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7 inch Mak , Pota 2, Stability, and Atatchment

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31 replies to this topic

#1 Deepskyclusterstruck

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Posted 24 November 2018 - 02:09 PM

I purchased a Porta 2 in combination with a Vixen 80mm achromat. The achromat atatched to the Porta Mount in a surprising though not entirely satisfactory manner. The Porta 2 had to bite into the paint of the preatatcheded mounting aparatus. I am now looking forwatd to a 7 inch Orion Mak and hoping(since the Pota 2 mount appears to be my most stable mount) that I can use the 7 inch with the Porta 2 in a way that wont damage the physical aesthetics of the scope itself. Are there places to screw in for atatchments that will not involve unsightly diggings into the appearance of the scope?



#2 Tyson M

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Posted 24 November 2018 - 02:18 PM

I tried the combination with a SW180 mak.

 

If my memory serves me right, you cannot raise the scope in altitude past like 30 degrees or so approx, it is too long, especially with the  diagonal in respects to hitting the center part of the mount head. 



#3 Deepskyclusterstruck

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Posted 24 November 2018 - 03:21 PM

I appreciate your rapid reply as well as the honest caveat about "if memory serves me right." That said...this seems counterintuitive to me. A Mak, even one with a long focal length should be short relatively speaking. I would think a shorter telescope would be less likely to have length issues with any mount. But I am relatively new to all this so perhaps Im wrong. Is this sometimes not the case? Im guessing the very fact that you tried this combination indicates that it atleast at some point was not obvious to you as well so maybe you can enlighten me further on this subject.

Edited by Deepskyclusterstruck, 24 November 2018 - 03:22 PM.


#4 JoeBftsplk

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Posted 24 November 2018 - 03:36 PM

Was thinking about doing this a couple of weeks ago. The responses were discouraging. Ended up deforking my ETX125 and will mount that on the Porta when rings arrive.

The 180 Mak is on hold.

#5 Deepskyclusterstruck

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Posted 24 November 2018 - 04:22 PM

I am almost always it seems taken one step further then the considerations initially envisioned with my questions here on CN. I view that as a good thing. So I will begin with one of the questions that arises from these useful responses.

What is deforking and how precisely is it accomplished(laymans terms please). What was it exactly that compelled you to put your order on hold? Insufficient info? I must admit Im tempted to cancel my order myself unless I get a clearer, fuller, more certain resolution to my inquiries but you did mention unencouraging reports so perhaps at the risk of seeming overly bold may I ask you what you discovered or heard that disuaded you? Your mention of rings relates at least to some extent to my my own issue and suggests to me a solution of sorts to my issue of digging but I'm not entirely sure. Rings are a part of my combo but as I have stated do not resolve the issue of digging...would standard rings solve this?

#6 Simon B

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Posted 24 November 2018 - 08:34 PM

I would very much advise against such a combination.

 

I tried mounting my VMC200L on my Porta II (with the more stable HAL130 tripod) knowing full well that it wouldn't be adequate; I was just curious. Sure enough, it was very wobbly. Settling time was on the order of 3-4 seconds, and I was worried for the integrity and longevity of the gears, especially the altitude gear.

 

The 180 mak is a heavier scope than the VMC200L, so I really can't see it working out too well - even a 150 mak would be pushing it on a Porta II


Edited by Simon B, 24 November 2018 - 08:41 PM.

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#7 dscarpa

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Posted 26 November 2018 - 08:54 PM

 I doubt it would work well. My IM715 was wobbly on my Voyager 1  though for some reason my around the same weight WO ZS110 triplet worked fairly well till the mount fell apart. David


Edited by dscarpa, 26 November 2018 - 08:54 PM.


#8 Rock22

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Posted 26 November 2018 - 09:25 PM

I use my Porta II and 180mm mak only when I feel I really need to see something quickly with the mak.  I have the Orion version of the 180mm mak, and it does "work" on my Porta II, but I definitely do not recommend it.  Mounting it requires some extra effort.  Though it seems stable enough, the scope is big and heavy for the mount.  Slow motion controls are not smooth.

