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Achromat Recommendation for my Granddaughter's First Telescope

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#1 Claytoncramer

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Posted 08 July 2020 - 07:10 PM

I am not prepared to spend the money for an apochromat for my granddaughter, whose current enthusiasm may disappear when she discovers boys.  Orion sells a number of reasonably priced achromats in the 70-90mm size, but mostly short enough focal lengths that I fear chromatic aberration may be an issue.  For 90mm, I believe f/10 is considered the minimum.  Meade sells a 90mm f/10 on an equatorial mount that seems price appropriate for a bright 11 year old.  Any comments or suggestions?  I have discounted a reflector because collimation is the enemy of all newbies, and I have yet to see a commercial refractor with collimation problems.



#2 Augustus

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Posted 08 July 2020 - 07:15 PM

IMO, you're fine as long as it's above f/6. I'd go for something like a Meade Infinity 102 or an ES AR102 on a Twilight I mount. If she has a cell phone the Celestron StarSense Explorer DX102 is pretty good too.


Edited by Augustus, 08 July 2020 - 07:16 PM.

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#3 petert913

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Posted 08 July 2020 - 08:12 PM

If she wants to see more,  a small Newtonian (table top) will capture more light.

 

https://tinyurl.com/y9ywa7u7


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#4 MalVeauX

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Posted 08 July 2020 - 08:23 PM

Heya,

 

I find children are often less fussy about CA than an adult that knows its the imperfection of the optics. I wouldn't stress it too much. Even a wild-with-CA fast achromat will show off great deep space with minimal CA there anyways, and the targets that are bright and rich with CA still show off excellent views. For example, despite Venus being very bright and just exploding with CA, it's still very obvious to see the crescent disc phases, and it's still easy to see Cassini's division on Saturn and the great bands of Jupiter, regardless of them all glowing with some purple edges. This is way less an issue as you pointed out compared to collimation and all that.

 

My only complaint about most achromatic doublets is that they come with janky poor focusers usually.

 

I think a 90mm F10 achromatic is an excellent way to go, as long as it's mounted well enough. Otherwise, any flavor 102mm F6~F10 would be great to start.

 

Heck, my favorite achromats are all F5 (80mm F5 and 120mm F5).

 

https://www.adorama....cnomxlt102.html

https://explorescien...fl-ar1021000eq3

https://www.telescop...cope/p/9024.uts

 

That said, if you can figure out the best inexpensive way to mount them, these 102mm F11 refractors have great focusers and are all around excellent:

 

https://www.teleskop...cher-Tubus.html

 

Very best,


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#5 eros312

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Posted 08 July 2020 - 08:30 PM

The Meade is a good choice, it's got a metal focuser and a molded in Vixen style finder shoe. Orion sells basically the same scope https://www.telescop...yCategoryId=335

I made the mistake of buying the Celestron Astromaster 90EQ. Sloppy plastic focuser and red dot finder that I could never get aligned right. Bad mount too. I don't recommend it at all. Hope this helps!


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#6 gnowellsct

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Posted 08 July 2020 - 11:50 PM

There are a lot of inexpensive achromatic refractors trying to find homes on Craigs list.  Just make sure you research the type of refractor to get a good one and get a good price.  Often times Craigslist people have unreasonable expectations about what their gear is worth.

 

Greg N


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#7 gnowellsct

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Posted 08 July 2020 - 11:54 PM

I would also point out that there are a fair number of achromats owned by amateurs who have passed on to bigger and better things and don't consider the money to be gained from an inexpensive achromat worth the trouble of listing and shipping.

 

Sometimes you can shake the tree and get these things to come loose.  The "Wanted" ads in Astromart are effective.  

 

"Wanted: inexpensive 1.25" oculars for child's first telescope"

"Wanted: 90mm or similar achromat for child's first telescope"

 

It might actually get you a better deal than you would anticipate.

 

Greg N


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#8 daquad

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Posted 09 July 2020 - 07:06 PM

I am not prepared to spend the money for an apochromat for my granddaughter, whose current enthusiasm may disappear when she discovers boys.  Orion sells a number of reasonably priced achromats in the 70-90mm size, but mostly short enough focal lengths that I fear chromatic aberration may be an issue.  For 90mm, I believe f/10 is considered the minimum.  Meade sells a 90mm f/10 on an equatorial mount that seems price appropriate for a bright 11 year old.  Any comments or suggestions?  I have discounted a reflector because collimation is the enemy of all newbies, and I have yet to see a commercial refractor with collimation problems.

