Prism Shoot-Out

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Shorty Barlow
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Prism Shoot-Out

#1

Post by Shorty Barlow »


Last year I decided on a shoot-out with two conventional 1.25" prism diagonals: a Takahashi TAKSD1 and a Baader Planetarium T-2.

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The telescope used was an Orion 90mm StarMax Maksutov intriguingly shown with a William Optics diagonal in this old jpg lol.

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Baader Planetarium Prism Diagonal T-2/90deg and Takahashi TAKSD1

These two prism diagonals were also compared against a third which is a 1.25" Baader Zeiss Amici (also equipped with a helical focuser).

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Baader Zeiss Amici

The target was primarily a setting twilight Venus, although I also intended to view Saturn as it was in conjunction with Venus on the 11th of December 2019. I didn’t have much time before both planets were too low. I mainly used an 18mm Astro Hutech ortho', giving 69x. Venus was very bright and easily seen early on with a 25mm AH orthoscopic. For Venus I also employed a Baader Double Polarising filter.

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Venus/Saturn conjunction

The Tak’ was up first.

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Apparently these diagonals are supplied with all Takahashi scopes. It is lightweight in design and I have read reviews stating that the housing is plastic. I'm pretty sure that it isn't and it is a light metal alloy or possibly aluminium. I'm not so sure about the base plate, it is probably a form of hard plastic so I'm not sure how it would wear over time. Unlike the Baader diagonals there is no filter thread in the nosepiece. Some have complained about the Tak's plastic collet snagging undercuts. I haven’t had any real problems although it helps if you use smoothies and barrels with shallow undercuts or those with lower lip flares (GSO, Tele Vue). The TAKSD1 gave a bright, sharp image with little or no light scatter and easily revealed the Venusian phase. The conventional Baader was next, followed by the Amici. Apart from the mirror reversing I could tell no difference between the Tak’ and the Amici. There was no hint of the prism roof with the Zeiss Amici. The Baader Planetarium T-2 also gave a sharp image, although I thought it was fractionally darker.

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The amount was almost imperceptible though and may have been my imagination. As Saturn became more prominent I switched all three to that. The Baader T2 helical focuser certainly makes a difference for fine focusing. Again, I had no problems with inserting and extracting eyepieces from these helicals, bearing in mind they have three set screws. I've had a lot of experience with these particular focusers as I've used them on my Newtonians for years. With a 7.5mm spacer the Baader is 70g heavier but the difference compared to the Takahashi feels negligible.

Weights:

Baader Zeiss Amici (helical focuser, 7.5mm spacer), 270g
Baader T2 (helical focuser, 7.5mm spacer), 200g
Takahashi TAKSD1, 130g

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I can't choose a real winner. The Takahashi gave a bright, sharp image as did the Baader Zeiss Amici. The Baader 'bog-standard' wasn't really any different and had the advantage over the Tak' of having a helical focuser. The Takahashi and standard Baader diagonals are about the same price. The Baader Zeiss Amici's extra weight compared to the others was quite noticeable.
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Richard South Africa
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Re: Prism Shoot-Out

#2

Post by Richard »


Me personally I dont think a premium diagonal helps that much better to spend on good eyepieces , but if you have it all then perhaps yes, nice diagonals by the way (both)
Reflectors GSO 200 Dobs
Refractors None
SCT C5 on a SLT mount
Mak 150 Bosma on a EQ5
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Re: Prism Shoot-Out

#3

Post by Shorty Barlow »


Richard wrote: Thu Jan 30, 2020 4:06 pm Me personally I dont think a premium diagonal helps that much better to spend on good eyepieces , but if you have it all then perhaps yes, nice diagonals by the way (both)
Thanks. The Tak' and the T2 were both under £100 (Sterling) for me which I think is pretty reasonable and comparable to other diagonals for what you're getting. The Baader Zeiss was more expensive. I think that the Baader T2 is probably the best value. The helical can even be replaced with a twistlock or a more conventional eyepiece holder without a compression ring. I'd probably worry about the Tak' holding a heavy eyepiece.

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Shown here on a Baader Zeiss Amici.

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Re: Prism Shoot-Out

#4

Post by Shorty Barlow »


Oh yeah, the Tak' comes out of the box without any dustcaps.

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The one you see here is mine lol.
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Bigzmey United States of America
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Re: Prism Shoot-Out

#5

Post by Bigzmey »


You have 3 good quality prisms SB, I expect them to produce similarly good results.

One of my favorite targets for optics testing is Orion Nebula. You can test optics transmission on the faint portions, contrast on the details in the brighter areas, and sharpness, resolution and light scatter on the Trapezium stars.

