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TPO 152mm f/6 newtonian ota

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#1 dmgriff

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Posted 17 November 2019 - 05:34 PM

TPO or Third Planet Optics (OPT house brand) D=152mm F=916mm f/6 newtonian ota, rings/dovetail, 199usd shipped.
 
 
Included are ota, 6x30 straight thru finder, 2in single speed Crayford, rings/dovetail. Steel tube weight = ~14 lbs, tube length = ~34in. Marketed as visual/photography.
 
Nice affordable newtonian ota. The single speed Crayford is hefty and functional. Needs a 2in/2in extension tube for visual focus in my use, one of my Borg 1.25in helical/insert should work for fine focus adjustment, instead of the extension.. Tube weights as much as my OOUK aluminum f/8 ota. Might be sturdy enough for some AP.
 
Add at least a EQ3 or appropriate alt/az (~300usd), and for a total of about 500usd you have a nice entry level visual set up. If you have a 900-1200mm fl, you already have a set of eps.
 
A couple of images....
 
On a Vixen Porta II
DSC00162

Some jitters,  usable with the slomos.

 

On a Astrozap GEM (manual lxd75)

DSC00165

Nice and sturdy.

 

The best 4.5in f/8 is a 6in f/6.....

 

Have not had a chance for astro viewing, of course....

 

Good viewing,

 

Dave


Edited by dmgriff, 17 November 2019 - 05:37 PM.

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#2 james7ca

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Posted 17 November 2019 - 06:10 PM

Here is a link (on CN) to a first light report that I did in April 2016 on this same scope (TPO 6" f/6):

 

  https://www.cloudyni...n/#entry7166212


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#3 dmgriff

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Posted 18 November 2019 - 07:19 AM

Image with Borg #7315/7316 1.25in helical focuser with 1.25in insert adapter for fine focus, substituted for 2in extension tube.
 
DSC00170

 

 

2in/2in extension tube and helical add about the same amount of travel...

DSC00169

 

 

Borg #4317 &  7315 1.25in helicals and #7316 insert adapter:

https://www.sciencec...s/html/7315.htm
https://www.sciencec...s/html/4317.htm
https://www.sciencec...s/html/7316.htm

 

There are also many similar helicals on the net...

 

Good viewing,

 

Dave


Edited by dmgriff, 18 November 2019 - 07:53 AM.


#4 Jon Isaacs

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Posted 18 November 2019 - 08:37 AM

If you want to upgrade the focuser to a two speed, Agena Astro sells a kit for the GSO focusers:

 

https://agenaastro.c...pgrade-kit.html

 

They're $60. 

 

Jon


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#5 howardcano

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Posted 18 November 2019 - 12:00 PM

I bought my TPO 6" f/6 Newtonian mostly for low magnifications, but I have been pleasantly surprised by its planetary performance, even with the relatively large central obstruction.

 

It works nicely on a dual-drive Skyview Pro GEM.


Edited by howardcano, 18 November 2019 - 12:02 PM.

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#6 belgrade

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Posted 18 November 2019 - 01:16 PM

Nice... I like it. I have a Celestron Omni XLT 150 and I love it. I’m amazed how much one can see with these on a sturdy mount!
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#7 dmgriff

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Posted 20 November 2019 - 08:25 AM

The TPO f/6 will replace my 6in f/8 dobsonian (Hardin DSH6), as it is too heavy for me to carry around anymore.
 
The TPO 6in f/6 on the Porta II is lighter than the dob, light enough for me to move around. Also, the whole setup transports well in my Dodge Caravan. Everything basically lays down flat in the van, a lower profile than a dob. Also, more aperture than my refractors on the Porta II.
 
I can use the f/6 ota on a manual eq5 I have in the back yard, or on the Porta II as a g&g/travel scope.
 
I believe I will be satisfied with the f/6 newtonian (assists my OOUK 6in f/8 ota).
 
DSC00174 (2)
I adjusted the slomo controls on the Porta II for my use with the reflector, added a 9x50 raci,  a inclinometer (use as desired), and a chair.

 

 

Good viewing,

 

Dave


Edited by dmgriff, 20 November 2019 - 08:42 AM.

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#8 james7ca

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Posted 20 November 2019 - 05:00 PM

If you want to upgrade the focuser to a two speed, Agena Astro sells a kit for the GSO focusers:

 

https://agenaastro.c...pgrade-kit.html

 

They're $60. 

 

Jon

That looks like a pretty good upgrade, but it will NOT fit my TPO 6" that I purchased in 2016 since my focuser doesn't match the product description (requirements). I don't know about the OP's focuser, but based upon the earlier pictures it looks to be the same.