Why an achromat?  I agree that CA would not be an issue for a kid, but dim views would be more problematic.  My choice would be something like an Orion 4.5" Dob.  You could help her collimate it; she might actually be interested in the workings of the scope.  

 

Once collimated, it will not be a problem.  Easy to set up.  No hassle with pointing.  Comes with a 6X30 finder.  250 bucks with a 30 day return policy.  As I said earlier, add a pair of binoculars and some books about observing and astronomy.

 

Dom Q.


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#9 Jon Isaacs

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Posted 09 July 2020 - 07:38 PM

Why an achromat?  I agree that CA would not be an issue for a kid, but dim views would be more problematic.  My choice would be something like an Orion 4.5" Dob.  You could help her collimate it; she might actually be interested in the workings of the scope.  

 

Once collimated, it will not be a problem.  Easy to set up.  No hassle with pointing.  Comes with a 6X30 finder.  250 bucks with a 30 day return policy.  As I said earlier, add a pair of binoculars and some books about observing and astronomy.

 

Dom Q.

 

Or an 6 inch F/8. The coma free diameter at F/8 is 11 mm, the 4.5 inch mirror is spherical, the 6 inch F/8 is nearly spherical.

 

The problem with the 90 mm and 100 mm achromats in Clayton's price range are the wobbly mounts. I've owned a few 90 mm F/10s and 11s as well as the F/6.5 Synta scopes. You can build a decent cheap achromat but not a decent decent cheap mount to go with it.

 

Jon


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#10 Bowlerhat

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Posted 10 July 2020 - 01:36 AM

The Meade is a good choice, it's got a metal focuser and a molded in Vixen style finder shoe. Orion sells basically the same scope https://www.telescop...yCategoryId=335

I made the mistake of buying the Celestron Astromaster 90EQ. Sloppy plastic focuser and red dot finder that I could never get aligned right. Bad mount too. I don't recommend it at all. Hope this helps!

That red dot is the bane of that scope, and non upgradeable too. You're stuck with it forever.


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#11 daquad

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Posted 10 July 2020 - 08:32 AM

Or an 6 inch F/8. The coma free diameter at F/8 is 11 mm, the 4.5 inch mirror is spherical, the 6 inch F/8 is nearly spherical.

 

The problem with the 90 mm and 100 mm achromats in Clayton's price range are the wobbly mounts. I've owned a few 90 mm F/10s and 11s as well as the F/6.5 Synta scopes. You can build a decent cheap achromat but not a decent decent cheap mount to go with it.

 

Jon

So true about the mounts.

 

Dom Q.


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#12 Simoes Pedro

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Posted 10 July 2020 - 09:39 AM

Maybe a 80mm short tube on an Alt-Az mount.

 

But I would prefer a 4.5" dob


Edited by Simoes Pedro, 10 July 2020 - 09:40 AM.


#13 csrlice12

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Posted 10 July 2020 - 10:58 AM

A 102XLT (f10) on the CG4....maybe costs a bit more initially, but the scope is good, mount is good, and it's a real setup and not a toy.  At f10, it's also easy on eyepieces.



#14 kmparsons

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Posted 10 July 2020 - 01:05 PM

I would definitely avoid an equatorial mount for a beginner. Also for a pre-adolescent, something not too bulky would be good. Here is an idea: The Astro Tech 60ED on a sturdy photo tripod, like the Orion XHD--if this would not go over your budget. 



#15 Wildetelescope

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Posted 10 July 2020 - 01:18 PM

I am not prepared to spend the money for an apochromat for my granddaughter, whose current enthusiasm may disappear when she discovers boys.  Orion sells a number of reasonably priced achromats in the 70-90mm size, but mostly short enough focal lengths that I fear chromatic aberration may be an issue.  For 90mm, I believe f/10 is considered the minimum.  Meade sells a 90mm f/10 on an equatorial mount that seems price appropriate for a bright 11 year old.  Any comments or suggestions?  I have discounted a reflector because collimation is the enemy of all newbies, and I have yet to see a commercial refractor with collimation problems.

