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Hypothetical 4" budget APO choices.. WWJD?

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#1 lamplight

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Posted 24 January 2013 - 10:59 PM

Vixen ED 100mm sf w portamount $1000
Meade 102mm ED APO $1000 used
Skywatcher pro SW ed 100mm about $750ish new

I like the 4" range for size and visual use, don't want to go bigger.. But I don't also want to go smaller... Might do a 90mm if there's some good value in a certain scope..

Pros and cons? Why are the skywatchers SO much cheaper than other APOs? (Other than looks :smirk:) Do they suck horribly? Are others in this price range less than great as well? I'm leaning towards the vixen, decent reviews, brand resell value.. I guess Meade would have that too. although I don't need the portamount it mount it might prove useful.

Find myself browsing refractors and while im happy with the xlt I would like an apo at some point so just .. You know.. Kicking the tires. Thanks!

#2 Jon Isaacs

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Posted 25 January 2013 - 06:35 AM

Pros and cons? Why are the skywatchers SO much cheaper than other APOs?



Skywatchers are good, bascially the same scope as the Orion ED-100, sometimes one sees these on astromart for $400. It's your standard Synta FPL-53 F/9 Doublet.

Both the Meade and the ED-100 look over priced to me.

Jon

#3 lamplight

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Posted 25 January 2013 - 07:13 AM

Thanks Jon just looking but noted. Will keep eyes peeled and keep reading

#4 Jon Isaacs

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Posted 25 January 2013 - 08:10 AM

Thanks Jon just looking but noted. Will keep eyes peeled and keep reading


There is a lot to know about refractors and apo's in particular. In my mind, the Synta 100EDs such as the Skywatcher represent an incredible value. Good optics, good color correction, reasonable mechanical components, nice scopes. At F/9 these scopes are 36 inches long, they are not so handy, definitely not a bird watching scope.

So then the search begins... maybe the ultimate in quality is the search. But often it's a shorter focal length, a sliding dewshield, these start bringing the 4 inch apo closer to being an overgrown 80mm... F/7 is pretty nice. The scopes are there, the 102EDs... like the Lunt and the StellarVue.

But the color correction suffers... so that means a triplet, eventually an FPL-53 triplet... So now were are at about $2000 and rising. Nice scopes, reasonably compact, excellent color correction, good quality mechanicals, a nice wide field of view, 3.5 degrees maybe.

A final step is dealing with the field curvature. Refractors have a curved field of view. The lowest magnifications, widest fields of view, the stars at the edge of the field are slightly out of focus when the stars in the center of the field are in focus. Photographically this is a problem, refractors require the use of a field flattener for this reason.

Visually, it's not a big problem but if one wants to spend even more money... There's the TeleVue NP-101 and Takahashi 106 FSQ. These are both 4 element apo-refractors with a two element rear section that acts as both a focal reducer, field flattener. The Takahashi is designed with astrophotography in mind and is capable of imaging a 10 degree field of view. The TeleVue is more aimed at the visual market place and with a 31mm Nagler provides an essentially perfect 4.5 degree field of view.

For most objects, the difference in the view between a TeleVue NP-101 and a SkyWatcher ED-100 is small. In some ways you don't get a lot for your extra $3000.

Jon

#5 MikeBOKC

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Posted 25 January 2013 - 08:45 AM

Might also look at the TMB 92 series . . . very nice optics and solid build.

#6 howard929

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Posted 25 January 2013 - 08:47 AM

For most objects, the difference in the view between a TeleVue NP-101 and a SkyWatcher ED-100 is small. In some ways you don't get a lot for your extra $3000.

Jon


Tsk. Tsk. True planetary observations are better left to those who are talented enough to buy the VERY best equipment. Any, even a slight deviation from the true path of excellence is left to those poor unwitting souls who are satisfied to (nose very high in the air here) settle for anything less.

I'm joking of course but I have read threads like that here on the forum. Crying out loud, they make it seem like Mount Rushmore would crumble into dust if they deviation from that path. And the dog would just explode.

Jon, good stuff there (as always). Really. Write a book.

#7 Fogboundturtle

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Posted 25 January 2013 - 11:26 AM

the Skywatcher is the best bang for the buck. I have the 80mm version and it been working great for me as visual and guiding scope.

#8 Paco_Grande

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Posted 25 January 2013 - 12:34 PM

...

Pros and cons? Why are the skywatchers SO much cheaper than other APOs?


