37 replies to this topic

[Procyon]

So you buy your first refractor. You're out on the field or backyard finally getting ready to test all your eyepieces that you've been comfortably using with your other type of scope all these years.

 

You insert a 40mm 70º and wonder why you can't achieve focus, thinking you need a few more mm of infocus, no big deal, try another one for now. You put in the 31.5mm 90º, perfect, with lots of infocus left. You step down to a 25mm 100º, same story as the 40mm, it needed a few more mm to reach focus.

 

You try a 20mm 100º, same story, next, 17mm 102º again same story, 12mm 92º this one works perfectly. A 9mm 101 and 5mm 110 work fine too. All 1.25" Pentax and Delos can't reach focus. The night pretty much ends up in a kind of frustrating way. Besides a great view of the Beehive.

 

Sure, I'm using a 2" Baader Clicklock Diagonal with 112mm of lightpath with an Orion Astroview Deluxe 600mm f/6 refractor, but how am I supposed to know what scope works with what eyepiece and diagonal?

 

Are there stats anywhere for knowing about which eyepieces will focus with which refractors? I read now in a few scattered posts that it has to do with focal points and planes and which eyepiece has them closer to the lens, but how does someone to know which eyepieces have them where? How much backfocus or total focus space does my scope even have?   I looked in the manual, garbage, nothing written. Do some refractors have a longer infocus travel mechanism? Am I lacking more infocus or outfocus for the 1.25"? I know all the 2" ones needed more infocus.

 

I'm not cutting up my scope tube thing neither buying a new 2" diagonal either. 

 

Do you guys know of any nice 2" eyepieces in the 15-24mm and 35-40mm range that would reach focus with this scope? And will a TSFLAT2 work with them?

 

PS> I tried all eyepieces with and without the TSFLAT2.

Edited by Procyon, 15 April 2025 - 07:12 PM.

[Mike W]

Alot of these companies are focused on A/P that needs alot of out focus, rather than making the A/P nuts buy extension tubes they make their tubes too long. You might be stuck with going to a 1.25" diagonal or:

 

Televue makes a 2-1.25" in-travel adapter.

 

https://www.televue...._page.asp?id=23

 

What scope? Does it have a focuser that rotates? Can you remove the rotator? We need more info.

Edited by Mike W, 15 April 2025 - 07:59 PM.

[Polyphemos]

…

What scope? Does it have a focuser that rotates? Can you remove the rotator? We need more info.

“Orion Astroview Deluxe 600mm f/6 refractor”, so I guess a 100 mm aperture scope which I can’t seem to find on the internet so far.

Edited by Polyphemos, 15 April 2025 - 08:18 PM.

[Mike W]

Orion Astroview Deluxe 600mm f/6 refractor

That's no help. How about a photo. If the tube is not threaded at the focuser I would cut it and re-drill the three screw holes.

Edited by Mike W, 15 April 2025 - 08:11 PM.

[Polyphemos]

That's no help. How about a photo. If the tube is not threaded at the focuser I would cut it and re-drill the three screw holes.

I agree, but that’s what we had to work with…

[CrazyPanda]

Refractors are supposed to have quite generous focusing affordance. They are supposed to work with the wide variety of light paths from 1.25" prisms to 2" mirrors, and they don't have the travel limitations that Newts do.

 

That refractor must be some kind of poorly designed outlier if it has trouble focusing with anything other than a native binoviewer in a diagonal.

 

You won't have much luck finding any kind of "focus compatibility" chart or information since this is usually not a problem.

Edited by CrazyPanda, 15 April 2025 - 08:43 PM.

[Procyon]

 

 

 

 

Edited by Procyon, 15 April 2025 - 09:27 PM.

[Lagrange]

Some manufacturers do list the available back focus distance for their scopes, but it seems that Orion didn't provide this detail for your scope. You could estimate it by measuring 600mm from the approximate centre of the lens, and then measuring the distance from that point to the end of the focuser drawtube when it's fully racked in.

 

With the problems you've had, it sounds like that distance isn't quite enough to accommodate the 112mm of the Baader diagonal plus the distance to the focal plane of those eyepieces that won't reach focus.

 

If you're able to change the eyepiece adapter attached to the focuser drawtube to a shorter one, this could buy you enough additional in-focus to solve your problem. If that isn't an option or it doesn't make enough of a difference to get your eyepieces to focus, your only options are to use a different diagonal (a prism has a shorter optical path length) or to shorten the telescope tube.

