Low Profile Focuser Issues..

[acme]

I need advice please…Am I missing something or I have I got to buy another piece of kit to use this scope.

I have a f4.8 short tube Orion Optics Newtonian, I changed the focuser for a lower profile one so I could achieve focus using a DSLR.

I then found I could not achieve focus using my eyepieces so I purchased a 2 inch extension tube I can get focus now with my eyepieces , thing is I can’t use a barlow with any of my eyepieces or achieve focus using a webcam with or without the extension tube in place.

What else do I need or where did I go wrong, I spent one of the very few clear nights this week faffing about trying to focus the webcam on a bright star before attempting to capture Saturn.

Collimation was spot on, cooling down time was allowed, no dew issues and the seeing was as good as we have had for ages, my other scopes were operating fine during the same session so I don’t think it was down to any of the above factors.

Any thoughts or advice would be most welcome

Acme

[spaceboy]

Sorry I cannot offer much help but if it's any consolation you will be joining a long list of others with failed attempts using low profile focuser's. I have read about so many problems with regards LP focuser's and focusing issues with one thing or another that it has me asking the question what is the common thing we are all doing wrong?? The manufacturers can't be selling these focuser's if focusing becomes such an issue. I had an old Helios 8" explorer with a simple little R&P focuser and I never once had any issues bringing my web cam to focus on anything I pointed it at. I later upgraded my Dobs crayford to a LPDS focuser and put my crayford focuser from that on to the Helios in replacement to the R&P. Do you think after that I could get the web cam to focus?? It was always that tiny bit out either inward or outward focusing and because modifications to the OTA was required to fit the larger diameter crayford that ended up as a lost cause. Putting the DS focuser on the Helios was no better with no end of fiddling to get focus it all seems to defeat the object of having the upgrade in the first place. I can just about get focus but not with out having EP adapters hanging precisely out of the focuser. The annoying part is that the focuser itself is superb and so smooth & sturdy to use with EP's that it makes visual observing a pleasure but for imaging it seems to be more hassle than they are worth. I think for beginners in imaging the old Helios Explorers are a hidden gem you can often pick one up for next to nothing.

I would be interested if anyone can offer advice but going off previous threads the general consensus is to adjust the primary further up the OTA which in my book again defeats the object of buying the focuser.

SPACEBOY

[Bizibilder]

The problem you have is quite straightforward: The telescopes focal point has not changed by you swapping the focuser to a low profile type. So you need to compensate, as you have done, by using an extension tube (to make the focuser "high profile" again!!). It is likely that the extension tube that you have is not long enough to allow the use of the Barlow or your webcam. Solution - buy a second extension tube!!

After a while you will have quite a collection - just like the rest of us

[acme]

Cheers guys,

So I have a brand new LPF for DSLR focus, a 2 inch extension tube for visual and what would you say I need then another 2 inch for use of my barlow and Webcam.. OMG add my barlow and eye piece and I will need tp buy some step ladders also..LOL

Acme.

[Si W]

The problem you have is quite straightforward: The telescopes focal point has not changed by you swapping the focuser to a low profile type. So you need to compensate, as you have done, by using an extension tube (to make the focuser "high profile" again!!). It is likely that the extension tube that you have is not long enough to allow the use of the Barlow or your webcam. Solution - buy a second extension tube!!

After a while you will have quite a collection - just like the rest of us

Yes, join the club, i to had to buy an extension, but the crayford was well worth the investment against the cheap plastic focuser that comes with the Meade sn10, which just spoils what is otherwise a good scope, i think what you need to do is weigh up the odds and see if there is any benefits or not.

[spaceboy]

The problem you have is quite straightforward: The telescopes focal point has not changed by you swapping the focuser to a low profile type. So you need to compensate, as you have done, by using an extension tube (to make the focuser "high profile" again!!). It is likely that the extension tube that you have is not long enough to allow the use of the Barlow or your webcam. Solution - buy a second extension tube!!

After a while you will have quite a collection - just like the rest of us

Looks like I've blown it then as the extension would have to be 15mm long and I haven't come across any thing that short.

[acme]

I just found out I had a 25 mm in a odd's and sod's box so I managed to get the barlow and an eyepiece to focius so all I need now is to try and get the wecam to focus and the jobs a good one...Here 's hoping for the next clear night .

So just to re cap ..LPF for DSLR focus.. 50mm extension for the eye pieces to focus remove the 50mm and replace with a 25mm extension for eye piece and a barlow.. Now god only knows what I need for the webcam..

Acme

[jleach29]

I must be one of the lucky ones with the LPF issues, I put it in and had no issues with my 8in Dob since then.

[spaceboy]

I just found out I had a 25 mm in a odd's and sod's box so I managed to get the barlow and an eyepiece to focius so all I need now is to try and get the wecam to focus and the jobs a good one...Here 's hoping for the next clear night .

So just to re cap ..LPF for DSLR focus.. 50mm extension for the eye pieces to focus remove the 50mm and replace with a 25mm extension for eye piece and a barlow.. Now god only knows what I need for the webcam..

Acme

:icon_scratch: This is where mine is all back to front? I have the 50mm extension for the barlowed web cam to work and have to remove every thing and balance the 2" to 1.25" adapter out of the focuser to get it to focus other wise. The 2"/1.25" fully inserted won't work so I have to pull it almost all the way out to get focus. I assume the fix to this is a barlow with out the element ??

Hope you have found your fix to the problem Acme!

SPACEBOY

[Dave2292]

I know this is an old thread but I'm having this problem with a helios 200m reflector. It will prime focus but can't focus a dslr or zwo mini even with all sorts of different extensions and barlow set ups, is this a lost cause haha? 

[Tommohawk]

Yes, the thread has quite a lot of dust on it! When you say it will prime focus, not sure what you mean. You mean it will focus with eyepiece?

[Neil H]

Hi mate i have a OO VX8L  i changed the focuser  i have to use 50mm extension  to focus for visual but i also had to move main mirror too. check the mirror mount on OO they have 2 screw holes on main mirror  mount so you can move mirror up the tube towards  secondary mirror it only moves it about 5 mm but makes a big difference  to the focus

[Dave2292]

57 minutes ago, Tommohawk said:

Yes, the thread has quite a lot of dust on it! When you say it will prime focus, not sure what you mean. You mean it will focus with eyepiece?

Sorry I mean the dslr will focus without any barlow but I figured this out now. Was a bit of a rookie error. The focuser I got came with an extension thst basically turns it back into a standard focuser haha my bad 

[cletrac1922]

On 06/03/2011 at 00:49, Bizibilder said:

The problem you have is quite straightforward: The telescopes focal point has not changed by you swapping the focuser to a low profile type. So you need to compensate, as you have done, by using an extension tube (to make the focuser "high profile" again!!). It is likely that the extension tube that you have is not long enough to allow the use of the Barlow or your webcam. Solution - buy a second extension tube!!

After a while you will have quite a collection - just like the rest of us

 

Had same issue with my10'' flex Dob when using 2'' focuser

I brought a slide extendable tube, and problem fixed

John