I did a few tests like this comparing mid range dielectrics from Orion, ES, Celestron and GSO to the Baader Prism and BBHS silver. Later I did the comparison on the Moon and Jupiter. The difference was quite obvious. Mid range dielectrics had noticeably more light scatter degrading resolution and fine details at high powers. BBHS also show more fainter stuff in nebula and galaxies.

The colors were richer in Baader diagonals, and with them I was also able to resolve fainter stars.

So, your scope performance is as good as the weakest link in the optical train, which includes diagonal.
Scopes: Stellarvue: SV102ED; Celestron: 9.25" EdgeHD, 8" SCT, 150ST, Onyx 80ED; iOptron: Hankmeister 6" Mak; SW: 7" Mak; Meade: 80ST.
Mounts: SW: SkyTee2, AzGTi; iOptron: AZMP; ES: Twilight I; Bresser: EXOS2; UA: MicroStar.
Binos: APM: 100-90 APO; Canon: IS 15x50; Orion: Binoviewer, LG II 15x70, WV 10x50, Nikon: AE 16x50, 10x50, 8x40.
EPs: Pentax: XWs & XFs; TeleVue: Delites, Panoptic & Plossls; ES: 68, 62; Vixen: SLVs; Baader: BCOs, Aspherics, Mark IV.
Diagonals: Baader: BBHS mirror, Zeiss Spec T2 prism, Clicklock dielectric; TeleVue: Evebrite dielectric; AltairAstro: 2" prism.
Filters: Lumicon: DeepSky, UHC, OIII, H-beta; Baader: Moon & SkyGlow, Contrast Booster, UHC-S, 6-color set; Astronomik: UHC.

Observing: DSOs: 3106 (Completed: Messier, Herschel 1, 2, 3. In progress: H2,500: 2180, S110: 77). Doubles: 2382, Comets: 34, Asteroids: 255
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Re: Prism Shoot-Out

#6

Post by Shorty Barlow »


Thanks Bigz, I have quite a few 1.25" prism diagonals.

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The only mirror diagonals I have are 2" dielectrics.

Image

I tend to use them for rich field or faint nebulae. At the moment this Baader gets the most use predominantly because it's comparatively light and the clicklock holds the 19mm Luminos securely.
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Re: Prism Shoot-Out

#7

Post by Bigzmey »


Baader Clicklock is definitely a well executed dielectric. Mine is permanently attached to 2" filter wheel. I use it mainly for nebulae and open clusters.
Scopes: Stellarvue: SV102ED; Celestron: 9.25" EdgeHD, 8" SCT, 150ST, Onyx 80ED; iOptron: Hankmeister 6" Mak; SW: 7" Mak; Meade: 80ST.
Mounts: SW: SkyTee2, AzGTi; iOptron: AZMP; ES: Twilight I; Bresser: EXOS2; UA: MicroStar.
Binos: APM: 100-90 APO; Canon: IS 15x50; Orion: Binoviewer, LG II 15x70, WV 10x50, Nikon: AE 16x50, 10x50, 8x40.
EPs: Pentax: XWs & XFs; TeleVue: Delites, Panoptic & Plossls; ES: 68, 62; Vixen: SLVs; Baader: BCOs, Aspherics, Mark IV.
Diagonals: Baader: BBHS mirror, Zeiss Spec T2 prism, Clicklock dielectric; TeleVue: Evebrite dielectric; AltairAstro: 2" prism.
Filters: Lumicon: DeepSky, UHC, OIII, H-beta; Baader: Moon & SkyGlow, Contrast Booster, UHC-S, 6-color set; Astronomik: UHC.

Observing: DSOs: 3106 (Completed: Messier, Herschel 1, 2, 3. In progress: H2,500: 2180, S110: 77). Doubles: 2382, Comets: 34, Asteroids: 255
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Re: Prism Shoot-Out

#8

Post by Shorty Barlow »


A 2" filter wheel sounds big.

Image

The SW dielectric here was bundled with my ED80, it's pretty decent. I like the Altair but it's a tad heavy on lighter mounts even with carbon fibre sides.
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Re: Prism Shoot-Out

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Post by Bigzmey »


