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This morning I was doing some cleaning in the astro shed and I started thinking about the 115 - 150 mm gap I have in my refractors.
Of course when a person starts thinking other ideas arrive!
120 mm is a good size but only 5 mm larger than the 115 mm and a 140 mm is only 10 mm smaller than the 150 mm...
So a 125 - 130 mm would be a nice fit, but should it be longer than f/7 or shorter?
Permanent use with a set of binoviewers would be a interesting idea so removing about 100 mm from the tube would be required.
What do you think? Possible refractors to sacrifice, long/ short focal length?
Gabrielle See Far Sticks: Elita 103/1575, AOM FLT 105/1000, Bresser 127/1200 BV, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS 100/1000, Vixen SD115s/885 EQ: TAL MT-1, Vixen SXP, SXP2, AXJ, AXD Az/Alt: AYO Digi II, Stellarvue M2C, Argo Navis encoders on both Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102 Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Tak prism, TAL, Vixen Eyepieces: Antares to Zeiss (1000101) The only culture I have is from yogurt
I think it should be a focal length that covers any gaps you may have right now. So if you go from say 500mm to 1200mm there's a definite gap there that should be filled.
∞ 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 EQ6R, 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 ∞ AP Gear: ZWO EAF and mini EFW and the Optolong L-eXteme filter ∞ 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."
I had for a while ES 127mm APO triplet F7.5. It was a very nice scope, very capable optically and not too heavy to handle. It required 50mm or 100mm (don't remember exactly) extension tube to reach focus with EP and 2" mirror diagonal, so it might have enough back-focus for BV with 1.25" prism.
Having a midrange fraq might be a good idea. My 152 is sort of portable, my 102mm much better. Not much in between.
-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
helicon wrote: ↑Tue Apr 18, 2023 8:10 pm
Having a midrange fraq might be a good idea. My 152 is sort of portable, my 102mm much better. Not much in between.
120ST F5 (Orion, SW) is a nice form factor for grab and go. Very compact and lightweight with quite noticeable step up in light gathering from 102mm.
JayTee wrote: ↑Tue Apr 18, 2023 7:36 pm
I think it should be a focal length that covers any gaps you may have right now. So if you go from say 500mm to 1200mm there's a definite gap there that should be filled.
500 to 1200 mm is fairly covered, the gap would be between 1200 - 1575 mm.
Gabrielle See Far Sticks: Elita 103/1575, AOM FLT 105/1000, Bresser 127/1200 BV, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS 100/1000, Vixen SD115s/885 EQ: TAL MT-1, Vixen SXP, SXP2, AXJ, AXD Az/Alt: AYO Digi II, Stellarvue M2C, Argo Navis encoders on both Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102 Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Tak prism, TAL, Vixen Eyepieces: Antares to Zeiss (1000101) The only culture I have is from yogurt
Bigzmey wrote: ↑Tue Apr 18, 2023 7:56 pm
I had for a while ES 127mm APO triplet F7.5. It was a very nice scope, very capable optically and not too heavy to handle. It required 50mm or 100mm (don't remember exactly) extension tube to reach focus with EP and 2" mirror diagonal, so it might have enough back-focus for BV with 1.25" prism.
A interesting choice but even I would have to question my sanity of taking a saw to the tube of a € 2.400 refractor!
Gabrielle See Far Sticks: Elita 103/1575, AOM FLT 105/1000, Bresser 127/1200 BV, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS 100/1000, Vixen SD115s/885 EQ: TAL MT-1, Vixen SXP, SXP2, AXJ, AXD Az/Alt: AYO Digi II, Stellarvue M2C, Argo Navis encoders on both Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102 Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Tak prism, TAL, Vixen Eyepieces: Antares to Zeiss (1000101) The only culture I have is from yogurt
helicon wrote: ↑Tue Apr 18, 2023 8:10 pm
Having a midrange fraq might be a good idea. My 152 is sort of portable, my 102mm much better. Not much in between.
70 - 115 mm is covered with the gap between 115 - 150 mm
Portability is great now, before I would have to carry the 150 mm (13kg) up/ down 6 flights of stairs to use it.
Now I just take 3-4 steps out of the shed.
Gabrielle See Far Sticks: Elita 103/1575, AOM FLT 105/1000, Bresser 127/1200 BV, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS 100/1000, Vixen SD115s/885 EQ: TAL MT-1, Vixen SXP, SXP2, AXJ, AXD Az/Alt: AYO Digi II, Stellarvue M2C, Argo Navis encoders on both Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102 Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Tak prism, TAL, Vixen Eyepieces: Antares to Zeiss (1000101) The only culture I have is from yogurt
Bigzmey wrote: ↑Tue Apr 18, 2023 7:56 pm
I had for a while ES 127mm APO triplet F7.5. It was a very nice scope, very capable optically and not too heavy to handle. It required 50mm or 100mm (don't remember exactly) extension tube to reach focus with EP and 2" mirror diagonal, so it might have enough back-focus for BV with 1.25" prism.
