Thanks to the forum for earlier help, I have a used Meade LX200 10" f/10. I believe, I now have good collimation. I am in the city so seeing is not great. What can I try to improve detail and contrast on the planets. Jupiter even on the best of nights only show three rings and not very clear. The planets seem very very bright, as if too bright, like a tv with the brightness way up and the contrast down. The edge of the planets seem even and clear, no halos. The moon however, seems perfect, great detail, great contrast. But mars, no snowcap or any detail, and Jupiter only three faint bands. Saturn no detail. I am using as a comparison my old 10" Newtonian, which I sold, but showed much greater details. Thanks, Ted
New at this.
Started by tchannel, 11/03/2003 07:28PM
Posted 11/03/2003 07:28PM
Opening Post
Posted 11/03/2003 11:21PM
#2
Hello there Ted,
I had the fortune of observing through a finese 10" Meade LX200 from an SDAA club member during my private ;-) star party around opposition timeframe, which was a heck of a lot brighter than it's now. Boy, that sweet SCT seemed to have plenty of contrast with the Mountain of Mitchell *clearly* seen (which was also easily seen with my 8-inch Dob nearby as well but not so easily seen through my 4-inch APO)! We tamed the brightness by using my #23 and #25 filter as well as my Baader Moon and Skyglow filter and keep the magnification at around 250x (max. that night). BTW, I can tell that the owner takes a very good care of his LX200 ;-)! BTW, he told me that he replaced the standard diagonal with the 2" TV Everbrite and his LX200 worked much better afterward (he said it not me ;-). Though I silently confessed I hardly touched my own 4" APO sitting nearby that night, I still prefered to view with the 4-incher for some reason night after night ;-).
So do employ some filtering and of course check your collimation and let it cooled down, Ted.
Ron B[ee]
PS - Alas if the 10" SCT weren't so weighty ... ;-).
I had the fortune of observing through a finese 10" Meade LX200 from an SDAA club member during my private ;-) star party around opposition timeframe, which was a heck of a lot brighter than it's now. Boy, that sweet SCT seemed to have plenty of contrast with the Mountain of Mitchell *clearly* seen (which was also easily seen with my 8-inch Dob nearby as well but not so easily seen through my 4-inch APO)! We tamed the brightness by using my #23 and #25 filter as well as my Baader Moon and Skyglow filter and keep the magnification at around 250x (max. that night). BTW, I can tell that the owner takes a very good care of his LX200 ;-)! BTW, he told me that he replaced the standard diagonal with the 2" TV Everbrite and his LX200 worked much better afterward (he said it not me ;-). Though I silently confessed I hardly touched my own 4" APO sitting nearby that night, I still prefered to view with the 4-incher for some reason night after night ;-).
So do employ some filtering and of course check your collimation and let it cooled down, Ted.
Ron B[ee]
PS - Alas if the 10" SCT weren't so weighty ... ;-).
Posted 11/04/2003 01:55PM
#3
Ted, how much magnification are you using? If the planets (like Jupiter) are "too bright", then you may not be magnifying them enough. Also, try colored filters. I've found that a #21 orange works really good on Jupiter. Others probably have their own favorite filters. Local atmospheric seeing can be causing you problems as well. You say that you're in the city. Are you observing over houses, buildings, or parking lots?
Comparing planets to the moon is like comparing apples to oranges. The moon is so big and has so much detail and it’s all very high contrast, so virtually any scope in virtually any conditions will show a lot of lunar detail. Planetary detail is inherently more subtle and more difficult to extract.
Good luck,
Doug Scobel
Comparing planets to the moon is like comparing apples to oranges. The moon is so big and has so much detail and it’s all very high contrast, so virtually any scope in virtually any conditions will show a lot of lunar detail. Planetary detail is inherently more subtle and more difficult to extract.
Good luck,
Doug Scobel
Posted 11/06/2003 11:08PM
#4
Ted,
Collimation has to right on...get someone to help you with that if you are unfamiliar with the process and results. Bob's Knobs help immensely.
Also, the scope has to be at thermal equilibrium. Give it plenty of time to reach ambient temperature.
A blackened, extended dew shield will make a noticeable difference, too. All that ambient light, even from a dark site, can cut down on contrast. You can make one yourself.
What kind of diagonal are you using? My old 10" SCT came with a cheap prism diagonal and when I replaced it with a good mirror Televue, it was like having a new scope when it came to planets.
Eyepieces are the next thing you might want to upgrade. Get a decent 10mm plossl, even a generic one might be better than the SMA that come with some SCTs. For planets, get the best eyepiece you can afford. Tak LEs, Pentax XLs, Radians are pricey, but all that light your scope gathers has to go through the eyepiece before it reaches your eyes. Cheap oculars will scatter light, reducing contrast.
After you've done all that, you will still notice a difference between SCT and say, refractor performance in planetary work that demands good contrast.
If you decide you really love planets, you'll eventually ditch the SCT or supplant it with a scope that has better contrast characteristics, like an APO or something with a small central obstruction. I've had just about every kind of scope there is - refractors, SCTs, Maks, Newts, MakNewts and a big (20") dob - and my MN56 and 4" APO are consistently the best at making low contrast planet features apparent. For example, they are the only 2 scopes (excluding the 20") in which an absolute beginner will be able to spot Jupiter's GRS without prompting from anyone.
KMM
Collimation has to right on...get someone to help you with that if you are unfamiliar with the process and results. Bob's Knobs help immensely.
Also, the scope has to be at thermal equilibrium. Give it plenty of time to reach ambient temperature.
A blackened, extended dew shield will make a noticeable difference, too. All that ambient light, even from a dark site, can cut down on contrast. You can make one yourself.
What kind of diagonal are you using? My old 10" SCT came with a cheap prism diagonal and when I replaced it with a good mirror Televue, it was like having a new scope when it came to planets.
Eyepieces are the next thing you might want to upgrade. Get a decent 10mm plossl, even a generic one might be better than the SMA that come with some SCTs. For planets, get the best eyepiece you can afford. Tak LEs, Pentax XLs, Radians are pricey, but all that light your scope gathers has to go through the eyepiece before it reaches your eyes. Cheap oculars will scatter light, reducing contrast.
After you've done all that, you will still notice a difference between SCT and say, refractor performance in planetary work that demands good contrast.
If you decide you really love planets, you'll eventually ditch the SCT or supplant it with a scope that has better contrast characteristics, like an APO or something with a small central obstruction. I've had just about every kind of scope there is - refractors, SCTs, Maks, Newts, MakNewts and a big (20") dob - and my MN56 and 4" APO are consistently the best at making low contrast planet features apparent. For example, they are the only 2 scopes (excluding the 20") in which an absolute beginner will be able to spot Jupiter's GRS without prompting from anyone.
KMM
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