The question about the Sky-Watcher might be, why are the others so expensive? Indeed, why? I've seen numerous posts here on CN, guys who've sold their TV 102s (or at least have both) and kept the Sky-Watcher ED100 because it's simply that good for the money! I'm impressed. Sky-Watcher would be my choice for sure for an ED of that f ratio.

#9 newtoskies

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Posted 25 January 2013 - 12:43 PM

lol Matt you gonna buy another scope..lol

#10 Fogboundturtle

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Posted 25 January 2013 - 12:54 PM

...

Pros and cons? Why are the skywatchers SO much cheaper than other APOs?


The question about the Sky-Watcher might be, why are the others so expensive? Indeed, why? I've seen numerous posts here on CN, guys who've sold their TV 102s (or at least have both) and kept the Sky-Watcher ED100 because it's simply that good for the money! I'm impressed. Sky-Watcher would be my choice for sure for an ED of that f ratio.


my only pet peeve and its really a minor thing, I found the 2 speed focuser to be not to my standard. That's because I have an very good focuser on my Meade Triplet. That's my only minor complaint about the Sky-Watcher. Its an easy fix too.

#11 JoLo

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Posted 25 January 2013 - 01:28 PM

I luv my AT106 triplet but have a gripe similar to Mr. Turtle's above....the two speed focuser is good, but not great. When using barlows and an extension with my Imaging Source camera, I run into some slippage...with just my DSLR, no problems. I am going to replace the focuser and be a happy boy.

For less than 2K, I got the 106, the ATQ65, and a flattener for the 106. Both are excellent scopes, the 65 does triple duty as a guide scope, my primary birding scope, and a mighty fine wide field imager in its own right.

Joe

#12 csrlice12

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Posted 25 January 2013 - 01:35 PM

J would take that 4" and reshape it into a large mirror............

#13 Jon Isaacs

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Posted 25 January 2013 - 01:54 PM

...

Pros and cons? Why are the skywatchers SO much cheaper than other APOs?


The question about the Sky-Watcher might be, why are the others so expensive? Indeed, why? I've seen numerous posts here on CN, guys who've sold their TV 102s (or at least have both) and kept the Sky-Watcher ED100 because it's simply that good for the money! I'm impressed. Sky-Watcher would be my choice for sure for an ED of that f ratio.


If "that good for the money" is the deciding factor, then a good quality, less pricy scope will nearly always win. One can make the same argument for the 102mm F/10 achromat versus the Synta ED-100's. As one moves up the ladder the differences are smaller and smaller.

No doubt about it, the Synta ED-100s are an amazing value. When they hit the market 7 or 8 years ago, they were about $1000 and that was a bargain. Now, they have come down in price, it's a lot of scope for the money. Mechanically, they are sufficient, very similar to the Synta Achromts, nothing fancy. If a three foot long, 100mm F/9 refractor will serve you needs, then it's certainly a good place to start.

Myself, I am generally on the budget side of things not in this case. I worked my way up to a 4 inch as a step up from an 80mm. Short focal length, short scope, well suited for an alt-az mount... an 100mm apo with body of an ED-80.

The classic is the Astro-Physics Traveler. These are the original 4 inch F/6 triplet... They haven't been made for about 10 years, used ones go for around $5000. Sue French uses an Traveler for her column.

Jon

#14 Tony Flanders

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Posted 25 January 2013 - 02:02 PM

I am generally on the budget side of things not in this case.


There's something to be said for that. One might argue that if you want a budget-priced refractor, why not buy a reflector? A 150-mm f/6 reflector would be roughly the same size and weight as a 100-mm f/9 refractor, considerably easier to mount, even more free from false color, and have much greater resolution and light-gathering.

At some level, perfection is the whole draw of refractors -- at least in the larger sizes.

#15 Paco_Grande

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Posted 25 January 2013 - 02:25 PM

my only pet peeve and its really a minor thing, I found the 2 speed focuser to be not to my standard.


I was going to mention that, but who knows? Each of us makes various trade-offs with our toys. I mean, the scope costs $750 and a Feathertouch costs half of that. But for a couple hundred a nice GSO might make sense. :shrug:

#16 Paco_Grande

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Posted 25 January 2013 - 02:29 PM

BTW, I understand it's just not really fair to compare the SW and the TV, it's like comparing a Mini Cooper to a Porsche. It's simply the value quotient, and that usually changes for each of us over time. What was important becomes less important, or vice versa, etc..

#17 bierbelly

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Posted 25 January 2013 - 03:27 PM

I wasn't aware that Jerry was interested in astronomy.