A interesting choice but even I would have to question my sanity of taking a saw to the tube of a € 2.400 refractor!
You might not to since it comes with shorten tube already.
The problem is spending € 2.400 to discover if I had to or not
Gabrielle See Far Sticks: Elita 103/1575, AOM FLT 105/1000, Bresser 127/1200 BV, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS 100/1000, Vixen SD115s/885 EQ: TAL MT-1, Vixen SXP, SXP2, AXJ, AXD Az/Alt: AYO Digi II, Stellarvue M2C, Argo Navis encoders on both Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102 Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Tak prism, TAL, Vixen Eyepieces: Antares to Zeiss (1000101) The only culture I have is from yogurt
If you must saw, how about this guy then? I had it briefly. The optics is good. The hardware is your typical Synta, basic but serviceable. Basically, shrank-down version of the 150mm you have.
Bigzmey wrote: ↑Tue Apr 18, 2023 10:13 pm
If you must saw, how about this guy then? I had it briefly. The optics is good. The hardware is your typical Synta, basic but serviceable. Basically, shrank-down version of the 150mm you have.
This one appears to fit right in the aperture range (probably not the FL range) of which you speak. But I think it may be too expensive by the time it arrives to you.
JayTee wrote: ↑Tue Apr 18, 2023 11:51 pm
This one appears to fit right in the aperture range (probably not the FL range) of which you speak. But I think it may be too expensive by the time it arrives to you.
I imagine by the time shipping, import and DPH are added the cost would likely be minimum 30-35% more
Gabrielle See Far Sticks: Elita 103/1575, AOM FLT 105/1000, Bresser 127/1200 BV, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS 100/1000, Vixen SD115s/885 EQ: TAL MT-1, Vixen SXP, SXP2, AXJ, AXD Az/Alt: AYO Digi II, Stellarvue M2C, Argo Navis encoders on both Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102 Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Tak prism, TAL, Vixen Eyepieces: Antares to Zeiss (1000101) The only culture I have is from yogurt
19/04/22 Edit:
I emailed TS about my idea and #2 is out of consideration, I had forgotten the telescope has a sub-aperture corrector directly in front of the drawtube.
Gabrielle See Far Sticks: Elita 103/1575, AOM FLT 105/1000, Bresser 127/1200 BV, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS 100/1000, Vixen SD115s/885 EQ: TAL MT-1, Vixen SXP, SXP2, AXJ, AXD Az/Alt: AYO Digi II, Stellarvue M2C, Argo Navis encoders on both Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102 Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Tak prism, TAL, Vixen Eyepieces: Antares to Zeiss (1000101) The only culture I have is from yogurt
Bigzmey wrote: ↑Tue Apr 18, 2023 10:13 pm
If you must saw, how about this guy then? I had it briefly. The optics is good. The hardware is your typical Synta, basic but serviceable. Basically, shrank-down version of the 150mm you have.
It was actually the first consideration, if I did not have the 115 mm that would like be the one.
Gabrielle See Far Sticks: Elita 103/1575, AOM FLT 105/1000, Bresser 127/1200 BV, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS 100/1000, Vixen SD115s/885 EQ: TAL MT-1, Vixen SXP, SXP2, AXJ, AXD Az/Alt: AYO Digi II, Stellarvue M2C, Argo Navis encoders on both Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102 Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Tak prism, TAL, Vixen Eyepieces: Antares to Zeiss (1000101) The only culture I have is from yogurt
Instead of sawing off a piece of the tube, can't you just use these binoviewers that claim to not affect the optical path and keep the focuser distance the same? It's only for 1.25" but at least you can keep your frac resellable if what they claim is true.
TS also has a nice collection of astro binos if you want to avoid using binoviewers. Should be F/4 or so with 10 mm eyepieces.
... Henk. Telescopes: GSO 12" Astrograph, "Comet Hunter" MN152, ES ED127CF, ES ED80, WO Redcat51, Z12, AT6RC, Celestron Skymaster 20x80, Mounts and tripod: Losmandy G11S with OnStep, AVX, Tiltall, Cameras: ASI2600MC, ASI2600MM, ASI120 mini, Fuji X-a1, Canon XSi, T6, ELPH 100HS, DIY: OnStep controller, Pi4b/power rig, Afocal adapter, Foldable Dob base, Az/Alt Dob setting circles, Accessories: ZWO 36 mm filter wheel, TV Paracorr 2, Baader MPCC Mk III, ES FF, SSAG, QHY OAG-M, EAF electronic focuser, Plossls, Barlows, Telrad, Laser collimators (Seben LK1, Z12, Howie Glatter), Cheshire, 2 Orion RACIs 8x50, Software: KStars-Ekos, DSS, PHD2, Nebulosity, Photo Gallery, Gimp, CHDK, Computers:Pi4b, 2x running KStars/Ekos, Toshiba Satellite 17", Website:Henk's astro images
A interesting BV though looking at the specifications I see 7 elements and a clear aperture of only 17.4 mm with a eyepiece field stop size of 22 mm.