 

That said, it appears that at least one of the customer comments on the Agena website says that the upgrade can be "made to work" on some focusers that don't conform to the product requirements.


Edited by james7ca, 20 November 2019 - 05:05 PM.


#9 dmgriff

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Posted 20 November 2019 - 05:43 PM

One of the low cost asian helicals with appropriate adapter from the net would be about 60usd, I believe.

 

Just need to know the correct thread and size of the male/female adapter(s).

 

Good viewing,

 

Dave

 

 

 



#10 dmgriff

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Posted 06 December 2019 - 09:14 PM

I took the TPO/Porta out early tonight for a little lunar viewing.

 

Eyepieces were 26mm Meade LP SuperPlossl, 15mm TV plossl, 12mm UO ortho, 9mm AstroHutech ortho, Antares (Japan) 2x 3-element, 3x barlows. All very sharp in native FL. The 15mm and 12mm barlowed nicely at 7.5mm, 6mm (1mm exit pupil) and 5mm. Very sharp and contrasty along the terminator. 

 

Like stated previously some jitters, and it is usable with the slomos for me.  About 2 seconds dampening time. I think about 180x with the 5mm equivalent is the highest magnification for me with the  g&g TPO/Porta setup due to the jitters. I think that is sufficient for g&g. Should handle much more magnification on the AstroZap GEM.

 

This is a great visual scope in my brief use. Do not think it would disappoint anyone.

 

Good viewing,

 

Dave

 

 

 


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#11 dmgriff

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Posted 12 December 2019 - 04:59 PM

Since my Borg #7315 helical and adapter are 1.25in, and I normally have it on my Vixen A81M refractor with a 1.25in diagonal, I purchased this Svbony 1.25in helical with 2in insert adapter for ~40usd for the 6in f/6 newtonian as a fine focus.

 

https://www.amazon.c...SSYY82QWFFZY2JY

 

The Svbony has tighter/stiffer movement than the Borg #7315, but it is about 1/3 the price of the Borg and adapter.

 

Svbony also sells the 1.25in helical only for ~30usd. If you want a 1.25in adapter insert, you will need a 1.25in T thread insert adapter, maybe a gender bender adapter to fit (on Ali express I believe). Total will be similar to the above.

 

The same 1.25in_helical/2in_adapter is mentioned in this CN thread:

 

https://www.cloudyni...er/?hl= helical

 

Additionally, I took the Borg #4317 (rotating helical) and 1.25in adapter off  another scope and it is much more smooth/sensitive to the touch than the non-rotating Svbony. The Borg #4317 and adapter is about twice the cost of the Svbony. The Borg will probably wind up on the TPO, but, I'll give the Svbony a try on the f/6 newt. Maybe, I can use the Svbony with some of my refractors for straight thru somehow?

 

Good viewing,

 

Dave


Edited by dmgriff, 13 December 2019 - 07:26 AM.


#12 dmgriff

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Posted 14 December 2019 - 05:03 PM

Just a FYI, FWIW, on the Svbony 1.25in helical with 2in adapter with my TPO/GSO 152mm f/6 newtonian as fine focus on a Vixen Porta II:

 

Just playing with the setup, the Svbony is really stiff to me in the general movement of the non-rotating focuser. My setup with the Porta II is subject to some jitters as is. The stiffness of the overall general movement of the Svbony makes it unusable on this particular setup for my use.

 

I have moved the Svbony to my C80ED kit.

 

 

Therefore, the Borg #4317 rotating helical and #7316 adapter are going on the 6in f/6 scope for fine focus.

.

 

Good viewing,

 

Dave


Edited by dmgriff, 14 December 2019 - 05:05 PM.


#13 dec12252

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Posted 06 June 2020 - 06:53 PM

I just purchased a TPO 6" f/6 reflector from OPT to add to my scope collection because for $200 it is a steal, and since childhood I have always wanted to own a simple 6" reflector.  I will mount it on my GP Mount.  Should work great for grab and go observing.

 

From time to time my wife notices that the scope I am using seems to be of a different size and shape than what she remembers.  I tell her that it is all a matter of perspective.  For example the full moon always appears larger when on the horizon than when overhead.  Similarly, a scope can appear bigger or smaller depending on the surroundings and ones viewpoint.  Has worked so far.

