Officina Stellare RC360 Pro ... has arrived!!

[marc4darkskies (Marcus)]

Originally Posted by gregbradley

Did you see much improvement increasing min move from.01 (very low anyway) to .2?

I changed mine from .1 to .5 and it made things worse by quite a bit. But that's a more subtle change. It implies minor errors .2 and below are not really errors at all that can be guided out? Or are below the seeing so it could be just as easily as seeing rather than a gear imperfection?

Greg.

Correct, I've deemed errors of 0.2 arcsec or less to be negligible for mount based corrections. And yes, clearly 0.01 was ridiculous but I'd never had cause to think it was hurting guiding. I can't say for sure that things have improved but, qualitatively, it looked like the guide errors settled down.

[gregbradley]

Thanks Marcus. I'll try that out myself.

Greg.

[multiweb (Marc)]

Originally Posted by marc4darkskies

Collimation: Almost resolved

• Really a result of my ignorance on how to collimate. Now gradually homing in on the optimal settings after ruining the initial factory settings. Learning how to use the Takahashi Collimation scope has helped a lot.

How did you manage to do that? With the holographic concentric pattern? So what the correct way of doing it?

[Joshua Bunn (Joshua)]

Originally Posted by marc4darkskies

• PME tracking rate too fast(??!!) Stars constantly drifting west - quite rapidly. I had noticed this before using the Tak but let it be guided out. At the longer FL it's now very obvious. Reducing the rate to 99.85% eliminated all residual drift in RA. I've seen others report this on the SB site but they were dismissed with the catch-all recommendation to invoke Protrack to remove polar alignment issues
• Still need to invoke ProTrack and see if this addresses part or all of the tracking rate issue mentioned above (if I restore it to 100%)

Hi Marcus,
was the drift you observed, without Protrack on and without autoguiding? simple flexure of the imaging train will have a similar effect to this I would imagine, which protrack will take care of.

[strongmanmike (Michael)]

Originally Posted by marc4darkskies

Just a short recap.

This was a big migration for me from the ultra simple days of imaging with the TOA (relatively light, perfectly collimated and short focal length). I underestimated the time and effort required, especially having to hold down a demanding job and being slave to the weather . As a result I can safely say that this kind of upgrade is not for the faint of heart or the impatient!!

A big thank you to those who have contributed their thoughts & suggestions along the way!

It has been exciting for us to watch on, I for one marvel at your thoroughness Marcus and I have confidence that you may well in fact surpass your stellar efforts with the AP wannabe TOA after all

Mike

[marc4darkskies (Marcus)]

Originally Posted by multiweb

How did you manage to do that? With the holographic concentric pattern? So what the correct way of doing it?

How did I do that? Well, think of trying to tune a Ferrari using a sledge hammer. Specifically:

• Making secondary tip/tilt adjustments during a star test that were way too big ... more that 1/8 turn
• Making multiple adjustments to the secondary without writing down what adjustments I did.
• Making large primary tip/tilt adjustments without marking the starting points.
• Not using the collimation scope to establish a baseline view of the system. I have no idea what the factory setting looked like through the collimation scope.

I am fixing it now using the collimation scope and only small primary tip tilt adjustments during star tests after marking the starting points with a whiteboard marker on the adjustment screws (large nobs). Any secondary adjustments indicated during a star test need to be TINY, be done one at a time and carefully noted and the result analysed. Since the collimation scope says the alignment of the secondary is already correct, great care is needed.

Unfortunately, the holographic laser is hard to use in the confined space of the obs. It's fine to do radial alignment of the secondary and to get close with secondary tip / tilt, but it needs to project the rings at some distance I think to be able to fine tune - and I’m currently thinking of how to do this.

Originally Posted by Joshua Bunn

Hi Marcus,was the drift you observed, without Protrack on and without autoguiding? simple flexure of the imaging train will have a similar effect to this I would imagine, which protrack will take care of.

Without protrack or autoguiding. Flexure would not manifest significantly (several arcseconds) in such a short time frame (60 seconds).

Originally Posted by strongmanmike

It has been exciting for us to watch on, I for one marvel at your thoroughness Marcus and I have confidence that you may well in fact surpass your stellar efforts ...

Mike

Thanks Mike - very kind words ... after I chose to ignore the TOA-envy comment that is

[marc4darkskies (Marcus)]

Well, two months has gone by and apart from some testing of stray light fixes and some daytime collimation (and learning!), this last few days has given me some clear nights. Seeing has been bad to average until the wee small hours of this morning when, during a couple of (tiny!) collimation tweaks the sky just went still

This is a single 5 minute exposure in the vicinity of NGC 6681 taken during a high waning gibbous moon and after some collimation tweaking. The seeing was excellent (for Sydney) and the best I've had so far. The drawback of course is that good seeing shows up even minor collimation issues!

Though collimation, particularly on the right hand side, is not yet acceptable, the good news is the smallest discernible separations are around 1.5 arcsec. Only calibration (with sub-optimal flats) and stretching was done. There was no decon or sharpening done of any kind.

I'm getting very close now and this is a very heartening result!

No point looking at a smaller version so here's the full res vers (remember - this is 0.59 arcsec / pixel!):
http://upload.pbase.com/gailmarc/ima...10844/original

Cheers, Marcus

[SkyViking (Rolf)]

That looks superb You've got a great FOV with nice crisp resolution for sure. I can see a bit of coma/distortion along the right edge, but it's certainly very minor.
Can't wait to see what images you can produce with your new toy

[Joshua Bunn (Joshua)]

Looks like you're nearly there Marcus. Small tweeks from now on hey with these fantastic scopes and big chips and high standards we set for them and ourselves, it does take some time, but the rewards certainly come.

