9 replies to this topic

[blackhole369]

Hi, I am seeking expert opinion on my Astro Telescope, I had no idea what is the mirror size, there's no markings in it. I really appreciate if someone can enlighten me. Thank you so much!

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[bobzeq25]

Measure (carefully, use a fabric tape and don't scratch the lens) the diameter of the clear lens. You have a lens, not a mirror.

Edited by bobzeq25, 21 March 2025 - 07:52 PM.

[vkhastro1]

Measure the front objective - probably clear aperture of 152mm

If so looks like it be the 152mm f/5.9 achromat.

[TOMDEY]

I'm convinced that it's a 75mm refractor doublet with a 1.25-inch star diagonal. Maybe 100mm, but I doubt it.   Tom

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Edited by TOMDEY, 21 March 2025 - 08:10 PM.

[ngc7319_20]

Looks like this is what you have... 152mm

 

 

https://web.archive....telescopes.com/

 

https://web.archive....-5-9-refractor/

Edited by ngc7319_20, 21 March 2025 - 08:15 PM.

[bobzeq25]

It should be very easy to distinguish between the likely possibilities. 75mm. 100mm. 125mm. 152mm.

[Jon Isaacs]

I'm convinced that it's a 75mm refractor doublet with a 1.25-inch star diagonal. Maybe 100mm, but I doubt it.   Tom

 

Measuring the objective with a tape measure is straight forward.. 

 

That said, 1.25 inch two speed Crayford focusers are extremely rare.  I don't know of any refractors that ever came with a 2 speed 1.25 inch focuser.  To me it looks like a 152 mm. 

Jon

[TOMDEY]

Measuring the objective with a tape measure is straight forward.. 

 

That said, 1.25 inch two speed Crayford focusers are extremely rare.  I don't know of any refractors that ever came with a 2 speed 1.25 inch focuser.  To me it looks like a 152 mm. 

Jon

Yeah --- it's possible that the ruler in the picture is a lot closer to the camera so the focuser just looks small. Heck... I can cover this entire screen on my PC with my little thumb in front of my eye... and the moon with the tip of my finger at arm's length.    Tom

Edited by TOMDEY, 22 March 2025 - 03:58 AM.

[kmparsons]

Yeah, Hands On Optics marketed these some years back. They offered a 102mm f/11 "Planet Killer" achromat (which I own) and a 152 mm f/5.9 rich field achromat. Should be great for low-power wide-field views, but loads of CA on bright objects. I think Ed Ting reviewed this one back when. 

[RichA]

Hi, I am seeking expert opinion on my Astro Telescope, I had no idea what is the mirror size, there's no markings in it. I really appreciate if someone can enlighten me. Thank you so much!

Nice looking telescope.  The focuser (at a glance) looks like a cut above the average owing to what looks like stainless steel shafting.