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Upgrading a Tasco 33TR

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#1 xvariablestarx

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Posted 03 July 2021 - 01:27 PM

Hi.

 

The weather is cloudy, so I gave myself a project; I took down my old Tasco reflector scope off the shelf and looked at what it had. I  replaced the "toy" 9x finder scope with a Vixen style finder bracket, so I can mount a modern red dot finder on it. I looked at the 3 Huygens eyepieces that came with the scope, they are 0.9...inch eyepieces, just like the focuser on the scope. I wonder if there is any adapter that will allow me to use 1.25 inch eye pieces with it? The mirrors on the scope have seen better days, but I think they will still function. I want to give the little scope a chance to do better than it did in the old days, when I knew a lot less about astronomy.

 

 

oldscope.jpg


Edited by xvariablestarx, 03 July 2021 - 01:36 PM.

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#2 xvariablestarx

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Posted 03 July 2021 - 01:57 PM

I have heard of some people using such adapters on refractors, but this is a reflector, so I want to know if it should still work?



#3 sdedalus83

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Posted 03 July 2021 - 01:59 PM

You might be able to use a .965-1.25 adapter, but it will require about 1.5” of inward focuser travel which you probably won’t get with this scope. You can test it by holding a 1.25” eyepiece at the end of the eyepiece holder. If your focuser drawtube is 1.25” OD(and your eyepiece holder tall enough), you could also remove the drawtube and use one of those helical focusers with a 1.25” barrel. The other way is to wait for a used focuser to pop up. There were low profile helical focusers which would require a shim to fit your tube contour but wouldn’t require you to cut a new hole. 


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#4 xvariablestarx

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Posted 03 July 2021 - 02:17 PM

You might be able to use a .965-1.25 adapter, but it will require about 1.5” of inward focuser travel which you probably won’t get with this scope. You can test it by holding a 1.25” eyepiece at the end of the eyepiece holder. If your focuser drawtube is 1.25” OD(and your eyepiece holder tall enough), you could also remove the drawtube and use one of those helical focusers with a 1.25” barrel. The other way is to wait for a used focuser to pop up. There were low profile helical focusers which would require a shim to fit your tube contour but wouldn’t require you to cut a new hole. 

I was able to get an pretty clear image by holding a 1.25 eyepiece at the end of the focuser. I don't think it would be very easy to replace the focuser itself, as the secondary mirror is on a single stalk and screwed into the inside of the focuser.



#5 sdedalus83

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Posted 03 July 2021 - 02:22 PM

I was able to get an pretty clear image by holding a 1.25 eyepiece at the end of the focuser. I don't think it would be very easy to replace the focuser itself, as the secondary mirror is on a single stalk and screwed into the inside of the focuser.

If that was at night with a longer focal length eyepiece, then the adapter might work. If you were looking at a terrestrial object, the focal plane will be farther from the primary than for an object at infinity.

 

this looks cheap enough to be worth a shot:

https://www.amazon.c...t/dp/B08HSCDSS1


Edited by sdedalus83, 03 July 2021 - 02:25 PM.


#6 xvariablestarx

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Posted 03 July 2021 - 02:26 PM

If that was at night with a longer focal length eyepiece, then the adapter might work. If you were looking at a terrestrial object, the focal plane will be farther from the primary than for an object at infinity.

The aperture is 75mm, the focal length 700mm, the eyepiece I used was a 25mm Plossl. I will try on the Moon or Jupiter when the skies clear.



#7 bdcmd

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Posted 03 July 2021 - 04:07 PM

If you have to stay with 0.965" eyepieces, OPT still lists Antares Plossls in that size and they appear to be comparable to GSO Plossl types with a 0.965 barrel. I use them in my small refractors, but have not used them in a reflector.  They come in 7.5, 12.5, 17 and 25 mm focal lengths.  Optically, very good in my small scopes, so would probably do very well in yours, assuming they would reach focus.   bdc


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#8 xvariablestarx

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Posted 04 July 2021 - 06:49 PM

I did a small test on Arcturus and some other bright stars, got the red dot finder as well aligned as the wiggly mount would allow, then try looking with with the longest focal length Huygens eyepiece that came with the scope. It was possible to see the star in the Huygens, but when I switched to the Plossl (25mm), I needed to move the focuser closer to the secondary mirror, but when i focused with the Plossl, it was superior to the Huygens. I think a 0.965 to 1.25 adaptor will work.

 

I noticed that the image, even in the Plossl was a bit dim, but I suspect that is because of a mixture of the sub 80mm aperture and the iffy condition of the mirrors.



#9 xvariablestarx

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Posted 07 July 2021 - 02:29 PM

Since the mirror is corroded, should I buy something like this to replace it?

https://www.aliexpre...-5998d51ad8a3-0



#10 xvariablestarx

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Posted 09 July 2021 - 09:01 AM

Ordered some rings/plate from Orion and a couple of mirrors from Aliexpress. It is worth experimenting at least, I don't have much to lose on this scope.



#11 xvariablestarx

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Posted 12 July 2021 - 09:32 AM

If anybody is interested, my 8 inch dovetail and 90mm tube rings arrived. I was able to mount the scope on something more secure

oldscope2.jpg


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#12 shredder1656

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Posted 12 July 2021 - 10:58 AM

Looks good. I hope it performs well!
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#13 xvariablestarx

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Posted 12 July 2021 - 11:18 AM

Looks good. I hope it performs well!

