Took the Bait: Bresser 208mm Newtonian

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mikemarotta
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Took the Bait: Bresser 208mm Newtonian

#1

Post by mikemarotta »


I received a marketing email from Explore Scientific on recent returns for sale. The price for this Bresser branded Newtonian was low enough that I was interested. The specifications said 22-lbs (10 kg) and I can lift that, carry it, and set it down comfortably. At 208mm (8-3/16 inches) it will gather a lot of light. The only potential problem is the collimation, which has always been difficult for me in the past.
advert image 1 .jpg
They say:
Comes complete with Aluminum Tube; No Tool Secondary Collimation; Finder Scope Base; 2-inch Crayford Focuser with 1.25-inch Adapter with Integrated T-thread to attach optional T-thread Ring; Cradle Rings with Slotted Handle (can be an attachment point for piggy-back cameras; and Vixen-Style Dovetail; Front and Focuser Dust Caps; Weighs 22 lbs.

The package includes a padded, top-loading Soft Carrying Case to protect the optical tube assembly while transporting the instrument to your backyard or your favorite dark sky site for an imaging run or deep sky visual observations.

Certified Pre-Owned items carry the standard Limited One-Year Warranty on mechanical and optical systems; however, because these items are pre-owned, they DO NOT carry a cosmetic warranty.

Item Number CPO-BR-N20839
Focal Length 812mm
Focal Ratio f/3.9
Eyepieces Accepts 1.25" and 2" Eyepieces
Weight 22lbs
Parabolic primary mirror 208mm Diameter; Aluminum with SiO3 Overcoat; Special low expansion H-PZ33
Material Secondary mirror 71.45mm Minor Axis (34% Obstruction); 97% Reflective EMD Coatings; Low Thermal Expansion Borosilicate Glass
The obstruction of the secondary reduces the effective diameter of the primary to 137mm clear view, still measurably larger (19%) than my AT 115 APO which is still in its carrying case and has never been outdoors.
---------------------------------------
Michael E. Marotta
Astro-Tech 115 mm APO Refractor Explore Scientific 102 mm f/6.47 Refractor Explore Scientific 102 mm f/9.8 Refractor Bresser 8-inch Newtonian Reflector Plössls from 40 to 6 mm Nagler Series-1 7mm. nonMeade 14 mm. Mounts: Celestron AVX, Explore Twilight I Alt-Az, Explore EXOS German Equatorial
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Re: Took the Bait: Bresser 208mm Newtonian

#2

Post by Thefatkitty »


Nice deal Mike! I'd love one of those for sure. At f/3.9, it will probably require more frequent collimation than say an f/8, but in that scope it shouldn't be too difficult. At least you won't need two people to do it :D

Hopefully you'll get it and your AT 115 APO out soon!!

All the best,
Mark

"The Hankmeister" Celestron 8SE, orange tube Vixen made C80, CG4 & AZ-EQ5 mounts.
Too much Towa glass/mirrors.

H/A - PST stage 2 mod with a Baader 90mm ERF on a Celestron XLT 102 (thanks Mike!)
Ca-K - W/O 61mm, Antares 1.6 barlow, Baader 3.8 OD and Ca-K filters with a ZWO ASI174mm.
W/L - C80-HD with Baader 5.0 & 3.8 Solar film, Solar Continuum 7.5nm and UV/IR filters with a Canon EOS 550D.

Oh yeah, and Solar Cycle 25 :D
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Re: Took the Bait: Bresser 208mm Newtonian

#3

Post by notFritzArgelander »


mikemarotta wrote: Tue Jul 13, 2021 8:43 pm I received a marketing email from Explore Scientific on recent returns for sale. The price for this Bresser branded Newtonian was low enough that I was interested. The specifications said 22-lbs (10 kg) and I can lift that, carry it, and set it down comfortably. At 208mm (8-3/16 inches) it will gather a lot of light. The only potential problem is the collimation, which has always been difficult for me in the past.
Image

They say:
Comes complete with Aluminum Tube; No Tool Secondary Collimation; Finder Scope Base; 2-inch Crayford Focuser with 1.25-inch Adapter with Integrated T-thread to attach optional T-thread Ring; Cradle Rings with Slotted Handle (can be an attachment point for piggy-back cameras; and Vixen-Style Dovetail; Front and Focuser Dust Caps; Weighs 22 lbs.

The package includes a padded, top-loading Soft Carrying Case to protect the optical tube assembly while transporting the instrument to your backyard or your favorite dark sky site for an imaging run or deep sky visual observations.

Certified Pre-Owned items carry the standard Limited One-Year Warranty on mechanical and optical systems; however, because these items are pre-owned, they DO NOT carry a cosmetic warranty.