 

On the Porta II (which is a great alt-az mount I should have purchased earlier), the 180mm mak can certainly point higher than 30-deg, much, much higher.

 

As for the marks on the dovetail bar that will be made by the mount screws, that seems rather unavoidable.  I would use a black Sharpie and color in the blemishes.  I did this after my 20mm 100-deg eyepiece that I bought for $209 fell about 2 feet onto some rocks and scratched up the edges... Looks brand new... from 3 feet away.  But it still works 100%, to my relief.

 

I have Sharpies in many colors to match all the items that might get scratched or dinged.


Edited by Rock22, 26 November 2018 - 09:26 PM.


#9 Tyson M

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Posted 26 November 2018 - 09:38 PM

 

 

On the Porta II (which is a great alt-az mount I should have purchased earlier), the 180mm mak can certainly point higher than 30-deg, much, much higher.

 

 

my mistake. I thought I had difficulty with a 2" diagonal and baader click lock clamp hanging off the back....I knew it was limited in altitude but I wasnt sure an exact figure. 



#10 Rock22

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Posted 26 November 2018 - 10:17 PM

my mistake. I thought I had difficulty with a 2" diagonal and baader click lock clamp hanging off the back....I knew it was limited in altitude but I wasnt sure an exact figure.


It does depend on which side the mount’s arm is. The scope will hit the center of the mount head if you mount the mak with the mount arm on the left.

#11 Brent Campbell

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Posted 27 November 2018 - 07:44 AM

I purchased a Porta 2 in combination with a Vixen 80mm achromat. The achromat atatched to the Porta Mount in a surprising though not entirely satisfactory manner. The Porta 2 had to bite into the paint of the preatatcheded mounting aparatus. I am now looking forwatd to a 7 inch Orion Mak and hoping(since the Pota 2 mount appears to be my most stable mount) that I can use the 7 inch with the Porta 2 in a way that wont damage the physical aesthetics of the scope itself. Are there places to screw in for atatchments that will not involve unsightly diggings into the appearance of the scope?

 

I purchased a Porta 2 in combination with a Vixen 80mm achromat. The achromat atatched to the Porta Mount in a surprising though not entirely satisfactory manner. The Porta 2 had to bite into the paint of the preatatcheded mounting aparatus. I am now looking forwatd to a 7 inch Orion Mak and hoping(since the Pota 2 mount appears to be my most stable mount) that I can use the 7 inch with the Porta 2 in a way that wont damage the physical aesthetics of the scope itself. Are there places to screw in for atatchments that will not involve unsightly diggings into the appearance of the scope?

Try this....

 

https://www.amazon.c...stromania&psc=1


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#12 Deepskyclusterstruck

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Posted 27 November 2018 - 04:33 PM

Definitely helpful. Thanks all!

#13 chuckscap

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Posted 04 December 2018 - 07:55 PM

Hi sorry it's not a Porta 2 mount, but I have my TEC 7  f/15 Mak on a Celestron Evolution mount and it works great.   I had to buy a 3 lb counterweight which I attached (gently) to the handle of the OTA, but otherwise no changes.  It clears the mount at zenith with an AP 2" diagonal and 35mm Panoptic.

 

cKqPafZ.jpg

 

cLe9rLq.jpg


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#14 Deepskyclusterstruck

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Posted 04 December 2018 - 08:12 PM

That looks cool and very strange

#15 chuckscap

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Posted 08 December 2018 - 06:33 PM

I know it would look "better" on a nice AP EQ mount, but since I'm a strictly visual observer, I find alt/az viewing so much nicer.   The mount is very solid and  the goto on the Evolution works like a dream.



#16 Hugh Peck

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Posted 08 December 2018 - 11:19 PM

No. The Porta II legitimate weight limit is 11 lbs. That's according to Vixen, not the US distributor who claims 20. I've put both a ETX 125 and a C-6 on one and it may look cool (or not) but the mount is definitely overloaded.

