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Four Inches Does Well for DSOs!

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#1 Gregrox

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Posted 18 November 2020 - 09:02 PM

I bought a used refractor on Craigslist, an old Celestron 102mm f/5 refractor branded as a "FirstScope," though not to be confused with the tabletop reflector of the same name. I bought it as a Christmas present for my cousin, since I figured a refractor--not needing to be collimated--would be better for them. I made a mistake--the mount, while sturdy and not too difficult to use, would definitely be too difficult for my cousin (who struggled with my Dobsonian while picking up the FirstScope (the tabletop reflector, not to be confused with the 102mm f/5 refractor of the same name) just fine). It uses slow motion cables with limited travel and the ergonomics are just kinda wrong.

 

I have been giving it a trial run to evaluate it, and although I decided that it's not good for the application I intended, I love the optics. I never thought a 4" telescope could perform so well. Bright, contrasty images of some of my favorite DSOs that my 4.5" Bushnell Voyager reflector struggled with, approaching what I see in my 6" reflector. I don't want to get rid of it, although I must if I am to afford a tabletop reflector for my cousin. Oh well.

 

One of the things that struck me is that despite being an entry-level product by Celestron, it's really pretty good. The modern entry-level Celestron stuff is rubbish by comparison--the finnicky mounts, 1.25" focusers, etc. It's probably the better part of 20 years old; the manual still refers to film photography.

 

The views of the Double Cluster in Perseus, E.T. Cluster, Orion Nebula, M31, and even newly explored M15, they'll stick with me for a while. It also throws up a **** good picture of the Moon, though it doesn't do well on planets--maybe about as well as the 50mm f/10 Galileoscope. Alas, I have taken no sketches or notes.

 

One day I'd like to get a 4" refractor for myself. For now, it's cheap reflectors.


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#2 Ihtegla Sar

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Posted 18 November 2020 - 09:25 PM

I have a ten or fifteen year old Celestron 102 f/5 that I originally got on a closeout sale for birdwatching.  I have only used it a few times for astronomy, but the optics seem good for low power wide field DSO viewing.  I got some really good views of M51 with it under some very dark skies that were showing hints of spiral structure and the bridge between the main galaxy and its companion.

 

Really wish I could find tube rings that would fit it for a reasonable price . . .  


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#3 clearwaterdave

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Posted 19 November 2020 - 05:04 AM

I have the modern version at f/6.5.,and besides the wonky mounting it came with it is a very nice scope overall.,I put it on pipes and it does quite well.,cheers

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#4 bobhen

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Posted 19 November 2020 - 07:06 AM

I’ve owned a Celestron 102mm F5 refractor (now marketed as the Synta, Sky-Watcher Star Traveler) for 16 years. This scope makes a wonderful lowish power daytime spotter, airline overhead compartment travel scope, and low power, wide filed, deep sky scope.

 

The scope grabs more light than the Synta 80mm F5s (I owned 2), making deep sky objects easier to spot. The scope does benefit from wide field eyepieces with good edge correction. The 102 F5 is light enough to ride on many of the available alt/az mounts. There are also many (just Google) daytime images of birds taken with the scope.

 

I now use mine with an Image Intensifier at F5 and around F3.5 with a reducer. With the Intensifier, the views of deep sky objects (California Nebula, Monkey Head Nebula, North American Nebula, etc.) are very impressive.

 

HERE is a review.

 

Below is mine with the Image Intensifier.

 

Bob

 

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#5 Jeff B

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Posted 19 November 2020 - 09:49 AM

Charles Messier loved his 4" achromat.


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#6 RAKing

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Posted 19 November 2020 - 09:53 AM

I did my first Messier Marathon with a Celestron C4-R achro and even though some of the objects were mere Q-tips, I had a blast. laugh.gif

 

I have done the Messier list several times since then and have added several hundred double stars to my personal catalog with my better quality 4-inchers.  But I still think there are a lifetime's worth of things out there to look at with a 4-inch refractor, so I will keep using mine.

 

Cheers,

 

Ron


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#7 jerr

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Posted 19 November 2020 - 11:31 AM

Charles Messier loved his 4" achromat.

and Galileo would offer a kingdom for it.


