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Littleguy80

1.25” Diagonal Recommendations

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I’m having some issues reaching focus with my Baader Zoom and Baader VIP Barlow with my 2” Diagonal. The same combination works with my 1.25” Herschel wedge. I’ve decided to try a 1.25” diagonal for the shorter optical path. This also has the advantage of being a bit lighter when travelling. Would appreciate any recommendations on a good 1.25” diagonal. My 2” diagonal is a William Optics which seems very good. The scope is an Equinox 80.

I’ve also posted a wanted ad in the classifieds should anyone be selling something suitable. 

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Posted (edited)

There really isn’t a lot to choose between the various 1.25” dielectric diagonals. I’ve used the WO and the Skywatcher and really couldn’t tell the difference. 

This one is a good buy though and quartz as well. Their 2” quartz diagonal is very good so would expect the 1.25” to be good as well.

https://www.harrisontelescopes.co.uk/acatalog/revelation-quartz-dielectric-diagonal-1.25.html

Edit:

Unfortunately seems to be out of stock everywhere 😠

Edited by johninderby
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My two 1.25" diagonals are a Tele Vue Everbright 1.25" and the Baader T2 Zeiss prism with a Baader Click-Stop 1.25" adapter on the eyepiece end. Hard to find faults with these two, apart from the price.

I have owned a few other 1.25" diagonals including the William Optics and some clones of it. While they are well made and optically sound, they use a thick internal junction ring to hold the 1.25" eyepiece holder to the body of the diagonal and that vignettes the FoV of the wider field stop eyepieces.

The less pricey Revelation 1.25" dielectric did not have the above issue and performed pretty well too.

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Posted (edited)

The Skywatcher doesn’t use a junction ring and the eyepiece holder screws into the body of the diagonal and doesn’t protrude inside the body.

Edited by johninderby

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1 minute ago, johninderby said:

The Skywatcher doesn’t use a junction ring and the eyepiece holder screws into the body of the diagonal and doesn’t protrude inside the body.

I was not saying that it did John.

The WO and other similar looking diagonals do though.

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Posted (edited)

+1 for the TeleVue's.

I have two of these --->classifieds-277350-0-45691200-1526138566.jpg.b83040223452ae8be571b7a19eefa189.jpg...but will not sell one. No matter how much you try and bribe offer me! :evil62: They're that good in my opinion. :thumbsup:

Edited by Philip R
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15 minutes ago, Philip R said:

+1 for the TeleVue's.

I have two of these --->classifieds-277350-0-45691200-1526138566.jpg.b83040223452ae8be571b7a19eefa189.jpg...but will not sell one. No matter how much you try and bribe offer me! :evil62: They're that good in my opinion. :thumbsup:

Nice - made by Vixen for Tele Vue.

My Tele Vue Everbrite looks like this:

Image result for tele vue everbrite 1.25
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2 hours ago, Littleguy80 said:

a 1.25” diagonal for the shorter optical path

The Tak prism does this - shorten the path - rather well for me. Nice and light for travel as well.

The TeleVue Everbrite is a very nice mirror.

TS offers dielectric mirror diagonals by GSO, these are made to a very good spec and work very well:

https://www.teleskop-express.de/shop/product_info.php/info/p1771_TS-Optics-1-25--TS-Optics-1-25--Star-Diagonal-with-ring-clamb---99----1-12-Lambda.html

 

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Posted (edited)

How do you use your Baader VIP Barlow with your 2" diagonal? Do you use it in 1.25" mode? 

I don't have any focus issue with the VIP barlow. Mine only has 2" nosepiece, therefore there is no issue with hitting the diagonal mirror. It is used with my zoom and docter eyepieces which connect to the Barlow in T2 mode.

Spacers are added between the Barlow and the eyepiece.

In my opinion, the VIP barlow is an extraordinary piece of equipment.

1558906315833715206634115657825.thumb.jpg.16fad057d0726c1238b91cf6df78280f.jpg

15589064161507698928007411952052.thumb.jpg.83b0d9c79b2263fb6591b0d18b269829.jpg

15589064745724506547766940545376.thumb.jpg.1c7d7dd271ff021178e63d7019190a18.jpg

15589065479924336950741031992308.thumb.jpg.cd7711dc022a9aa7348611a283a77816.jpg

Edited by Piero
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6 minutes ago, Piero said:

How do you use your Baader VIP Barlow with your 2" diagonal? Do you use it in 1.25" mode? 