Item Number CPO-BR-N20839
Focal Length 812mm
Focal Ratio f/3.9
Eyepieces Accepts 1.25" and 2" Eyepieces
Weight 22lbs
Parabolic primary mirror 208mm Diameter; Aluminum with SiO3 Overcoat; Special low expansion H-PZ33
Material Secondary mirror 71.45mm Minor Axis (34% Obstruction); 97% Reflective EMD Coatings; Low Thermal Expansion Borosilicate Glass
The obstruction of the secondary reduces the effective diameter of the primary to 137mm clear view, still measurably larger (19%) than my AT 115 APO which is still in its carrying case and has never been outdoors.
Congratulations on your purchase!

However I'd like to point out that your estimate of only 137mm of clear view may be unduly pessimistic. It depends on whether you are considering light gathering power versus contrast and resolution effects.

For contrast and resolution simply subtracting the secondary diameter from the primary diameter is a fair rough estimate, though still a little pessimistic. It will have a sightly better resolution on double stars than a 137mm perfect apochromat and a bit better planetary contrast if in perfect collimation. That underlined bit depends on point spread function analysis and is perhaps more information than needed.

Where the 137mm equivalent estimate goes seriously wrong is on light gathering. That goes as the unobstructed area, not linear dimension. You only have a 12% area loss and so the light collection is equivalent to a 195mm unobstructed perfect apochromat.
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
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Re: Took the Bait: Bresser 208mm Newtonian

#4

Post by helicon »


Let us know when you receive it Mike!
-Michael
Refractors: ES AR152 f/6.5 Achromat on Twilight II, Celestron 102mm XLT f/9.8 on Celestron Heavy Duty Alt Az mount, KOWA 90mm spotting scope
Binoculars: Celestron SkyMaster 15x70, Bushnell 10x50
Eyepieces: Various, GSO Superview, 9mm Plossl, Celestron 25mm Plossl
Camera: ZWO ASI 120
Naked Eye: Two Eyeballs
Latitude: 48.7229° N
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Re: Took the Bait: Bresser 208mm Newtonian

#5

Post by The Happy Parrot »


Nice find! Looking forward to your first impressions.
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Re: Took the Bait: Bresser 208mm Newtonian

#6

Post by Ylem »


Nice 👍
That should be a fine performer!
Clear Skies,
-Jeff :telescopewink:


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Re: Took the Bait: Bresser 208mm Newtonian

#7

Post by Bigzmey »


Congrats on the new toy Mike! As nFA already indicated, a proper way to account for the secondary obstruction is to go by area not by diameter. Your 8" newt will gather ~2.9x more light than 115mm refractor and will reach far far deeper on DSOs.

There is no way it will ride on ES Twilight 1 mount though. :) What mount you will be using?
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: Took the Bait: Bresser 208mm Newtonian

#8

Post by JayTee »


I saw that same ad this morning. Good thing I already have an 8" Newt!

Cheers
∞ Primary Scopes: #1: Celestron CPC1100 #2: 8" f/7.5 Dob #3: CR150HD f/8 6" frac
∞ AP Scopes: #1: TPO 6" f/9 RC #2: ES 102 f/7 APO #3: ES 80mm f/6 APO
∞ G&G Scopes: #1: Meade 102mm f/7.8 #2: Bresser 102mm f/4.5
∞ Guide Scopes: 70 & 80mm fracs -- The El Cheapo Bros.
∞ Mounts: iOptron CEM70AG, SW EQ6, Celestron AVX, SLT & GT (Alt-Az), Meade DS2000
∞ Cameras: #1: ZWO ASI294MC Pro #2: 662MC #3: 120MC, Canon T3i, Orion SSAG, WYZE Cam3
∞ Binos: 10X50,11X70,15X70, 25X100
∞ EPs: ES 2": 21mm 100° & 30mm 82° Pentax XW: 7, 10, 14, & 20mm 70°

Searching the skies since 1966. "I never met a scope I didn't want to keep."

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Re: Took the Bait: Bresser 208mm Newtonian

#9

Post by notFritzArgelander »


Bigzmey wrote: Tue Jul 13, 2021 11:47 pm Congrats on the new toy Mike! As nFA already indicated, a proper way to account for the secondary obstruction is to go by area not by diameter. Your 8" newt will gather ~2.9x more light than 115mm refractor and will reach far far deeper on DSOs.

There is no way it will ride on ES Twilight 1 mount though. :) What mount you will be using?
Plus it will resolve globular cluster stars.
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
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Re: Took the Bait: Bresser 208mm Newtonian

#10

Post by mikemarotta »


Well... I got a window of clear skies from 2100 to 2230. All of the stars were smears, even at the center. So, I did not have it collimated. That being so...

Collimation is easy with "no tools" nuts on the screws. I just do not know what it is supposed to look like when it is done. I have never done it correctly and after five years gave a Newtonian telescope to the Goodwill rather than fight with it any more. Another potential advantage here is the shorter tube: about 36 inches (900mm) front to back. So, as noted above by TheFatKitty, I can reach it while I work at the fine "star collimation" after setting the secondary mirror.

