My telescope's field of view is tiny (about a quarter inch through the focuser w/ 25 mm eyepiece)

  • Stargazing
  • Thread starter Brian Muller
  • Start date
  • #1
I have an Orion 130 reflector. Never had a telescope before. The field of view is about a quarter inch through the focuser with the 25 mm eyepiece. Does anybody know what I am doing wrong or if there is something wrong with the telescope itself? I'm at my wit's end. Any help would be greatly appreciated.
 

Answers and Replies

  • #2
Bandersnatch
Science Advisor
3,223
2,432
Hi Brian, welcome to PF.
One thing that comes to mind is that the eyepiece is not inserted properly. Perhaps the mounting screws were not unscrewed fully before inserting the eyepiece, so that it sits higher in the focuser than it should (i.e. it's resting on the screws).
 
  • Like
Likes Brian Muller
  • #3
russ_watters
Mentor
21,446
8,461
I have an Orion 130 reflector. Never had a telescope before. The field of view is about a quarter inch through the focuser with the 25 mm eyepiece. Does anybody know what I am doing wrong or if there is something wrong with the telescope itself? I'm at my wit's end. Any help would be greatly appreciated.
"A quarter of an inch" doesn't really mean anything in this context, so it is tough to tell what you really mean. Did the scope come with a 10mm eyepiece too? Are you saying it's a worse view through the 25mm than the 10mm? What do you see when you look at the moon, for example; can you see the whole thing?

Do you have glasses or might your eye otherwise be too far from the eyepiece?
 
  • #4
Drakkith
Staff Emeritus
Science Advisor
21,729
5,712
I have an Orion 130 reflector. Never had a telescope before. The field of view is about a quarter inch through the focuser with the 25 mm eyepiece. Does anybody know what I am doing wrong or if there is something wrong with the telescope itself? I'm at my wit's end. Any help would be greatly appreciated.

The field of view through a telescope is usually only a few degrees at best. Often even less than that. I can barely see the entirety of the full moon through one of my telescopes, even with my widest angle eyepiece inserted, and the Moon is only half a degree in diameter.

One of the things you need with any telescope is a smaller 'finder scope' attached to the side. This small scope should have a much larger field of view and, if you have aligned the finder scope with the main scope, should make it much easier to find what you're looking for in the sky. If you have one, make sure to align it with the main scope during the daytime, as it will be nearly impossible to do so at night.
 
  • #5
If I'm not mistaken, I believe he means that when looking through the eye piece only a small amount of area is viewable. Not sure how to put it but when he should be able to see "O" he is only able to see "o" instead with the surrounding area being blacked out. So somewhere there is a misalignment.
 
  • Like
Likes Brian Muller
  • #6
Thanks! The eye piece is in correct. I think it is my eye relief. My eye sight is not what it used to be. My dad can see through it fine. My eye has to be almost touching the lens to see it fill up. Thinking about getting a camera Mount and try that out and put it on my computer screen. In the meantime, I'm going to see if I can see anything on the next clear night. I will get back to you all. It's much appreciated!!!
 
  • #7
Drakkith
Staff Emeritus
Science Advisor
21,729
5,712
My eye has to be almost touching the lens to see it fill up.

That's normal.
 
  • #8
russ_watters
Mentor
21,446
8,461
That's normal.
....and it is common for cheap eyepieces (like what can come with a budget telescope) to have really poor eye relief. you may want to consider buying a replacement.
 
  • #9
9
8
....and it is common for cheap eyepieces (like what can come with a budget telescope) to have really poor eye relief. you may want to consider buying a replacement.
And for some very expensive eyepieces! I use spectacles and cannot use some optically excellent Pentax and Televue eyepieces specifically because the eye relief is too short.
 
  • Like
Likes russ_watters
  • #10
sophiecentaur
Science Advisor
Gold Member
27,196
5,907
I use spectacles and cannot use some optically excellent Pentax and Televue eyepieces specifically because the eye relief is too short.
Have you tried without spectacles? This wouldn't be a solution if you have strong astigmatism but it could be worth trying. You can get your eye much closer to the EP that way.
 
  • #11
9
8
It's not a problem for me - I can view without specs but I choose not to for various reasons. I use other eyepieces (and binoculars) with longer eye relief and they are great for me. It's one reason why Astro Societies are so useful - you can try other prople's equipment and sometimes borrow things to try which saves making expensive mistakes. My favourite Leica zooms were about £750 new when I bought them as used (but still expensive) items and I have some £30 eyepieces which are also great. My other half's favoutite eyepiece is a £10 plossl! Where possible, try before you buy and see what works *for you*!
 
  • #12
sophiecentaur
Science Advisor
Gold Member
27,196
5,907
It's not a problem for me - I can view without specs but I choose not to for various reasons. I use other eyepieces (and binoculars) with longer eye relief and they are great for me. It's one reason why Astro Societies are so useful - you can try other prople's equipment and sometimes borrow things to try which saves making expensive mistakes. My favourite Leica zooms were about £750 new when I bought them as used (but still expensive) items and I have some £30 eyepieces which are also great. My other half's favoutite eyepiece is a £10 plossl! Where possible, try before you buy and see what works *for you*!
It surprises me that, with all your apparent experience of eyepieces, you are quoting "a quarter of an inch" as a field of view. Field is expressed as an angle or it doesn't mean a lot.
 
  • Like
Likes davenn and russ_watters

Related Threads on My telescope's field of view is tiny (about a quarter inch through the focuser w/ 25 mm eyepiece)

Replies
4
Views
5K
Replies
5
Views
2K
Replies
9
Views
5K
Replies
2
Views
4K
Replies
13
Views
2K
  • Last Post
Replies
4
Views
3K
Replies
18
Views
3K
Replies
226
Views
6K
  • Last Post
Replies
1
Views
2K
Top