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102ED for Sure -- but F7 or F11?

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#1 Bomber Bob

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Posted 16 November 2019 - 12:02 AM

Coming up on the 2nd anniversary of ordering my APM 152ED, and I will be buying one of these 102mm ED refractors...

 

The Astro-Tech F7  -->  https://www.astronom...a.html?___SID=U

 

- OR -

 

The TS-Optics F11  -->  https://www.teleskop...AP-Focuser.html

 

My sessions are 95% visual observing, and my imaging is almost exclusively planetary.  I already have 2 outstanding Classic 4" achromatics -- F10 & F15 -- so I really don't need another 4" refractor... and?  The F7 is a better fit in my line-up, but I've read lots of very good posts on the F11.  IOW:  I can think of lots of pros / cons...

 

If you've owned either / both of these EDs, I'd appreciate your opinions on them:  Optics, mechanics, fit & finish, and anything else you'd like to share.

 

Thanks!!

 

 



#2 Astrojensen

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Posted 16 November 2019 - 02:07 AM

Well, you already know my stance on the topic, so no need to elaborate ad infinitum, but for planetary observing, I *strongly* recommend the f/11. To recap:

 

 

Optics: Excellent, very close to a TMB 100/800 I had on loan, except for a tad of false color (really a non-issue, in most cases it's not visible at all). 

 

Mechanics: Good to excellent. The removable tube section part on mine wasn't so well excecuted, but once I changed it to Baader M68 parts, it works perfectly. 

 

Fit and finish: Excellent (once the removable section is gone and changed to M68 parts). 

 

 

Caveat: You need to have it on a big, heavy mount, because these scopes love high magnifications and you're going to use them, because the optics are amazing, so you need all the stability you can get. 

 

 

Clear skies!
Thomas, Denmark


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#3 Jond105

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Posted 16 November 2019 - 03:37 AM

Well... I of course would say the 102ED, lighter, manageable mounting requirements, wide field, and, you get a nice CN discount. Always nice to support our sponsors. 
 

 

Though, if it were me, I’d go the F/11. Why, because I’ve been spoiled with color free images. And at high power I really don’t want to see color. So since you aren’t throwing in the SW100ED, I’d say go F/11 for better color at the higher powers. 


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#4 stevew

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Posted 16 November 2019 - 04:13 AM

Coming up on the 2nd anniversary of ordering my APM 152ED, and I will be buying one of these 102mm ED refractors...

 

The Astro-Tech F7  -->  https://www.astronom...a.html?___SID=U

 

- OR -

 

The TS-Optics F11  -->  https://www.teleskop...AP-Focuser.html

 

My sessions are 95% visual observing, and my imaging is almost exclusively planetary.  I already have 2 outstanding Classic 4" achromatics -- F10 & F15 -- so I really don't need another 4" refractor... and?  The F7 is a better fit in my line-up, but I've read lots of very good posts on the F11.  IOW:  I can think of lots of pros / cons...

 

If you've owned either / both of these EDs, I'd appreciate your opinions on them:  Optics, mechanics, fit & finish, and anything else you'd like to share.

 

Thanks!!

As you already have a couple of long focus 4 inchers, I'd suggest the F-7 Astro-Tech as an alternative to what you have and for a more easily deployable instrument.

Having a small 4 inch scope means it gets used more often.

If it is well corrected it will easily be able to handle higher powers with a barlow or short focal length eyepiece.

It will also be interesting for you to make comparisons to your other 4 inchers.


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#5 Jon Isaacs

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Posted 16 November 2019 - 05:26 AM

My own thinking:

 

A 4 inch refractor should an all around scope, it does everything quite well and is essentially limited by its aperture.  Larger aperture scopes will be better at the planets and double stars so it's better to choose the shorter focal length that is more portable and more versatile.  An 102mm F/7 is capable of terrestrial and even birding from a stationary site. 

 

6638360-Osprey 2 Bright CN.jpg
 
(Taken with an Astro-Tech AT-102ED)

 

Mechanically, the two scopes are likely very similar.. My friend Jack's AT-102ED is a beautiful scope with very good fit and an very good focuser.  There is slight CA visible at high magnifications on bright targets. 

