New Dob Help

[flyte]

Hi, hope someone could help me, I just bought a new 8 inch SW Dob and every thing seemed to be going well assembling it. But when I went to align the finder scope I started having problems. I live in a very built up area so I cant find something to focus on in the Dob without it being really fuzzy ( there nothing that I can see that far enough away), I can find stuff in the finder scope but then cant see it in the eyepiece, Ive tried using both the eyepieces it came with, with no avail. I cant get out of the house and take it somewhere to align the scope as I cant drive, Is there any other way I can align the finder scope as I tried using the Dob without aligning the finder scope but it was stupidly annoying, I couldn't even find the moon. Also What eyepiece will magnify the most? I know it sounds like a silly question but When looking at stars both the 25 and the 10 seem to look the same?

Many thanks

Sam.

[Grunthos]

Hi, hope someone could help me, I just bought a new 8 inch SW Dob and every thing seemed to be going well assembling it. But when I went to align the finder scope I started having problems. I live in a very built up area so I cant find something to focus on in the Dob without it being really fuzzy ( there nothing that I can see that far enough away), I can find stuff in the finder scope but then cant see it in the eyepiece, Ive tried using both the eyepieces it came with, with no avail. I cant get out of the house and take it somewhere to align the scope as I cant drive, Is there any other way I can align the finder scope as I tried using the Dob without aligning the finder scope but it was stupidly annoying, I couldn't even find the moon. Also What eyepiece will magnify the most? I know it sounds like a silly question but When looking at stars both the 25 and the 10 seem to look the same?

Many thanks

Sam.

Best bet might be to try and align on the most distant object you can see (a TV ariel perhaps?) or failing that go for the moon again. Try looking down the tube of the scope to get a rough alignment then it's "just" a case of shuffling around.

Use the 25mm lens.

Don't worry, you'll get it eventually...

[flyte]

Best bet might be to try and align on the most distant object you can see (a TV ariel perhaps?) or failing that go for the moon again.

Use the 25mm lens.

I sopose Ill try the moon again, just got to wait until it comes over the roof of my house , So does the 25 magnify more than the 10 right?

Thanks for the quick reply.

[rowan46]

I like to use polaris to fine tune my finder it doesn't move as much as the moon and have to agree use the 25 not the 10 it doesn't magnify as much

[flyte]

Never thought about that Ill have to try it on Polaris.

Thanks!

[Grunthos]

The 10mm magnifies more than a 25mm.

You can work out the magnification by taking the focal length of you telescope (in mm) and dividing it by the sixe of your eyepiece (in mm).

In your case (assuming your 8"/200mm dobo has a focal length of 1200mm) gives:

25mm EP = 1200/25 = x48

10mm EP = 1200/10 = x120

[flyte]

The 10mm magnifies more than a 25mm.

You can work out the magnification by taking the focal length of you telescope (in mm) and dividing it by the sixe of your eyepiece (in mm).

In your case (assuming your 8"/200mm dobo has a focal length of 1200mm) gives:

25mm EP = 1200/25 = x48

10mm EP = 1200/10 = x120

Ahh I see, I was thinking the bigger the number the bigger the magnification, a newby mistake I'm sure. thanks for clearing that up.

[UnderTheRain]

I alligned mine on a star pick something easy like betelgeuse. I found it with my ota and lined the finder up after, I found it very easy that way.

To find my target star I just lined it up by looking along the top of the tube then along the side to get it roughly in view then just centred it with my alt az bolts. Then just lined my finder up on the same star. Then your free to go looking for the dimmer objects. It might seem backwards but it's dead easy.

[stevetynant]

when I first tried to do this - I stacked the 2 Inch and the 1.25 Inch convertors on top of each other and then tried with the 25mm lens - finder scope was great but couldn't focus on anything with the main scope until someone on this forum explained where I was going wrong.

Now I tend to find a bright star in the Main scope and then fix the finderscope each time- its not that difficult when you do it a few times - got a Reigl on the way (although everything I order with FLO seems on back order at the moment - perhaps its the Cox effect I guess)

the lower Numbers identify more magnification - so a 25mm lens does not magnify as much as the 10mm one - stick to the 25mm to get your finder scope aligned first should be a lot easier - best of luck

[Tinker1947]

You want to think about a Telrad, there easy to use and you keep both eyes open, plus there's a shed load of free maps, just Google "Telrad Maps"

Telrad finder

[Sarah]

I usually try to align on the moon, or a planet. Otherwise I would go for a nice bright star.

As already mentioned, I find it useful to try to look up the length of the outer edge of the scope to try to point it in the right area to start with. I find the Rigel QuikFinder easier to use than a finderscope.

Stick with it, once you have the finder aligned, it will make it easier find things in your scope.

And it helps if your scope is focused too. I recently had trouble finding Jupiter to align on when setting up for imaging. After ages I realised that the scope wasn't focused so that was why I couldn't find Jupiter anywhere in the vicinity it should have been!