View Full Version here: : Barlow versus new eyepiece and low power eyepiece
faramir
08-09-2007, 10:17 PM
I am new to this hobby and have a meade LX90GPS with a TV10mm radian and a Meade 26mm plossl. At times it would be nice to have a bit more power and alternatively also at times a low power wider field of view. Is there any advantage of a 5mm radian over a 2x powermate? Is there a lower power limit beyond which distortion becomes a problem? At present I have meades standard diagonal but plan to upgrade to a ? GSO 2" dielectric star diagonal.
xelasnave
08-09-2007, 10:43 PM
When I started I wanted both.. it seems we like to go for more mag. but I now find that less appealing.....I have a 6mm ep and never use it..
the higher the mag, the less light you get.
But we all want to try for it and you will be no different there I guess but as a generalisation an ep view will be better than with a barlow.. still having said that I would probably get one anyways.
I have so much stuff I read about on wet nights but it is mostly unused.. a 2x and a 3x barlow, eps under 12mm just sit in the box.
Good luck dont be in a hurry what you are using now will do a great job.
alex
faramir
09-09-2007, 10:21 AM
Thanks Alex. Suspect I need to go to a star party or club evening to have a look at different items before I consider purchasing.:)
Faramir, I concur wth the above, most definitely start at the lower power end and work up from there. You will get most use with lower mag first off than be frustrated with vibration/seeing with higher powers. I'd suggest something in 35-45mm and at least 65-70 FOV to give you much wider fields than you getting at present, there is huge range of EPs out there to suit your needs and budget. Then you could either barlow that or next perhaps consider something in the 15-17mm range. Another thing I strongly recommend is to buy one EP or accessory at a time and get use to how the set up behaves, what it provides you, and also how your observing habits pan out. This will help you make the best informed judgment for your next acquistion, especially for someone new to the area. Cheers, Fox
faramir
09-09-2007, 11:33 AM
Thanks Fox. Looking through previous posts it appears that with my scope there maybe problems with to low a power and very wide field eyepieces. Not sure how true this is. I have been considering the 35mm panoptic but the price means it will be a while before I consider getting this.
wolfman
09-09-2007, 10:16 PM
I use a Meade 5000 series 34mm in my LX200, 80 percent of the time.
For a mid price Eyepiece in a slow scope it is wonderful, big wide flat field, and sharp to 90 %, and very easy to look through. Good buying at the $450 mark. As for the higher mag' I would have thought the 10mm you have would be close to as high as you can go on most nights anyway.
Also try the Bintel 2' Quartz Dielectric Diagonal, quite nice and a huge upgrade from the standard 1.25'.
faramir
10-09-2007, 09:19 PM
Wolfman what is the advantage of the Bintel quartz star diagonal over the other Bintel BK7 2" star diagonal? The disadvantage seems to be 54 dollars.
wolfman
11-09-2007, 12:22 AM
Most likely none! hahaha, depends if you think the really cool "Quartz" logo on the front of it is worth the $54.
I have no experence with the other Diagonal, I was just bringing what I own and can recomend to your attention.
Apparently from what I have read the Quartz mirror will not degrade over time and will retain its 99% reflectivity unlike the more basic one.
Geoff45
11-09-2007, 09:16 AM
I think that it's always better to go for the option where you have less stuff in your optical train. IMO a 5mm eyepiece will perform better than a 10mm eyepiece of the same quality plus a barlow---if nothing else, the image will be a little brighter because no light is lost by reflection/transmission of the barlow. I only use a barlow for prime focus solar system imaging when it is the only option for getting a longer focal length.
Geoff
casstony
11-09-2007, 09:25 AM
I've tried to investigate the quartz vs BK7 issue and have not been able to find any benefit in owning the quartz, although I don't know of anyone who has directly compared the two diagonals under the sky. AFAIK the quartz would only be better if GSO took the time to more finely polish the surface or if they applied less dielectric layers to the BK7, but such information is not available.
faramir
11-09-2007, 09:08 PM
Thanks everybody. Sounds like I should put the $54 dollars towards a dew shield which I also need rather than the quartz diagonal.
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