 

Jon


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#6 Bomber Bob

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Posted 16 November 2019 - 08:02 AM

Well... I of course would say the 102ED, lighter, manageable mounting requirements, wide field, and, you get a nice CN discount. Always nice to support our sponsors. 
 

 

Though, if it were me, I’d go the F/11. Why, because I’ve been spoiled with color free images. And at high power I really don’t want to see color. So since you aren’t throwing in the SW100ED, I’d say go F/11 for better color at the higher powers. 

I limited this selection to 2 choices because the last time I looked at so many candidates I confused myself!

 

Yes, I like the idea of supporting our Sponsor, and the AT gets good reviews.  Also, my 3 current "APOs" are all F8, and I've found that to be a very convenient OTA.  OTOH, my Dakin 4" F10 is my "workhorse" refractor, and I like the double star & star cluster views in it.  (And a side by side between the F10 & the F11 would be interesting to me.)

 

I'm also thinking about buying Both, comparing them directly, and keeping just one.  But... knowing myself... I'd wind up keeping both -- and I really (really!) don't need 4 x 4" refractors!

 

On the WTB Decision:  In 2017, I waited until the Black Friday Sales to click that Buy Button.  No lie, I was down to the wire between the APM 140 vs. 152.  IMO, both these EDs are a good price Now, but would y'all wait the 2 weeks, or go ahead and get the order in before the real Shipping Insanity starts?


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#7 vkhastro1

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Posted 16 November 2019 - 08:39 AM

Well, you already know my stance on the topic, so no need to elaborate ad infinitum, but for planetary observing, I *strongly* recommend the f/11. To recap:

 

 

Optics: Excellent, very close to a TMB 100/800 I had on loan, except for a tad of false color (really a non-issue, in most cases it's not visible at all). 

 

Mechanics: Good to excellent. The removable tube section part on mine wasn't so well excecuted, but once I changed it to Baader M68 parts, it works perfectly. 

 

Fit and finish: Excellent (once the removable section is gone and changed to M68 parts). 

 

 

Caveat: You need to have it on a big, heavy mount, because these scopes love high magnifications and you're going to use them, because the optics are amazing, so you need all the stability you can get. 

 

 

Clear skies!
Thomas, Denmark

Definitely agree with Thomas ! Go with the Starwave 102ED f/11.

 

I owned a Stellarvue SV102ED (f/7), SV110ED (f/7), TV102 (f/8.6), Vixen FL102S (f/8.8) and  Altair Starwave 102ED (f/11) - unfortunately not all at the same time but at least 3 at one time.

 

This is what remains:

 

Vixen FL102S (Fluorite doublet) was optically and physically superior to the TV102 FPL53 doublet).

 

Altair Starwave 102ED over the SV102ED and SV110ED - better contrast.

(The fit of the binofriendly section of my Starwave 102ED is excellent. However the ability to quickly convert to binofriendly use with the use of the Baader M68 focuser upgrades makes it a dual purpose scope). I am not sure if binoviewing with no OCS is a priority for you but it is for me).


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#8 drd715

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Posted 16 November 2019 - 08:40 AM

I limited this selection to 2 choices because the last time I looked at so many candidates I confused myself!

Yes, I like the idea of supporting our Sponsor, and the AT gets good reviews. Also, my 3 current "APOs" are all F8, and I've found that to be a very convenient OTA. OTOH, my Dakin 4" F10 is my "workhorse" refractor, and I like the double star & star cluster views in it. (And a side by side between the F10 & the F11 would be interesting to me.)

I'm also thinking about buying Both, comparing them directly, and keeping just one. But... knowing myself... I'd wind up keeping both -- and I really (really!) don't need 4 x 4" refractors!

On the WTB Decision: In 2017, I waited until the Black Friday Sales to click that Buy Button. No lie, I was down to the wire between the APM 140 vs. 152. IMO, both these EDs are a good price Now, but would y'all wait the 2 weeks, or go ahead and get the order in before the real Shipping Insanity starts?

A difficult decision. I have been quite fascinated by the F-11 ed as a planetary/lunar scope providing a sharp image. (I may get one yet). But the F-7 would be superior for wider viewing such as Andromeda and as a grab-and-go setup on a light mount. I guess you better get both to do that comparison.