A while back, I picked up a 60 mm f11 sears brand Towa from the early 70s off eBay for 50 bucks.  It is my sons favorite scope to use.  I bought a cheap 0.965 to 1.25 mirror diagonal to use with it.  Mounted originally on an old camera tripod, now on a twighlight 1.  Use a vixen dovetail and some nock off rings for a Canon lens.  Probably about 150  bucks for scope, rings dovetail and diagonal.  The optics are surprisingly sharp.   It is a thought.   Agree that the biggest issue is the mount.  Personally I would recommend the 4.5 or 6 inch dob.  Collimation is a good way to see how serious someone is about the hobby;-) 

 

jmd 


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#16 Supernova74

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Posted 10 July 2020 - 01:25 PM

um!?? You say it’s for gran daughter are you sure it’s not for you 


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#17 Anony

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Posted 10 July 2020 - 01:44 PM

IMO, you're fine as long as it's above f/6. I'd go for something like a Meade Infinity 102 or an ES AR102 on a Twilight I mount. If she has a cell phone the Celestron StarSense Explorer DX102 is pretty good too.

I own an Infinity 102 and wouldn't recommend it to anybody.

 

The mount is pretty lousy (and that's being generous). They have a new Starpro lineup, if the OP really wants a Meade refractor, at least go for one of the Starpros, better mount.

 

Agree about the Starsense -- don't own one but if going the refractor route, that seems like a safe bet. The app stuff looks really cool and I expect a kid would rather target by phone than look at star charts.


Edited by Anony, 10 July 2020 - 01:46 PM.


#18 Chris Y

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Posted 10 July 2020 - 11:31 PM

At the end of May, I got the Explore Scientific First Light AR102/1000 f9.8 with Twilight I for my grandson.  He doesn't have an opinion on it yet, since he's only 10-1/2 months old now, but his parents are really enjoying it!  lol.gif

 

I haven't looked through it yet, but from the pictures/videos the kids are getting with their cell phones the CA appears to be very tolerable.

 

https://explorescien...-ar1021000maz01


Edited by Chris Y, 10 July 2020 - 11:44 PM.

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#19 skookum

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Posted 11 July 2020 - 12:20 AM

I am getting back into astronomy after being away for 15 years. I'm trying to bring my two sons along with me.  My youngest just turned 4 (bedtime is before sunset, except on weekends).  My oldest is 12 (perfect age, you'd figure). The oldest's enthusiasm is tepid, but it's there.  Together we share eyepiece time on a Vista 508 (Canadian brand of Synta's 80mm F/5.0 achromat, the ST80).  Usually, I hold the smartphone and guide him to something cool so he can learn to star hop.  It's fun.  The wide field of view makes it much easier for him to learn how to navigate the sky.  I have a 120ST on the way so we each have similar instruments.  That way, we can sky-hop to cool stuff together.  We'll see how that goes.

 

The point is that short achros are so cheap, they serve as the perfect tool to introduce kids to the hobby.  First of all, they're essentially expendable.  No one likes to talk about sacrificing instruments.  But let's face it.  These are kids.  They will bump and bang the instrument around while they learn how to carry it.  A reflector's collimation will not survive that kind of abuse.  Who wants to subject an ED doublet or a triplet to that either? 

 

Second, short tube achros are light and easy for a kid to tote around.  A longer tube just makes that part of the hobby more work than it needs to be.

 

Finally, short tube achros show a lot of sky.  The right targets are mind-blowing.  And to a kid, C and A are just the first two letters in candy. I would avoid an EQ mount unless someone experienced will be there the first few times to make sure their polar axis isn't pointing at Jupiter.  Take kids to outreach events to they can peer through bigger hardware and learn what wonders can be seen with better, more expensive instruments.  But as far as inspiring your granddaughter to want to peer into the heavens, I think a short tube achromat is quite sufficient.

 

If I were in your position Claytoncramer, I'd look for the telescope with the widest field of view per dollar I can find.  An ST80 on a decent alt/az mount would fit the bill nicely. Put some quality eyepieces in the box (not Naglers, but you know what I mean), and I think you're setting your granddaughter up for a pleasant introduction to the hobby.


Edited by skookum, 11 July 2020 - 12:46 AM.

