Cheers Rick. I'm a bit of a reflector novice but, to my eye, those stars look pretty good too! For completeness though, I really should do an outside focus collimation series (what you see here is inside focus)
Quote:
Originally Posted by allan gould
Nice test images, Markus. Looking forward to first light.
Allan
Thanks Allan. Buuut ... that was first light! Next step is to do a TPoint model so I can start imaging ... for real!
It's worth mentioning this again ... this is out-of-the-box collimation!!! Maybe I'm just lucky, but that's very impressive!
Okay, after reviewing the result, doing some reading and getting feedback from Gino in Italy on the above, some minor tweaking of collimation is required to achieve optimal performance. Now, could the person who caused the clouds and showers to roll in please step forward!
In other news, while the native, uncorrected optics are F8, I found out that the flattener used causes an increase in focal length to F8.7! I discovered that while doing my first plate solves & TPoint run (0.59 instead of 0.64 arcseconds/pixel image scale) and this has now been confirmed by Gino. This is more good than bad news for me since I'm after narrow field views!!!
Yes those plate solves would have not worked with a change in focal length, though as you say it is a good thing to get a slightly narrower field of view. Looking toward the images Marcus. I am keen to find out what these scope are like as I see this as a likely contender to the replacement of my RC12" at some point in the future.
Yes those plate solves would have not worked with a change in focal length, though as you say it is a good thing to get a slightly narrower field of view. Looking toward the images Marcus. I am keen to find out what these scope are like as I see this as a likely contender to the replacement of my RC12" at some point in the future.
It did actually work even when I told it the image scale was 0.64 - I guess the difference wasn't large enough to confuse the software.
Here is an interesting picture. The mirror is attached to the cell (the red anodised plate) centrally. The cell also has 5 radial supports each comprising a pillar and a grub screw (highlighted) that holds a metal plastic-backed disc in contact with the side of the mirror to prevent any small radial movements of the mirror. During transport, one of the discs had come loose and fallen out - almost certainly because the grub screw wasn't tight enough. To fix this I lifted the carbon fiber tube up to reveal the cell and gain access to these pillars to replace the disk.
You'll also notice the heavy duty spring that loads the collimation screws for the main mirror. No wonder the screws are tight!!
By the way, before I did the fix for the missing radial support, my first TPoint model (126 data points) was 14.6 arcsec RMS. I guess I should probably bolt the scope to the PMEs versaplate - currently it's only attached via the dovetail and friction.
Last edited by marc4darkskies; 03-01-2014 at 03:27 PM.
I fiddled with collimation a bit last night and got it as good as I can.
It was a hot & sweaty night but the sky stabilised nicely so I took 3x5min test subs (1x1 binning) of the vicinity of NGC 3263 last night to check star shapes. There's now only very minor egg shape in the corners, mostly at the top of the frame. I'm going to call it good though!!
Each box is full res and only 2.3 x 1.7 arc minutes (ie a very small patch of sky) at 0.59 arc second/pixel. The boxes represent the extremities and middle of the frame. The 3 subs I took were dark subtracted and sum combined. They were stretched of course but no flats, decon or sharpening of any kind. Some of you might notice why I'm pretty chuffed with this raw result!
Last edited by marc4darkskies; 04-01-2014 at 01:39 PM.
This commissioning thing never ends!! Here's how I mounted my flat panel yesterday (Gerd Neuman's Aurora Flat Panel) after a lot of head scratching.
A Vogel articulated tip/tilt wall mount monitor arm (a small one) - bought at JB HiFi plus a bit of DIY thrown in to attach it to the dome. It allows the panel to be positioned orthogonally and close to the front of the OTA. I can remove the panel and support easily. Just needs a lick of black paint now.
Here is an interesting picture. The mirror is attached to the cell (the red anodised plate) centrally. The cell also has 5 radial supports each comprising a pillar and a grub screw (highlighted) that holds a metal plastic-backed disc in contact with the side of the mirror to prevent any small radial movements of the mirror. During transport, one of the discs had come loose and fallen out - almost certainly because the grub screw wasn't tight enough. To fix this I lifted the carbon fiber tube up to reveal the cell and gain access to these pillars to replace the disk.
You'll also notice the heavy duty spring that loads the collimation screws for the main mirror. No wonder the screws are tight!!
Marcus - just wondering what the orange coloured things are between the mirror and the red plate (above the colimation bolt) in the second image?
Here's how I mounted my flat panel yesterday (Gerd Neuman's Aurora Flat Panel) after a lot of head scratching.
- that's pretty easy 
