Help - SWED80 focus confusion

Colsmith · #1 06-02-2009, 07:58 AM

Hi Guys,

I recently acquired a Skywatcher ED80 Pro. It din't come with EPs so I asked the vendor to supply a couple to get me started and I ended up with (cheap) 25mm and 15mm 1.25" plossels. In a separate transaction I also purchased a 2" diagonal.

With just the EPs I am unable to focus - I run out of inward travel. With the diagonal I can focus both EPs, but almost at the limit of inward travel. Does this sound right?

I also purchased an Orion Illuminated 12.5mm Plossl which wont focus with or without the diagonal.

Do I have a problem with the 'scope or is this usual?

Thanks for your help,

Colin.

JohnG (John) · #2 06-02-2009, 09:19 AM

Hi Colin

If you are using the telescope as a straight through configuration, you will need an Extension Tube, you can get various lengths from Bintel, they sell them quite cheaply. If you are planning to delve into Astrophotography, you will also need the extension tube.

As far as using the 2" Diagonal, so long as the eyepiece comes to focus, it doesn't matter, some will be further out than others. As far as your Orion Illuminated eyepiece is concerned, you may have to put a short extender before the diagonal to push the focus point out a bit.

All part of the learning process

.

Cheers

Colsmith · #3 07-02-2009, 10:35 AM

Thanks for the response John, however I'm still confused.

I'm running out of inward travel, wouldn't an extender just make that worse? Anyway, for the price of an extender, I'm happy to give it a try.

JohnG (John) · #4 07-02-2009, 01:13 PM

Hi

Sorry, I misunderstood what you were saying, if you can't go inward enough, you may have to try an 1 1/4 diagonal, that will give you slightly more travel. Failing that, straight through with an extension tube which is a pain.

Cheers

wasyoungonce (Brendan) · #5 07-02-2009, 10:39 PM

My ED80 is racked in quite a bit with my eyepieces & diagonal (50mm GSO).

I am using TV Plossls: 32, 20, 15 & 12 which are all parafocal (at same focus) so refocusing is minimal but they all focus OK. In fact I need the diagonal to reach focus...which is normal.

Just check your 2 inch focus draw tube ring & adaptor is screwed inwards as much as possible, see pic.

Merlin66 (Ken) · #6 08-02-2009, 04:38 AM

Unusual!!
I have an ED80 and you definately need the diagonal ( or a 50mm extension for straight thru) but all the eyepieces and the webcam etc can all come to focus.
As suggested you could try a 1.25" diagonal; but I'm a little surprised??!!