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Any APOs you would avoid?

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#76 Nippon

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Posted 06 April 2021 - 08:53 AM

Not sure who posted the comment about the 115 mm refractor that was barely good at 30 times per inch and that it would only be good enough possibly to give to a kid starting out? I think that's somewhat foul play considering the probable price difference between that refractor and a Takahashi or a astrophysics or whatever high end you want to swing at it.
Some of us don't have that kind of money. Doubtful that a 'kid' is going to have that kind of money either by the time they have to get the scope, mount,eyepieces etc to make everything work. I definitely don't consider Chinese apochromat refractors low end. Also 30x per inch is on the low end for my eastern scopes, that I do know.

I have never met a refractor that is not a toy and in proper working order that can not muster x50 per inch. Good samples of  premium models can get too or near  x100 per inch but I only find that useful for close doubles or the Moon on very good nights. And even then mostly just for the fun of it. To paraphrase Al Nagler don't use more magnification than needed to reveal the detail you wish to see.


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#77 russell23

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Posted 06 April 2021 - 09:03 AM

I have never met a refractor that is not a toy and in proper working order that can not muster x50 per inch. Good samples of  premium models can get too or near  x100 per inch but I only find that useful for close doubles or the Moon on very good nights. And even then mostly just for the fun of it. To paraphrase Al Nagler don't use more magnification than needed to reveal the detail you wish to see.

Agree!  Observing the Moon on nights of excellent seeing I’ve been able to get to 100x per inch with both my SW120ED and my SV102 Access.  On the planets 50-70x per inch is no issue with those scopes. 


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#78 gezak22

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Posted 06 April 2021 - 09:07 AM

I would only avoid those without user reports as I don't want to be a beta tester.



#79 teashea

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Posted 06 April 2021 - 09:31 AM

I dunno, not many. Reaching back to think of all of the negative reports on apos I've heard of, there aren't a lot.

 

I've heard a bunch of negative reports about the Takahashi Sky 90 although I've never personally seen one (or any Takahashi).

 

The old Meade 5-7" apochromats (particularly the 7") are notorious for having bad lens cells and becoming hopelessly miscollimated. That's probably the worst experience with apos I've heard over the years.

It is interesting that some people did not like the Sky90 because the overwhelming number of reports were so positive. Very curious.  

 

All my Takahashi telescopes are excellent.  Wonderful optics and beautiful build and finish quality.


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#80 teashea

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Posted 06 April 2021 - 09:33 AM

Ok, you win, not going to argue on this post.  I would much rather have a variety of scopes to pick from on a given night based on seeing conditions then just one scope.  30X per inch is still lower than I have used on my 130 to give what 'I' consider fantastic views of  Jupiter and Saturn.  Seeing conditions permitting I have used my 6mm Delos without image break down.  Never done a side by side with a better refractor because I frankly just don't know anyone around here that owns one. I'm not out to gauge performance.

I just don't believe the marginally better performance of a scope that cost 3x mine is worth it...that is just my opinion.

Oh, and I don't believe either of the two APO scopes I own would be scopes to avoid.

I can understand that.  To me the 3x price is worth it - for the optics and build and finish quality.



#81 teashea

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Posted 06 April 2021 - 09:35 AM

Often miffs me to see post on refractors with collimating  issues, oldest design in telescope history and yet certain scopes even from high end manufactures still struggle, just hits me as something that would be standardized by now, I’ve heard my AT edl will have an adjustable cell while the regular ED does not, really no idea if I will ever have to adjust or why the design is different.... it honestly does not seem cost should be a consideration on this although it does seem more prevalent the more money you speed

Precision and build quality cost money.  It costs more to engineer and manufacture a lens cell that does not need collimation.  


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#82 teashea

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Posted 06 April 2021 - 09:39 AM

 

It's no legend. As a mechanical engineer/researcher, i consider it a design flaw. Here's the problem:

 

The NP-101 objective cell is held in place with three screws. The tilt of the objective is held in alignment by these screws. The holes in the objective cell are larger than the screws so this allows a certain amount of room adjusting the tilt. 

