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Zac64

Need help with old telescope

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I found my old Meade 230 refractor recently and I put it all together with no missing peices. Last night I decided to take it out and look at the moon, only problem was it was SUPER blurry. You can almost barely tell it was the moon.

When I look through the lens it’s always the colour of the object I’m looking at so I don’t understand. I cleaned everything but still nothing. I have a video showing what I mean. 

If anyone can tell me how to fix this I will be very happy.

97BA0C52-B294-4B99-80E3-911DBE68D4F0.MOV

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Looks like it's way out of focus , turn the black knob til it focuses

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17 minutes ago, knobby said:

Looks like it's way out of focus , turn the black knob til it focuses

I did try that but it only did a super tiny difference 

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Posted (edited)

Have you inserted the 'diagonal' before the eyepiece. This turns the image through 90 degrees making it easier to view when the scope is pointing up. It also adds several centimetres to the length of the light path, needed to bring the image to a focus with the eyepiece. The bottom image shows the diagonal attached.

EMC_5001.thumb.jpg.7aa0545feeaab4e89cf0c6d2d7bd41be.jpg

P4190018.jpg.c366dfb0927de1570ad5681f569a8b9f.jpg

If you don't have the diagonal you'll need to insert an extension tube before the eyepiece to make the optical path length the same and enable it to focus. As a check with the eyepiece loosely placed in the telescope pull the eyepiece away from the telescope while still looking through it and it should come into focus at some point.

Edit! Oops! Just looked at your video and the diagonal is inserted. :blush: Ignore what I put.

How much travel is there when you turn the focuser from end to end. It should be around 10cm or so. Are you looking through a window in your video? This will degrade the image to some extent.

What focal length eyepiece are you using (The number in mm written on it.) The smaller the number the higher the magnification. Start with an eyepiece of around 20mm to 26mm if you have one to make focusing easier as the magnification will not be so great. Magnification is focal length of the telescope divided by the focal length of the eyepiece.

Alan

Edited by symmetal

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32 minutes ago, symmetal said:

Have you inserted the 'diagonal' before the eyepiece. This turns the image through 90 degrees making it easier to view when the scope is pointing up. It also adds several centimetres to the length of the light path, needed to bring the image to a focus with the eyepiece. The bottom image shows the diagonal attached.

EMC_5001.thumb.jpg.7aa0545feeaab4e89cf0c6d2d7bd41be.jpg

P4190018.jpg.c366dfb0927de1570ad5681f569a8b9f.jpg

If you don't have the diagonal you'll need to insert an extension tube before the eyepiece to make the optical path length the same and enable it to focus. As a check with the eyepiece loosely placed in the telescope pull the eyepiece away from the telescope while still looking through it and it should come into focus at some point.

Edit! Oops! Just looked at your video and the diagonal is inserted. :blush: Ignore what I put.

How much travel is there when you turn the focuser from end to end. It should be around 10cm or so. Are you looking through a window in your video? This will degrade the image to some extent.

Alan

Yes my focuser is 10cm long and in the video I was looking at a far away lamppost from my window. But when I tried last night on the moon it was giving the same unfocused image and there was no fix.

Let me try to explain the problem in more detail, when the telescope was in place and I looked above my eyepiece I could see a little dot being the moon, but when I got closer to put my eye in it was almost as if I kept looking at the little dot but really up close making it blurry, I knew I was looking at the moon up close but I couldn’t focus on it.

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I'd edited after you'd quoted. What's the eyepiece focal length? What's written on it?

Alan

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11 minutes ago, symmetal said:

I'd edited after you'd quoted. What's the eyepiece focal length? What's written on it?

Alan

The focal length is 25mm I also have a 9mm

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25mm should be an ideal focal length for getting started giving a magnification of 28x. I'm at a loss as to the reason for your problem at the moment. As you adjust the focuser the image of the far away streetlamp should get smaller and brighter going in one direction even if it doesn't focus. This shows the direction you need to keep going in order to reach focus even if you can't get there for some reason. Hopefully a more experienced visual observer can help you out as I'm just an imager now. :icon_scratch:

Alan

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I watched the video; not a bad kit.  The eyepiece appeared scratched-up, and with debris on the lenses.  Is the mains lens, at the front, similar?  That could be your problem.  The diagonal of your kit probably contains a mirror.  Check the mirror inside as well.  I've taken eyepieces apart before and cleaned them; the main lenses, too.  Do you feel comfortable doing that?  The main lens at the front could be very good optically, but I would upgrade the diagonal and eyepieces, if it were my own, and then go from there.  Here's a good star-diagonal...

https://www.rothervalleyoptics.co.uk/celestron-90-degree-star-diagonal-125.html

Eyepieces, diagonals, etc, are fully one half of the telescope kit.  You can't use a telescope without them, and you can use those items without a telescope.  Therefore, if the mains lens, the doublet, is of good quality, or better even, you want those items to be as well.

Here's an achromatic-doublet, like your own, that I cleaned up a while back...  

objective4.jpg.33c32e098a0e0b4dd58c99069827ece2.jpg

But that's from a much older kit, early '60s I think, if not the late '50s.  I can't stress enough the need to check out the doublet.  If it's of good quality, then the only way to test it is if the eyepieces and diagonal are in good order.

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It's just an idea, but were you looking through a closed window?  Though I must admit it does look like dust etc. on the scope glass

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As my Towa was in pretty bad position when I got it, similar to yours. 

Check the Crown and Flint element is spaced correctly. 

Also if the crown and flint element is spaced correctly. 

Then point the telescope at the moon or preferably a planet. And slowly turn the crown element in relation to the flint element. You don't want the flint element to move. After you've made one small adjustment check the view. Keep doing this until the best possible view is achieved. 

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While refurbishing vintage Ross refractors, I found that if the cemented crown/flint objective assembly was put in the cell the wrong way round, the results were dire. If the elements can be separated, that offers further possibilities for assembling the objective wrongly.  

You can use a piece of card or tissue as a projection screen to see where the objective is coming to focus, and if you have a diagonal and eyepieces from another telescope you could try them. By elimination it should be possible to solve the problem.

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