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The little Tasco that could

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#1 Glassthrower

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Posted 20 June 2007 - 10:28 AM

Although the observing weather has been very poor for weeks now, I have managed to get some fleeting sucker holes in the cloud deck over the last couple of days. During that time, I have used my little Tasco 60mm f/11 as a grab and go. I have managed to point it at Saturn, Jupiter, the Moon, and a couple of star fields. Although seeing and transparency have been poor on average, I can tell the scope has sharp optics.

Using the 1.25"/.965" hybrid prism diagonal I bought from Tony White, I have used the 15mm Lanthanum barlowed 3x on the moon, for about 140x. The image was going dim by that point, but still quite sharp. Far less color than I am accustomed to seeing in my 100mm f/6. Images through the 7mm Nagler at 100x are also nice. Jupiter was crisp with two equatorial belts and polar shading visible at 100x. Jupiter sustained usuable magnification up to about 120x.

The focuser is still a little stiff, but very little image shift. Thankfully I am not having the same issue as Bonco - the fit between the diagonal and the friction-fit drawtube (no set screw) is quite tight. Although, I would not trust it with large heavy eyepieces. I also have a mirror hybrid diagonal on the way that I will compare against the prism hybrid. FWIW, Gary Russell is selling the mirror hybrids (metal body) on eBay for about $15.00 shipped. Good deal.

I did manage to jerry-rig the 6-point Towa finder bracket to the Tasco tube, using just one mounting screw instead of two. I just don't have a good quality 5x24 finder for the Tasco, so I am using a better 6x30 long eye relief Celestron finder that I also got from Tony. Thanks again Tony. :)

Clear classic skies,

MikeG

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#2 GeneDiG

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Posted 20 June 2007 - 03:34 PM

Mike,

Don't give up on the 5x24!

A while back I took the old 5x24 finder that came with my 11t and modified it. First,I took out the aperature stop. Yipes! However, I with a little shaving and press fitting I was able to fit a .965 90 deg star diagonal onto the end of the tube.

Placed a B&L 10x widefield stereo micorscope EP in the diagonal. Couldn't get it to focus, so I wound up cutting the tube to about 4 inches long. Placed the microscope EP in and bingo! The image I got was quite nice, with the spherical aberation I first had when I pulled the aperature stop out.

I'm at work now so I can't get any pics, but I'll try and take a few when I get home.

Total cost: $5.00 for the .965 diagonal. I had the eyepiece for many years but I understand they can be had for as little as 10 bucks.

Hope this helps,
Gene

#3 Jon Isaacs

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Posted 21 June 2007 - 06:17 AM

>>>Using the 1.25"/.965" hybrid prism diagonal I bought from Tony White, I have used the 15mm Lanthanum barlowed 3x on the moon, for about 140x. The image was going dim by that point, but still quite sharp. Far less color than I am accustomed to seeing in my 100mm f/6. Images through the 7mm Nagler at 100x are also nice. Jupiter was crisp with two equatorial belts and polar shading visible at 100x. Jupiter sustained usuable magnification up to about 120x.
-----

Mike: That sounds very much like the Tasco 59T that I bought at a garage sale quite a few years back. It was just the OTA and I bought it with the idea of having a good laugh on S.A.A. but instead I was quite surprised by the brightness and sharpness of the image. I was using an Ultima 2x barlow plus 10mm Plossl for something around 150x.

The lack of false color and blackness of the background is impressive with these scopes. The scopes essentially meet the more stringent "5x rule" (focal ratio =5 x aperture in inches) for acceptable false color. Suiter says this is a 1/4 wave criteria and they are nice.

I always thought it would be interesting to set up a good quality 60mm F/11.7 like yours with a 2 inch focuser. With the 700mm focal length and a 2 inch eyepiece, a 3.5 degree TFoV is possible, bright targets like the Pleiades would be stunning I think. It would be quite similar to masking your AstroView 100F/6 down to 60mm.

Glad you are having fun with your scope.

jon

#4 GeneDiG

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Posted 21 June 2007 - 10:11 AM

I always thought it would be interesting to set up a good quality 60mm F/11.7 like yours with a 2 inch focuser.


Does anyone make a nice quality 2 inch or 1.25 focuser for these old achros?

Gene

#5 Jon Isaacs

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Posted 21 June 2007 - 01:35 PM

>>>Does anyone make a nice quality 2 inch or 1.25 focuser for these old achros?

Gene
-----

I don't think so. I do have a Synta type 2 inch focuser and my plan was to adapt it to that Tasco but then I found someone who could use the scope so I shipped it off.

Some of the 80mm Scopes use a 90mm Tube, the Meade 310 seems to. I think that 2 inch focusers are available for a 90mm tube, the Celestron ED-80 has a 90mm tube, the Megrez 80II's have an 90mm Tube.

Jon

#6 GeneDiG

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Posted 21 June 2007 - 02:25 PM

I've seen Antares focusers for 80mm and up refractors but I've yet to see one for a 60mm. I wonder if there is a market?

#7 Preston Smith

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Posted 21 June 2007 - 02:35 PM

I always thought it would be interesting to set up a good quality 60mm F/11.7 like yours with a 2 inch focuser.


Does anyone make a nice quality 2 inch or 1.25 focuser for these old achros?

Gene



Try this one:

http://www.meridiant...user/fcr07b.htm

It is the ONLY one I have found with a LOT of research.