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#20 Chris Y

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Posted 11 July 2020 - 02:04 AM

As far as an alt-az mount, I love my ES Twilight I.  I have two of them.  But Astronomics has the same mount under the Astro-Tech brand, called the Voyager 2, for $199.95.  That's $45 cheaper than the Twilight i's current sale price of $244.99, and $90 cheaper than the Twilight I's regular price of $289.99.

 

The slow motion controls are very smooth, and it will easily support a smaller refractor the size you're loking at.  My first one carries my ES 152mm Mak-Cas, which weighs 17 pounds...before you add a little extra for the RACI and C6/8 dew shield I added to it.

 

https://www.astronom...t.html?___SID=U



#21 Chris Y

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Posted 11 July 2020 - 06:35 PM

I am not prepared to spend the money for an apochromat for my granddaughter, whose current enthusiasm may disappear when she discovers boys.  Orion sells a number of reasonably priced achromats in the 70-90mm size, but mostly short enough focal lengths that I fear chromatic aberration may be an issue.  For 90mm, I believe f/10 is considered the minimum.  Meade sells a 90mm f/10 on an equatorial mount that seems price appropriate for a bright 11 year old.  Any comments or suggestions?  I have discounted a reflector because collimation is the enemy of all newbies, and I have yet to see a commercial refractor with collimation problems.

Check out the Meade StarPro AZ series of scopes.  I seriously considered one of these before I went with the ES for my grandson.  They get good reviews and, at least from what I've read, the tripod/mount is of good quality.  It also has slow motion controls.

 

The 70mm is f10, and the 80mm is f11.3, so either of those should have reduced CA.

 

Edit: The 80mm with mount/tripod weighs just over 10 pounds, so that would be easy for her to handle, plus it's $20 cheaper than the Astro-Tech Voyager 2 mount/tripod I mentioned in my previous reply. 

 

https://www.amazon.c...r/dp/B07J5H7WN9


Edited by Chris Y, 11 July 2020 - 06:50 PM.


#22 Anony

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Posted 12 July 2020 - 11:50 AM

Check out the Meade StarPro AZ series of scopes.  I seriously considered one of these before I went with the ES for my grandson.  They get good reviews and, at least from what I've read, the tripod/mount is of good quality.  It also has slow motion controls.

 

The 70mm is f10, and the 80mm is f11.3, so either of those should have reduced CA.

 

Edit: The 80mm with mount/tripod weighs just over 10 pounds, so that would be easy for her to handle, plus it's $20 cheaper than the Astro-Tech Voyager 2 mount/tripod I mentioned in my previous reply. 

 

https://www.amazon.c...r/dp/B07J5H7WN9

 

Starpros look good, especially the 90mm/102mm sizes compared to the earlier Infinity lineup.

 

Although if someone considers that 80mm at $180, I'd say why not simply go with a starsense explorer instead -- https://www.highpoin...refractor-22451

 

Not sure how that mount compares though... think most have said it's at least adequate.


Edited by Anony, 12 July 2020 - 11:50 AM.

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#23 Chris Y

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Posted 12 July 2020 - 02:47 PM

Starpros look good, especially the 90mm/102mm sizes compared to the earlier Infinity lineup.

 

Although if someone considers that 80mm at $180, I'd say why not simply go with a starsense explorer instead -- https://www.highpoin...refractor-22451

 

Not sure how that mount compares though... think most have said it's at least adequate.

The StarSense series would be a great choice too.  If the tripod seems a bit shaky it could be solved by hanging some weight from the spreader or lower tripod area.  That would serve to keep tension on the legs, and also lower the center of gravity while making the assembly less top heavy.  Also, be sure all of the nuts/bolts/screws are snugged so there isn't any mechanical slop in the tripod/mount.  Tightening everything often fixes a lot of shakes.


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#24 StarHugger

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Posted 12 July 2020 - 03:03 PM

Or just go old school, nice focuser with this one too.

https://www.cloudyni... 80mm F11 Japan
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#25 k5apl

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Posted 14 July 2020 - 05:26 PM

I would go with a 6 inch Dobsoninan reflector.  Easy to look through and push around the sky.  And its easy to take outside and set up.  If she wants to continue with astronomy, then move into a refractor.  


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