1.25 to 2inch adapter

[Simon Dunsmore]

Hi, 

Quick question, I have a lovely William optics diagonal. I'm looking to buy a Skywatcher Skymax 127. The problem is that the diagonal is 2inch and I believe the draw tube is 1.25. 

Can I use something like this as an adapter as long as I stick with 1.25 eyepieces? I'm pretty certain if I use 2inch eyepieces I'll get some vignetting???

I'm also aware that I will need sufficient back travel to allow for focusing. Any wisdom on this would be appreciated. 

Cheers 

Simon 

[John]

Should there be a link to and adapter or something Simon ?

2 inch diagonals do have longer light paths than 1.25 inch ones but that should not pose a problem for the mak-cassegrain because they have a lot of of focus travel.

 

[johninderby]

Or you could just buy the WO SCT nosepiece for your diagonal.

https://www.firstlightoptics.com/adapters/william-optics-sct-adapter-for-2-diagonals.html

A few years ago Skywatcher changed the screw thread on the back of the scope to a standard SCT thread so you will have to check to see which thread is on the back of your mak. If it’s the old thread you will need an adapter.

https://www.firstlightoptics.com/adapters/lynxastro_makcas-sct_adptr.html

Edited June 19, 2020 by johninderby

[Simon Dunsmore]

8 hours ago, John said:

Should there be a link to and adapter or something Simon ?

2 inch diagonals do have longer light paths than 1.25 inch ones but that should not pose a problem for the mak-cassegrain because they have a lot of of focus travel.

 

Hi John, 

Yes, sorry the link is 

https://agenaastro.com/blue-fireball-1-25-2-eyepiece-adapter.html

I've been giving it some thought though, I'm a little worried about leverage on the draw tube. If I add the adapter, diagonal, barlow and eyepiece. I'm leaning towards keeping the 2" diagonal for my existing scope (skywatcher 130 pds and 72ED) and biting the bullet and buying an Altair 1.25 dialetric diagonal for the Mak. 

BTW, I have a 2. 5x GSO barlow on order, do you think that this will also suit the Mak? 

Cheers 

Simon 

[Cosmic Geoff]

The Mak should come with a 1.25" diagonal. But if you want to spend money on a replacement, that's up to you.

The Mak has a long focal ratio which renders a Barlow largely unnecessary.

[Louis D]

On 20/06/2020 at 01:06, Simon Dunsmore said:

Hi John, 

Yes, sorry the link is 

https://agenaastro.com/blue-fireball-1-25-2-eyepiece-adapter.html

I've been giving it some thought though, I'm a little worried about leverage on the draw tube. If I add the adapter, diagonal, barlow and eyepiece. I'm leaning towards keeping the 2" diagonal for my existing scope (skywatcher 130 pds and 72ED) and biting the bullet and buying an Altair 1.25 dialetric diagonal for the Mak.

No, don't get that adapter.  Get a proper 2" visual back and adapter as noted above.  You won't notice much if any vignetting, but bright objects will have an oval aberration on the opposite side as they pass the edge of the rear baffle.  I put the Mak to SCT Adapter linked above on mine and then put a standard SCT 2" visual back on that.  That way, I can use the same 2" diagonals in both my refractors and Maks.  If you already have the SCT threads on the back of your Mak, skip the adapter and proceed straight to the visual back.  You'll be able to expand your true field of view from 1 degree with a 32mm Plossl to 1.7 degrees with a widest field eyepiece such as a ES-68 40mm.

[wookie1965]

Would one of these work I have used them in a Frac diagonal. If it will dont buy one I will send you one free.

https://www.ebay.co.uk/i/132997336391?chn=ps&norover=1&mkevt=1&mkrid=710-134428-41853-0&mkcid=2&itemid=132997336391&targetid=910259638509&device=c&mktype=pla&googleloc=9046510&poi=&campaignid=10195651334&mkgroupid=107296273132&rlsatarget=pla-910259638509&abcId=1145985&merchantid=137674249&gclid=EAIaIQobChMIjJeatc2X6gIVi-3tCh3fkwg7EAQYAiABEgIy1fD_BwE

[Simon Dunsmore]

5 hours ago, wookie1965 said:

Would one of these work I have used them in a Frac diagonal. If it will dont buy one I will send you one free.

https://www.ebay.co.uk/i/132997336391?chn=ps&norover=1&mkevt=1&mkrid=710-134428-41853-0&mkcid=2&itemid=132997336391&targetid=910259638509&device=c&mktype=pla&googleloc=9046510&poi=&campaignid=10195651334&mkgroupid=107296273132&rlsatarget=pla-910259638509&abcId=1145985&merchantid=137674249&gclid=EAIaIQobChMIjJeatc2X6gIVi-3tCh3fkwg7EAQYAiABEgIy1fD_BwE

Hi, 

Thanks so much for your message and very kind offer. Looking at the picture, I'm not sure that there would be enough depth on the 2" part to hold the diagonal, but I could be wrong. 

Thanks again 

Simon 

[wookie1965]

2 minutes ago, Simon Dunsmore said:

Hi, 

Thanks so much for your message and very kind offer. Looking at the picture, I'm not sure that there would be enough depth on the 2" part to hold the diagonal, but I could be wrong. 

Thanks again 

Simon 

I used one on my Tal 100rs when it had a 1.25" diagonal only took it out when I bought a 2" diagonal.