#8 EJN

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Posted 21 June 2007 - 03:15 PM

Also,

http://www.handsonop...ts_antares.html

FOCR1 & FOCR2

#9 Preston Smith

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Posted 21 June 2007 - 03:32 PM

Also,

http://www.handsonop...ts_antares.html

FOCR1 & FOCR2


FYI - These are for 80mm scopes - too big for 60mm scopes. I just checked with Hands-On Optics. Bummer! I liked them better then my resource! :bawling:

#10 Pedestal

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Posted 21 June 2007 - 05:33 PM

I always thought it would be interesting to set up a good quality 60mm F/11.7 like yours with a 2 inch focuser.


Does anyone make a nice quality 2 inch or 1.25 focuser for these old achros?

Gene



Try this one:

http://www.meridiant...user/fcr07b.htm

It is the ONLY one I have found with a LOT of research.


FWIW: It was the only one I found, a year or so ago, also. I bought one. It is ok, for the money. It's not made of pressed sheet metal, at least!
Hubert

#11 twhite

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Posted 21 June 2007 - 05:42 PM

I wanted to get one of the Antares/GSO focuser for this 3" f/15 I was going to re-assemble with a new tube and focuser. After getting my hands on one, I was glad that I didn't... it's WAY too chunky. That little focuser in the link Preston put in his message would work quite well, actually...I might just have to get one of those! Then at least I can put this thing together and either use it or sell it or something... :)

#12 Preston Smith

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Posted 21 June 2007 - 06:04 PM

Now if you REALLY want to spend some $$$ contact this guy to see if he will make a custom one for your 60mm..... if you do I want a full report!

http://home.comcast....ck/wyorock.html

Don't drool too much!

#13 fxxm747

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Posted 21 June 2007 - 07:20 PM

I was going to suggest the same. Really these are to be compared with the top of the line folks. There prices are nice for what you get (at this point) and they will provide you with custom adapter made to fit your particular scope however you want it. And its VERY reasonable. Give them a shout Mike! The really nice thing is you can use it other scopes you have.

#14 Glassthrower

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Posted 21 June 2007 - 07:25 PM

Mike,

Don't give up on the 5x24!

A while back I took the old 5x24 finder that came with my 11t and modified it. First,I took out the aperature stop. Yipes! However, I with a little shaving and press fitting I was able to fit a .965 90 deg star diagonal onto the end of the tube.

Placed a B&L 10x widefield stereo micorscope EP in the diagonal. Couldn't get it to focus, so I wound up cutting the tube to about 4 inches long. Placed the microscope EP in and bingo! The image I got was quite nice, with the spherical aberation I first had when I pulled the aperature stop out.

I'm at work now so I can't get any pics, but I'll try and take a few when I get home.

Total cost: $5.00 for the .965 diagonal. I had the eyepiece for many years but I understand they can be had for as little as 10 bucks.

Hope this helps,
Gene


Gene, I have a very old Tasco spotting scope eyepiece that I may try this with. I forgot that I had it. It has an odd barrel size, but I once manually held it in my diagonal and it came to focus in my f/6 achro. Pretty sharp. I may try it as a finder ep.

Mike: That sounds very much like the Tasco 59T that I bought at a garage sale quite a few years back. It was just the OTA and I bought it with the idea of having a good laugh on S.A.A. but instead I was quite surprised by the brightness and sharpness of the image. I was using an Ultima 2x barlow plus 10mm Plossl for something around 150x.

The lack of false color and blackness of the background is impressive with these scopes. The scopes essentially meet the more stringent "5x rule" (focal ratio =5 x aperture in inches) for acceptable false color. Suiter says this is a 1/4 wave criteria and they are nice.

I always thought it would be interesting to set up a good quality 60mm F/11.7 like yours with a 2 inch focuser. With the 700mm focal length and a 2 inch eyepiece, a 3.5 degree TFoV is possible, bright targets like the Pleiades would be stunning I think. It would be quite similar to masking your AstroView 100F/6 down to 60mm.

Glad you are having fun with your scope.

jon


Jon,

Masking down the aperture of the 100mm f/6 would also reduce the focal ratio, possibly cleaning up some abberations from the view. That's something I never thought to do with bright targets. It just seems so counter-intuitive to mask down aperture for anything but solar. I may try this for kicks since my urban sky is so bright.

I have also wondered about aftermarket focusers for small classic scopes. How sweet would it be to have a Unitron with a Moonlite or Feathertouch 2" crayford in it. (preserve the original focuser of course)

If I recall correctly, and to fuel some of the discussion about 60mm focusers, the small APO scopes like the WO 66mm and others have crayford focusers. It may be possible to find the source of these small crayfords or to find a WO small crayford on the used market. I forget if the small WO have the crayford, I am just pulling that name from the hat. Everybody is making these small premium scopes now - Astronomy Technologies, etc.

Barring access to a machine shop, the options are pretty limited. Although the focuser on this little Tasco 60mm is quite good for what it is, I am spoiled on a good crayford. I miss the 10:1 microfocus which is such a luxury at higher powers when critical focus can get tricky. It would be nice to have a generic small crayford with a series of flange rings to fit most classic scopes of common tube diameters - 50mm, 60/62mm, 75/76/80mm, etc. Then one could simply swap the focuser from scope to scope. That might be an idea for one of your collectors out there who has a metal fabrication shop (or access to one) and a collection of small vintage scopes.

Regards and clear skies,

MikeG

PS - put me down on the preorder list for one.

#15 Jon Isaacs

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Posted 21 June 2007 - 08:09 PM

Mike:

First: Masking your 100mm F/6 down to 60mm or even 50mm or so can provide some interesting views. I masked mine down to about 45mm to look at Venus, quite a transformation. A pure white Venus against a black sky, definitely worth doing.

About the focuser: In my view, these scopes don't really need Crayfords because at F/11.6 a smooth rack and pinion is gives you plenty of control. I prefer to keep the old scopes close to stock and leave the high tech stuff for the new ones that need it to make them work.

Jon


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