 

Dave


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#14 howardcano

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Posted 07 June 2020 - 02:46 PM

From time to time my wife notices that the scope I am using seems to be of a different size and shape than what she remembers.  I tell her that it is all a matter of perspective.  For example the full moon always appears larger when on the horizon than when overhead.  Similarly, a scope can appear bigger or smaller depending on the surroundings and ones viewpoint.  Has worked so far.

 

Dave

That's a very useful argument, and it's good to hear that it has worked so far!  My problem is that my wife always assumes I'm up to something clandestine.

 

Oh, and congrats on the scope!  I love mine.


Edited by howardcano, 07 June 2020 - 02:46 PM.


#15 Stopforths

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Posted 07 June 2020 - 03:48 PM

I bought my TPO 6" f/6 Newtonian mostly for low magnifications, but I have been pleasantly surprised by its planetary performance, even with the relatively large central obstruction.

 

It works nicely on a dual-drive Skyview Pro GEM.

I've owned 2 skywatcher 6 inch f-5's that deliver on planets also.  The current one has virtually identical star images either side of focus and loves 180 on jupiter which is high in the sky here.

 

Slightly more to see than my 4 inch f14 achromat on Jupiter more detail etc but the vixen 115eds a high end scope shows a little more detail on Jupiter.

 

whats the obstruction on the f6? its 45mm on the skywatcher  f5 which is set up for 1.25 inch eyepieces.


Edited by Stopforths, 07 June 2020 - 03:49 PM.


#16 dmgriff

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Posted 07 June 2020 - 04:44 PM


whats the obstruction on the f6? its 45mm on the skywatcher  f5 which is set up for 1.25 inch eyepieces.

The OPT specifications indicate 45mm for their GSO f/6 version.

 

Good viewing,

 

Dave
 


Edited by dmgriff, 07 June 2020 - 04:45 PM.


#17 howardcano

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Posted 08 June 2020 - 11:28 AM

whats the obstruction on the f6? its 45mm on the skywatcher  f5 which is set up for 1.25 inch eyepieces.

The secondary on mine measures 50mm.



#18 Starman1

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Posted 09 June 2020 - 05:16 PM

6" f/6.

Assuming:

3" mirror radius

3/4" mirror clearance

1/8" tube thickness

2" focuser height from tube (racked in)

1" additional distance to focal plane so that barlows and all eyepieces can work.

Low power eyepiece of 30mm with 82° field.

 

The correct secondary mirror size is: 50mm

Now, design it for 1.25" eyepieces, and the secondary gets smaller.

Design it for a shorter focuser, and the secondary gets smaller.

Design it with the focal plane only 3/4" above the focuser (possible with 1.25" eyepieces), and the secondary gets smaller.

 

I remember going through this in the '80s when i built a 6" f/5 scope.  I used a 51mm secondary and my secondary to focal plane distance was only 6-1/8" and it was designed for 1.25" eyepieces.

I was limited by secondary sizes available, though.


Edited by Starman1, 09 June 2020 - 05:17 PM.


#19 dmgriff

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Posted 10 June 2020 - 03:21 PM

I replaced the gso stock mirror with a owl/osi f/6 with new secondary included.

 

I swapped out the primaries, but, I have not unwrapped the secondary yet (thinking about the existing spider or new, etc).

 

owl/osi state on the website that their secondary is 1.55in or 40mm.

 

So, definitely leaning toward 1.25in eps? That is ok by me, as I am mostly lunar/planetary/clusters and some nebulae.

 

Good viewing,

 

Dave



#20 dmgriff

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Posted 07 July 2020 - 05:15 PM

As information:

 

(I do not think a manual is available for the scope.)

 

To remove the mirror cell from the ota on my sample of the GSO 6in f/6 ota, just unscrew the three  main collimation knobs on the rear of the ota. The mirror and part of the cell will pull out. BE CAREFULL NOT TO LOSE THE SMALL COMPRESSION SPRINGS. If you lose one, go to your local hardware store and snip something similar, or search the net.

 

If you unscrew the retainer ring on the rear of the ota, since it is retained by bolts and nuts, the nuts will fall in the ota when loosened. Replacing the ring, bolts and nuts is not simple, there is not a lot of space in the cell.

 

Also the stock GSO mirror is 3/4in thick. If you replace the stock mirror with say a 1 inch mirror, you will need longer screws that hold the mirror in the cell. The original screws are 25mm to retain a 3/4in mirror with the included rubber gaskets. A 1 inch mirror requires 30 mm screws with the original gaskets. The screws are M3.

 

May save some irritation.

 

Good viewing,

 

Dave


Edited by dmgriff, 07 July 2020 - 05:54 PM.



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