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Last updated: 27 January 2005
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Last updated: 27 January 2005 |
Subject: ETX-125 and Galaxies Sent: Tuesday, January 25, 2005 11:14:09 From: Robert Fritz (robert_fritz@gmx.de) Isaw the previous Post and now I wonder .. I originally had palled to buy myself the ETX-125 on the commeing weekend. Now I saw that it only has "limited" Deep Sky performace. But one of my intentions was to see some Deep Sky Object. (Visually, not with CCD-Cameras). So ist it possible to describe a bit what I should expect from the ETX-125 ? How much of the Andromeda Galaxy would I see for exemple ? If it really is limited in that way what I am currently affraid of I might better choose the ETX-105 to safe some money and later (maybe in a year or two upgrade the an LX200). So please, if possible, describe a bit how much I can expect, and what would be too much of expectation. Thanks a Lot ! RobertMike here: Read through the Helpful Information: User Observations; there are some reports there that should help. HOWEVER, keep in mind that the eye is a pretty lousy imager for faint extended objects like nebulae and galaxies. As I noted on the ETX-125 Feedback page last update, you can expect to see some details and shapes but most will be "faint fuzzy blobs". That's true even as you increase the aperture (to what most amateurs can avoid). Yes, I saw a lot of dust lanes in an edge-on galaxy but that was with a 3.5 meter telescope at Kitt Peak. In the ETX or even LX200 you likely won't see that much detail. You asked specifically about M31; when viewed through a narrow field telescope you will see the nucleus for the most part. Viewing M31 through binoculars or a wide-field instrument will let you saw the spiral arms (as faint fuzzy areas).
Subject: re: difference between ETX-125 and ETX-90 Sent: Monday, January 24, 2005 20:53:51 From: Richard Seymour (rseymour@wolfenet.com) You (meant to) write: >The [125] is only about 1.5 inches wider [that the 90] Although it is true that it is "only 1.5 inches wider", as a -percentage- that's 50% more diameter (well, it's 125 vs. 90, which is only 38% wider... and i'm going to use -that- number for the rest of this:) What matters for most telescope use is the -area- of the light collector, not simply the diameter. And the -area- of a 125 (12271 sq mm, not adjusting for the central obstruction) is almost -twice- the 6361 sq mm area of the ETX90. So that's twice as much light. (the truth is a little less than that, since the central obstruction of the secondary mirror is wider, too). Twice as much light means you can magnify the image further before it gets too fuzzy to be useful, or it means you can see 0.3 dimmer magnitude with the same magnification. 0.3 more magnitude may not -sound- like much, but it's the difference between "not seeing" and "faintly seeing" some objects. If you really want more light-gathering, look into the LXD75 family. They are not as "portable" as the ETX125, but they can gather much -more- light for the price. have fun
Subject: etx125 galaxy/nebula usefulness Sent: Monday, January 24, 2005 11:58:39 From: thomas robison (tbrobison@mac.com) first, i am a newcomer to astronomy. second, your website has been extremely helpful in all aspects of learning. thank you and everyone else for sharing years of experience on your site. my question is this, why would the etx125 not be considered a useful galaxy/nebula observing platform/telescope? i saw this mentioned in a telescope etail store description and thought i had seen many photos of galaxies and nebulae made with the etx125. thanks in advance, tom robison seattle, waMike here: Certainly the ETX-125 (and even the smaller ones) can be used to view galaxies and nebulae. From a dark site you can see some details and shapes. But for serious visual work you need a larger aperture and perhaps even a shorter focal length. But, as you noted, you can, with patience and experience, do some amazing astrophotography with the right equipment.
Subject: difference between ETX-125 and ETX-90 Sent: Saturday, January 22, 2005 12:51:07 From: oren gotlib (slayer31@adelphia.net) I don't know how long its been since the ETX-125 has come out nor how long ive hed my ETX-90 but i know that i saw it in the store when i went to buy the 90. After about 2 to 3 years I got more in tune with telescope technology wet many emails for you i have read online are still a little hard for me to understand. A couple days ago i decided that maby i should get an ETX model 125 due to the fact that the wider the aperture the more light or color the telescope gathers. I have been on the good side of the ETX-125 and wanted to go ahead sell my ETX-90 for one. Then i got a little confused after doing some research. The 90 is only about 1.5 inches wider in aperture, which to me that doesn't seem like much. Then i read some of your emails. Some talked about better, smoother otors in the 125 but truely i just want to know if i will see more colors, clearer pictures, or even wider eye sight. If you could go ahead and give me some advanteges and disadvantages about the ETX-90 vs. ETX-125 i would really appretiate it, especially knowing im only 15 and the extra $400 dollars is a bit high. Respectfully OrenMike here: The ETX-125 came out in mid-1999. The aperture increase is noticeable, and if you add the UHTC coatings you effectively gain about another inch aperture in the amount of light that reaches your eye. But depending upon the objects you view and the conditions you view them under you may or may not be able to take advantage of that increase. But under good conditions you will see more details and more colors; just don't expect a dramatic increase like you would see if you went with an 8" or larger telescope. Feel free to read the Helpful Information: User Observations; there are many excellent reports there.
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