Definitely a difference in mount requirements.

The good thing is that the price/value on both of these scopes is excellent.

Wish I could find a similar F-11 ed in a 130mm ed objective size, but doesn't seem to exist in the reasonable price range.

Sent from my SM-N950U using Tapatalk

#9 jag767

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Posted 16 November 2019 - 09:07 AM

F11, no question. Startest on mine is stunningly excellent, and it consistantly punches above its weight.
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#10 punk35

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Posted 16 November 2019 - 09:19 AM

I have the AT102ED, and before that a Celestron C4R 4”f10 achro.  The C4R gave good views but it only took one session with the AT102ED to notice that the views were better. Less CA, and a more crisp view of everything. I’m not sure if that’s because of the ED glass, a better overall figure of the lens or both. The AT also has a very nice two speed focuser and a beautiful paint job. 
CA is there, but it’s not terrible and I was surprised how much less there was in the AT at f-7 compared to the f-10 achro.

 

I think the F-7 is a better fit in your lineup.


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#11 Xeroid

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Posted 16 November 2019 - 11:58 AM

Get both and test otherwise if you get just one, YA WILL KNOW ABOUT THE OTHER and it will drive you nuts..lol.gif


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#12 Bomber Bob

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Posted 16 November 2019 - 01:21 PM

Get both and test otherwise if you get just one, YA WILL KNOW ABOUT THE OTHER and it will drive you nuts..lol.gif

Have you been talking to my Therapist?  He is such a blabber-mouth!  I do try to take a conservative approach with gear:  I listened to y'all yak about fluorites for years before I bought one.  Ditto for Takahashi until I finally bought one.  Ditto for these China-made EDs before I bought one.  I've been so happy with my 152, and I get so much observing done with my 4" fracs -- that's why I'm pulling the trigger.  But, two near-identical EDs?   OTOH, these prices are so low compared to what we had 40 years ago... and you get so much more scope!

 

BIF:  I can blame Thomas for this buy -- all that ED this & F11 that.


Edited by Bomber Bob, 16 November 2019 - 01:24 PM.

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#13 Mr. Mike

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Posted 16 November 2019 - 01:26 PM

I dunno - I think F/11 is too restrictive of a FOV for overall use.  If its just for local celestial objects then fine but F/7 is way more versatile.  And, if the optics are done right then the flase color diference should be trivial.  Or just do what I did and get an F/7 triplet for a little more and say goodbye to false color entirely. :)


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#14 Tyson M

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Posted 16 November 2019 - 02:02 PM

I think you answered your own question with your opening post.  You have a couple long focal length refractors already in that aperture size.

The AT102 is another "tool" in your tool belt, which means it is likely to serve a purpose or hole left currently unfilled.


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#15 Bomber Bob

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Posted 16 November 2019 - 02:18 PM

So, is the OTA WT on the sites pretty accurate?

 

AT F7 = 9 lbs

TS F11 = 11 lbs

 

It's not a Yuge concern -- my Dakin F10 weighs 14 lbs! -- but every bit helps with portability.  Add at least 1 finder + 2" diagonal + 2" eyepiece, and grab & go becomes tote & stop.  I'd be more likely to use the F7 on an AZ vs. an EQ mount except for planetary, so that's kinda a wash.

 

Honestly, the features seem near identical to me, so it boils down to The Views, and what I tend to use my 4" refractors for most often.

 

I plan on getting my order in next week, so I'll be thinking out loud on this thread a lot.


Edited by Bomber Bob, 16 November 2019 - 02:42 PM.

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#16 Astrojensen

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Posted 16 November 2019 - 02:31 PM

I dunno - I think F/11 is too restrictive of a FOV for overall use. 

That's not really been my experience at all, but perhaps I'm less than a wide-field enthusiast than most people. I believe the purpose of a telescope is precisely to get close to the objects we like to see. For the very low power views, binoculars or a much smaller telescope really is better suited, in my opinion. 

 

And it's not like the 4" f/11 is super narrow anyway, as the 40mm ES68 can give a TFOV over 2.4° wide. 

