Focussing Problem

[skir]

Gah, I've got the flu and was't suggesting you get naked! I did of course mean to write "Bear with me"!

thought it was a bit forward of you! Yes it does move up and down, but no worries keep the suggestions coming as I could easily be doing something daft!

looking further at star map sadly they don't seem to do an android version. I'm thinking about a nexus 7 tablet as I could connect that up with Bluetooth to the scope for less than the cost of an iPad mini alone.

But first things first: I need to get this focus problem sussed.

[skir]

What sort of minimum distance would something need to be from the scope to focus with a 32mm EP?

[dephelis]

What sort of minimum distance would something need to be from the scope to focus with a 32mm EP?

I would have thought you could focus on something much less than 100m away. I can focus my 150P with a 26mm EP on my kitchen wall from our front door and that is about 15-20m.

[skir]

I would have thought you could focus on something much less than 100m away. I can focus my 150P with a 26mm EP on my kitchen wall from our front door and that is about 15-20m.

ok well it certainly was a lot further than that that I was trying to focus it to.

I'm wondering if its worth just buying an extender to see if that does the job. Thing is I've spent a fair bit recently and if it doesn't do the job then that's another £20 quid gone. It would be good to know what the solution is before spending any more cash.

If I were to buy one what should I be getting a 50mm or 80mm? Also as one day I want to get into ap would it be worth buying an extension with the capability to be used with ap gear or is it all incompatible?

[cosmojaydee]

For AP the normal problem would be inward travel rather than outward

[skir]

For AP the normal problem would be inward travel rather than outward

what I was meaning really was: if I have to buy an extension tube would it be worth buying one with the capability of adding a camera into the system in future?

[Wobbly Bob]

Give Ian a ring at Altair Astro, I am sure he will be able to resolve the foccusing issue. I personaly uise a Red Dot finder ( TELRAD ) to get as near as pos to a bright star in the desired region, then the finder scope for fine tuning. The TELRAD does not require another screwed mount as it has double sided stiky on the base plate.

[cosmojaydee]

what I was meaning really was: if I have to buy an extension tube would it be worth buying one with the capability of adding a camera into the system in future?

Well , I can only speak from my experience I've had so far. If you are looking to attach a DSLR, I do not use any extension tube , the "T" adapter is placed directly into the draw tube but each OT will be different . If you purchase an extension tube, obtain a 2" diameter one rather than a 1.25" , you already have the 1.25" adapter, this will enable you to use it in conjunction with a "T" adapter if needed

[skir]

Well , I can only speak from my experience I've had so far. If you are looking to attach a DSLR, I do not use any extension tube , the "T" adapter is placed directly into the draw tube but each OT will be different . If you purchase an extension tube, obtain a 2" diameter one rather than a 1.25" , you already have the 1.25" adapter, this will enable you to use it in conjunction with a "T" adapter if needed

Thanks for that.

Is it possible to have too long an extension? (sorry that sounds a bit dodgy I know ) in that you couldn't get to focus in the other directon? If that makes any sense at all!

[cosmojaydee]

Thanks for that.

Is it possible to have too long an extension? (sorry that sounds a bit dodgy I know ) in that you couldn't get to focus in the other directon? If that makes any sense at all!

Sure it possible, but if you add say a tube 1" in length , add that to the draw tube length and you still don't get focus I would safely say you have issues with the OT

[skir]

Ok so got an extension through today and was instantly able to focus. So that was something else missing from my 2nd hand scope .Just a relief that's all it was as I was beginning to question my own sanity the other night!

[cosmojaydee]

That's great news

[skir]

That's great news

thanks for your help.

[skir]

Mmm, back to square one Whilst I could get the 32mm ep to focus on a chimney pot at about 30-40 metres it would not focus at infinity. So tonight I cut up a cardboard bog roll centre to simulate a 35mm extension. I could not get focus at all with this. It got close but would not come to a sharp image on the chimney pot, but I couldn't get the cardboard 100% straight so that may have had a bearing.

​

I have no idea what to do now, I've checked the Collimaton and that seems ok. I'm going to totally re-collimate tomorrow to see if that sorts it. I'm on the verge of giving up with this scope tbh. Someone suggested cupping my hand around the top of the focusser to see if I can then focus I'll try that tomorrow after re-collimating. In the mean time if anyone has some suggestions?

[rwilkey]

These came with the scope I have.

(A) is an extension tube, I have to use with a 2" EP to get focus as this increases backward travel(away from the OT).

( is the 1.25" adapter which can either be

1) be placed into the extension tube

so you would get focuser, extension tube,1.25 adapter

2) be placed directly into the focuser

so you would have , focuser , 1.25" adapter

A) is not an extension tube, it is the 2" adaptor and is supposed to be used on its own with a 2" ep in the focuser. It should never be used coupled up with the 1.25" adaptor, it should be swapped when you use 1.25" ep's. At least that's how mine works.