[Lagrange]

I've just seen the pics you posted.

 

Does the scope have a camera angle adjuster fitted? If it does then you should be able to remove it and attach the eyepiece holder directly to the focuser drawtube which would give you a significant amount of extra in-focus.

[Procyon]

I've just seen the pics you posted.

 

Does the scope have a camera angle adjuster fitted? If it does then you should be able to remove it and attach the eyepiece holder directly to the focuser drawtube which would give you a significant amount of extra in-focus.

Hey there, do you mean any of this stuff? 

 

I added a manual on the next post, forgot Orion closed down.. 

 

 

 

 

 

Edited by Procyon, 15 April 2025 - 09:19 PM.

[Procyon]

Here's the manual.

 

 Orion Deluxe 100mm f6 .pdf   146.15KB   15 downloads

[Lagrange]

The bit that looks like a camera angle adjuster is the black and chrome part with the thumb screw attached that's nearest the body of the focuser in the pics of the entire scope.

 

These usually work by loosening the thumb screw which then lets you rotate the adjuster along with any camera / diagonal / eyepiece attached to it, then you tighten the screw to lock it into place in the new position. 

 

They're useful things to have but they do take up some of the available back focus of a telescope, so having one installed may cause problems reaching focus with some diagonals and eyepieces.

[Lagrange]

Here's the manual.

 

Orion Deluxe 100mm f6 .pdf

 

Thanks. This manual shows that it does indeed have a camera angle adjuster (the black and sliver section on the focuser drawtube) but it doesn't say whether and how it can be removed.

 

Normally they just unscrew.

[Procyon]

Alot of these companies are focused on A/P that needs alot of out focus, rather than making the A/P nuts buy extension tubes they make their tubes too long. You might be stuck with going to a 1.25" diagonal or:

 

Televue makes a 2-1.25" in-travel adapter.

 

https://www.televue...._page.asp?id=23

 

What scope? Does it have a focuser that rotates? Can you remove the rotator? We need more info.

Yeah, it has a focuser that can rotate. 

[ris242]

remove the diagonal and place the eyepiece straight in.

 

looking at something like the moon that is bright.........hold a piece of paper behind the scope. move it closer and further away from the eyepiece to find the focal plane.

 

 

the other option if you have removed all the extra spacers and still can't reach focus...........does the clicklock come off the diagonal........if so, remove it and hold the eyepiece above the open end.

[Mike W]

Take a photo of just the back of the scope then a photo one at a time as you take each piece off. A photo of all the pieces laying there doesn't help.

[Procyon]

Is this a camera angle adjuster? If I unscrew the knob, I can rotate it and the diagonal. I tried twisting the whole part, but it won't budge. I see a small screw that can be twisted using an Allan key. Should I try removing it?

 

 

Attached Thumbnails

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Edited by Procyon, 15 April 2025 - 09:42 PM.

[Mike W]

Yes, that's the camera angle adjuster that you don't need. Any way you can remove it and still use the vision back or the piece that clamps on your diagonal? I looks like you loosen the allen screw that keeps it from unscrewing.

Edited by Mike W, 15 April 2025 - 09:42 PM.

[Procyon]

Yes, that's the camera angle adjuster that you don't need. Any way you can remove it and still use the vision back or the piece that clamps on your diagonal? I looks like you loosen the allen screw that keeps it from unscrewing.

OK I'll try and see if it loosens with an Allan key.

[Mike W]

OK I'll try and see if it loosens with an Allan key.

Loosen the allen screw then screw the whole camera adjuster off and replace it with the 2" visual back.

[Procyon]

Loosen the allen screw then screw the whole camera adjuster off and replace it with the 2" visual back.

Done. I see all this now. Hmmm which is the 2" visual back lol.

 

 

[Mike W]

Wait, you have to unscrew that silver part off the draw tube.

Edited by Mike W, 15 April 2025 - 09:56 PM.

[Procyon]

Is it this? But it seems stuck to the camera adjuster thingy. As if it's one big piece.

 

[Procyon]

What now you think?

 

 

 

Edited by Procyon, 15 April 2025 - 10:13 PM.

[Mike W]

No not the set screws the silver ring that's on the back of the scope that has an allen screw in it.