 

 

Clear skies!
Thomas, Denmark


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#17 Don Taylor

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Posted 16 November 2019 - 02:42 PM

Thomas beat me to it - i don't have the 40mm ES68 but the Meade 40 mm SWA 5000 cousin. If i need anything wider i use the Borg77 or binoculars.
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#18 Bomber Bob

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Posted 16 November 2019 - 02:45 PM

I already have 2 x F5 RFTs for low-power sweeping -- Jaegers 4" & ATM 5" triplet (non-ED!) -- but the AT might replace the Jaegers.



#19 vkhastro1

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Posted 16 November 2019 - 03:08 PM

That's not really been my experience at all, but perhaps I'm less than a wide-field enthusiast than most people. I believe the purpose of a telescope is precisely to get close to the objects we like to see. For the very low power views, binoculars or a much smaller telescope really is better suited, in my opinion. 

 

And it's not like the 4" f/11 is super narrow anyway, as the 40mm ES68 can give a TFOV over 2.4° wide. 

 

 

Clear skies!
Thomas, Denmark

My 56mm Series 4000 smoothie pseudo-Masayuma eyepiece provides a 2.6° FOV @ 20X in the Starwave 102ED f/11.

Fantastic wide field views with superb contrast (jet black background).

The view of the Double Cluster is amazing.


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#20 Toddeo

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Posted 16 November 2019 - 03:39 PM

For the money- the AT102ED can't be beat!  Go for it-you wont regret it!!!!!


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#21 Mr. Mike

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Posted 16 November 2019 - 03:47 PM

That's not really been my experience at all, but perhaps I'm less than a wide-field enthusiast than most people. I believe the purpose of a telescope is precisely to get close to the objects we like to see. For the very low power views, binoculars or a much smaller telescope really is better suited, in my opinion. 

 

And it's not like the 4" f/11 is super narrow anyway, as the 40mm ES68 can give a TFOV over 2.4° wide. 

 

 

Clear skies!
Thomas, Denmark

Fully understood, Thomas.  I didn’t mean to say one focal length was better than the other, just different use cases for each of us.  I prefer the wider FOV and of course give up magnification for that. All good. :)


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#22 Galicapernistein

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Posted 16 November 2019 - 03:50 PM

If you don’t get the F11, you’ll never know how it compares to your F10 achromat. And if you decide not to keep it, you’ll have no problem selling it.


Edited by Galicapernistein, 16 November 2019 - 03:53 PM.

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#23 Jon Isaacs

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Posted 16 November 2019 - 04:01 PM

That's not really been my experience at all, but perhaps I'm less than a wide-field enthusiast than most people. I believe the purpose of a telescope is precisely to get close to the objects we like to see. For the very low power views, binoculars or a much smaller telescope really is better suited, in my opinion. 

 

And it's not like the 4" f/11 is super narrow anyway, as the 40mm ES68 can give a TFOV over 2.4° wide. 

 

 

Clear skies!
Thomas, Denmark

 

For the things a 4 inch F/11 does better than a 4 inch F/7, there's a vast spectrum of telescopes that are better than either.

 

For the things a 4 inch F/7 does better than a 4 inch F/11, it's a sweet spot, smaller scopes don't have the optical prowess, binoculars don't have the versatility. 

 

That's how it works for me.. 

 

Jon


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#24 25585

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Posted 16 November 2019 - 04:04 PM

I dunno - I think F/11 is too restrictive of a FOV for overall use.  If its just for local celestial objects then fine but F/7 is way more versatile.  And, if the optics are done right then the flase color diference should be trivial.  Or just do what I did and get an F/7 triplet for a little more and say goodbye to false color entirely. smile.gif

If you can get a TSA102, and the ED1.5x extender, voilà, a 7.5 or 11, apo triplet.


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#25 Astrojensen

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Posted 16 November 2019 - 05:03 PM

Fully understood, Thomas.  I didn’t mean to say one focal length was better than the other, just different use cases for each of us.  I prefer the wider FOV and of course give up magnification for that. All good. smile.gif

Absolutely!

 

 

Clear skies!

Thomas, Denmark




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