pctechtx Posted June 29, 2021 Share Posted June 29, 2021 My brother-in-law gave/loaned me an old f8 114/900 telescope that had been setting a long time. During cleaning process I scratched the primary mirror. I replaced it with an 114/850. With no lens I can see the trees on the reflector but can't see a total visible circle. Some black round thing takes up 1/3 to 2/3 of the view. I dinked around with the spider (might be wrong on terminology) attempting to get a better view. I never attempted viewing before cleaning and I've never used a telescope before. I purchased a svbony sv205 to use with it. My intent is to digitally record observations. When I look through the eye piece holder without a lens I can see things reflected off mirror. When I insert a lens I can not see anything when testing in daylight but light. I'm assuming the collimation is my issue. I am hoping to find assistance understanding these devices. The primary I removed was polished on one side. The primary I bought is polished on both sides. When looking at it, I chose to use the side that gave similar reflection as the 900 showed. I really don't know what to do here and would love some suggestions. I am grateful for any energy offered towards this. Blessings! Quote Link to comment Share on other sites More sharing options...
AstronomyUkraine Posted June 29, 2021 Share Posted June 29, 2021 23 minutes ago, pctechtx said: My brother-in-law gave/loaned me an old f8 114/900 telescope that had been setting a long time. During cleaning process I scratched the primary mirror. I replaced it with an 114/850. With no lens I can see the trees on the reflector but can't see a total visible circle. Some black round thing takes up 1/3 to 2/3 of the view. I dinked around with the spider (might be wrong on terminology) attempting to get a better view. I never attempted viewing before cleaning and I've never used a telescope before. I purchased a svbony sv205 to use with it. My intent is to digitally record observations. When I look through the eye piece holder without a lens I can see things reflected off mirror. When I insert a lens I can not see anything when testing in daylight but light. I'm assuming the collimation is my issue. I am hoping to find assistance understanding these devices. The primary I removed was polished on one side. The primary I bought is polished on both sides. When looking at it, I chose to use the side that gave similar reflection as the 900 showed. I really don't know what to do here and would love some suggestions. I am grateful for any energy offered towards this. Blessings! I assume the telescope is a newtonian. The black round thing sounds like the secondary mirror. Both the secondary and primary mirror need collimating. You might not achieve focus by just attaching your camera to the focuser, once collimated you can attach the camera or an eyepiece to see if you can achieve focus, if not, you will probably need an extension to the focuser. Quote Link to comment Share on other sites More sharing options...
Marmot Posted June 29, 2021 Share Posted June 29, 2021 I agree with AsroUkraine. You clearly have a Newtonian telescope and therefore if you have replaced the primary mirror and tinkered with the secondary, they will need collimating. If you search on the net you will find instructions on how to do this (videos on YouTube also). Getting your scope collimated would be a good first step before you progress to other things. Quote Link to comment Share on other sites More sharing options...
pctechtx Posted June 30, 2021 Author Share Posted June 30, 2021 Thanks for the 2 responses. What method is best in y'all's opinion: laser collimation and crosshair'd eyepiece collimation? Quote Link to comment Share on other sites More sharing options...
Nightspore Posted June 30, 2021 Share Posted June 30, 2021 Quote Link to comment Share on other sites More sharing options...
pctechtx Posted June 30, 2021 Author Share Posted June 30, 2021 (edited) removed Edited June 30, 2021 by pctechtx lack of quote Quote Link to comment Share on other sites More sharing options...
pctechtx Posted June 30, 2021 Author Share Posted June 30, 2021 4 minutes ago, Nightspore said: This device is not a laser embedded, right? Quote Link to comment Share on other sites More sharing options...
Nightspore Posted June 30, 2021 Share Posted June 30, 2021 1 hour ago, pctechtx said: This device is not a laser embedded, right? Just a low tech Cheshire. Using a Cheshire. 1 Quote Link to comment Share on other sites More sharing options...
pctechtx Posted June 30, 2021 Author Share Posted June 30, 2021 To make sure I am using the correct side of primary mirror, is there a method of testing? I also am curious if mirrors can be polished, that way I can use original. Quote Link to comment Share on other sites More sharing options...
AstronomyUkraine Posted June 30, 2021 Share Posted June 30, 2021 1 hour ago, pctechtx said: To make sure I am using the correct side of primary mirror, is there a method of testing? I also am curious if mirrors can be polished, that way I can use original. Take the mirror out and place a staright edge across the mirror, the correct side should be slightly concave. 1 Quote Link to comment Share on other sites More sharing options...
MarkAR Posted July 1, 2021 Share Posted July 1, 2021 Not 100% sure but would changing the focal length of the mirror from 900mm to 850mm affect the distances involved for achieving focus??? Quote Link to comment Share on other sites More sharing options...
pctechtx Posted July 1, 2021 Author Share Posted July 1, 2021 36 minutes ago, MarkAR said: Not 100% sure but would changing the focal length of the mirror from 900mm to 850mm affect the distances involved for achieving focus??? I have no idea, kind of why I am here asking questions. I'm gracious for all inputs. I've ordered a cheshire. I'll be back after it arrives within a week. This is a Meade tele. Anyone know if the mirrors are polish-able? Quote Link to comment Share on other sites More sharing options...
