MORE Guiding Woes

What a maddening hobby!   Same problem.

Here was my plan from last time:

Things to try:

1)  Disassemble the dual-saddle and tighten everything down.  DONE

2)  Do another polar alignment.  DONE

3)  MOVE both the camera and guidescope to one side. Couldn't do it.  Switched Camera and Scope poistions. 

4)  ADD more weight on top by adding maybe another camera. Used a different camera dovetail which was twice as heavy. 

5)  Cover the connection of the USB-Serial module w/hand warmers.   Maybe the
electronics are getting too cold???  DUMB IDEA.

Same results.  

I also tightened the DEC and RA Gear mesh according to AP's instructions and the guiding is worse by a long shot (went from .6" RMS to 1.8").  The lines are spiky and my total RMS is around 1.8" which is on the crappy side of "okay".

In any event...   Tired of gathering bad data, I also went to the Pyramid 13.8volt power supply wondering if the cold 10 degree temps were crippling the voltage from the Optima battery.   

I'm collecting 30 min shots of the Spaghetti Nebula.   Just trying a different part of the sky and more time.

I just don't get it.


[Later.....]    Still have lines corresponding with R.A.    I collected a bunch of data with the Tak102 at 15 min.    It could be that the system only works with some minimum weight like 15 lbs.   I don't believe it, but I need to verify it tonight.

Later.....]    >sigh<  Another failed night of imaging.   Tried to test the Tak by doing a 20min exposure, but just got a bizarre star trailing pic.    The darn rotator on the collar wasn't locked down and the telescope turned for the 20 min exposure.   PLUS the scope slipped down from its rings.    Holy crap.    Or just crap.

[Even Later...]  The more I think about it, the more I think that it's flex in the system -- specifically in the extremely longish refractor assembly which required a tube extension to get the autoguider to focus.   I can test this tomorrow night.  

Guiding Frustration...

So, I just took 9 fifteen minute subs of the Angelfish in H-alpha.   But they show small amounts of trailing.   The five minute test was completely fine.   I stopped guiding and tightened everything down -- especially the Dec and RA lockdown finger screws.

The trailing appears up and down generally in a N-S direction which I think corresponds to Declination.

I'm waiting for a test exposure.  If it shows the same trailing, I may try guiding only in one direction for DEC.

It could be the camera mount.    I just don't know of a better way to secure that stupid camera mount. There's so much opportunity for slippage with that single 1/4-20 bolt/screw.

[Little later...]  Still trailing, but appears slightly (25%?)  less.   I just swtiched to Dec corrections only in the South.   If that helps even more then maybe that points to DEC backlash?

Also, this could be all differential flex.   I'm using a dual-saddle configuration, guiding with a  80mm refractor on one side and the camera on the other.

What's weird is that I'm not having these problems with the Tak102 and a guidescope which weighs like twice as much.   That makes me think there's flex in this system somewhere.

[Little later...]   It's 9 degrees outside.   My ass is cold.   Literally.

The last sub had some trailing -- better than before, but still....    ARGH!!!!

I initiated the Meridian flip, re-focused (not sure I did a good job as my fingers were frozen),
re-calibrated PHD and started another run of 15 min subs.

[End of the session...]   Guiding went to crap at around 3 arc sec RMS.   Still showing that weird vertical guiding error.

Things to try:

1)  Disassemble the dual-saddle and tighten everything down.

2)  Do another polar alignment.

3)  MOVE both the camera and guidescope to one side.

4)  ADD more weight on top by adding maybe another camera.

5)  Cover the connection of the USB-Serial module w/hand warmers.   Maybe the
electronics are getting too cold???


So frustrating.....  :(

Preliminary Angelfish

Only about 2 hours of data.....

Adding more data tonight...   >sigh<

 

(5 years later:  Uh...  what camera?   what mount?   what filter?  what settings? >sigh<)

Thwarted By Christmas.....LIGHT POLLUTION

So, betwixt the howling winds and numerous cloudy fronts, I've been trying to shoot some targets on my to-do list.  One of those objects is a large, faint structure known as the "Angel".   I last tried back in February, but I didn't realize how faint the structure was.   In the meanwhile, I figured that if I hit it with maybe 70-80 subexposures, I'd get something decent.

So I started taking exposures in the early morning hours of the 24th.  Unlike the night of the 22nd, it was a calm, decent night with okay transparency and seeing.   I shot about 24 frames at F/4, 1600 ISO, 600 sec -- all through the 135mm lens.

