Not enough forward focus - EOS 1100D and 200P

[Dodge]

Hi guys,

I've seen this problem discussed a couple of times, but I'm not quite sure what the solution is.

I have a 200P on an EQ5 with a Crayford focuser capable of taking 2" and 1.25" eyepieces. With the scope came an adapter that clicks onto my EOS (Is this a t-ring?) and is attached to a 2" tube I can slot into my focuser. The problem is that I can't get enough forward focus.

I've heard using a Barlow moves the focal point back enough, but I don't want to do that. As I understand it, I need either a low-profile focuser (don't really want to do that) or lower profile adapter rings.

Here's what I've got:

The 2" tube part rotates, and looks like it can be removed.

My 200P has a metal ring that screws into the focuser, which allows the 2" eyepiece holder to be clamped in, and I have a 1.25" adapter that can clamp into that. Should have taken pics really, will add these when I get home from work.

As I understand it, I need an adapter to screw the camera to the focuser, bypassing the first ring, the 2" eyepiece holder and the 1.25" eyepiece holder.

Is that right?

Any info appreciated.

[Stephen]

First up the 2" part should not rotate, you need to tighten the grub screws.

Secondly, assuming you have the standard focuser that has a t-thread under the 1.25" adaptor (unscrews off.)

A t-ring (here First Light Optics - T Rings) will get you closer to the secondary, but it's not a guarentee that you will be able to focus.

If your tube white or blue? How old is it?

If it's older, you will still need to either move the primary up the tube or get a low profile focuser or bodge it on somehow even with the t-ring I'm afraid.

[Cornelius Varley]

There should be a T thread on the end of the focuser draw tube.

Peter

[Dodge]

Thanks guys, it's a black / white tube version. I think I'm confused with what a T-ring is - I assumed it was the camera fitting, but now I think it may be the thread type inside the focus tube?

Here are some more pics - this one is the stock arrangement with the 2" eyepiece adapter:

This one is with the eyepiece holder removed - no threads there:

And this is the inside of the focus tube - and a thread! Is ths the t-thread? In which case I believe I may need a t-thread to EOS adapter.

Much appreciated folks!

[MikeWilson]

The 2" tube part rotates, and looks like it can be removed.

That thing looks like an EOS adaptor with T-thread and a T-thread to 2" nosepiece.

It shouldn't rotate. Tighten that thread up

(The thread that you see in your above picture - whatever it is, it isn't a t-thread).

[Dodge]

That thing looks like an EOS adaptor with T-thread and a T-thread to 2" nosepiece.

It shouldn't rotate. Tighten that thread up

(The thread that you see in your above picture - whatever it is, it isn't a t-thread).

Here's is separated - there's a thread inside the EOS attachment, the 2" part has two threads - the thread at the top in the pic is the same as the EOS, then there's a slightly narrower part which is also threaded.

They are held together with three tiny grub screws - they're not screwed together.

[MikeWilson]

Here's is separated - there's a thread inside the EOS attachment, the 2" part has two threads - the thread at the top in the pic is the same as the EOS, then there's a slightly narrower part which is also threaded.

They are held together with three tiny grub screws - they're not screwed together.

Where those two pieces are held together with three tiny grub screws I expected to see a t-thread. It's most common to have an EOS adapter with a female t-thread on it.

Then you can attach whatever extension rings, tubes or coma corrector accessories via their male t-threads, not grub screws.

[Stephen]

There's a bigger problem here, the OP has not located the T-thread on the scope yet

Can you post a picture of the 1.25" attachment please?

[MikeWilson]

Unless I'm misunderstanding something (which is more than possible, I assure you ;P), the OP doesn't need any t-threads on the scope. He's got a 2" focuser, so any 2" nosepiece will slot in there and get fixed into place by the two screws.