I don't have any focus issue with the VIP barlow. Mine only has 2" nosepiece, therefore there is no issue with hitting the diagonal mirror. It is used with my zoom and docter eyepieces which connect to the Barlow in T2 mode.

Spacers are added between the Barlow and the eyepiece.

In my opinion, the VIP barlow is an extraordinary piece of equipment.

1558906315833715206634115657825.thumb.jpg.16fad057d0726c1238b91cf6df78280f.jpg

15589064161507698928007411952052.thumb.jpg.83b0d9c79b2263fb6591b0d18b269829.jpg

15589064745724506547766940545376.thumb.jpg.1c7d7dd271ff021178e63d7019190a18.jpg

15589065479924336950741031992308.thumb.jpg.cd7711dc022a9aa7348611a283a77816.jpg

I haven't tried it with a 2" nose piece. The VIP didn't come with one. I bought it second hand so I'm not sure if that's normal or not. I do have the 2" nose piece from the zoom though that I could try. Will pop out and give that a go now. Thanks for the suggestion!

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Posted (edited)

Regarding 1.25" diagonals, I have a TV everbrite which works very well. Said this, if I didn't have one my current choice would be the T2 Baader Zeiss prism diagonal with 2" nosepiece. The latter will allow you to use your 2" filters directly.

There are many other valid options.

Edited by Piero
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1 minute ago, Littleguy80 said:

I haven't tried it with a 2" nose piece. The VIP didn't come with one. I bought it second hand so I'm not sure if that's normal or not. I do have the 2" nose piece from the zoom though that I could try. Will pop out and give that a go now. Thanks for the suggestion!

Sorry, I don't follow. 

The VIP is sold as: VIP lens mounted on a 1.25" nosepiece, 2 T2 spacers, a ring, and a 2-to-1.25" adapter.

The latter can be used as a 2" nosepiece. What I did was simply to detach the VIP glass from the 1.25" nosepiece and attach it to a Baader Tak ring, which was then screwed to the 2-to-1.25" adapter directly. The T2 spacers were screwed on top of the same adapter. If your zoom is made by Baader, it is more than likely that it can connect via T2. Therefore you can connect it to the VIP via the T2 ring as I showed you in the above photos.

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Posted (edited)
57 minutes ago, Piero said:

Sorry, I don't follow. 

The VIP is sold as: VIP lens mounted on a 1.25" nosepiece, 2 T2 spacers, a ring, and a 2-to-1.25" adapter.

The latter can be used as a 2" nosepiece. What I did was simply to detach the VIP glass from the 1.25" nosepiece and attach it to a Baader Tak ring, which was then screwed to the 2-to-1.25" adapter directly. The T2 spacers were screwed on top of the same adapter. If your zoom is made by Baader, it is more than likely that it can connect via T2. Therefore you can connect it to the VIP via the T2 ring as I showed you in the above photos.

I think it was actually me not following! Well I got it to focus but I'm not sure if I did it right. When screwed into the 2"-1.25" adapter the barlow element was effectively upside down compared to when it was in the 1.25" nose piece. This didn't seem right though. Was that what you meant?

088277B2-90D9-4488-BF54-B271F1D18B8D.thumb.jpeg.0ad7fe7ce402ae74bb732f0b6b07364e.jpeg

Edited by Littleguy80

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+1 for the Takahashi diagonal as a small, light, super short light path 1.25" diagonal.

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Posted (edited)

The Tak prism diagonal is very good. So is the Baader T2 prism (I have the non - Zeiss one). It has a 32mm aperture so less likely to vignette, and being prisms, both have a shorter light path than mirror diagonals.

The Baader T2 prism set is good value  at £95, and very flexible, and includes the excellent Baader focusing eyepiece holder on the eyepiece end and a 1.25" nosepiece on the scope end..

https://www.365astronomy.com/Baader-Prism-Diagonal-T-2-90-degree-32mm-Set.html

you can remove the latter to replace with a Baader 2"-T2 nosepiece if you wish😊.

