AndyUK

On 27/05/2019 at 07:06, Brian28 said:

Hi Carole , cracking pic ..

im struggling with the Hubble pallet even more than the normal pallet 😂, as most of the data is normally captured with Ha when you assign to the Green channel , everything is green ! Or at least on my images ..😳 

Anyway .... super  pic and very nice processing ..😉

Brian 

 

Brian - As Carole's noted the "secret" behind hubble palette is using selective colour - I always found THIS link pretty useful in getting something close, and you can then tweak the colour further, either by repeating some of the changes and/or amending the layer transparency to taste...

... But back to Carole's image...  Very nice indeed, Carole! .  (I'm hoping I might even be able to capture some data myself sometime - maybe this year?)

Great to have you back, John... . 

Thanks Dave - It looks as though my error is trying to use the ball-head for framing rather than relying on the "fine tuning mount assembly"...

Hi Dave, I do have a hot-shoe mounted RDF and of course once calibrated that makes it easy to get to the closest high mag/named star (which I can just about manage using my phone to help :))... it’s just that hop from that star to the DSO I struggle with, especially when I’ve been trying to use the ball-head (ie not RA buttons / DEC  knob on the adjuster)...

I'm fairly new to my Adventurer - I bought it last October/November so that I can take it abroad but I've been monitoring this thread for some time and have to say I'm very enthused about the prospects .  With a mate's assistance, we took mine out for a test last weekend - The transparency was atrocious, but we went through the process of setting it up and all seemed to perform pretty much in line with what I expect to be using it for...

However, as I've always used a goto mount (and/or platesolve), I knew that was one thing I was going to miss badly when trying to find DSO's at longer FL - To my shame, starhopping doesn't come naturally to me .  However, we thought we'd see how a 70-200/f2.8 would perform - No problem getting Arcturus in the frame and again, tracking / focus looked promising, so we thought we'd see if we could get M3 on the sensor @ 200mm...  and failed miserably... even when zoomed out to 70mm!

Unfortunately using setting circles was / is also beyond us both (again, FAR too used to the simplicity of goto / EQMOD / platesolving!), but I did find an interesting article for manual goto using dead reckoning on DPReview, so thought I'd post it here in case anyone else is in the same boat as me. 

A “Manual Goto” method for use with the Star Adventurer mount

When using a simple mount like the Skywatcher Star Adventurer with a telephoto lens to photograph faint deep sky objects, the problem arises of how to locate the target.

This is a manual GoTo method that allows the mount to be moved from a known position to a desired new target position using dead reckoning.  It only works if the camera is mounted on the Star Adventurer “Fine Tuning Mounting Assembly”: the necessary control is lost if the camera is mounted on a ballhead.

The method makes use of the fact that object coordinates in the RA/Dec system are readily available (ie Stellarium app) so that a move from one place to another can be easily described in terms of a change in RA and a change in Dec coordinates. The key is that the motor on the mount only moves the imaging camera in RA, and the control knob on the Dec bracket only moves the camera in Dec. Thus, the necessary RA correction is made with the motor (and the N/S direction slider) and then the necessary Dec correction is made by turning the control knob on the Dec bracket.

The detailed procedure is as follows.

·         Find the coordinates (RA in hours / minutes / seconds; Dec in degrees / arcminutes / arcseconds) of an “easily identifiable star” near the target

·         Find the coordinates (RA, Dec) of the target.

·         Work out how many minutes RA must change to move from the initial star to the target and how many degrees Dec must change to move from the initial star to the target

·         Calculate the direction (S or N on the mount three position slider) and time that the mount needs to run at 12x speed to make the necessary RA correction:

·         Observers in Northern Hemisphere:

For every minute increase in RA coordinate, the SA has to run [S, 12x] for 4.62 seconds.

For every minute decrease in RA coordinate, the SA has to run [N, 12x] for 5.45 seconds

      NOTE:  Opposite for Southern Hemisphere

·         Calculate the number of rotations of the Dec adjustment knob that are needed to make the Dec correction, given that I measured one full rotation of the knob to be equivalent to 2.95 degrees.  The knob has 10 ridges on it, so it’s easy to make 1/10 of a turn, or about 0.3 degrees.

If Dec needs to increase, the knob must be turned so that the camera turns towards the N celestial pole.

If Dec needs to decrease, the knob must be turned so that camera turns away from the N celestial pole

·         Get the mount polar aligned and turn tracking on at the normal 1x rate and direction

·       Centre the camera on the “easily identifiable star”

·       Make the RA adjustment [turn tracker off; set N-S slider appropriately; set speed to 12x; wait the required time; turn tracker off, set N-S slider appropriately for normal tracking; turn normal tracking back on]

·         Make the Dec adjustment

I’ve tested the procedure (Northern hemisphere settings) by moving from Elnach to a point between the Jellyfish nebula and the Shoe-buckle cluster.

·         The overall angle between Elnach and the target was 11 degrees and 45 minutes

Initial star (Elnath) is at:                      RA 5h 27m 31s   Dec 28 degrees 37’ 15”

      The target was at:                                RA 6h 14m 56s   Dec 23 degrees 28’ 19”

      Difference:                                            RA + 47.5m         Dec - 5 degrees 9 m

·         Location after the GoTo move:          RA 6h 11m 25s,   Dec 23 degrees 40’ 15”

Error:                                                   RA – 3.5m            Dec + 12m

Overall, these errors mean that the image centre was about 50 arcminutes from the desired target.  A 300mm lens on an APS-C camera has an angle of view of about 5 degrees so an error of less than a degree means, with this sensor size and focal length, that the target will be within the field of view after the GoTo move.

Has anyone used a process such as this (or something similar?).  If anyone has any experience/tips on framing at longer FL, please pile in .