After stacking the images and having a preliminary look, I discovered a problem I dreaded:  a light pollution gradient !!!     Normally, light pollution isn't much of an issue unless you're shooting directly over the neighbor's houses.   But starting about a week ago, everyone had their Christmas lights on.   The neighbors to one side (directly under my target) have strung a bunch of lights in their front yard.   After letting my eyes get dark adjusted, I could see the air glowing above their house -- presumably from all the moisture.  It really didn't occur to me until I started shooting that it would be an issue.  The 135mm lens has a hefty, solid metal lens shield that extends about 3 inches out from the front of the lens.   But it didn't matter.

The image has been heavily stretched in Photoshop to bring out the faint nebulosity.

Most of the subexposures for this image were about 40-60 degrees up in the air.   Yet the left-hand side which corresponds to the ground is swamped with light pollution.

Here's a negative version to see the structure with a little more contrast:

So, I thought about getting a light pollution filter, but I think the better option is to simply wait 3 weeks and start shooting after the lights are down.

BOO for Christmas light pollution!  

....a little while later:  

I wanted to note that during the night the exposures started showing a slight oblong shape to the stars.  The guiding was perfect so I attribute it to some sort of flex.   Last Feb when I tried shooting this on the Orion Sirius mount, I had the same problem.  

This last time, when I brought the camera in, I noticed that the locking knobs that hold down the dovetail were slightly loose.    I assumed it was just the locking screw that holds the camera down, but it may be a combination of things.

Note to self:   Cinch down everything really tight AFTER slewing the scope AND BEFORE starting another run.

More Problems (Notes to Myself)

Just so I can remember how to move the alt-az knobs on the mount when doing the DSLR iterative method of polar alignment.....

When the scope is pointed to the south and you're doing the "left button, then right button thing" with the hand pad, then the following holds true:

If the line ends on the RIGHT or ABOVE the initial line, then loosen the Left Knob.

And if the line ends on the LEFT or BELOW the initial line, then loosen the RIGHT KNOB.

WHEN THE SCOPE IS SOUTH:   Basically, loosen the knob opposite the direction of the end line of the V.


When the scope is pointed to the east and you're doing the left/right button thing,
then the following holds true:

If the line is to the RIGHT or ABOVE the initial line, then you must TIGHTEN (push up)
the altitude.

If the line is the LEFT or BELOW the initial line, then you must LOOSEN (or drop) the altitude.

WHEN THE SCOPE IS EAST:  Basically, left is loosen, right is tight.


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I confirmed the finicky behavior of PHD2 and BYEOS when setting up dithering.   When I tried to enable the server in PHD2 and connect both the mount and QHY5L-II, the system basically crashed.
All my devices became a problem.   Had to restart the computer to get everything going again.

SO.....  the procedure is with a clean taskbar (NO OTHER OPEN APPS) open PHD2 and enable server.   DO NOTHING ELSE and close PHD2.

Then re-open PHD2 and connect ONLY the camera.   Start a looping 2 sec (or whatever) feed from the autoguider, wait to get some images, then hit STOP.   Connect the mount, then re-start the loop.  And you can begin calibration.

The dithering was fine via BYEOS.

When I tried Sequence Generator Pro I tried to dither, but it was out of SYNC so that after a run of 2 minute images, PHD2 would show crazy dec corrections.  But before any settling could take place, SGP would start another exposure.    Bad.

As far as SGP auto-focus, I got it to work better but I wasn't really confident I was getting the best focus possible.   Part of the problem was that I couldn't find a really good exposure to let the autofocus do it's thing.   When I set it to 6400 ISO and 1-2 seconds, the autofocus routine would start identifying all the noise as stars and it often thought that first focus was the best.   >SIGH<   When it showed images, it was obvious that the stars were out of focus.

It took me awhile (a long while) to discover an exposure combination that allowed the auto focus to work.  I seemed to get close with 1600 ISO and 10 seconds while increasing the nebula rejection setting to about 1/3.....  this worked okay.   Oh yeah, step size of 3 and choosing 9 data points.  AND your focus has to be close in the first place.

----------------------------

The nice thing is I was able to get better guiding with PHD2 in terms of aggressiveness and min movement settings.   It seemed the best guiding occurred when Dec corrections  were only happening in one direction.   The RA oscillation seemed to almost get cut in half.   But I'm not sure this works with dithering.


Anyways, so I'm faced with a very dissatisfying first encounter with SGP and auto-focusing.   I've spent two nights trying to get things working and I feel like I need more time to tinker, but I also feel like I'm wasting precious imaging time.