 

It also means that it's possible that if the cell is bumped somehow, it can get knocked out of alignment.  In my mind as an engineer, there should be set screws that allow positive adjustment of the tilt. As it was, I built my own...

 

When I purchased my NP-101 used in 2010, someone had already fussed with the alignment screws and at 300x I could see the diffraction rings were not radially symmetrical.. 

 

I built myself a collimation jig so I could loosen the screws and tweak the collimation. This is that story:

 

https://www.cloudyni...g-my-tv-np-101/

 

post-3933-14073119232914_thumb.jpg

 

Since I wrote that, others have had issues as well.

 

The good news is that since I collimated it in 2010, it has remained in collimation despite having traveled at least 10,000 miles in its soft case in the bed of a pickup plus taking a nose dive into the dirt when I bumped into it and knocked the tripod over..  the Telrad helped absorb the energy.

 

 
 
Jon

 

very informative.  Thanks for the good analysis.



#83 Nippon

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Posted 06 April 2021 - 11:06 AM

 

It's no legend. As a mechanical engineer/researcher, i consider it a design flaw. Here's the problem:

 

The NP-101 objective cell is held in place with three screws. The tilt of the objective is held in alignment by these screws. The holes in the objective cell are larger than the screws so this allows a certain amount of room adjusting the tilt. 

 

It also means that it's possible that if the cell is bumped somehow, it can get knocked out of alignment.  In my mind as an engineer, there should be set screws that allow positive adjustment of the tilt. As it was, I built my own...

 

When I purchased my NP-101 used in 2010, someone had already fussed with the alignment screws and at 300x I could see the diffraction rings were not radially symmetrical.. 

 

I built myself a collimation jig so I could loosen the screws and tweak the collimation. This is that story:

 

https://www.cloudyni...g-my-tv-np-101/

 

post-3933-14073119232914_thumb.jpg

 

Since I wrote that, others have had issues as well.

 

The good news is that since I collimated it in 2010, it has remained in collimation despite having traveled at least 10,000 miles in its soft case in the bed of a pickup plus taking a nose dive into the dirt when I bumped into it and knocked the tripod over..  the Telrad helped absorb the energy.

 

 
 
Jon

 

I remember seeing your rig you built for TV collimation after I had to collimate the lens cell of a Pronto. And I thought that's the way to do it. I agree the three screws in the oversized holes really give an opportunity to get knocked out of collimation. I was relived to read somewhere when I later owned a TV 85 that those screws are not just threaded in to the aluminum tube but in to pem nuts on the inside of the tube. Which with a flashlight you can see as bumps in the TV flocking. Most scopes I know of these days the cell is threaded on to the tube with no adjustments to square the cell to the tube. So if everything is right when it is built it is pretty hard to knock it out short of bending the tube.



#84 Wildetelescope

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Posted 06 April 2021 - 01:24 PM

Refractors are not immune to collimation issues. Triplets are much more susceptible than doublets and probably have to go back to the factory for collimation.

 

I have an NP-101. The previous owner had messed with the collimation. I was able to align it myself.

 

https://www.cloudyni...g-my-tv-np-101/

 

TeleVue customer support is telephone based and you just might get Al Nagler.  When I had a question about my Paracorr 2, David Nagler answered and turned me over to Paul Dellechiaie, Paul designed the Paracorr 2.

 

It doesn't get any better than that...

 

Jon

My suspicion is that there are many more happy NP TV 101 users than not.  My TV102 is built like a tank.

 

JMD  


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#85 Bowlerhat

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Posted 06 April 2021 - 03:41 PM

Maybe a Chinese optical house could build an objective that would stack up to Astro-Physics, TEC, or LZOS. Or even Canon Optron.

 

But no one is seeing that yet, are they?

This is true, I think we never really know what's going on inside the internal market. It reminds me of korean astro stuffs which are known but obscure that finally made it through western market.

We don't even know, say, if it's a custom order, maybe? Something like tak FCT 150 or Showa 150 FRT. 


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#86 25585

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Posted 06 April 2021 - 04:06 PM

I have never met a refractor that is not a toy and in proper working order that can not muster x50 per inch. Good samples of  premium models can get too or near  x100 per inch but I only find that useful for close doubles or the Moon on very good nights. And even then mostly just for the fun of it. To paraphrase Al Nagler don't use more magnification than needed to reveal the detail you wish to see.

