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Topics - James Pederson

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I just purchased a Zhumell 12" as my GRAB and GO scope. It was on craigslist and the price was SO low, that I couldn't pass it buy. Got it for just under $400! It is two pieces - the stand and tube. Each piece is under 40 lbs. I need to walk down 5 steps and then 15 feet into the driveway and I am observing.

However, the tube is AWKWARD to say the least. I was thinking about adding two handles, one to each side of the aluminum tube to carry it. Has anybody else out there done anything similar to this? The handles on my CPC1100 make maneuvering and carrying the fork/tube VERY easy and that weight 70 lbs. Does anybody know of an easy way to carry the tube minus the handle? If anyone has mounted handles, what handles would somebody recommend? Does anybody think that the aluminum tube can have handles added without ruining the structural integrity of the tube?

I went with the 12" Zhumell because of many trees and buildings are in my townhouse complex, so nearly everything I look at will be within 10 to 20 degrees from zenith. At 6'4", the eyepiece height of the 12" is much more comfortable for me than an 8 or 10".

Thanks for any help you can provide!


Eyepieces Questions & Recommendations / Need advice on new zoom lens
« on: January 09, 2018, 12:54:46 AM »
I have 2 scopes, both are used for terrestrial viewing. we are looking down about 1000 ft over a river and can see the boats and marina about 2.5 miles away. The wife uses both daily.
One is a cheap 80 mm 400 mm fl. the other is a Celestron Nextstar 127SLT @ 127 mm 1500 mm fl.
We are very happy with both.
Currently I have a very cheap 3x barlow and a 25 mm eyepiece = 48 X mag.
Currently I have a 25 mm eyepiece = 60 X mag.
Both have 16 mm eve relief.

I want to buy a cheap zoom lens to get a tad more mag. I'm looking at the Celestron.
This lens is a 8 - 24 mm with 15 mm eye relief at 8 mm.

Opinions please. Don't forget we're happy with the cheap 80 mm 400 mm one and the barlow.

I'm putting together a list of eyepieces that I'd like to eventually add to my collection. Two of the eyepieces are a Vixen NPL 30mm Plossl and an ES 24mm 68 degree eyepiece. In doing some calculations on how they would perform in my setup I found out that the Plossl may end up being pointless, unless I'm missing something. In my setup the 30mm Plossl would give me a TFOV of roughly 0.84 degrees with a magnification of 59x. The 24mm 68 degree eyepiece would give me a TFOV of 0.91 with a magnification of 73x. It seems to me that the 24mm eyepiece renders the 30mm Plossl pretty much useless. Is there anything I'm missing or am I correct?

Beginners Forum / Observation Chair Is King, Not Aperture
« on: December 29, 2017, 04:28:19 AM »
People in the hobby say, "aperture is king". I respectfully disagree. I say "observation chair is king". What is the use of having all that great resolution, with a back bone that feels like it is broken. I have a hydraulic swivel chair. Doggone it, I want to be comfortable.Attached Thumbnails

ATM, Optics and DIY Forum / Correct Secondary mirror size?
« on: December 27, 2017, 10:42:19 AM »
I am building a 12.5 in f/5 telescope, and I did my calculations for my secondary mirror size and I got a size of 2.14 inches would be the closest and best secondary size, could I please get some more veteran builders to say if this seems reasonable? Any response is greatly appreciated!

Beginners Forum / Distortion near edges of 6' SCT. Eyepieces?
« on: December 26, 2017, 10:56:06 PM »
Hi Everyone. After spending some time celebrating with my first SCT (Celestron 6SE) I'm noticing that there is a good amount of distortion near the edges of the field.  My previous two scopes were refractor's so I'm not sure whether that is normal to the SCT design or if it is possible the basic eyepieces I'm using contribute to this.  I get slide celebrities at the center and near the center, it is just as I get towards the borders I see the star shapes distorting.  It is nothing I can not live with, however I've some serious gaps along with my eyepieces and wished to start adding a few to fill the gaps.  If there are those that don't cost a fortune and would aid with the distortion, then I would start by buying them.  My current eyepieces are - Celestron 25mm plossl, Meade MA9mm & Meade PL4mm.  The 4mm appears to be pushing the limits of the extent under ordinary seeing to me personally.  I feel like I have tunnel vision when using it.  I really don't know whether there is a better design that will allow high magnification for this extent.  I want something involving the 25mm & 9mm and something wider than 25mm.  I really don't know whether a 2" diagonal would be ideal for that.  Any suggestions will be appreciated.


Reflectors Telescopes Forum / Jacked up mirror and replacement
« on: December 24, 2017, 01:30:12 PM »
Hello all,

I've a GSO 12" that I've always been skeptical about this mirror quality with.  Just last week I took it on to NOVA optical plus it seems my suspicion was right.  The wavefront was just all over the place and there was a peculiar place closer to the center of this mirror.  I would like to encourage anybody who believes there might be a problem to have their mirror appeared at.

While the mirror has been gone for refiguring I've decided to go ahead and replace the secondary as well.  My query is this.  Looking at the secondary dimensions on Antares and protostar I notice that the size they offer you that's nearest to the GSO is 2.6" vs. the 2.75 of this stock secondary.  Will this be a problem or should I be good to go?  Also is there any advantage to moving with the 1/30 wave vs. something such as the 1/15 wave.  I'm no optician, therefore I do not really understand the difference to much other than 1/30 is somewhat better and more expensive.  Visually though will there be any diver able difference and if so where can the limit occur?  Thanks in advance for your responses.

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