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#8 BillP

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Posted 19 November 2020 - 11:34 AM

4" scopes are absolutely fantastic observing companions.  I have owned 2.4" to 10" scopes and used scopes up to 20", after all of that I chose the 4" as my primary observing companion.  It's fantastic on doubles, a joy for lunar, satisfyingly capable for planetary, quite adept for the very many prominent DSO in the sky (with a special forte in open clusters IMO), and also fun for white light solar.  best of all though, it has a small form factor meaning one can have the entire rig with mount fairly lite and best of all it is ready almost as soon as you are to observe even in cold weather!  Best friend an observer can have IMO.  It is the only aperture class I would characterize as a "companion" in the hobby.


Edited by BillP, 19 November 2020 - 11:40 AM.

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#9 BillP

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Posted 19 November 2020 - 12:00 PM

So many 4" refractor offerings available today too!

 

https://www.bhphotov...BCABEgLcdPD_BwE

 

https://www.google.c...HW_IBpYQ8wIIhgc

 

https://www.google.c...HW_IBpYQ8wII1gc

 

https://www.bhphotov..._4_0_102mm.html

 

https://www.google.c...HVwEDGoQ8wIInAg

 

https://www.google.c...HVwEDGoQ8wIIpAY

 

https://www.google.c...HW_IBpYQ8wII7gU

 

https://explorescien...ign=sag_organic

 

https://www.bhphotov...ni_XLT_102.html

 

https://www.adorama....ource=adl-gbase

 

https://www.google.c...TDyg4FBDzAgibBg

 

https://www.teleskop...ttelformat.html

 

https://www.teleskop...3dad04566f2c836

 

https://www.takahash...-telescope.html

 

https://www.takahash...-refractor.html

 

 

 

 

 


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#10 Echolight

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Posted 19 November 2020 - 01:43 PM

and Galileo would offer a kingdom for it.

Galileo had a kingdom?



#11 BillP

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Posted 19 November 2020 - 03:33 PM

Galileo had a kingdom?

Yes he did.  He was very well known, chair of mathematics at the University of Pisa, made multiple significant discoveries both in pure and applied science, over a dozen written works, had many high friends among the church, universities, other famous scientists of the day including internationally.  So his kingdom was the limelight of prestige, power, notoriety and influence.


Edited by BillP, 19 November 2020 - 03:35 PM.

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#12 Jon Isaacs

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Posted 19 November 2020 - 05:32 PM

In theory, I have a 4 inch F/5 Celestron achromat, I think they called it a spotting scope.  Currently my nephew has it, he bought a place in the high desert to provide a Covid-Oasis.

 

It does a good job at low power-wide field which is what smaller refractors do best. Other scope with more aperture are more capable at higher powers, they go deeper, show more detail,  have greater resolution.  

 

But for the things a 4 inch shows better than other, larger scopes, this simple 4 inch F/5, is a real performer whose weak point is the same as nearly all short focal length refractors, z curved focal plane, stars at the edge of the field and at the center cannot be in focus simultaneously. 

 

With a well corrected wide field eyepiece like the 31 mm Nagler, the curvature is apparent. It's something one can live with..

 

A fun scope..

 

Celestron 102mm F5 backyard.jpg
 
Jon

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#13 Bomber Bob

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Posted 19 November 2020 - 05:59 PM

About 5 years ago, I built a 4" F5 RFT using a vintage 1970s A. Jaegers lens:

 

JaegerMeister 4 - VersaGo 2 AZM S02.jpg

 

I used almost all antique / vintage parts.  Moonlight made a 2" adapter to step-down the B&L projector assembly.  I called it JaegerMeister -- awesome wide field views.

 

Fortunately for our grandkids, I later bought & restored this 5" F5 non-ED triplet:

 

ATM 5x5T - Restore S33 (Meade Blue 60mm Finder).jpg

 

Almost zero CA at the center of field, and sharp enough at 200x for lunar & planetary viewing, too...


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#14 Jeff B

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Posted 19 November 2020 - 06:23 PM

Yes he did.  He was very well known, chair of mathematics at the University of Pisa, made multiple significant discoveries both in pure and applied science, over a dozen written works, had many high friends among the church, universities, other famous scientists of the day including internationally.  So his kingdom was the limelight of prestige, power, notoriety and influence.

Yeah, all true, but despite his kingdom, he was also thrown in jail (house arrest actually) for going up against The Church for his writings and arguments concerning Copernican theory that the Earth moved around the Sun.   But imagine what would have happened if he had a decent 4" scope.  He'd gotten himself into some real trouble I bet.


