The 64,000 dollar Question ?

[Frankskywatcher]

Ok here goes !
I’ve always been afraid to ask this question but it’s been bugging me.
Since I got the AD 10” I have never had to use the 35mm extension tube, nothing focuses in it and all my lens focus fine without it, so why do they give you one what am I missing here ?

[Lady Fraktor]

Not all eyepiece designs focus at the same general point.
The Speers-Waler style were famous for running out of in focus when used with newtonian telescopes.
Set it aside if you do not need it, though you may in the future.

[KingNothing13]

I have no idea what I did wrong when I pulled my mirror out in my AD10 the first time I cleaned it (it had a leaf stuck to it ), but since then I have had to use the 35mm extension tube to get to focus.

At this point, to me, it is just one of those things that was annoying at first, but now it just is.

[Unitron48]

Don't own an Apertura, but several members of our club own AD8's. They routinely use the extension for different EP's.

Davew

[helicon]

I haven't had to use it yet on my Z10. Not exactly sure why

[Makuser]

Hi all. I had a Cave Astrola 10" Newtonian when we lived in Illinois shown here with my eldest son (who is now 47):

It had a rack and pinion 1.25" eyepiece focuser and there was one eyepiece, due to it's long focal length, that gave me focusing trouble (a Criterion 50mm Hastings):

However, with the very long barrel it had, instead of seating it all the way down in the eyepiece holder, I would just pull it out part way and then secure it. Worked out fine.
I don't have this problem with my Orion XT12 Dobsonian here in Florida, as it has the more modern 2 speed Crayford 2"/1.25" eyepiece focuser with a much longer focus travel:

I don't know if any of this will help you but the partly pulling out a long focal length eyepiece in the holder and securing is a trick that a lot of amateurs use.

[Richard]

Its to use 2 inch eyepieces that cant do a 1.25 bit off a waste if one does not have a 2 inch focuser a 2 inch eyepiece needs generally more

[JayTee]

Just thinking out loud here, if a DSLR can be brought to focus with the focuser in the near all the way down position then you would need, for some eyepieces, that extension to bring them to focus because the difference between the camera focal point and the EP focal point is sometimes very large.

[Frankskywatcher]

Not all eyepiece designs focus at the same general point.
The Speers-Waler style were famous for running out of in focus when used with newtonian telescopes.
Set it aside if you do not need it, though you may in the future.

Thank you for saying that. I saw on another forum that is just all DOB telescopes no refractors and a guy was asking this exact question but nobody really answered him and then I got to looking at mine and I’m thinking “I’ve never used this thing I’ve never been able to focus anything in it “so thank you for answering me

[Frankskywatcher]

I have no idea what I did wrong when I pulled my mirror out in my AD10 the first time I cleaned it (it had a leaf stuck to it ), but since then I have had to use the 35mm extension tube to get to focus.

At this point, to me, it is just one of those things that was annoying at first, but now it just is.

Now that’s interesting so you’re saying that somehow the focal length changed and in doing so you then then needed that 35 MM extension tube am I getting what you’re saying correctly that’s very interesting thank you

[Frankskywatcher]

Don't own an Apertura, but several members of our club own AD8's. They routinely use the extension for different EP's.

Davew

I think you’re onto something there Dave,it might just be with the three EP’s that I have that the focal length is ok so I haven’t had to use the extension tube as of yet .
I’ve only got the two that came with it and Mac user gave me a wide lens EP but those are the only three I own.

[Frankskywatcher]

I haven't had to use it yet on my Z10. Not exactly sure why

There you go see that’s the whole thing, I haven’t had to use mine either and I don’t know why ?
Cannot seem to get a definitive answer on why they supply it when the two EP that they give you with the telescope preform and function perfectly without that extended length, that’s why I said the $64,000 question lol

[Frankskywatcher]

Hi all. I had a Cave Astrola 10" Newtonian when we lived in Illinois shown here with my eldest son (who is now 47):
Cave 10.jpg
It had a rack and pinion 1.25" eyepiece focuser and there was one eyepiece, due to it's long focal length, that gave me focusing trouble (a Criterion 50mm Hastings):
50mm Hastings A.JPG
50mm Hastings B.JPG
However, with the very long barrel it had, instead of seating it all the way down in the eyepiece holder, I would just pull it out part way and then secure it. Worked out fine.
I don't have this problem with my Orion XT12 Dobsonian here in Florida, as it has the more modern 2 speed Crayford 2"/1.25" eyepiece focuser with a much longer focus travel:
Bertha.jpg
I don't know if any of this will help you but the partly pulling out a long focal length eyepiece in the holder and securing is a trick that a lot of amateurs use.

Hello my friend,I was thinking of you just last night when using the eyepiece you gave me as we had really good clear conditions here.
I’m thinking more along the lines of what you suggest,that is I just haven’t run across an EP yet that needed more of the focal length.
You know it’s funny when I changed the focuser on that little four-inch scope the one that someone gave me that had the broken rack and pinion on the focuser knobs that was a .97 and I put a 1,1/2 focuser on it .
Now with any eyepiece in that focuser at all it’s almost all the way out but it works lol

[Frankskywatcher]

Its to use 2 inch eyepieces that cant do a 1.25 bit off a waste if one does not have a 2 inch focuser a 2 inch eyepiece needs generally more

Now you really got me thinking because my 10 inch A.D. apertura is a 2 inch focus or what’s an adapter for inch and a half the 2 inch eyepiece that came with it is a 30 mm wide field fully multicoated and I have not had to use the extended tube with that two winch EP it just goes right into the telescope so again I don’t really need the extender to focus my 2 inch EP that came with it, because it focuses just fine in the focus without the tube.

[Frankskywatcher]

Just thinking out loud here, if a DSLR can be brought to focus with the focuser in the near all the way down position then you would need, for some eyepieces, that extension to bring them to focus because the difference between the camera focal point and the EP focal point is sometimes very large.

OK I’m a little confused here as I don’t do Astro photography and I’m trying to follow what you’re saying. All I know is I’ve never had to use it I only have three pieces all of them work fine without it and I’m wondering why they send it with the telescope.

[Lady Fraktor]

As I said before, hang on to it as eventually you will find a eyepiece that will require it.

A different example of things packaged for whatever reason, when Celestron released their clone of the Vixen GP/ SP mount they even included the short Vixen dovetail plate that only really works with Vixen telescope tube rings. Everybody that bought a CG-5 got that plate though it was useless to 99% of the people that bought the mount.
Years later I bought a Vixen refractor and when it arrived it had no dovetail plate. After digging in the oddment box I found the Celestron plate and was out viewing with my new refractor