[strongmanmike (Michael)]

Wow, two months worth of mega data that Paul will be very proud of you

Mate diplayed at 67% no one would suspect a thing

Keep the faith, I see perfection on the horizon

Mike

[marc4darkskies (Marcus)]

Originally Posted by SkyViking

That looks superb You've got a great FOV with nice crisp resolution for sure. I can see a bit of coma/distortion along the right edge, but it's certainly very minor.
Can't wait to see what images you can produce with your new toy

Won't be long now, thanks Rolf. Just need a few more clear nights to master this star collimation thing (in the dark, on a step ladder, in a cramped observatory and not knowing / forgetting which way to turn what adjustment screws! )

Originally Posted by Joshua Bunn

Looks like you're nearly there Marcus. Small tweeks from now on hey with these fantastic scopes and big chips and high standards we set for them and ourselves, it does take some time, but the rewards certainly come.

Cheers Josh! I confess I was starting to worry - just a little bit - but now I can see the optics will indeed perform the way I'd hoped. Just need this cursed weather to cut me some slack to get the stars to their rightfully round shape!

Originally Posted by strongmanmike

Wow, two months worth of mega data that Paul will be very proud of you

Mate diplayed at 67% no one would suspect a thing

Keep the faith, I see perfection on the horizon

Mike

With the Tak I think my average was around 8-10 hours and there is no reason to think that will increase!!! Besides, 10 hours on the OS will be equivalent to about 14 hours on the Tak (operating at F11.7).

67%?!!! Never!!! Wash your mouth out!!

Cheers, Marcus-full-res-Davies

PS: I'll be a happy chappy if I can just nip at the heels of perfection!

[marc4darkskies (Marcus)]

Okay, last post to this thread to close it off.

Stars now appear to be round to the edges of the field (in so-so to average seeing)! Soooo, time to start imaging again!! .... if I remember how that is and if the clouds, moon and seeing cooperate!! Seems like the only clear nights I get these days are when the moon is up!!

Hmmmm, maybe time to get into NB!

Cheers, Marcus

[RickS (Rick)]

I'm looking forward to some images from the new scope, Marcus!

[allan gould]

Baited breath here.
Allan

[strongmanmike (Michael)]

Marcus - the afternoon before the next clear night without work the next day

Wanna go for a Telescope?

[marc4darkskies (Marcus)]

This is only 2 hours of luminance data so it's early days for this image (!). There isn't enough signal yet to be able to mitigate the noise so yep, it's still there! This also stopped me from doing much processing - but I at least made it look presentable I hope. I need at least another 2 to 4 hours of Lum to make a meal of it.

In any case ... this was the real first light of the new (now collimated) scope!!!!!!
The seeing on the night was only average with raw FWHM of 2.06 arcseconds for the stacked frame. I did some mild deconvolution which bought that down to 1.75 arcseconds. Stars appear round (enough) from edge to edge. ... I'm well pleased!

Full Res & full frame (less a bit of edge trimming for stacking artefacts): http://www.pbase.com/gailmarc/image/155783443/original

Cheers, Marcus

PS: This is of course NGCs 5101 (left) and 5078 - a mind bogglingly beautiful field! Next post will be in the Deep space section when it's finished!

[niharika]

Nicely done Marcus, level of details are already popping my eyes

[MrB (Simon)]

Wow, so many fuzzies!
I lost count after 30-something.
You're just teasing us, can't wait to see the finished image.

[Paul Haese]

Hi Marcus. Will you try 30 minute subs for me please? Say 3 if you can. I am curious as to what you will get with that duration subs. I have been doing 30 minute subs on the 12" and getting very good ADU results.

The stars look slightly rectangular to me. This might well be guiding related though or maybe a dud sub somewhere. The STL is certainly noisier than the STXL. I had forgotten how much extra noise there is from the 10 degrees less of cooling. Time for a new camera????

This scope has the corrector in the baffle is that right? How much back focus do you get with these scopes?

[marc4darkskies (Marcus)]

Originally Posted by niharika

Nicely done Marcus, level of details are already popping my eyes

Originally Posted by MrB

Wow, so many fuzzies!
I lost count after 30-something.
You're just teasing us, can't wait to see the finished image.

Thanks guys!

Originally Posted by Paul Haese

Hi Marcus. Will you try 30 minute subs for me please? Say 3 if you can. I am curious as to what you will get with that duration subs. I have been doing 30 minute subs on the 12" and getting very good ADU results.

No. Not until I do Ha. I never do 30 min LRGB subs - waste of time. I'm also interested in seeing if there is any flexure, but it will have to wait until I do a neb shot.

Originally Posted by Paul Haese

The stars look slightly rectangular to me. This might well be guiding related though or maybe a dud sub somewhere. The STL is certainly noisier than the STXL. I had forgotten how much extra noise there is from the 10 degrees less of cooling. Time for a new camera????

A keen eye and a tight zoom there Paul . As it happens, you're critiquing my hasty processing. I was careless and used an action with a minimise filter step (bad Marcus!). If you want to see the raw (except for stretching) picture see:
http://upload.pbase.com/gailmarc/ima...94720/original

There is a new camera in my future too

PS: I've now updated the original image to remove the processing error that caused the slightly square stars.

Originally Posted by Paul Haese

This scope has the corrector in the baffle is that right? How much back focus do you get with these scopes?

236mm optimally. I have a motorized secondary so I can change it. But I'd need to be careful not change the mirror spacing so much as to degrade the image.

Cheers, Marcus