200x would be good where I live, at the foot of hills, edge of a valley. Its how well & how much I see at any magnification that counts. 120mm beats 100mm. My 150mm F8 Newtonian is beaten by my 120mm refractors, but my 200mm to 300mm aperture scopes, Dobs & a SCT, show much much more. Often a 200mm Dob is ideal for convenience & handling in & out of cars. Its F6 solid tube so collimation stays OK. I use an 80mm finder, which doubles as a rich field scope in its own right.

 

Taking a refractor on its own out, I would choose a 100mm, as they need less heavy mounts & tripods.


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#87 godelescher

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Posted 06 April 2021 - 05:01 PM

I'm glad this thread has taken a life of its own. I just wish more than a couple of people had actually answered the question I originally asked. I guess no one wants to, though. That's just as informative.

 

Thanks anyway.



#88 russell23

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Posted 06 April 2021 - 05:46 PM

I'm glad this thread has taken a life of its own. I just wish more than a couple of people had actually answered the question I originally asked. I guess no one wants to, though. That's just as informative.

 

Thanks anyway.

I think it is the way you asked the question.  It is one thing to recommend for a specific piece of equipment.  It is another to recommend against a piece of equipment.  That happens sometimes, but in general most people would prefer tell you why they like A over B than tell you to avoid B. 


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#89 godelescher

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Posted 06 April 2021 - 06:02 PM

I think it is the way you asked the question.  It is one thing to recommend for a specific piece of equipment.  It is another to recommend against a piece of equipment.  That happens sometimes, but in general most people would prefer tell you why they like A over B than tell you to avoid B. 

I think, in general, most people just want to talk about themselves and make themselves seem interesting. Generally speaking, of course.


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#90 Nippon

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Posted 06 April 2021 - 06:10 PM

And sometimes a person blames a scope for poor performance when it's an operator who does not know what they are doing. I read one where the guy said such and such scope was terrible, a waste of money. When asked what the situation that he was using it was he said he was trying to view Saturn if  I remember correctly and he said he was viewing through an open window in his living room.



#91 GoodAsh

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Posted 06 April 2021 - 07:22 PM

I think, in general, most people just want to talk about themselves and make themselves seem interesting. Generally speaking, of course.


+1

#92 russell23

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Posted 06 April 2021 - 07:27 PM

I think, in general, most people just want to talk about themselves and make themselves seem interesting. Generally speaking, of course.

Do you think that explains why people haven’t really answered your original question?  

 

My interpretation of the discussion on this forum is that people love to talk about their equipment and what they like and dislike about it.  So there is always an element of “themselves” in their discussion of the equipment.  I don’t think there is anything wrong with that. 


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#93 Kevin_A

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Posted 06 April 2021 - 08:58 PM

It sounds like a spacing/flattener issue, especially with issues in the corners.  I also had issues in the corners with the 61a and the ASI294MC Pro, until I got the correct backspacing, it may be more prevalent with a full frame/mirrorless camera.  I don't think pinched optics are only limited to the corners, but across the field...?  I may be wrong...

 

There are a lot of these little scopes out there, the WO Z61, AT60ED, Apetura 60EDR, and TS had one also..

 

The first scope i received had 2 corners where the stars had coma and were elongated outwards and 1 corner was good and the other corner they were elongated sideways.... no spacing can fix that and i tried. The second replacement has 4 difraction spikes even when the rear screws are loose. The stars get better if you have many dew heaters running but even then they are not round but spikey..... and that is the center stars and all over the frame on both aps-c and fullframe.

It is still good for visual but thats not my intended use. Cheers!


Edited by Kevin_A, 06 April 2021 - 08:59 PM.


#94 Wildetelescope

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Posted 06 April 2021 - 09:26 PM

I'm glad this thread has taken a life of its own. I just wish more than a couple of people had actually answered the question I originally asked. I guess no one wants to, though. That's just as informative.

 

Thanks anyway.