I am getting an adapter to use modern eyepieces with it, then will be the real test.



#14 BlueTrane2028

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Posted 12 July 2021 - 12:43 PM

If you have to stay with 0.965" eyepieces, OPT still lists Antares Plossls in that size and they appear to be comparable to GSO Plossl types with a 0.965 barrel. I use them in my small refractors, but have not used them in a reflector.  They come in 7.5, 12.5, 17 and 25 mm focal lengths.  Optically, very good in my small scopes, so would probably do very well in yours, assuming they would reach focus.   bdc

I shouldn't have known about those .965 Plossls, will probably end up with a set as my childhood refractor is a .965.  Been using an adapter diagonal to run 1.25" eyepieces, but options... nothing wrong with them.

Plus, sometimes decent old scopes are .965, having usable eyepieces for them would be nice just to have on hand should such a thing enter my possession.



#15 BlueTrane2028

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Posted 12 July 2021 - 12:45 PM

If anybody is interested, my 8 inch dovetail and 90mm tube rings arrived. I was able to mount the scope on something more secure

attachicon.gifoldscope2.jpg

I made an alt-az pipe mount for a 76mm reflector once.  Yours came out a billion times better in appearance.

 

Here's hoping you find a workable solution for the eyepieces, a couple of those Antares Plossls would be good if the adapter doesn't go so well.


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#16 xvariablestarx

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Posted 12 July 2021 - 01:01 PM

I made an alt-az pipe mount for a 76mm reflector once.  Yours came out a billion times better in appearance.

 

Here's hoping you find a workable solution for the eyepieces, a couple of those Antares Plossls would be good if the adapter doesn't go so well.

I think I checked on those .965 Plossls, and they were out of stock. In your opinion, if the 1.25 inch adapter doesn't work, would it be better for me to try and put a 1.25 inch focuser on it instead?



#17 Jimceez

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Posted 12 July 2021 - 02:10 PM

Opt has the 12.5mm, 17mm & 25mm in stock.  Just checked it.


Edited by Jimceez, 12 July 2021 - 02:13 PM.

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#18 BlueTrane2028

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Posted 12 July 2021 - 03:41 PM

Opt has the 12.5mm, 17mm & 25mm in stock.  Just checked it.

And, lucky for OP, those are the most appropriate ones for their telescope IMO.



#19 xvariablestarx

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Posted 12 July 2021 - 03:45 PM

I will buy something from Opt, if the adaptor doesn't work.


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#20 Jimceez

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Posted 12 July 2021 - 06:20 PM

Another resource is Surplus Shed.  They configure their own eyepieces and are pretty good.  They have some .965 eyepieces configured.

 

https://www.surpluss...item/L3317.html

 

also have a very cheap adapter

 

https://www.surpluss...item/M4727.html


Edited by Jimceez, 12 July 2021 - 06:22 PM.

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#21 xvariablestarx

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Posted 13 July 2021 - 06:24 AM

Another resource is Surplus Shed.  They configure their own eyepieces and are pretty good.  They have some .965 eyepieces configured.

 

https://www.surpluss...item/L3317.html

 

also have a very cheap adapter

 

https://www.surpluss...item/M4727.html

Lots of stuff there, a dangerous place to show me lol.


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#22 xvariablestarx

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Posted 13 July 2021 - 06:28 AM

I found out that the original mount of the Tasco scope, uses a short 1/4 inch screw to secure the scope to the mount head; essentially is a mount fit for the purpose of mounting a small binoculars, so that is what I did. This put the mount to use, and saves it from being thrown out/stored away. I was missing the pan handle, so I stuck a long 1/4 inch screw in there also.

 

binomount.jpg


Edited by xvariablestarx, 13 July 2021 - 06:29 AM.

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#23 Jimceez

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Posted 14 July 2021 - 04:58 PM

Lots of stuff there, a dangerous place to show me lol.

The difference between men & boys is the price of their toys….


Edited by Jimceez, 14 July 2021 - 04:58 PM.

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#24 xvariablestarx

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Posted 17 July 2021 - 01:20 PM

Tested out the Tasco with its more stable mount, last night. It was much easier to use, along with the red dot finder, but the corrosion on the mirrors was also obvious. I wish there was a quicker way to correct that than waiting for mirrors from Aliexpress, but I guess that is the only cheap option for now.

 

I may post pictures again when I get the 1.25 adapter next week. I am also working on the Tasco's old tripod so may take a pic of that when its done also.



#25 Jimceez

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Posted 17 July 2021 - 03:39 PM

Tested out the Tasco with its more stable mount, last night. It was much easier to use, along with the red dot finder, but the corrosion on the mirrors was also obvious. I wish there was a quicker way to correct that than waiting for mirrors from Aliexpress, but I guess that is the only cheap option for now.

 

I may post pictures again when I get the 1.25 adapter next week. I am also working on the Tasco's old tripod so may take a pic of that when its done also.

You may be able to put a setting circle on your mount.  Telescope warehouse has them for like $3.  I have a couple I got from them.  4” diameter.  If you need a pic, I could post it if you would like.


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