Well, diffusion nebulae come in all sizes. Capitalizing on 2" wide field EPs with 6" fast refractor makes perfect sense. For planetary nebula I use 1.25" wheel in 8" SCT.
Anza-trio.jpg
Scopes: Stellarvue: SV102ED; Celestron: 9.25" EdgeHD, 8" SCT, 150ST, Onyx 80ED; iOptron: Hankmeister 6" Mak; SW: 7" Mak; Meade: 80ST.
Mounts: SW: SkyTee2, AzGTi; iOptron: AZMP; ES: Twilight I; Bresser: EXOS2; UA: MicroStar.
Binos: APM: 100-90 APO; Canon: IS 15x50; Orion: Binoviewer, LG II 15x70, WV 10x50, Nikon: AE 16x50, 10x50, 8x40.
EPs: Pentax: XWs & XFs; TeleVue: Delites, Panoptic & Plossls; ES: 68, 62; Vixen: SLVs; Baader: BCOs, Aspherics, Mark IV.
Diagonals: Baader: BBHS mirror, Zeiss Spec T2 prism, Clicklock dielectric; TeleVue: Evebrite dielectric; AltairAstro: 2" prism.
Filters: Lumicon: DeepSky, UHC, OIII, H-beta; Baader: Moon & SkyGlow, Contrast Booster, UHC-S, 6-color set; Astronomik: UHC.

Observing: DSOs: 3106 (Completed: Messier, Herschel 1, 2, 3. In progress: H2,500: 2180, S110: 77). Doubles: 2382, Comets: 34, Asteroids: 255
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Re: Prism Shoot-Out

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Post by Shorty Barlow »


Bigzmey wrote: Thu Jan 30, 2020 11:11 pm Well, diffusion nebulae come in all sizes. Capitalizing on 2" wide field EPs with 6" fast refractor makes perfect sense. For planetary nebula I use 1.25" wheel in 8" SCT.

Anza-trio.jpg
An impressive triumvirate Bigz!

:telescopewink:

Speaking of filters; my 1.25" Lumicon Swan Band Comet Filter should be arriving any day now. I've only been waiting for three months ... :shock:
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Re: Prism Shoot-Out

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Post by Bigzmey »


Shorty Barlow wrote: Thu Jan 30, 2020 11:45 pm
Bigzmey wrote: Thu Jan 30, 2020 11:11 pm Well, diffusion nebulae come in all sizes. Capitalizing on 2" wide field EPs with 6" fast refractor makes perfect sense. For planetary nebula I use 1.25" wheel in 8" SCT.

Anza-trio.jpg
An impressive triumvirate Bigz!

:telescopewink:

Speaking of filters; my 1.25" Lumicon Swan Band Comet Filter should be arriving any day now. I've only been waiting for three months ... :shock:
Thanks! I like it. :D Since then I have upgraded 8" SCT to 9.25" EdgeHD SCT, can't wait to take it for a spin to the desert.
Scopes: Stellarvue: SV102ED; Celestron: 9.25" EdgeHD, 8" SCT, 150ST, Onyx 80ED; iOptron: Hankmeister 6" Mak; SW: 7" Mak; Meade: 80ST.
Mounts: SW: SkyTee2, AzGTi; iOptron: AZMP; ES: Twilight I; Bresser: EXOS2; UA: MicroStar.
Binos: APM: 100-90 APO; Canon: IS 15x50; Orion: Binoviewer, LG II 15x70, WV 10x50, Nikon: AE 16x50, 10x50, 8x40.
EPs: Pentax: XWs & XFs; TeleVue: Delites, Panoptic & Plossls; ES: 68, 62; Vixen: SLVs; Baader: BCOs, Aspherics, Mark IV.
Diagonals: Baader: BBHS mirror, Zeiss Spec T2 prism, Clicklock dielectric; TeleVue: Evebrite dielectric; AltairAstro: 2" prism.
Filters: Lumicon: DeepSky, UHC, OIII, H-beta; Baader: Moon & SkyGlow, Contrast Booster, UHC-S, 6-color set; Astronomik: UHC.

Observing: DSOs: 3106 (Completed: Messier, Herschel 1, 2, 3. In progress: H2,500: 2180, S110: 77). Doubles: 2382, Comets: 34, Asteroids: 255
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Re: Prism Shoot-Out

#12

Post by Shorty Barlow »


Bigzmey wrote: Fri Jan 31, 2020 12:42 am
Shorty Barlow wrote: Thu Jan 30, 2020 11:45 pm
Bigzmey wrote: Thu Jan 30, 2020 11:11 pm Well, diffusion nebulae come in all sizes. Capitalizing on 2" wide field EPs with 6" fast refractor makes perfect sense. For planetary nebula I use 1.25" wheel in 8" SCT.

Anza-trio.jpg
An impressive triumvirate Bigz!

:telescopewink:

Speaking of filters; my 1.25" Lumicon Swan Band Comet Filter should be arriving any day now. I've only been waiting for three months ... :shock:
Thanks! I like it. :D Since then I have upgraded 8" SCT to 9.25" EdgeHD SCT, can't wait to take it for a spin to the desert.
Sounds like a good spin plan.
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