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#15 Gregrox

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Posted 20 November 2020 - 07:53 PM

I sold the telescope which started this topic tonight. It's a good first telescope, just not one for the person I bought it for.

 

I will get a 4" refractor again one day. Like all diseases, those without much money suffer the most from it, for they can not easily get treatment. Such is true of refractoritis as well.


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#16 Corcaroli78

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Posted 21 November 2020 - 08:38 AM

I bought a used refractor on Craigslist, an old Celestron 102mm f/5 refractor ....

I own also a 102 f/5 and yes, it is really capable for DSO´s.

 

photo_1.gif

 

Mine is an affordable mass produced Skywatcher St 102 which has provided me a lot of joy within the expectations, but it performs surprisingly well and, due to the air spaced objective, the CA is less than expected. I would not call it a planetary scope but i like the views!! the bands of Jupiter, the Cassini division, and the major details of Mars.

 

With it, I have "discovered" with so much excitement the North America Nebula, the Veil nebula and M51 (whirpool galaxy) was clearly defined. 

 

I can buy another scope, more capable (like AT102 f/7), but this ST102 is so light that i resist to give up the grab and go capability. So much for so less..  (special remark that i can not sell it as it was gift from my wife smile.gif  )  

 

Carlos


Edited by Corcaroli78, 21 November 2020 - 08:50 AM.

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#17 Gregrox

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Posted 21 November 2020 - 10:28 AM

i never actually showed a picture of the telescope i briefly had.

 

the exact same physical model (in different paint jobs and mountings) has shown up several times in this thread already.

 

20201120_210919.jpg

 

A SkyScanner 100 is now on backorder for my cousin. A step backwards in optical quality, but the scope was never for me anyway, it was always meant to be a gift. Plus the lack of CA might mean it performs better on planets, but I'm not sure. Since my cousin picked up the FirstScope easily but struggled with my 6" Dobsonian, I figured the limited-travel slow motion controls and sort of stiff manual motions would just be a little too difficult.


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#18 shaesavage

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Posted 22 November 2020 - 09:19 AM

My Televue Genesis SDF has become my top choice when I go to a dark sky...and I have a Skywatcher 120ed. The wide fields that the Genesis provides are incredible!


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#19 BillP

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Posted 22 November 2020 - 04:50 PM

Yeah, all true, but despite his kingdom, he was also thrown in jail (house arrest actually) for going up against The Church for his writings and arguments concerning Copernican theory that the Earth moved around the Sun.   But imagine what would have happened if he had a decent 4" scope.  He'd gotten himself into some real trouble I bet.

He got in trouble two times with Church authorities, first in 1616 where he was suspected of heresy due to a writing on heliocentric theory of Copernicus stating it was factual.  Copernicus' book was at that time banned because it stated it also stated it was factual that the Sun was the center.  The Church had that work edited to assert that the idea of Sun center was only being proposed as an argument to the Church sanctioned belief that it was not, and the Church allowed to be published.  The Jesuit order of the Catholic Church was also encouraging Galileo at the time to put forth support for heliocentric theory and were advising him how to do that with political delicacy (which Galileo failed miserably at unfortunately, especially in the 1632 trial).  That 1616 trial lasted only half a day and he was acquitted of that charge as they believed his story that he only stated in writings that it was a possibility and not a belief (he actually falsified a copy of his original writing saying that others altered the writing he showed them to make it look like he stated it as fact instead of as a proposition).

 

Later in 1632 Galileo again published that it was a fact that the Sun was center and in public discourse on the topic accused the Pope of being stupid (that disrespect had a good part to do with his trial outcome).  He tried to again tell them that his writing only suggested that it might be, but this time they did not buy it and the heresy charge stuck.  For that he was only imprisoned for 1 day, then allowed to stay in his villa outside of Florence under house arrest only, where he entertained several famous people of the day and continued to write and publish.  So not so bad as it sounds as he lived at home and could do most everything wanted except leave and travel.  During his house arrest period he published two more works:

Dialogue Concerning the Two Chief World Systems,
Discourses and Mathematical Demonstrations Relating to Two New Sciences.

 

The Church did finally concurred with the scientific arguments in 1822 concurring with the heliocentric model.

 

https://newsroom.ucl...catholic-church


Edited by BillP, 22 November 2020 - 05:07 PM.

