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Topics - satimoja

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I'm brand new to amateur astronomy, having just acquired my first scope - an 8", f6 dob (XT8 Plus, specifically). I've taken it out every clear night and I'm already sure that this will be a hobby I will be investing some time (and money) in. I've spent some time reading through these forums, and have read through two highly recommended books ("Nightwatch" & "Turn Left at Orion"), but there are some things I could use some further advice on:

1. Light pollution: I live in an urban environment (Alameda, CA - basically downtown Oakland) and the light pollution is awful. I have 3 young kids, include a 1 month old, so my ability to get away from home to seek out dark skies will be limited for the foreseeable future. I understand that many deep sky objects will remain out of reach from my location, but I still want to seek out all the open clusters and multi star systems and any other bright objects that I can from my own backyard. Considering my gear, and that I have no GoTo technology, I'm reliant on star hopping to find my targets, which is quite difficult with my severe light pollution.I had considered getting an extreme wide angle eyepiece at low power with which to break through the pollution to navigate the skies for star hopping purposes.Is this a feasible solution? Perhaps coupled with a broadband filter?Any other advice on star hopping in severe light pollution without GoTo technology? Also, can you please recommend a resource for light pollution maps?

2. Filters:I'm considering purchasing two different filters, a broadband filter to dampen light pollution (noted above - although I question how helpful it will be), and a narrowband filter for nebula viewing from home and on rare occasions when I can get away from the city. Regarding the narrowband, I've read great reviews on the DGM NPB, so that's currently at the top of my list. With that in mind, I'd rather not pay the full $150, so I'm mulling the idea of getting the "cosmetic 2nd" discounted piece from Amazon (, but I'm concerned about the fact that the flaws include "cosmetic flaws, such as pinholes, sleeks, or light scratches". Are these flaws significant when it comes to filters?Or should I trust DGM when they say "flaws which have zero impact on optical performance. Spectral characteristics are the same high quality as our first quality filters and side by side performance is indistinguishable."

3. Eyepieces:There's so much information out there on eyepieces, it's difficult to settle on which eyepieces to target next. The XT8 Plus comes with an Orion 10mm plossl and 28mm "Deep View". The plossl seems well enough for now, but I don't feel that the Deep View provides enough FOV for a lower power eyepiece, so I think a low power, wide angle eyepiece will be my next purchase.With that in mind, any recommendations on the ideal "True FOV" to shoot for low power viewing? I know 2"+ will be necessary to take in all of thePleiades and Andromeda (for example), but is 2" considered overkill, or is this a good TFOV to shoot for? Any other eyepiece advice you can provide regarding building a strong initial eyepiece set would be helpful as well (considering mid to high-tier options).

Thanks a lot!

Mounts Questions & Expirience / iOptron ZEQ25gt Alignment and tracking help
« on: December 29, 2017, 03:31:33 PM »
Hi I recently bought a used an IOptron ZEQ25gt, and I am looking for some help with getting it polar aligned and I have a Hand controller question as well.
My OTA: Celestron C6 A-XLT
Mount: iOptron ZEQ25gt with mini tower
Power source: Plug into wall on my balcony
It is my first setup also...
I am doing a rough polar alignment since I have a south facing balcony and I can't see Polaris (I am also on the 4th floor). I just make sure the north facing peg faces north per my compass, and everything is properly balanced-and date time inputted into hand controller. I have been getting my alignment pretty close since when I do a solar system alignment or a one star alignment it gets close within the spotting scope and I just make adjustments to center it into my eye piece. However, I have noticed It only accurately tracks for about 1 minute or a bit longer, I have even tried going to "set to target" and make adjustments there but still the same issue--shouldn't the mount keep tracking it continuously?
I have tried multiple star alignments but the star database doesn't give me enough stars that face south to make the alignment hence why I usually do 1 star or solar system alignment.
Any suggestions?
I wonder if this may be a cause of an issue my Hand controller always defaults to 2011 so it appears I need to change the battery, however, the screw heads are damaged so I can't unscrew and open up the controller and change the batttery...I am assuming the battery just holds the date and time when powered off, so I don't mind updating it during each use....But do you think a low battery could cause the unit to not accurately sync and track a target?

Eyepieces Questions & Recommendations / Eyepiece AFOV calculation
« on: December 29, 2017, 02:49:42 AM »
I am having some trouble with the eyepiece AFOV calculations resulting in low numbers, like 77.6 degrees for a 31mm Nagler, for example, and looking for some help in understanding this result.

I have an eyepiece spreadsheet I found online to compare eyepieces, and I noticed that the spreadsheet uses a calculated eyepiece field stop, from the published AFOV, the focal length of the eyepiece and the telescope objective lens/mirror focal length.

I want to modify the spreadsheet so that I can enter a real value for the field stop, then calculate both the apparent and true fields of view (afov and tfov) from that. So I found a list of calculations that I am trying to use, at:

These calculations are:

Magnification = Focal Length Scope / Focal Length Eyepiece
Real FoV = Apparent FoV / Magnification
RealFoV = (Eyepiece Field Stop / Focal Length Scope) * 57.3

Some quick subsitution yields a calculation for AFOV:

Apparent FoV = Real FoV * Magnification = (Eyepiece Field Stop / Focal Length Eyepiece) * 57.3

So, for the 31mm Nagler I get:

Apparent FoV = (42mm/31mm) * 57.3 = 77.6 degrees

So, what am I doing wrong? Or is the apparent field of view really 77.6 degrees for an "82 degree" 31mm Nagler? I don't think so, because all of the eyepieces for which I did this calculation, showed results that were lower than their published AFOV.

Any help appreciated.


ATM, Optics and DIY Forum / Aluminizing and sio coating
« on: December 26, 2017, 08:00:53 PM »
I'm Dev ojha from Indore India.  I'm making mirror for telescope.  In india any technique to aluminizing coating or mirror and some other aluminizing and coating service in india.  I started many experiment on those but until now nothing good one biggest difficulty is lack of funds.

Reflectors Telescopes Forum / Quality of Discovery Optics mirrors?
« on: December 24, 2017, 03:03:26 PM »
I had been considering the prices for refiguring a 8" mirror, and I saw that Discovery Optics offers Pyrex 8" f/6 mirrors at $299.  This is lower compared to the price of refiguring + coating + 2 way shipping, and offers an upgrade of substrate material.  It's also considerably lower compared to a lot of additional manufacturer's 8" mirrors.  Does anyone have experience with them?  I presume they are good, however I thought I would ask a bit first.  Thanks!

Beginners Forum / Need Help using Celestron CPC 1100 HD Telescope
« on: December 23, 2017, 10:24:04 PM »
Hey Everybody,

I recently just bought the Celestron CPC 1100 HD Telescope (http://www.celestron...rized-telescope) and am having difficulty using it.  Thus far I've been very unhappy with the vision that I have observed using the telescope.  I believe I'm doing something wrong and the guide really hasn't been much help.  It came with an Luminos 23 millimeter eyepiece and I also purchased the ac adapter for use with the scope.  I setup the finder scope and obtained that aligned just fine.  I was also able to align with the scope using the three star alignment method.

Everything I see from the telescope thus far doesn't offer much detail.  I thought I would be able to observe some of the solar objects that other individuals have posted images of so far I haven't seen anything even close to resembling this amount of detail.  I'm very frustrated with it and kinda at my wits end.  I have until Feb 1st to return it, but figured I could seek some guidance from more experienced users of telescopes.

Does anybody have any suggestions for me?  Any links that might assist me?  What could I do wrong?


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