The primry mirror has a little black ring at the center. I could see that with the low magnification 32mm, though it went away if I viewed off-center.

At 22 lbs (10 kg), the telescope is easy to lift, carry, set, and control. I can hold it in place on the dovetail with one hand while I run down the screws to clamp it in. It has a nicely formed hand grip opposite the Vixen bar.

The finder slot was compatible with the finder from another telescope. I got it lined up on the Moon easily and then targeted Zubenelgenubi with no problem. At 47X (17 mm ocular, no Barlow) the pair was clear and nicely separated, though not the little circles I have come to expect.

At 22 lbs the Bresser 208mm Newtonian is too much weight for the Explore Twilight I Mount which is rated for 17 lbs. The telescope went down great, coming up in altitude was not possible. So, it needs a new mount.

And all things considered, I am going to wait for a computerized "go to" finder mount. It was said here on TSS I believe but seems to be common wisdom that after many years of learning the sky at my age what I really want is to view deep space objects, not hunt for them. It's like the guy who buys a muscle car with automatic transmission: I know how to shift gears, I just don't need to do it anymore.

So, this is going back into the shipping container for a few months while I wait for the right mount, a collimation eyepiece, and a new finder. (Right now, I took on a great project that pays half of what I was getting in April.)

Finally, as for collimation, I borrowed Harold Richard Suiter's Star Testing Astronomical Telescopes: A Manual for Optical Evaluation and Adjustment (Willmann-Bell, 1994) from my local library. It is a detailed procedure manual for owners of reflector telecopes. AbeBooks has several right now and priced right for someone who makes twice what I do. This is going to have to be a project requiring some dedication and attention. I am not a mechanical person. Long ago, I wrote a tear-down and rebuild manual for a six-axis robot. The six-week assignment only took two years, but I learned alot along the way.
---------------------------------------
Michael E. Marotta
Astro-Tech 115 mm APO Refractor Explore Scientific 102 mm f/6.47 Refractor Explore Scientific 102 mm f/9.8 Refractor Bresser 8-inch Newtonian Reflector Plössls from 40 to 6 mm Nagler Series-1 7mm. nonMeade 14 mm. Mounts: Celestron AVX, Explore Twilight I Alt-Az, Explore EXOS German Equatorial
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Re: Took the Bait: Bresser 208mm Newtonian

#11

Post by JayTee »


Hi Mike,

Don't forget to reference the mount payloads list in this post as you begin your research for a new mount for your new newt.
viewtopic.php?f=54&t=1041

Cheers
∞ Primary Scopes: #1: Celestron CPC1100 #2: 8" f/7.5 Dob #3: CR150HD f/8 6" frac
∞ AP Scopes: #1: TPO 6" f/9 RC #2: ES 102 f/7 APO #3: ES 80mm f/6 APO
∞ G&G Scopes: #1: Meade 102mm f/7.8 #2: Bresser 102mm f/4.5
∞ Guide Scopes: 70 & 80mm fracs -- The El Cheapo Bros.
∞ Mounts: iOptron CEM70AG, SW EQ6, Celestron AVX, SLT & GT (Alt-Az), Meade DS2000
∞ Cameras: #1: ZWO ASI294MC Pro #2: 662MC #3: 120MC, Canon T3i, Orion SSAG, WYZE Cam3
∞ Binos: 10X50,11X70,15X70, 25X100
∞ EPs: ES 2": 21mm 100° & 30mm 82° Pentax XW: 7, 10, 14, & 20mm 70°

Searching the skies since 1966. "I never met a scope I didn't want to keep."

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Re: Took the Bait: Bresser 208mm Newtonian

#12

Post by Ylem »


Sounds sweet Mike.
Nothing like 8" to bust those clusters with :)
Clear Skies,
-Jeff :telescopewink:


Member; ASTRA-NJ



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Re: Took the Bait: Bresser 208mm Newtonian

#13

Post by mikemarotta »


JayTee wrote: Fri Jul 16, 2021 6:45 pm Don't forget to reference the mount payloads list in this post as you begin your research for a new mount for your new newt. viewtopic.php?f=54&t=1041
I thanked you in the other thread, but thanks, again!

Mike M.
---------------------------------------
Michael E. Marotta
Astro-Tech 115 mm APO Refractor Explore Scientific 102 mm f/6.47 Refractor Explore Scientific 102 mm f/9.8 Refractor Bresser 8-inch Newtonian Reflector Plössls from 40 to 6 mm Nagler Series-1 7mm. nonMeade 14 mm. Mounts: Celestron AVX, Explore Twilight I Alt-Az, Explore EXOS German Equatorial
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Re: Took the Bait: Bresser 208mm Newtonian

#14

Post by j21blackjack »


It's been a few months since the last post in this thread. I just received my 208 last week. How has yours been? How's the collimation process on it?
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