 

ETX-125 with Porta II.jpg

 

IMG_0812-2.jpg


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#17 Deepskyclusterstruck

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Posted 09 December 2018 - 09:29 PM

How about a SkyView Pro Equatorial? My hope: Still light enough to carry but capable of supporting the Mak. Maybe not either?

#18 Deepskyclusterstruck

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Posted 09 December 2018 - 09:39 PM

I looked at the weight of the mount wrong. Igads! Do I want to need the help of a chiropractor?

#19 Hugh Peck

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Posted 09 December 2018 - 10:16 PM

The Astro-Tech Voyager/ES Twilight will work with the 125. This is the A-T version with a 125 on it. The 2" focuser was just to see what it looked like.

 

IMG_0229-1.jpg



#20 Hugh Peck

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Posted 09 December 2018 - 10:25 PM

This is the plate I used to hold it.

https://www.bhphotov...te_for_the.html

 

IMG_0228-1.jpg



#21 Deepskyclusterstruck

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Posted 09 December 2018 - 10:52 PM

No. The Porta II legitimate weight limit is 11 lbs. That's according to Vixen, not the US distributor who claims 20. I've put both a ETX 125 and a C-6 on one and it may look cool (or not) but the mount is definitely overloaded.

ETX-125 with Porta II.jpg

IMG_0812-2.jpg



#22 Deepskyclusterstruck

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Posted 09 December 2018 - 11:01 PM

Haven't clicked the links but how could there be that big a difference?

#23 Simon B

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Posted 10 December 2018 - 12:13 AM

No. The Porta II legitimate weight limit is 11 lbs. That's according to Vixen, not the US distributor who claims 20. I've put both a ETX 125 and a C-6 on one and it may look cool (or not) but the mount is definitely overloaded.

 

Are you saying your Porta II is overloaded with those scopes? That's odd, as I sometimes use a Meade 6" SCT (5.0kg) on mine, and it's near the limit but basically fine - vibrations are under a second.

 

The ETX125 is ~3.3kgs and the C6 is ~3.6kgs IIRC, I would imagine the Porta II can handle these just fine



#24 Jon Isaacs

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Posted 10 December 2018 - 06:27 AM

My two cents:

 

Orion lists the weight at 15.9 pounds with a length of 22.5 inches. That's the bare bones scope. It'll need a few shield, maybe cradle rings and other accessories. It's also about 8 inches in diameter which puts weight off center and increases the load on the mount. It'll be 18-20 lbs when it's ready to go.

Furthermore, this a scope with a 2700 mm focal lsngth. Even with a 2 inch diagonal and a 40 mm SWA, it will barely reach a 1 degree TFoV. This a scope designed for high magnifications. It needs a sturdy mount to perform to anything near it's capabilities.

I've owned a Portamount with the sturdier Hands on Optics wooden legs for more than 10 years. This is a mount designed for an 80 mm refractor, it's a good fit for an 80 mm F/7 ED/apo.  It can be used with a shorter focal length 4 inch Apo if one has reduced expectations. But a 4 inch Apo like the I have is capable of 300x on double stars but also is capable of very low power, wide field views, 4.9 degrees at 13x. In the low to mid power range, freedom from vibration is much less important.

I would also be concerned that the mount would be top heavy and with the weight of the large diameter tube offset from the centerline and shifted back, I would be concerned that it could easily topple over. In some orientations, the legs are narrower, provide less stabilizing moment. 

Bottom line:  This scopescope is much too large and heavy for this mount. Normally I would say that the quickest way to ruin a good scope is to under-mount it.  a scope that vibrates when focusing, in a slight breeze or when it is touched is a scope you will be fighting with to get reasonable views.With a scope that does it's best work at higher magnifications, this is even more true.

In this case however, I think there's the additional risk of the scope tipping over and actually damaging the scope.

This scope deserves a decent mount... it's a $1000 scope, it needs a worthy mount.

Jon


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#25 Paul G

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Posted 10 December 2018 - 08:19 AM

If you want alt-az I'd look for a used Universal Astronomics Unistar or Unistar Deluxe and put it on a stable tripod. It's designed for a 30-40 pound payload and would be a great choice for a scope with that long a focal length.


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