For focusing, I know many simply open the lens up, ISO 25,600, zoom in 10x, centre a nice bright star and then bring it in and out of focus until happy that it's as good (small) as they can get it.  However, I'm a great fan of bahtinov masks...  There are 2 main types - Those that clip into the lens filter thread, and etched filters that slide into square filter holders.

The clip in masks are a lot cheaper, but when I tried one I found the view using a 24mm lens (even f1.4 / ISO 25,600, live view 10x zoom) was too dim for me.  There are also Y masks which might be brighter (but I've not tried one of those with a lens - Maybe someone else can comment?). 

I use an etched filter - There are two I know of - Lonely speck and Kase.  Not cheap, and I have to admit I do struggle seeing the "whiskers" at 24mm, but it works pretty well at 70mm .

(For framing I also have a hot-shoe mounted red-dot finder, but I've not used mine yet as I've only used 24mm and 70mm lenses so far...)

That's a real shame John - I too feel your disappointment. When I saw your post pop-up on my phone, I wasn't able to read it but was hoping for so much better this time around .

From my own personal experiences, and regardless of brand or cost, almost everything nowadays seems fraught with potential QA pitfalls... Whenever I buy anything new a quote from Naked Gun always creeps into my head -

Hapsberg:   Do you gamble Lieutenant?

Dreben:       Every time I order out.

Wow - Now THAT's what you call service .  The forecast near Bath is showing clear skies Saturday, Sunday and Monday nights - I hope you're seeing / get the same!

What a fantastic and detailed report, John - Thank you very much! 

It looks as though the good weather's going to continue for a bit longer (geographically speaking, we're more or less neighbours ), so fingers crossed you get the replacement soon. 

Wow - That IS a beast of an OTA .  I very much look forward to hearing more reports on this...

That's a lovely field for this pair, James - As Scott noted, for many it would take many nights to cover all this... and the fact that this is just 1 hour's worth of data is really quite phenomenal

A superb result, Steve...

(And the next project will be...?!)

Words fail me... totally...  Huge commitment, an incredible accomplishment and an almost unbelievable result - Congratulations to you both!

I'm also very much looking forward to seeing the results from this scope... (Not that I could ever afford to buy one though - In fact, I'm not sure I could even afford to buy the reducer!)

Gina, I don't know if it will fit, but as someone else posted, the 0.75x Riccardi reducer *might* do the trick - On my 80/f6 the spacing requirement is a very generous 81mm.  TS list a number of spacings, including the SW150 triplet (74mm), but of course with the Esprit 80 being so new, they probably haven't had the chance to ascertain what the spacing is yet.  It might be worth monitoring their website, or sending them an email, perhaps...?  They're certainly not the cheapest flattener/reducers ( ), but if it will work, it would take you down to a fairly interesting 300/f3... .

I haven't had a Synguider for quite some while now... but I STILL have a soft spot for it.  I only really changed for two reasons, the first of which was that the original reason for buying it was because I didn't ever see myself using a laptop for guiding/capture (I now have a CCD camera, so that blew that!) and the second reason was that if it loses the guidestar, and you're not watching it, then it won't re-acquire again or even bleep at you - It just displays a message on the back of the screen (which wasn't good for me as I like to doze for 60-90 mins at a time, otherwise I'd be useless at work the following day!). 

But those reasons aside, for being in the field with a DSLR, then I still think they're a very good solution if you don't want to be constrained to using a laptop - I used to default to 10min exposures when using the DSLR (ocassionally using 15 mins in the winter), but in testing did get up to 25mins with little issue (other than rotation due to poor PA!)

From what you're describing, I would have to agree with David that you may be trying to guide on a hot pixel...  Maybe you could test this by pointing scope/Synguider at (say) a named star and seeing what that looks like on the Synguider and maybe then you'll be able to pick out where the hot pixels are?  For me the biggest secret to getting the Synguider to work was getting the focus right (again, I used to use a named star).  Once you've got the focus sussed on a really bright star, (which may require reducing the exposure down to something silly like 32ms and then tweaking the focus to get the highest brightness value), you can then move to your DSO and set the exposure to the full 4096ms and see what stars are in the field.  If you use the handset to move the mount a tiny amount, you should see the stars move (to differentiate them from any hot pixels)

I remember for me there was a temptation to reduce the exposure to ridiculously low values, but I later preferred to guide at either 2048 or 4096ms if I could, but again, it's important not to guide on TOO bright a star (although sometimes I was forced to do so in order to get a low enough brightness setting...)

Austin - That grid pattern... Obviously not much you can check out from where you are, but could that be the bayer matrix?

Ah... I can see them now - It does look like it might be some kind of electrical (or maybe lack of shielding?) interference or, as Jessun suggested, an artefact being introduced via the USB cable...

It looks as though you've got it working just fine Carole ! Spacing's (fairly) easily resolved, but I'm afraid on this scale I can't see the faint lines you've mentioned - Maybe it's a bias artefact?

(Congrats on a succesful night - I just drowned my sorrows and went to bed... Still, probably best to get this thread back on topic...!)

How frustrating for all... I wonder when the law of averages is going to kick in...?

(Very jealous in the SW - Currently chucking it down... )

I certainly will wish you luck... You must have ever so slightly different skies than we have in the SW - It would probably be very good for taking flats... without having to cover the front of the scope.

I stand corrected...!

Would this be the same set up for a CG5 Celestron mount (EQ5)?

The only thing you need to be aware of (and I think it may have been alluded to in the thread above), is that the upgrade kit is also for the EQ3/2, which seems to require the cog to be fitted the other way round (and on mine, the EQ3/2 requirement was "the default". On goto's it initially flew around in some very odd places looking for stars (like looking for Vega under next door's garden ). It's simple enough to reverse the cog though...