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#20 Jim Curry

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Posted 23 November 2020 - 12:15 AM

Nice read, Bill.



#21 Jon Isaacs

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Posted 23 November 2020 - 08:07 AM

My Televue Genesis SDF has become my top choice when I go to a dark sky...and I have a Skywatcher 120ed. The wide fields that the Genesis provides are incredible!

 

I have a later model TeleVue 4 inch F/5.4 as well as a 120mm Orion Eon, same optics as the Skywatcher.  I have had a 120mm Eon for a number of years but I have never taken it to dark skies, it's always the TeleVue 4 inch.  I do have to admit though that it's used in conjunction with a reflector. 

 

Jon



#22 aa6ww

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Posted 23 November 2020 - 10:51 AM

The Celestron 4" F/5 was my original finder scope piggy backed on my C14. 

 

...Ralph



#23 shaesavage

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Posted 23 November 2020 - 04:26 PM

I have a later model TeleVue 4 inch F/5.4 as well as a 120mm Orion Eon, same optics as the Skywatcher.  I have had a 120mm Eon for a number of years but I have never taken it to dark skies, it's always the TeleVue 4 inch.  I do have to admit though that it's used in conjunction with a reflector. 

 

Jon

Haha, one of my observing buddies usually has his 12” reflector to give an aperture assist.  



#24 RichA

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Posted 23 November 2020 - 08:48 PM

I bought a used refractor on Craigslist, an old Celestron 102mm f/5 refractor branded as a "FirstScope," though not to be confused with the tabletop reflector of the same name. I bought it as a Christmas present for my cousin, since I figured a refractor--not needing to be collimated--would be better for them. I made a mistake--the mount, while sturdy and not too difficult to use, would definitely be too difficult for my cousin (who struggled with my Dobsonian while picking up the FirstScope (the tabletop reflector, not to be confused with the 102mm f/5 refractor of the same name) just fine). It uses slow motion cables with limited travel and the ergonomics are just kinda wrong.

 

I have been giving it a trial run to evaluate it, and although I decided that it's not good for the application I intended, I love the optics. I never thought a 4" telescope could perform so well. Bright, contrasty images of some of my favorite DSOs that my 4.5" Bushnell Voyager reflector struggled with, approaching what I see in my 6" reflector. I don't want to get rid of it, although I must if I am to afford a tabletop reflector for my cousin. Oh well.

 

One of the things that struck me is that despite being an entry-level product by Celestron, it's really pretty good. The modern entry-level Celestron stuff is rubbish by comparison--the finnicky mounts, 1.25" focusers, etc. It's probably the better part of 20 years old; the manual still refers to film photography.

 

The views of the Double Cluster in Perseus, E.T. Cluster, Orion Nebula, M31, and even newly explored M15, they'll stick with me for a while. It also throws up a **** good picture of the Moon, though it doesn't do well on planets--maybe about as well as the 50mm f/10 Galileoscope. Alas, I have taken no sketches or notes.

 

One day I'd like to get a 4" refractor for myself. For now, it's cheap reflectors.

This how manufacturers hide price inflation.  With food, they offer smaller portions/packages/cans for the same money, with scopes, they go cheap.  The battle for bottom-feeder buyers is the domain of Meade, Celestron, Bushnell, "National Geographic" and a slew of other sellers who don't care about what it does to their reputation.  I'm just glad a few hold the line at cost-cutting.



#25 Jon Isaacs

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Posted 25 November 2020 - 03:43 PM

One of the things that struck me is that despite being an entry-level product by Celestron, it's really pretty good. The modern entry-level Celestron stuff is rubbish by comparison--the finnicky mounts, 1.25" focusers, etc. It's probably the better part of 20 years old; the manual still refers to film photography.

 

 

You can still buy a Skywatcher 102 mm F5 thats nearly identical to the older Celestron 102 mm F/5, barely adequate focuser and all.

 

They might have mentioned photography but there's a lot of chromatic aberration so its really not a reasonable scope for astrophotography.

 

But 20 years ago, there were no affordable ED/apos.. thing are so much better today.. $400 buys an AT-80ED with a quality build, a focuser unseen 20 years ago (except for Feathertouch) and ED optics. $600 buys an AT-102ED.  People were paying more than $600 for achromats.

 

RichA's comment aside, we've never had it so good...

 

Jon


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