Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - tioraigenroi

Pages: [1] 2 3 ... 8
1
Reflectors Telescopes Forum / Re: Understanding Reflectors...
« on: February 09, 2018, 11:35:02 AM »
Oh I forgot the incredible...

Vixen VSD 380mm F/3.8

2
whats a go fund me ?, i fond a pick of me and my 12" at the convention and a pick of it On the side walk in front of my house on a home made stainles steel german mount. when the comet hit Jupiter. Of which I qill swear til i go to my grave I saw befor it was discovered right near the planet unless it was a faint edge oon galaxy

3
Beginners Forum / Re: "Refractors are best for planetary viewing"
« on: February 04, 2018, 09:41:06 AM »
Quote
I think it can be debated whether a 6 inch refractor and an 8 inch SCT would be better for DSOs. Considering many factors (central obstruction, reflectivity of mirrors, etc) I suspect it would be pretty close. Especially true if the refractor was an APO or ED. Planetary I agree the chromatic aberration would be a bit annoying, but still useable. If planetary was the goal I'd use the SCT.

I don't see it being close on DSO's.8" vs 6"is an extra 0.62 magnitude. Even allowing some for reduced transmissionand central obstruction it is still going to be about 0.4 magnitudes of difference and without the chromaticaberration problem. And you still retain the extra resolving power of the full 8" vs. 6" aperture. I would anticipate it being quite noticeable on globulars in how many begin to resolve, how deeply they resolve, andhow bright they appear overall. And for galaxiesthe closer you get to the limits of visibility the more apparent it will be there as well.

The area where the 6" will havedistinct advantage is in the low power wide field views.

4
Mounts Questions & Expirience / Re: To POTH, or not to POTH?
« on: February 03, 2018, 07:23:58 AM »
Thank you for the information Laura. This may be helpful.
John, I do apologize for temporarily hijacking your thread.

5
Quote
Quote

Quote

Given the Chief's ability to distort threads, I don't see how it can be that sharp optically.. 

Jon
Have you ever looked through one?

Dave:

It was meant as a bit of humor, that's what the  was about. I included it in part to point out that this thread is drifting off topic as many do, in part because I struck me as kind of funny. I have no doubt that a Chief can supply sharp views. This thread is about OA Newtonians and not Chiefs.

Jon
LOL ... I'd suggest that perhaps you'd have done better to have not continued the conversation about the CHief and perhaps have made a comment more on topic ...

Off-axis Newts. A while back, I had used OSLO to conduct a comparison of a 6" f/10 "classical" Newtonian (20% CO) with a 6" f/10 off-axis Newtonian (unobstructed). Unfortunately the Word file is too large to attach here. Some of the salient points were:

1) The OTA for the off-axis Newt was slightly longer for a given separation between the optical axis and the image plane; but not enough to be an issue.

2) On-axis, both systems were essentially "perfect" ... but at 1/4 degree off axis (1/2 degree field), the OPD for the off-axis newt was about 4x worse than the "classical" Newt. It should be noted that the OPD of the "classical" Newt had a "hole" as a result of the central obstruction.

3) The spots showed the "classical" Newt suffered from coma off-axis; but at f/10 it was still essentially diffraction limited out to a 1/2 degree field. The off-axis Newt suffered from astigmatism with about a 1/3 degree field that was essentially diffraction limited.

4) The Point Spread Function (PSF) showed the "classical" Newtonian was clearly better at the edge of the 1/2 degree field.

So, for the f/10 systems that I compared, both had essentially "perfect" on axis performance; however the "classical" Newtonian (with 20% CO) clearly had better off-axis performance.

Choosing an f/10 system was perhaps favorable for the "classical" Newtonian; its on-axis performance may suffer with faster focal ratios as the CO increases (at least in the case for the smaller apertures). It was a result of this "comparison" that I started looking more closely at the CHief as perhaps a more viable way to get an "unobstructed" Newtonian.

6
Mounts Questions & Expirience / Re: Pelican Case for G11 with Gemini ...
« on: February 02, 2018, 10:43:45 PM »
I agree Hilmi. I had a Pelican case for my CGEM mount and the edges started to get smashed down. I do like how Dave layered his though. Instead of glueing all the layers together. But I kind of find that to be a pain. I know I sound like a little girl as I say that but I like simple. I'm wondering what Scopeguard cases cost. I don't see a price list on the website. I'm guessing around $400. I'm suprised nobody has a case specific to the G11. Theres more of those mounts on there than there are rivets on the Queen Mary.

7
Beginners Forum / Re: Reducing Chromatic Aberration
« on: January 31, 2018, 01:12:16 PM »
Quote
It is up to the individual to decide whether they want as much color shift as the Baader 495 Longpass filter gives or not - but the 495 LP eliminates the purple fringe completely. It is my filter of choice for a large, fast achromat. With the filter you can get much sharper star images at higher magnifications than without the filter.

So with an achromat I just permanently mount the 495 LP filter on my star diagonal and use it for deep sky, double stars, lunar, planetary.

Dave

There's been a lot of discussion in the Refractor Forum on the suitability of using the Baader 495 Longpass filter to eliminate CA in achromats ... spearheaded by Dave.