Nightspore Posted July 1, 2021 Share Posted July 1, 2021 1 hour ago, MarkAR said: Not 100% sure but would changing the focal length of the mirror from 900mm to 850mm affect the distances involved for achieving focus??? That would be my guess too. Quote Link to comment Share on other sites More sharing options...
AstronomyUkraine Posted July 1, 2021 Share Posted July 1, 2021 5 hours ago, pctechtx said: I have no idea, kind of why I am here asking questions. I'm gracious for all inputs. I've ordered a cheshire. I'll be back after it arrives within a week. This is a Meade tele. Anyone know if the mirrors are polish-able? Have you got an image of your scope. It would give us an idea what kind of scope you have. As for polishing a mirror, it can be done, but will take a lot of time and effort. Up to 100 hours to polish a mirror, and that would depend on how deep the scratch is. Quote Link to comment Share on other sites More sharing options...
pctechtx Posted July 3, 2021 Author Share Posted July 3, 2021 On 7/1/2021 at 12:48 PM, AstronomyUkraine said: Have you got an image of your scope. It would give us an idea what kind of scope you have. As for polishing a mirror, it can be done, but will take a lot of time and effort. Up to 100 hours to polish a mirror, and that would depend on how deep the scratch is. I will photo it later if time permits. Scratches are fine, not deep, makes the mirror look hazy. I will research what is involved since it's possible. I haven't researched much on telescopes. I was just hoping to get my own proofs of what is in the skies. Thanks for y'all's time and energy. I will add pics of the tele as time permits. Blessings and to those in the USA have a safe Independence Day weekend. May God bless us all! Quote Link to comment Share on other sites More sharing options...
Nightspore Posted July 4, 2021 Share Posted July 4, 2021 Quote Link to comment Share on other sites More sharing options...
pctechtx Posted July 5, 2021 Author Share Posted July 5, 2021 On 7/1/2021 at 12:48 PM, AstronomyUkraine said: Have you got an image of your scope. It would give us an idea what kind of scope you have. Attached is label on tele. 1 Quote Link to comment Share on other sites More sharing options...
Nightspore Posted July 5, 2021 Share Posted July 5, 2021 Looks a bit like a rebadged GSO. Could be a Bird-Jones. Quote Link to comment Share on other sites More sharing options...
pctechtx Posted July 5, 2021 Author Share Posted July 5, 2021 2 hours ago, Nightspore said: Looks a bit like a rebadged GSO. Could be a Bird-Jones. Not sure about the corrective lens they are talking about in the Bird-Jones. Is it part of the actual lenses? I only see a primary mirror and a reflector in the telescope. Nothing is inside the lens holder. Attaching lens photos (it's .965) Quote Link to comment Share on other sites More sharing options...
pctechtx Posted July 5, 2021 Author Share Posted July 5, 2021 Here are more photos of the device Quote Link to comment Share on other sites More sharing options...
Nightspore Posted July 5, 2021 Share Posted July 5, 2021 Oh right. Probably just a bog-standard Newtonian then. Not that different to my TS Optics (GSO) f/6, 150mm in the fact that it's just bog-standard. My guess would be that the mirror you're using as a replacement isn't focusing on the secondary properly as it's the wrong mirror and has the wrong focal length. The odds are you can put the original back in. I doubt you'll notice a scratch on the mirror surface when viewing. I don't know who manufactured the Meade Newtonians but most primary mirrors have a circle mark in the centre of the mirror to aid collimation. You won't see it when actually observing. The replacement mirror sounds like it's vignetting from reading your original post. Put the original mirror back in. The eyepieces look like old Huygens. Might make nice paperweights. Quote Link to comment Share on other sites More sharing options...
pctechtx Posted July 6, 2021 Author Share Posted July 6, 2021 10 hours ago, Nightspore said: Oh right. Probably just a bog-standard Newtonian then. Not that different to my TS Optics (GSO) f/6, 150mm in the fact that it's just bog-standard. My guess would be that the mirror you're using as a replacement isn't focusing on the secondary properly as it's the wrong mirror and has the wrong focal length. The odds are you can put the original back in. I'll put the original back in and see. Thanks. Blessings! Quote Link to comment Share on other sites More sharing options...
Nightspore Posted July 6, 2021 Share Posted July 6, 2021 (edited) 3 hours ago, pctechtx said: I'll put the original back in and see. Thanks. Blessings! That would be the best plan. My Newtonian rarely gets used as I'm more of a refractor kind of bloke. So if I ever clean mirror surfaces it is only with Baader Fluid. How to Clean Telescope Mirror: A Step-by-Step Guide Good luck. Edited July 6, 2021 by Nightspore 1 Quote Link to comment Share on other sites More sharing options...
pctechtx Posted August 29, 2021 Author Share Posted August 29, 2021 I'm confused by a few things and hope for clarifications. The telescope provided to me is 114/910 and label says f/8. If I create a new tube for the 850 mirror I bought, the secondary mirror should be placed at 33.46457 inches from PrimaryMirror correct? Should the 910's SecondaryMirror function for the 850 PM if I place it in the correct location or will I need new lenses and SM? Thanks for your time and blessings! Quote Link to comment Share on other sites More sharing options...
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