I am getting a used 12 inch lx200. It has a 2” Star diag. with 1.25 adapt. I want to get a 2x Barlow for it to double my eyepiece (future) collection. I need advice since I am new to this expensive hobby and don’t want to screw up and buy something that won’t work with this scope, or cheapen the view potential. I am thinking I just need a 1.25 inch version even though I have a 2 inch diag. It seems you don’t want to Barlow the big field of view 2 inc. eyepieces anyway. Plus, I don’t have any !!!!I think I am more interested in high mag. pinpoint detail viewing of planets and DSO’s, instead of large panoramic views of the sky. From what I have read, I have narrowed it down to a 2x 1.5 televue or the same in a GTO (gto quality kinda’ scares me though!!). I don’t understand enough about this to know if I should be looking at the televue powermate instead or a "shorty" Barlow. I will be open to spend some money,$150+, on this Barlow so that I don’t have to update in the future when I can afford a nagler quality lens. I would like to have the non-marring ring in it so the EP doesn’t get goobered up. I HAVE GLASSES but have used a p.o.s. 4mm on my old “walmart special” with some success. I will be looking at buying a eyepiece in the 15mm area to compliment the 26mm that comes with it.
Barlow purchase question??
Started by Dale Ro, 01/24/2004 07:50PM
Posted 01/24/2004 07:50PM
Opening Post
Posted 01/24/2004 07:56PM
#1
If you are simply nearsighted or farsighted, you can remove your glasses and refocus to compensate, or at least you probably can; I am so nearsighted it takes a lot of in travel, but your SCT has tremendous focus range so that shouldn't be a problem. Removing glasses to view then back on to see charts, look up etc. is a pain, but workable. If, however, you are astigmatic then you _may_ need to leave your glasses on when viewing. Even this is a "maybe" though because the small exit pupils of high power effectively stop down your eye and improve astimgatism, often completely, and of course it's only the higher powered eyepieces that really present eye relief issues.
Don't know wide field viewing if you've never had a quality scope to do it with. Even so, a 12" SCT will not afford really wide views, even with the 6.3 recucer if you choose to use it.
Just some thoughts that occur to me, I'll leave the barlow question to those with experience of 2" barlows.
Don't know wide field viewing if you've never had a quality scope to do it with. Even so, a 12" SCT will not afford really wide views, even with the 6.3 recucer if you choose to use it.
Just some thoughts that occur to me, I'll leave the barlow question to those with experience of 2" barlows.
Posted 01/24/2004 08:15PM
#2
I would agree with the sentiment that a 1.25" Barlow is what most people need. Some people Barlow 2" eyepieces, but in a star diagonal this is mechanically troublesome, and it adds unnecessary weight to small and medium size telescopes. Seems to make some sense with big Newts, though, where the Barlow can be inserted to its parfocal point and the weight is not an issue.
Rather than Barlow their big 2" eyepieces with a 2" Barlow, most people would be better served by a careful selection of 1.25" eyepieces and possibly a Barlow or Powermate.
The 1.25" Tele Vue Barlow is an excellent choice. You'll have to check with your 2" diag whether it will contact the mirror. It probably won't, but if it does you can put some slipjoint washers on the barrel or buy a Tele Vue high-hat 1.25" adapter. Either will solve the problem. The only less expensiver model that I would half-way recommend is the 2x Celestron Ultima or one of the equivalent models, like the Orion Shorty Plus. IMO, the 2x Tele Vue Barlow is better and not much more expensive when purchased used on Astromart. If you buy it new, you should be assured of getting a compression-ring type with captive thumbscrew.
Another solution is a 1.25" 2.5x Powermate. That unit will work better than a Barlow with Plossls. The reason is that regular Barlows may cause some vignetting (the apparent field of view is reduced, sometimes significantly, e.g. from 50 degrees down to 40 degrees) and increase the eye relief noticeably in longer focal-length Plossls. The 2.5x Powermate will eliminate or minimize both these failings of ordinary Barlows, so it's well worth considering, but unfortunately, a 1.25" 2.5x Powermate costs $190+ new, which is rather steep.
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Mike
Rather than Barlow their big 2" eyepieces with a 2" Barlow, most people would be better served by a careful selection of 1.25" eyepieces and possibly a Barlow or Powermate.
The 1.25" Tele Vue Barlow is an excellent choice. You'll have to check with your 2" diag whether it will contact the mirror. It probably won't, but if it does you can put some slipjoint washers on the barrel or buy a Tele Vue high-hat 1.25" adapter. Either will solve the problem. The only less expensiver model that I would half-way recommend is the 2x Celestron Ultima or one of the equivalent models, like the Orion Shorty Plus. IMO, the 2x Tele Vue Barlow is better and not much more expensive when purchased used on Astromart. If you buy it new, you should be assured of getting a compression-ring type with captive thumbscrew.
Another solution is a 1.25" 2.5x Powermate. That unit will work better than a Barlow with Plossls. The reason is that regular Barlows may cause some vignetting (the apparent field of view is reduced, sometimes significantly, e.g. from 50 degrees down to 40 degrees) and increase the eye relief noticeably in longer focal-length Plossls. The 2.5x Powermate will eliminate or minimize both these failings of ordinary Barlows, so it's well worth considering, but unfortunately, a 1.25" 2.5x Powermate costs $190+ new, which is rather steep.
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Mike
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