If you are really looking for negative feedback on scopes, you will find it for pretty much EVERY brand here on CN, INCLUDING the really expensive ones.  Just takes a quick search of the threads. The reality is that most scopes that you can buy today are actually pretty darn good for their respective price point.  All brands have QC issues, and generally the more you spend the less likely you will run into them.  If you purchase from a reputable vendor, like Astronomics, they will usually take care of any QC issue that arises with a minimum of fuss.  The mass produced optics that come out of China and Taiwan have gotten REALLY good.  Most complaints(outside of quality control issues) regarding gear today are quite subjective when you drill down into them.  That does not mean they are not valid to the individual who has the complaint, but rather that complaint might not be broadly applicable.  The Televue example earlier in the thread is a good example.  Every Televue scope I have personally looked through has been excellent to my eyes.  If my Televue scope were to ever loose collimation, I would personally have no problem spending the money to send it to TV to collimate.  This is true for my TV102, and would certainly be true if I owned one of their Petzvals.  Others will not purchase Televue scopes because they are not designed to be collimated by the user.  I can understand that choice.  But that does not mean TV makes a bad scope.   I would suggest that understanding what you want from the scope in terms of performance, and what you are willing to pay for that performance is probably of greater value in deciding which scope to buy, than hearing other peoples horror stories. 

 

Best of Luck.

 

JMD


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#95 Jaimo!

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Posted 06 April 2021 - 09:42 PM

The first scope i received had 2 corners where the stars had coma and were elongated outwards and 1 corner was good and the other corner they were elongated sideways.... no spacing can fix that and i tried. The second replacement has 4 difraction spikes even when the rear screws are loose. The stars get better if you have many dew heaters running but even then they are not round but spikey..... and that is the center stars and all over the frame on both aps-c and fullframe.

It is still good for visual but thats not my intended use. Cheers!

I just can't imagine why it would only "pinch" in the corners? 



#96 Traveler

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Posted 06 April 2021 - 10:53 PM

I would avoid every 80-120mm APO when one didnt get a view (visualy) through a 250 - 400 euro 150mm F8 Newton...on DSO's, Moon and planets...those Newtons can give worldclass APO's a very hard time...take a look through one if you consider an APO first... 

 

(and to be sure, this statement is about the views through the instrument only, not about other things)


Edited by Traveler, 06 April 2021 - 10:55 PM.

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#97 RichA

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Posted 06 April 2021 - 11:48 PM

WO Megrez 88mm.  White scope, gold band on the bottom of the dewshield.  Just a downright poor performer,  the one I had.  I've owned a couple hundred scopes and aside from one or two SCTs  that didn't make the grade, this was the bottom.


Edited by RichA, 06 April 2021 - 11:49 PM.


#98 RichA

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Posted 06 April 2021 - 11:51 PM

It is interesting that some people did not like the Sky90 because the overwhelming number of reports were so positive. Very curious.  

 

All my Takahashi telescopes are excellent.  Wonderful optics and beautiful build and finish quality.

Sky 90 due to its focal ratio pushed the boundaries for a doublet of that diameter.  Better in that case to get a triplet from AP, maybe Baader


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#99 Mitrovarr

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Posted 06 April 2021 - 11:53 PM

Sky 90 due to its focal ratio pushed the boundaries for a doublet of that diameter.  Better in that case to get a triplet from AP, maybe Baader

What I've heard is that it gets out of collimation really easy and is hard to fix.



#100 Suavi

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Posted 07 April 2021 - 02:29 AM

I would avoid every 80-120mm APO when one didnt get a view (visualy) through a 250 - 400 euro 150mm F8 Newton...on DSO's, Moon and planets...those Newtons can give worldclass APO's a very hard time...take a look through one if you consider an APO first... 

 

(and to be sure, this statement is about the views through the instrument only, not about other things)

That is a great idea. My first telescope was a 150mm F/8 Newtonian, and although it was rather inexpensive and therefore built quality was on a simple side, it did perform wonderfully, to my eyes at least. Now I have two f/6 triplets, one 80mm and the other 105mm, and even though I had fun with the Newtonian, I do not miss it for a few reasons that matter to me.




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