One of these:

First Light Optics - T Rings

And then a T-thread-to-2"-adapter is what I used to start, then I changed out the 2" adapter for a Baader MPCC:

First Light Optics - Baader MPCC Coma Corrector

[MikeWilson]

The 1100D shouldn't be that far off focus from any of the other EOS cameras, should it?

I wonder if there's not some other reason as to why the OP cannot get focus using the standard focuser on a 200P...

[Stephen]

Unless I'm misunderstanding something (which is more than possible, I assure you ;P), the OP doesn't need any t-threads on the scope. He's got a 2" focuser, so any 2" nosepiece will slot in there and get fixed into place by the two screws.

I was working from the original post where the OP said they cannot attain focus with the 2" nosepiece

[Stephen]

The 1100D shouldn't be that far off focus from any of the other EOS cameras, should it?

I wonder if there's not some other reason as to why the OP cannot get focus using the standard focuser on a 200P...

Hmm you may be on to something there. The old 200P won't focus, but the newer ones should!

The newer scopes (black) don't need that 2" EP adaptor in there do they? I think 2" fitments go straight in now ...

[Dodge]

There's a bigger problem here, the OP has not located the T-thread on the scope yet

Can you post a picture of the 1.25" attachment please?

It's a bigger problem than that, I'm still not convince I know what a T-thread is!

Anyway, here's the 1.25" eyepiece adapter separated:

[Cornelius Varley]

The adapter on the right of the picture should have a threaded portion around the top of it. The T adapter should screw onto it.

Peter

[Black Knight]

The adapter on the right of the picture should have a threaded portion around the top of it. The T adapter should screw onto it.

Peter

Yep, that's right. Just the T-ring and not the nosepiece as well.

[Dodge]

The adapter on the right of the picture should have a threaded portion around the top of it. The T adapter should screw onto it.

Peter

Yep, that's right. Just the T-ring and not the nosepiece as well.

Ok - the 1.25" adapter collar screws into the main part, and there is a thread on the outside of the main part - that's the t-thread right?

If that's the case - my EOS adapter is just for inserting into a 2" eyepiece holder, and I need an EOS to t-thread adapter to attach to the bottom part of the 1.25" adapter like the one posted earlier:

First Light Optics - T Rings

The 2" eyepiece adapter is quite long, if the adapter is fairly short I've got a fighting chance of getting focus I reckon.

You guys are absolute gents - I appreciate all your help.

[Black Knight]

First Light Optics - T Rings

That's the beastie. Just screws onto the 1.25" eyepiece adapter (with the barrel removed). This is how I used to connect my DSLR to my old 200P. The newer 200Ps allow you to insert a 2" T adapter directly into the focuser (without the extra 2" adapter), which is not possible on the older models.

[Stephen]

Finally we're there

If you still can't get enough focus like this, I'm afraid we're looking at more drastic means

[Dodge]

Finally we're there

If you still can't get enough focus like this, I'm afraid we're looking at more drastic means

Yep, thanks gents - it's added to my FLO shopping list. I'm not in a mad panic and i didn't buy the scope for astrophotography anyway (what I've already got works a treat in my Tal) so I won't be doing anything serious to the focuser / mirror.

I've got a lovely 28mm SW Nirvana in my hand I'm more desperate to try, but it's blowing a hoolie outside.

[malc-c]

I might of jumped in too late - hope this helps

[Stephen]

Great picture malc, would of made things so much easier earlier LOL

[Dodge]

I might of jumped in too late - hope this helps

Cheers Malc - just spotted your reply to my post in the other thread too!

Anyway - all's happy on the t-ring front, I'll order one up soon enough. Now if you can just sort out the weather....

[malc-c]

LOL - sorry guys... better late than never though

[RikM]

I don't think this is right. The 2" EOS adaptor in the original post goes straight into the 2" collar on the draw tube. You don't need the 2" eyepiece adaptor in between.

Forgive the shoddy camera work, but it should go together like this:

[malc-c]

Great picture malc, would of made things so much easier earlier LOL

LOL - sorry guys... better late than never though