Light, portable 102 refractor for portamount
Posted 02 January 2013 - 10:36 AM
You might want to consider it.
Posted 03 January 2013 - 11:37 AM
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...
Posted 03 January 2013 - 02:02 PM
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.
Posted 04 January 2013 - 08:11 AM
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.