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Would this be a good telescope for a beginner?

Started by Lucid, 03/22/2016 11:04PM
Posted 03/22/2016 11:04PM Opening Post
I have a digital camera for telescopes (a USB-objective) and a cheap Newtonian telescope, which is a bad combination if you want to make close up pictures of the moon. Therefore, I want to buy a refractor-telescope (since it is easier focusing, according to several people).

Would this be a good telescope to make close-up pictures of the moon? I am not interested in making pictures of stars, only the moon and the planets.

http://www.amazon.com/TwinStar-iOptron-Computerized-Equatorial-Refractor/dp/B0038MQ1S2/ref=sr_1_fkmr0_1?s=photo&ie=UTF8&qid=1458711223&sr=1-1-fkmr0&keywords=refractor+gps+milimeter

Posted 03/23/2016 06:49AM #1
Posted 03/23/2016 08:50AM #2
You can probably get pleasing snapshots of the moon with that combo - but little else. Planets would be way way too small; needs a bigger scope and experience. A great book would be The Backyard Astronomer's Guide by Terence Dickenson. This would answer your question and hundreds more! It's slightly outdated, but the most informative / least intimidating that I have come across. Enjoy the hobby! Tom Dey

29-inch Dob in a dome
36-inch upgrade soon
LUNT 80/80 solar scope
FLI 6803 cam
APM 100mm APO Binos
JMI RB-16 Night Vision Binos
Zeiss 20x60 IS binos
Posted 03/28/2016 07:15PM | Edited 03/29/2016 01:55AM #3
Hello Jo Luijten,

I looked up your Celestron Powerseeker 127EQ and I can understand that you are having problems taking photos of the Moon. I would suggest that the EQ-1 mount is the bigger problem, vs. the Newtonian nature of the telescope itself. On a sturdier, better quality, tracking mount, the Newtonian Optical Tube Assembly might actually work better or OK, but I'll leave that for now.

I have some experience with the iOptron Cube GPS GOTO mount (which can either be an EQ mount or an ALT-AZ mount) that you asked about since I own several iOptron mounts. I've used the Cube in both EQ and in ALT-AZ and in my opinion the ALT-AZ mode is easier for beginners. My first iOptron Cube was similar to the setup you saw in your link. The other two answers you received so far are "no" and "go Read a book" I agree with both, but wanted to explain why. The iOptron cube is not a bad choice for learning about GOTO mounts (which is a steep learning curve for most beginners), but the tripod it comes with is too light weight for the purpose of holding the mass of the scope solidly enough for any type of astrophotography. I have used chains (see link below) to make my tripods less flimsy and then have moved the cube to an older, more solid wood tripod. That helped a lot. Leveling the mount IS KEY FOR AN ALT-AZ MOUNT and making an initial guess where Due South is also very important, but a magnetic compass can help here.

A real torpedo level instead of the tiny, junky bubble level is a key to success as well. If you get the ALT-AZ mount level, then the mount "knows" where the center of the earth is at (exactly straight below). Then you only need to "sync" to a single object, like the moon and correct for the offset (in azimuth only) between where south really is compared to where you told it where you thought South was at. Do this by changing the azimuth only to make the green laser (see below) point to the real object and you are "off and running" to find things near your first object. Learning on Jupiter or the Moon (or the sun) make life much simpler than starting with all those alignment stars that most beginners have trouble naming or finding. Expect to learn the star names over time. Practice when it is cloudy or still daytime. Put a wood pointer in place of the scope and get to know the iOptron Cube first, then take it outside in the daylight and use the sun and the shadows on the ground. Use the full moon, then 1st quarter moon with the scope and the green laser (See below).

A few years ago, I had looked at the predecessor to the inexpensive refractor you had a link to and instead decided to buy the Maksutov Cassegrain 90mm ("Mak" for short). A Mak is a long telescope in a short package. The key difference is the Mak is a higher "f" number than the refractor (f13 vs f5). Your current scope is 1000mm focal length and 127mm diameter which makes it an f = 1000/127 = 7.87 or about f8. If I understand you correctly, you are having trouble getting a good focus with your f8 ? The focus travel is shorter for a f5 and longer for a f10, so it is twice as easy to get and f10 scope to focus since the focus knob travels twice as far in an f10 as in an f5. I think you need a longer focus travel, not a shorter focus travel. Another thing to consider is a two speed focusser (which has course and fine adjustment knobs).

The f5 refractor is also a poor choice for your application because it is so fast (low f number) that it would have significant false color on bright objects like the moon. The Mak does a much nicer job on the moon because it is a slow system AND because it uses mainly mirrors to focus the light so that Reds, Greens and Blues all come to focus at the same point. In contrast, the low cost f5 refractor only uses two lenses that are an inexpensive attempt to get Red & Blue light to come to focus in the same place (called an Achromat) but this means that Green and other colors aren't precisely focused when Red and Blue are and there is a problem with false color "halo" effects (mainly Violet) messing up your views. Expensive refractors use either more glass (triplet, 4-lense Petzval, etc.) or use very expensive glass that makes the expensive telescopes APOCHROMATIC instead of ACHROMAT only.

I have only used my setup for visual observations, so your experience will be different if you try your camera. I use a 40mm (x30) eyepiece and a 8mm (x175) to 24mm (x50) zoom eyepiece with the Mak 1200mm, which gives me a good visual experience.

The 90mm Mak with a sun filter does a really nice job of viewing sunspots on the full disk of the sun and the transit of Venus across the face of the sun was very nice. At night, the Mak does well on the moon and bright planets like Jupiter and Saturn. Mars is harder, but with the co-operation of cool-dry-thin air of the Cascade mountains far away from the lights of the city, Mars is very satisfying every other year when it is in good position (called oposition). I junked the lousy finder on the iOptron unit and mounted a Green laser in its place. With careful mounting, I am able to see the green laser in the eyepiece and get it exactly centered in the eyepiece. This is necessary to accurately align the Cube Mount to two stars. when this is done, the GOTO works very well. One caution is that the 12 Volt DC connection can be flakey. I had to research and buy the correct connectors so that I could get a reliable power connection to the Cube.

In summary, "No" is a good short answer, but if you are willing to invest the time and spend the additional money, the iOptron (with the Mak) can become a reasonable next scope for you in my opinion. Or keep your 127, add a new focusser, look at the iOptron MiniTower to put it on and keep having fun with astronomy !!!

I hope this helps,

Ed

P.S. Check out this link: http://www.cloudynights.com/page/articles/cat/user-reviews/review-of-the-ioptron-smartstar-a-%E2%80%9Ccube%E2%80%9D-mount-r2662

P.P.S. Here's the Mak: http://www.ioptron.com/product-p/8740.htm and here's the Mak on the Mount :http://www.ioptron.com/product-p/8604b.htm

P.P.P.S. Here's the Green Laser pointer Link: http://www.telescope.com/Orion-SkyLine-Deluxe-Green-Laser-Pointer-amp-Telescope-Bracket/p/24780.uts BUT Note that the Orion Shoe is bigger than the iOptron finder shoe, so you will need to make an adapter. I know, Is this really for beginners ???