Thanks, Dave.

Since a picture is worth a thousand words ... here's a rooftop shot of an old barn with power lines over it ... taken with 70mm f/5.4 achromat ... with and without the 495 filter ... untouched 5X blowup (except for the color corrected image).

Second image .... same barn, same scope, same camera and lens at 1X ... left image no filter, right image color corrected 495 filter.

Draw your own conclusions .... accordingly.

Attached Thumbnails




8
Quote
In an 1978 episode of Good Times titled "J.J.'s Condition", Season 5 Episode 19 I saw a 6 or 8 inch Celestron SCT in one of the scenes.

It was a C8. The C6 didn't come out until the beginning of the millennium.

9
Beginners Forum / Re: Can I trust skatronic?
« on: January 31, 2018, 12:33:36 PM »
Quote
Anybody know about skatronic please let me know. Really appreciate it. GT2015


Um, you did just read this thread, right? The site in question is only a month old so this is probably all that we're going to be able to tell you.

10
Reflectors Telescopes Forum / Re: Clean cigarette tar from mirrors.
« on: January 31, 2018, 11:20:21 AM »
Cleaning technique: (this WILL work, and it's very gentle):
https://www.youtube....h?v=9Y8xFnXFVGQ

11
Mounts Questions & Expirience / Re: New CGEM DX plagued with problems.
« on: January 31, 2018, 10:44:27 AM »
Quote
Quote

1) Beta firmware to fix a bug in Celestron's code. That's on Celestron to make it right.
2) The hardware is a bit trickier since you performed the hyper-tune yourself, likely partially invalidating the warranty. (maybe someone else can clarify how that would work and/or whether my comment wrt to it is true or false)

The firmware was tested and no problems were found. It was released as version 6.51.

As for warranties, everyone seems to be afraid of invalidating warranties. No one reads them. In a nutshell, if you break it you pay for it. If it's a manufacturer fault they fix it. HyperTune is not a modification, just an adjustment to improve its mechanical functionally. I'm not concerned about that. I just want the control to work.
Fair enough. I wasn't aware the firmware had been ruled out. I must have missed that in your opening comments.

I'm not "afraid " to invalidate a warranty, but there are levels of DIY that can cause warranty invalidation, depending on a given vendor and their terms...

Personally, I'd send the rig back to Celestron for servicing if I couldn't resolve runaway problems on a new mount, modified or not...

12
ATM, Optics and DIY Forum / Re: Superior Optics, Columbus, OH
« on: January 31, 2018, 09:11:05 AM »
Quote
Got to go to my crossing guard job
what were you a safety growing up. LOL

I can't say how *** that is on here. LOL

13
General Astronomy & Observing / Re: Sunset Moonrise Twilight Calculator
« on: January 31, 2018, 08:04:17 AM »
Thanks for reporting this problem. Strange thing is that lots of people are using this tool already without having to log in, that makes it difficult to pinpoint what could be causing this. So I removed the login completely on the server, let me know if this helps...!

14
Quote
Quote

I wonder how stiff tractor beams are?

More seriously, I'm told that wire supports have much weaker diffraction spikes than relatively thick vanes.

Also need more tension. I like a middle ground. Actually, a wire won't reflect as much wrong light onto the primary.
Don't need much tension at all, with 8 wires, 4 top, 4 bottom they just need to be firm. Works extremely well once you've got it all aligned which is the fun part as I found out. The mirror support is also very lightweight as no adjustment system is required, the wires ( guitar strings actually ) do it all.

15
Beginners Forum / Re: Doing research in what would be a good fit for me
« on: January 31, 2018, 05:46:07 AM »
AntyScience:

Reading through this thread reminds me a lot of where I was a couple of months ago. I also had a small scope as a kid and, on my return to astronomy, was excited about the possibility to do both AP and visual. Who doesn't enjoy astro photos?

I also chose to set AP aside at least for now due, if nothing else, to the seeming overwhelming options/choices for "even visual astronomy"  . There is so much to learn and explore before picking up the camera. I also have my family (who is pro visual) and a rough budget to consider, so I can't really do everything at once. I also spend a lot of time in front of a screen for my job, so it's nice to be able to *not* stare at a screen for a bit. For me, more interested in DSO viewing and having a car, this means a 10" Dobsonian reflector, which is probably about as heavy as I want to port around.

What I read is your initial interests are centered on self-directed, portable planetary and lunar visual astronomy. And then maybe some light astrophotography, but maybe not. Maybe some DSOs. Which means you are prioritizing portability and flexibility. I am by no means an equipment expert, but in the price range you are specifying, it sounds like the job of for a catadioptric (e.g. SCT) telescope to me, in the range of 6-8" aperture. They are lightweight and relatively compact for their aperture, and with a focal reducer can widen the field of view out if you want to.

As some have mentioned, a tripod could be used to take wide field photos without having to go too deep down the path of AP gear and methodologies. Maybe that could be a good starting place to test the AP waters (when you're ready)?

Good luck figuring it all out!

Pages: [1] 2 3 ... 8