Problems with SGP and Autofocus

What else is new?  Tried to go out and run Sequence Generator Pro with Autofocus and while I could get autofocus to function, it often shot past best focus and gave me out-of-focus stars.   I tried for about an hour before I gave up.   I can't figure out if it's some backlash issue or something else.

Overall, I felt I wasted time.   But not really.  I'll have to go out and try again.

I did have some success in getting better guiding in PHD2...that is, until I tried to Polar align
and had the scope bang against the pier really hard.   WHAT THE HELL!   Infuriating that
I didn't react quickly enough when I saw the scope heading towards the pier.

Up until that point, I was getting the best guiding I'd ever seen with RA aggressiveness set to .7 and Dec aggressiveness at .65.   I was getting a total RMS in the .6 to.8 range consistently.

After banging the scope, I'm pretty sure I knocked polar alignment out of whack AND probably introduced some extra gear mesh issues.   DAMN!   I had spent about an hour getting that
polar alignment nailed.   RA guiding went to crap and I had crazy oscillation numbers up to 1.1
in PHD2.

Next time, I need to really get the right angle polar alignment scope configured so I cut down on these 1-2 hour polar alignment routines.

I suspect I'll need to remesh RA and possibly DEC.

I want to have a go at the Angel Nebula (IFN) which is North of M81/82.   Looking at my preliminary pics, I believe I need to center the image on NGC 3343 (or NGC 3348) using the 135mm lens and the Canon T3i.    I believe I need to collect about 75 x 15 min exposures which will be a 5 night affair.

I think I can start exposing at 12:30.   If I'm smart, I can start the evening shooting the Angelfish Nebula (Meissa) over those same nights.

As I don't have a provision for autofocusing that lens, I'll need to do this manually.  Ugh.

M42... Required Image

So I've been taking pics of this nebula since I started astrophotgraphy sometime in the late 80's.  Back then, I was using a 8 inch Meade Schmidt-Cassegrain that my mom bought for me.   (Well, I asked and she okay'd it.)   Astrophotography was done with film and there were many choices.   Invariably, the results were blurry smears of red.  Guiding was done through a finder scope with a reticle eyepiece.  I shot many rolls of film, but nothing really came out to my satisfaction.

I didn't realize at the time that guiding a 2000mm focal length scope through a 60mm guidescope was never going to really work.  I tried lots of combinations, but the end result was always disappointing.

Anyhow, fast forward 25 years and I got this image of M42, the Orion Nebula, and NGC 1977, the Running Man nebula.

I had to devote several nights to getting the exposures to make this image.   This was shot on the nights of Nov 24, 25, 30, then Dec 14 and 15.   I used 31 x 15 min exposures, 46 x 5 min exposures, 35 x 2 min exposures, 35 x 15 seconds, and 35 x 5 seconds.   That's about 13 hours of exposure.  I actually shot about 17 hours of total exposure, but I only used the best 80% of the shots to process the image.   Scope:  Takahashi TSA102S w/Televue .8x focal reducer/flattener.  Mount:  Used AP1200.   Misc:   Guided w/Orion 50mm guidescope and QHY5II-L autoguider.

It's kind of a mandatory shot for any astrophotographer, but I wanted to do it because I knew I would get something worthwhile as it's so bright.

There are issues with the image.    The darker dust structures around the edges of the brightest parts are noisy.   I got those structures from those longer 15 min subexposures, but I think I need like 3-4 times the number of 15 minute exposure which means another 3+ nights of imaging this object.   Getting extra 15 minute shots would increase the signal-to-noise ratio which translates into less noise and more structure.

I was sorta lazy with using layer masks (a technique in Photoshop) and some of the stars are not the right brightness (too large) relative to other stars.

Sharpness is an issue.   Overall, I think the image is a little blurry - except near the core of the Orion nebula where the Trapezium is located (the tiny grouping of 4 stars near the center).   And that Trapezium is weirdly detailed with respect to everything else.

The overall color is little garish to me.   I know this object gets overly saturated by most people and I ended up doing the same thing.

Also, there is some curvature in all the corners, but most obviously in the upper right and left respectively.   I've known about this for awhile, but I haven't bothered to address it.  *I think* it's focuser tilt as the curvature seems to be different depending on the orientation of the camera.  I also picked up some spacers to place between the flattener and the camera.   More crap to address.

If you look closely to the bottom edge, just to the right of the center you can see some artifacts from the constant parade of satellites I had to deal with.   Actually the satellites aren't moving, there's a bunch of geostationary satellites that happen to be located in M42

Overall, to me, it's a "meh."   But I'm glad I did it.