From: Terrence Redding <tredding@mac.com>

Date: November 13, 2009 9:04:10 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Re: ST3 Pro Exposure calculator...


Thanks for the explanation.  Even after I figured out what OAG meant I had it in my head that it was part of a camera, or a separate guide scope and camera.  I completely skipped past the visual nature of the OAG and its use for manually guiding.


Several months ago I trained the PEC for my scope and read about guiding with a 9mm eye piece with cross hair.  I assume an OAG would have a similar presentation.  In the case of the PEC training, I did that through the main scope so flexure was not an issue.


Still interesting.  I finally used Astro-IIDC and a Powermate 2.5X through the 14" scope and used the electronic cross hair to keep the scope on the target for the 30 plus minutes of training required.  It was certainly easier to watch the monitor as I kept the star in the cross hair view.  I ran through the process several times.  It was a piece of cake.


Thank you for taking the time to share your information.


Terry

 

On Nov 13, 2009, at 9:48 PM, Ray Byrne wrote:

Hi Terry,


An OAG is an "Off Axis Guider" It is a tube that the imager (or formely a camera) attaches to and has a small prism which picks off a part of the incoming light cone which is outside the imaging area of the receiver and allows the astro imager to find a guide star. It's plus point is that it doesn't suffer with problems with alignment (normally referred to as flexure that occurs by using a separate instrument - a guidescope) with the telescope taking the image but its main down side is finding a suitable guidestar in the limited area available to it.


What I have found really extremely useful is applications available on the iPod touch (or iphone) for use at the telescope or just gazing up "Starmap" is one and for the Moon "Moon Atlas" and "MoonMap Pro". Moon Atlas is my favourite and help so well when I'm close in there to find my way around and not get lost, it also help me identify what I'm seeing.


To be honest I bought the iPod Touch just for these apps. they were just £5.99 each but now I'd not be without My iPod for lots more than that (I watched Lawrence of Arabia one afternoon on it when I had to visit my mother-in-law she didn't even notice).


Ray

On 14 Nov 2009, at 02:17, Terrence Redding wrote:

Mark,


I have been a visual observer since 1985.  An armchair observer before that.  This hobby just gets better over time.  In 1986 a friend and I organized a club in order to share the experience of Halley's Comet with a larger group.  Today I could do what nearly everyone in the local club does, and simply follow their lead.  But with the advent of the Internet - I prefer to share the hobby with others using a Mac and seek ways to do what others are doing with a PC, but with a Mac.


I am so new to this, having been away for 15 years - that I constantly see terms that I am not familiar with.  For example - tonight I don't recognize OAG???  I returned to astronomy thinking I would enjoy imaging.  But after a year of getting better with a DSI II and a DSI II Color, and well impressing myself, I decided to focus on science and if I were to image, to do it with a Mac.


I am not familiar with ST3, but I have The Sky, and The Sky X Serious Astronomer Edition, and several other planetarium programs.  By far my favorite is Starry Night.  I use it to plan most observations, and to simulate events before they happen.  I have owned the program since about version 2 and it just keeps getting better.  More recently I have acquired Voyager 4.5.  It is excellent as well - though not nearly the program SN is.


I routinely use the programs to first find an asteroid, or star, become familiar with the sky, and then control the scope.  The Sky X SAE provides access to the most information but often takes five times as many keystrokes to do the same thing I do in SN with two or three.  In some cases it takes five times as many keystrokes.  It is not written by people use to the Mac interface.


If I can't find an object with SN, I am able to find it most times in Voyager 4.5.  But when all else fails - The Sky X SAE never fails me.


In addition to imaging with Astro-IIDC, which I got specifically for planetary work, I would suggest you look into Nebulosity - I haven't spent much time with it yet.  But I have a DSLR Canon that I will eventually use with the program.