Dave

Edited by F15Rules
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Posted (edited)

I also use the Baader Zeiss prism diagonal in my Tak FC100, but with a 2" nose piece. The short light path in conjunction with a direct attachment to the diagonal, of my binoviewers, gives me a very secure set up and the ability to use all my eyepiece pairs at native focus.

Edited by Saganite
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Posted (edited)
9 hours ago, Littleguy80 said:

I think it was actually me not following! Well I got it to focus but I'm not sure if I did it right. When screwed into the 2"-1.25" adapter the barlow element was effectively upside down compared to when it was in the 1.25" nose piece. This didn't seem right though. Was that what you meant?

088277B2-90D9-4488-BF54-B271F1D18B8D.thumb.jpeg.0ad7fe7ce402ae74bb732f0b6b07364e.jpeg

Hi,

To do what I did, you need to screw the VIP barlow into this adapter https://www.baader-planetarium.com/en/baader-tak-adapter-m43-x-0.75--t-2-(t-2-part-12).html (Baader: # 2458199). The Barlow will be mounted in the right direction. The Tak M43 side is not used, instead the other side which is T2, is attached to the 2-to-1.25" adapter.

Also, the ring fixed on a 15mm spacer at the bottom can be removed. The spacer should be attachable to the end of your zoom directly, I believe.

Note that with this configuration, the VIP barlow is essentially used in T2/2" mode. This is what I want because mine is used only with my bigger zoom and docter. It might not be what you want. Said this, the VIP is highly configurable. For instance, with another 2-to-1.25" adapter installed on top, you can use your 1.25" eyepieces too.

Edited by Piero
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1 hour ago, Saganite said:

I also use the Baader Zeiss prism diagonal in my Tak FC100, but with a 2" nose piece. The short light path in conjunction with a direct attachment to the diagonal, of my binoviewers, gives me a very secure set up and the ability to use all my eyepiece pairs at native focus.

Just a quick question as I don't want to change the topic of this thread. Do you have the f 7.4 or f 9 version? If the former, have you noticed any lateral chromatic aberration using the prism on this telescope? 

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Hi Piero,

Mine is the DC. I have not really noticed any Lateral Chromatic aberration, but I do not need an OCS in the system at all to reach focus, and if I recall correctly, the OCS  if attached to the binoviewer, ie after the diagonal  could make this possibility worse. The set up as I have it is really quite superb. I hope that helps.

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2 hours ago, Piero said:

Just a quick question as I don't want to change the topic of this thread. Do you have the f 7.4 or f 9 version? If the former, have you noticed any lateral chromatic aberration using the prism on this telescope? 

It's an interesting question. I'll have to try my Baader Zeiss T2 diagonal with my F/6.5 Vixen ED and see if I can see any added CA. I certainly don't notice any with my F/9 Tak FC100.

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My FS128 is between these two, at F8.1. It shows no CA relating to the Baader T2 prism😊.

Dave

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5 hours ago, F15Rules said:

My FS128 is between these two, at F8.1. It shows no CA relating to the Baader T2 prism😊.

Dave

I should also have added that I use the prism in my Vixen ED103s as well. This scope operates at F7.7, and shows no prism added CA either😀..

Dave

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It is a quite controversial topic, I think. Some very experienced observers report that prisms should not be used below F9 due to the increase in lateral chromatic aberration, whilst others use prism diagonals with faster telescopes and have a very positive opinion about them.

Interestingly, Televue sells only mirror diagonals for their medium fast refractors. On the other hand Takahashi sells a prism diagonal.

A question I would really like to know the answer (but this would likely derail this thread...) is whether the Tak-100 DF is slightly undercorrected. As far as I am aware a prism diagonal overcorrects an optical system. If so, a prism could actually improve the view of the Tak 100 doublet a little bit compared to mirror diagonals.

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Posted (edited)

It seems that some scopes work better with a prism and some with a mirror diagonal and for others it makes no difference so there is no hard and fast rule other than that for most scopes the longer the focal length the better a prism works.

Perhaps it’s that some brands like Tak have been designed for a prism and others for mirror diagonals. In the end it comes down to trying both in a scope and seeing which works better for you.

Edited by johninderby
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That's also my impression. 

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