#18 lamplight

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Posted 25 January 2013 - 03:41 PM

I ask him all the deep questions :) (I am a fan)

#19 Jon Isaacs

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Posted 25 January 2013 - 03:43 PM

BTW, I understand it's just not really fair to compare the SW and the TV, it's like comparing a Mini Cooper to a Porsche. It's simply the value quotient, and that usually changes for each of us over time. What was important becomes less important, or vice versa, etc..


I think it is fair to compare a TeleVue 102 to the Skywatcher ED-100 They are both very similar scopes, the Televue has a focal length of 880mm, the Skywatcher 900mm. It is even fair to compare the Skywatcher ED-100 to the TeleVue NP-101 even though the NP-101 has a 540mm focal length with it's legendary flat field and total lack of chromatic aberration. I have made that comparison myself.

Comparisons are valuable because they provide information and understanding, awareness. There is a choice to made between a Skywatcher 100 and a TV NP 101... However, comparisons should be made without expectations...

Tony's point is an important one. Apo refractors are a pursuit of perfection. Without looking through a variety of scopes, looking at a variety of scopes, it's hard to understand what the differences are, what is the difference at the eyepiece between a $750 Skywatcher and a $4000 TeleVue?

The Skywatcher ED-100 is quite perfect. The TeleVue NP-101 is just about as perfect as we mortals will ever experience.

Jon

#20 bierbelly

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Posted 25 January 2013 - 04:11 PM

I ask him all the deep questions :) (I am a fan)


So do/am I...and I'm pretty sure I know what his answer would be... :cloudy:

#21 lamplight

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Posted 25 January 2013 - 04:26 PM

Well I bought a nice JMI focuser ona whim and then started thinking I should put this ona better scope.. So the comments on focuser upgrades are good news. I didn't realize there were such big differences even in APOs so ill get reading. I am just now understanding that the color correction needed varies from design to focal length and I d just assumed that all APOs had corrected color. Jerry would go for the purest view for sure. I'm wondering if its even worth it where I live as I've been using my achro a lot with the cold (easy to bring out) and I can't find a lot of the objects I have found with my SCT, so I just don't know. Now I see an sv102 for 700, and a vixen ed103s for 1500. See these used ones are going for about 75% of new, so while not a steal they're not breaking the bank. I did not intend this to be a teach me everything about APOs , this must get so boring for you guys.. Ill do my own research, but I do thank you for making me aware of some of the differences so I can go from there. I'm thinking at a used price it might be nice to just see side by side how one of these doublets compares to my achro.


So can I ask: in a more affordable doublet design, what kind of focal ratio should I be looking at in a 100mm 4" scope with the -least- chromatic aberration ? Nothing faster than say F/7 or is that pushing it? Is the question too oversimplified? :bow:

All the years combine.. They melt into a dream... - stellarvue, I mean Stella blue. ;)

#22 lamplight

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Posted 25 January 2013 - 04:29 PM

lol Matt you gonna buy another scope..lol


Still have to pay the balance on my DOB when it is ready to ship so I have to, gasp, take it slow on this.. :shocked:

#23 Jon Isaacs

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Posted 25 January 2013 - 04:36 PM

Matt:

I suggest reading this review of the Astro-Tech 102ED, it's essentially the same scope as the StellarVue 102ED, the Orion 102ED Premium and the Lunt 102ED.

Astro-Tech 102ED

You might notice my able assistant, Monkulus who was pictured earlier this week viewing through a 125mm Cometron Jr.

Jon

#24 lamplight

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Posted 25 January 2013 - 04:36 PM

Maybe I need to rethink this . I have reflector and SCT for added light grasp. Only reasoni wanted to stay at 4" as that seemed the largest size that I wanted to deal with to get the most aperture. I just got a new book in to , the Messier objects, and was reading about M79 which I've been unable to detect other than as a faint star in the reflector. I'm sure part of that is the seeing as I haven't had anything good since the fall even on "clear " nights, but even so I'm sure I didn't have perfect conditions then and did not have trouble finding and viewing M79 with the SCT .

Maybe just an 80mm triplet for grab n go and occasional AP (NOT first priority!). But then extra aperture is always good right? Argh.

#25 Paco_Grande

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Posted 25 January 2013 - 08:53 PM

I think it is fair to compare a TeleVue 102 to the Skywatcher ED-100 They are both very similar scopes,


Well, yeah. Compare up to a point. I've owned both Mini Coopers and Porsches and can safely say the Mini is just as fun to drive, plus you don't have the worry of parking dings, nor the cost of repairs. That said, when it comes down to it, the lap times between a Mini and a Porsche don't provide any useful information to a prospective buyer. You also need to drive both to understand. :whistle:






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