The neat thing about high self-directed learners is that we will persist - strive - struggle - and are often distracted - but make progress.  Give us a few years and we will have learned a great deal - even if we don't follow the straight path presented in most educational enterprises - we eventually get there - and often exceed our initial goal to learn a thing.


Now I will have to Google ST3 and see what the heck it is you guys are talking about.


Any way, it will be interesting to see you pursue DS imaging - I may try to tag along and learn with you.


Be well,


Terry


On Nov 13, 2009, at 8:36 PM, Mark Gaffney wrote:

 

Hi Ray, 

I hope to do some imaging of DSO`s before too long. I`ve been I think methodical about what I need-in the way of OAG`s & cameras etc. To use the OAG I`ve gleaned that it`s a good idea to have The Sky or something that will facilitate the finding of guide stars. ST3 will help too I think (if you`ve got things set right- which it`s taken me a while to get right- For instance it became evident I`d need a mono camera to do it properly & ST3 isn`t set up for the usual Astro IIDC cameras). ST3 will tell you for instance for each filter used in mono imaging the optimum time for using it & exposure time. Milton has been doing this for many years & knows all the ins & outs (it`s been great to pick his mind many times!). There are times though when I`ve struck off on my jag about what I thought I`d need. I still need a couple of items to do DSO`s- a filter wheel & some filters, which I won`t have completed on current expenditures until next year. Until then I hope to experiment with the CRG-OAG a bit & familiarise myself. I appreciate most people who use Astro IIDC do planetary or lunar imaging (am I right?)- Milton is basically the only one who contributes new work on DSO`s to the files here...

No need for you to stress out about my antics.....you`ve been another important mentor!


Mark.

On 14/11/2009, at 11:44 AM, Ray Byrne wrote:

Hi Mark,


On more than a couple of occasions I've spent time and effort trying to help you with your problems and mostly they are along the lines of keep it simple and poor Milton seems to give of his best all the time. It seems to me that you are determined to keep mucking about with gadgets and software in some effort to find the holy grail of astronomical imaging/observing. Don't get bogged-down with all this stuff!


If you give me a reply that is just more of the same trials and tribulations about gear and software I'll not bother trying to help anymore - sorry and good luck



On 13 Nov 2009, at 22:47, Mark Gaffney wrote:

P.S. Anyone interested- If you have Leopard you should be able to click on "Quick Look" next to where it says "Attachment" & get a bigger view.


Mark.

On 14/11/2009, at 9:30 AM, Mark Gaffney wrote:

Milton, 

I know I`m just an armchair imager of DSO`s & perhaps an advanced beginner otherwise but I thought people might be interested in the process? Nor am I trying to push an unwanted expenditure of money on this software...it`s efficacy may be unproved in my case but I`m pretty sure there are many who are able to use it successfully. Here`s another screenshot in which I`ve added filters (a Luminance one is set here), altered the seeing index to "Good" & added a setting for "Bright Nebulosity". I`m afraid this calculator window (as I`ve set it) specifies a 0.33 reducer for M 42-another thing you advised me against.. if only to save me money! (I have the Meade one now)...Surely a one minute exposure, or 53 seconds as it says is "in the Ball park" for this subject (given the parameters) whatever the variability of the SNR values?Sorry the image is a little small this time. Opening it in "Preview" & zooming it is probably the best option..


Mark. 


<Picture 4.png>

On 14/11/2009, at 8:44 AM, milton_aupperle wrote:

Mark;

--- In Astro_IIDC@yahoogroups.com, Mark Gaffney <markgaffney@...> wrote:

-------SNIP

>I know you
> don`t set much store by such calculators Milton but it may be useful
> yet!

I'm not against anything.

However until you actually prove that these calculations are even vaguely meaningful by imaging one of these targets with their suggested exposures, your just wasting your time.

Hypothetical imaging doesn't put photons on the CCD. You only gain practical experience by going out and shooting targets in a methodical fashion, with plenty of notes so that you don't repeat the same mistakes over and over and over again.

HTH..

Milton Aupperle