knowing now (per you comment) that I should easily be able to), it leads  me even more to believe that the issue is with the lens itself.

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Posted (edited)
14 minutes ago, MountainDog said:

That is correct - I cannot attain focus on the moon with the 9mm. Knowing now (per you comment) that I should easily be able to), it leads  me even more to believe that the issue is with the lens itself.

Can you focus using the 25 with the Barlow?

Edited by DeathWarpedUp

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I used to have a Celestron130slt and 100% you should be able to achieve focus with the 9mm. In fact the entire moon should be perfectly framed in the FOV at that (x72) magnification.

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I think this is pointing to something being wrong with the 9mm eyepiece :icon_scratch:

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Yes, I agree with John. I purchased a Celestron X-Cel LX series 18mm eyepiece for my 130slt. A nice lens (and becomes 9mm with a 2x Barlow).

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Ordered a new 9mm X-Cel today - my 25mm is also an X-Cel.  It's backordered so not sure when it will arrive, but I'll let you guys know what the outcome is once it gets here.

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Well. the new 9mm has arrived and works like a champ. Confirms for me that the 9mm sent to me with the telescope was a dud. I will be relaying that to the nice folks at Celestron.

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