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Equipment Discussions >> Refractors

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Kon Dealer
professor emeritus


Reged: 01/05/11

Loc: Cambridge UK
Re: Light, portable 102 refractor for portamount new [Re: AlienRatDog]
      #5599351 - 01/01/13 10:45 AM

Had a ST120 and let it go for two reasons;
1 too much CA
2 too big for my SynscanAZ mount.

The CA has to be seen to be believed!!


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Locoman
scholastic sledgehammer
*****

Reged: 03/09/09

Loc: Abilene, Kansas
Re: Light, portable 102 refractor for portamount new [Re: AlienRatDog]
      #5599811 - 01/01/13 03:18 PM

Quote:

About how long is your ST120, I suppose if I get a refractor with similar dimensions, I would be set...



With the dew shield about 25" , without dew sheild about 19". This doesn't include diagonal.


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Locoman
scholastic sledgehammer
*****

Reged: 03/09/09

Loc: Abilene, Kansas
Re: Light, portable 102 refractor for portamount new [Re: Kon Dealer]
      #5599838 - 01/01/13 03:34 PM

Quote:

Had a ST120 and let it go for two reasons;
1 too much CA
2 too big for my SynscanAZ mount.

The CA has to be seen to be believed!!



I fail to understand why people make these kind of statements. The stated purpose for it is for deep sky objects. It is not meant for planets, moon or bright stars. It is a wide field scope. If I buy an F/15 scope then complain that it is a terrible wide feild scope on here people would laugh at me. I don't mean to be harsh but it is what it is! Also, isn't the Synscan basically the same as the SLT? The SLT mount can handle quite a bit on a heavy duty tripod!


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Kon Dealer
professor emeritus


Reged: 01/05/11

Loc: Cambridge UK
Re: Light, portable 102 refractor for portamount new [Re: Locoman]
      #5600922 - 01/02/13 10:03 AM

Quote:

Quote:

Had a ST120 and let it go for two reasons;
1 too much CA
2 too big for my SynscanAZ mount.

The CA has to be seen to be believed!!



I fail to understand why people make these kind of statements. The stated purpose for it is for deep sky objects. It is not meant for planets, moon or bright stars. It is a wide field scope. If I buy an F/15 scope then complain that it is a terrible wide feild scope on here people would laugh at me. I don't mean to be harsh but it is what it is! Also, isn't the Synscan basically the same as the SLT? The SLT mount can handle quite a bit on a heavy duty tripod!



This is because I had read a few reviews that said the CA in a ST120 was "overstated" and that if it did prove troublesome was "easily addressed" with a fringe-killer, or similar.
Well it wasn't- in both cases.
Also the mount struggled with it, particularly in altitude.
What I learnt from this is that telescopes and one's views of them (and through them) are very personal. What works for one may well be unacceptable to another.


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Locoman
scholastic sledgehammer
*****

Reged: 03/09/09

Loc: Abilene, Kansas
Re: Light, portable 102 refractor for portamount new [Re: Kon Dealer]
      #5600968 - 01/02/13 10:33 AM

I guess my ST120 may a good one because the other night Jupiter looked very good. I don't usually look at planets, moon and brighter objects with it but I wanted to try it on my SLT and it was a full moon night. Still, it is a great grab n go scope for the $ and if one sticks with dso's for which it was intended then CA is not an issue.

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Mr Onions
Two Time International Photographical Competition Winner
*****

Reged: 04/14/07

Loc: Newcastle upon Tyne.
Re: Light, portable 102 refractor for portamount new [Re: Locoman]
      #5600974 - 01/02/13 10:36 AM

William Optics has a new 102mm coming out soon.
You might want to consider it.


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AlienRatDog
Carpal Tunnel
*****

Reged: 07/15/05

Loc: Ann Arbor
Re: Light, portable 102 refractor for portamount new [Re: Mr Onions]
      #5601842 - 01/02/13 07:52 PM

Where can I read up on it?

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Mr Onions
Two Time International Photographical Competition Winner
*****

Reged: 04/14/07

Loc: Newcastle upon Tyne.
Re: Light, portable 102 refractor for portamount new [Re: AlienRatDog]
      #5602339 - 01/03/13 04:18 AM

Was on their Facebook page.
In red trim like the 81GT


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Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Light, portable 102 refractor for portamount new [Re: Locoman]
      #5602798 - 01/03/13 11:37 AM

Quote:


I guess my ST120 may a good one because the other night Jupiter looked very good.




I suspect it has more to do with the observer and the conditions, the bright moon in particular, than having a good one. In my experience, achromats are very consistent in their color correction, I have owned several ST-80, all are about the same, I have owned several 80mm F/11s of varying ages and qualities and yet, are have been very similar. Color correcting an Crown-Flint achromat has been well understood for nearly 200 years.

I have owned two 100mm F/6s, both are very similar and the chromatic aberration definitely hinders the view of Jupiter and brighter objects. As you stated previously, an 120mm F/5 achromat is a low power, wide field scope. Based on the fact that it will have significantly more false color than a 100mm F/6, I think that is a fair accessment.

So, when Kon Dealer points out that the false color is excessive, you can either agree that it is and say that it is a low power widefield scope or you can say that Jupiter looked very good.

But if you say Jupiter looked very good, then Kon needs to state that there is an excessive amount of false color and he had been mislead into thinking it might provide "very good" views of Jupiter.

I happened to be viewing Jupiter last night with my 100mm F/6 achromat. The view was "adequate" though Jupiter was surrounded and covered with purple haze. I switched to my 80mm F/7 apo and saw a clear and significantly more detailed view even though the aperture was reduced...

Jon


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SteveG
Post Laureate
*****

Reged: 09/27/06

Loc: Seattle, WA
Re: Light, portable 102 refractor for portamount new [Re: AlienRatDog]
      #5603077 - 01/03/13 02:02 PM

Quote:

Where can I read up on it?




Unfortunately, nothing to read yet as the 4" version isn't on the market. I'm looking forward to hearing how well this 5 element refractor is for both visual and imaging. The 4" might be good competition for the NP101 line from TV.

I'd love to hear from anyone who has the 3", 5-element version.


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Kon Dealer
professor emeritus


Reged: 01/05/11

Loc: Cambridge UK
Re: Light, portable 102 refractor for portamount new [Re: SteveG]
      #5603420 - 01/03/13 05:47 PM

Well stated Jon

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Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Light, portable 102 refractor for portamount new [Re: Kon Dealer]
      #5604213 - 01/04/13 08:11 AM

Just to get back to the original topic.. sort of..

If ARD (AlienRatDob) wants a shorter focal length 4 inch refractor, there are a number of choices but unless he spends a substantial amount of money, the only gain visually will be the wider field of view. The mid power and high power views should be better with his current scope, the ED-100.

It seems to me that if the only problem is the stability of the Portamount, then that can be addressed either by improving the Portamount or with a different mount that is more stable.

Jon


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Scott BeithAdministrator
SRF
*****

Reged: 11/26/03

Loc: Frederick, MD
Re: Light, portable 102 refractor for portamount new [Re: Jon Isaacs]
      #5604869 - 01/04/13 02:00 PM

A used AT102ED or SV102ED would get my vote.

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