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Additional lock points on SW 300P Flextube


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Well, it turns out that the two holes at the bottom end of the trusses are at right-angles to where the tightening screws make contact - is this normal? (I bought the 250px 2nd -hand so not sure if these trusses come ready assembled on the tube or not); I tentatively tried to rotate one of them but it didn't seem to want to move and I don't want to risk any damage if they're not intended to move!

Next I measured the noted 110mm and just slipped the scope down that amount before tightening the screws to see if reaching focus was now possible - it made no difference at all: stars which are nicely pin-pointed visually (with the tube fully extended) were again seen as small discs even when using EOS Backyard to assist with the focussing.

Anyone got any ideas?

Anyone had the same focusing issue for astrophotography with a 250px Flextube and found that fitting a low-profile focuser was the answer?

Cheers,

Key.

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Hi.

How are you attaching the camera to the telescope? Are attaching at prime focus or via an eyepiece/barlow?

If you are attaching it at prime focus make sure you are attaching it directly to the base of the focus tube, not on the end of the eyepiece holder.

300P T mount

You just need to screw on the T2 adapter on there. This will dramatically shorten the light path.
If you are connecting via a 1.25" barlow or eyepiece I can thoroughly recommend a Baader low profile eyepiece holder.

Baader eyepiece holder

I've raised the SW one on the left so the point they sit in the focus tube are the same. So you can see how much it shortens the focal length!
Cheers.
Edited by mitchelln
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Hi Mitchelin, thanks for your reply. Yes, I'm using prime focus. I'm away for a couple of days now but will try to get photo's or at least describe the set up when I get back. I'm hoping you're onto something and I've just got an unnecessary piece of gear that's extending beyond the focal point.

Cheers, Key.

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Hi.

We should be able to sort it. I've never had any problems focusing my Canon at prime focus. SkyWatcher will have tuned it to work.

With barlows and eyepieces it's been an entirely different matter! Always been able to come up with a combination that works though :)

Sent from my GT-N7105 using Tapatalk

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Hi Mitchelin,

I've been having a look at my scope and attachments; my set up looks very much like in your photo's for prime focus use as these pic's show:

T-Ring and adapter attached to the focus tube: post-12807-0-09386100-1385745081_thumb.j

T-ring and adapter exploded view: post-12807-0-26384400-1385745257_thumb.j

Close-up of the T-ring which I've discovered can be taken apart but unfortunately even then it can't be fitted directly into the focus tube after removing the 2" eyepiece holder: post-12807-0-03247500-1385745427_thumb.j

Grateful again for any further ideas or suggestions.

Cheers,

Key.

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Anyone got any ideas why I can't achieve prime focus with the set-up shown?

Visually the stars appear fine but they appear as small discs even when using EOS Backyard to assist with the focussing - very frustrating!

Help!!!

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