The BVs that I use have been re-worked so are a bit better than that. 3 elements left side 26 mm CA, right side 28 mm, and 28 mm CA at the nosepiece.
The idea is that by modifying the telescope tube you would not need to use any OCA (optical corrector assembly) to reach focus, everything stays at its native f/l. This way there is no having to match OCA, long/ short diagonals and being stuck using limited range of eyepieces.
My Stellarvue 80 mm is setup for this but requires removal of the focuser then a 102 mm section of the tube then reattach the focuser. Not something you want to be doing in the field.
Thank you for the ideas though
Gabrielle See Far Sticks: Elita 103/1575, AOM FLT 105/1000, Bresser 127/1200 BV, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS 100/1000, Vixen SD115s/885 EQ: TAL MT-1, Vixen SXP, SXP2, AXJ, AXD Az/Alt: AYO Digi II, Stellarvue M2C, Argo Navis encoders on both Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102 Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Tak prism, TAL, Vixen Eyepieces: Antares to Zeiss (1000101) The only culture I have is from yogurt
Lady Fraktor wrote: ↑Wed Apr 19, 2023 6:17 pm
The idea is that by modifying the telescope tube you would not need to use any OCA (optical corrector assembly) to reach focus, everything stays at its native f/l. This way there is no having to match OCA, long/ short diagonals and being stuck using limited range of eyepieces.
My Stellarvue 80 mm is setup for this but requires removal of the focuser then a 102 mm section of the tube then reattach the focuser. Not something you want to be doing in the field.
For those who have an astrograph, I presume there would be zero problems attaching binoviewers since an astrograph pushes the focal plane out far enough? And for any truss Dobsonians that have a truss hole for AP it would be OK too? That is my situation, I have been considering getting a BV.
... Henk. Telescopes: GSO 12" Astrograph, "Comet Hunter" MN152, ES ED127CF, ES ED80, WO Redcat51, Z12, AT6RC, Celestron Skymaster 20x80, Mounts and tripod: Losmandy G11S with OnStep, AVX, Tiltall, Cameras: ASI2600MC, ASI2600MM, ASI120 mini, Fuji X-a1, Canon XSi, T6, ELPH 100HS, DIY: OnStep controller, Pi4b/power rig, Afocal adapter, Foldable Dob base, Az/Alt Dob setting circles, Accessories: ZWO 36 mm filter wheel, TV Paracorr 2, Baader MPCC Mk III, ES FF, SSAG, QHY OAG-M, EAF electronic focuser, Plossls, Barlows, Telrad, Laser collimators (Seben LK1, Z12, Howie Glatter), Cheshire, 2 Orion RACIs 8x50, Software: KStars-Ekos, DSS, PHD2, Nebulosity, Photo Gallery, Gimp, CHDK, Computers:Pi4b, 2x running KStars/Ekos, Toshiba Satellite 17", Website:Henk's astro images
Nothing that complex, the OCA is screwed onto the nosepiece of the BV. Many people use a 2x barlow for their BVs to work but there is a difference between how a barlow and OCA work. Because I have different focal length refractors I have 4 different OCA: 1.3x,1.4x,1.6x,1.8x to get closer to native f/l.
By removing a section of telescope tube I will be removing the lightpath length of the BVs, and no need to modify a diagonal.
This way a regular diagonal can be used and no OCA is required. BVs typically add about 100+ mm to the focal length so the OCA is required to reach focus.
Many people use BVs with newtonians but I am not sure what OCA would be needed or if modification to the mirror position is required,
a lot of BVs come with a 1.6x
They are relaxing to use since you are using both eyes. When the planets are out I can sit and view for hours without fatigue.
I am really not sure how they would work with a astrograph though.
Gabrielle See Far Sticks: Elita 103/1575, AOM FLT 105/1000, Bresser 127/1200 BV, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS 100/1000, Vixen SD115s/885 EQ: TAL MT-1, Vixen SXP, SXP2, AXJ, AXD Az/Alt: AYO Digi II, Stellarvue M2C, Argo Navis encoders on both Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102 Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Tak prism, TAL, Vixen Eyepieces: Antares to Zeiss (1000101) The only culture I have is from yogurt