Telescope focusing

[bayredd]

I have a cheap bushnell 18-1561 that probably hasn’t been made in YEARS. I have a 24, 12.5, and 4mm eyepiece. I also have a 2x Barlow and a 1.5x erecting eyepiece. I tried looking at the moon tonight starting with the lowest power, 24mm eyepiece. I couldn’t get the telescope to focus, went all the way to both ends of the focusing spectrum. But when I added the 1.5x or 2x Barlow eyepieces to the 24mm eyepiece it focused no problem! I’m not sure why this is. I had the same issue when trying to focus in daylight on some far away trees. Anybody have any ideas on how to fix this or why it is happening? Thank you in advance!

[TerryMcK]

Welcome to the forum. There seems to be a few posts on the wider internet about this. Some stating it is a toy (not my words), others saying they have a similar problem but nothing conclusive about how to fix it.

 

I did find this which might have the manual for it https://www.opticsplanet.com/bushnell-warranty.html

[Nightspore]

12 hours ago, bayredd said:

I have a cheap bushnell 18-1561 that probably hasn’t been made in YEARS. I have a 24, 12.5, and 4mm eyepiece. I also have a 2x Barlow and a 1.5x erecting eyepiece. I tried looking at the moon tonight starting with the lowest power, 24mm eyepiece. I couldn’t get the telescope to focus, went all the way to both ends of the focusing spectrum. But when I added the 1.5x or 2x Barlow eyepieces to the 24mm eyepiece it focused no problem! I’m not sure why this is. I had the same issue when trying to focus in daylight on some far away trees. Anybody have any ideas on how to fix this or why it is happening? Thank you in advance!

 

Hello. I'm guessing this may be what your scope looks like (below). I don't know much about these, I'd say it was a small achromatic refractor around 50-60mm aperture. 

 

 

It appears to have been originally supplied with certain accessories. It might sound like an odd question, but are you attempting to use the telescope without the diagonal?

 

 

'Diagonals' are usually 90° or 45° mirrors or prisms that enable the telescope to be pointed upwards at the zenith (and anywhere between) while observing relatively horizontally through the eyepiece.

 

 

Most telescopes now are designed to be used with a diagonal. If a long focal length eyepiece is placed directly into the telescope visual back there may not be enough back-focus. The shorter focal length eyepieces may focus. A Barlow lens actually increases the telescope focal length, which may explain why you could achieve focus when using it. If you are using a diagonal it might just need an extension tube. These can be obtained from most astronomy retailers.

Edited April 11, 2022 by Nightspore