1.25 diagonal Astro Physics quality

[25585]

My best 2 inch diagonal is an Astro Physics one. But I do not have a 1.25 inch of the same quality. 

What choices are there, use to be for short 500mm to 2000mm scopes, & in-between?

[Timebandit]

 

 

The Takahashi 1.25 prism diagonals are supposed to be very good for the money. I understand the diagonal body is not supposed to be of the most solid construction. But optically they are supposed to be very good. And best of all at around £89 new ,then you do not need a second mortgage.

I hope this helps☺

 

 

 

[John]

I've owned a couple of the 1.25" Tele Vue Everbrights and they were good. Very nicely machined from a single block of alloy like their 2" counterparts. Currently I have a couple of 1.25" diagonals, the Baader T2 Zeiss which I use in 1.25" mode most often (on the eyepiece side anyway) and a low cost Revelation Dielectric 1.25" that I use with my TV Ranger. That seems to perform well too, despite it's relatively low cost. I don't notice my 2" Astro Physics Maxbright being noticably better than either the Baader / Zeiss or even the Revelation, apart from in build quality over the latter, in all honesty

I've also owned a 1.25" William Optics dielectric in the past which was well made and performed fine but it has a thick collar at the bottom of the eyepiece tube which vignettes the FoV of the widest 1.25" eyepieces.

 

[Louis D]

1 hour ago, John said:

I've also owned a 1.25" William Optics dielectric in the past which was well made and performed fine but it has a thick collar at the bottom of the eyepiece tube which vignettes the FoV of the widest 1.25" eyepieces.

Hmmm.  I've got the same one but have never noticed any vignetting.  I'll have to take a look at it.  I rarely use widest field 1.25" eyepieces anyway.  I usually switch out the visual back and move to a 2" diagonal if I want widest field.  I mostly use the 1.25" diagonal for binoviewer usage to shorten the optical path to reach focus.

[John]

1 hour ago, Louis D said:

Hmmm.  I've got the same one but have never noticed any vignetting.  I'll have to take a look at it.  I rarely use widest field 1.25" eyepieces anyway.  I usually switch out the visual back and move to a 2" diagonal if I want widest field.  I mostly use the 1.25" diagonal for binoviewer usage to shorten the optical path to reach focus.

You can see the collar that I'm referring to in the image below. Otherwise the WO is a good diagonal. I tend to agree though that, when I want widefield, I use a 2" diagonal most of the time.

 

 

[25585]

Given that I use Baader Eudiascopic 35mm, TV 40mm & 32mm Plossls and Vixen LVW 22mm (65 deg) - would any of those TFOV be vignetted? All my other 1.25 are shorter FL with less TFOV than the Vixen. 

[John]

With the WO 1.25" diagonal I found that I lost the sharp edge of the FoV with eyepieces that had either the maximum or close to the maximum field stop diameter possible in the 1.25" barrel format. Apart from the Vixen LVW 22, the others you mention fall into that category. I think the LVW 22 might be OK because it's field stop is slightly smaller. I personally experienced this with the TV 32mm plossl and the 24mm Panoptic. It might not be a big deal - more an annoyance. The effect is a slightly narrower and fuzzy edge to the AFoV.

 

 

[Louis D]

On 17/05/2018 at 11:36, John said:

You can see the collar that I'm referring to in the image below. Otherwise the WO is a good diagonal. I tend to agree though that, when I want widefield, I use a 2" diagonal most of the time.

 

 

I finally got around to verifying that my WO diagonal does indeed have this inexplicably large lip in it as well.  I eyeballed it have about a 22mm clear aperture which means it will work with my Arcturus binoviewer without vignetting.  I guess I'll be on the lookout for a GSO 1.25" dielectric diagonal.

@JohnThanks for pointing this out to me.  I had never noticed it.

[25585]

I have a Tak prism due Tuesday, but am interested in an Amici prism as well. 

Given that @iPeace & @parallaxerr have had to return Baader prism diagonals, reported in their threads about such, I feel uncertain about buying a Baader prism. 

For mirror, I will avoid WO. A TV seems safe there.