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By Richard Shaw
I acquired a second hand Coronado PST. The focus knob doesn't seem to have any effect on the image and, although it turns, it feels as if something inside the scope is "slipping".
Is it worth opening up and taking a look to see the focus knob in action?
Is there anywhere that services the PST without sending it outside the UK?
Are there any nasty surprises if I open it up (springs, pressure points etc)?
By Andrew Larmour
Absolute newby here - my first foray into astronomy. I bought a Saxon 1400mm 6" refractor secondhand complete with a EQ mount for a bargain price and I'm keen to get it working properly for both planetary and deep space observations.
I invested in a few extras such as a laser collimator and a 3x barlow. I think I have a handle on how it all works including the EQ mount. I took the scope out for a test over Easter - which just happened to coincide with a ISS transit of the full moon. Rippa, I thought, that would be great to capture on my first night of observations. The problem I have is the complete inability to focus the scope to anything like sharp enough.
I have some photos I took with the scope attached:
The scene with the normal camera lens for my daylight practice session
A shot of a distant house with the telescope (using a Nikon D7000 on a t-mount adaptor)
The same house with the barlow attached
A shot of the moon- no barlow - as sharp as I could get it - certainly no way to see the silhouette of the ISS with the scope this out of focus
When I was collumating the scope, I noticed a that the reflection on the primary mirror was not a single spot but rather a line
... which means that the laser on the collimator target is a line rather than a dot
I confirmed that this is not a problem with the shape of the laser beam coming from the collimator by showing the shape on my hand at a distance of 14m
I'm not sure if the distortion of the laser is the fault of the secondary mirror or the lens(es) in the bottom of the eyepiece mount. I'm also not sure if this distortion is what is causing the inability to focus the scope, but I suspect that both issues are symptoms of the same problem.
I'd appreciate any ideas on what to do next to resolve the focus issue.
Two questions if I may.
1. Can the three screws marked by yellow arrows in the picture below be used to mount a second finder shoe on the C11 EDGE HD scope, permitting both a straight through and a right angle finder to be fitted?
2. The EDGE has field flattening optics inside; is the distance from the visual back to the chip critical, or by making adjustments to the position of the mirror to achieve focus on a chip say 250mm away from the visual back mean the field will still be flat at that distance?
So my birthday just past so money to splash on astro stuff , i will have my 1000D modded by juan at cheapastrophotography and also have ordered an autofocuser from deepsky dad https://deepskydad.com/autofocuser i know they can be done DIY but this is a neat package and costs about the same as a SW autofocuser and a hitechastro focusmaster and i`m no electronic wizard and pavel seems to have a good product and works with ascom and confirmed it works with APT i will update in a few weeks time when hopefully i will have received and tried out .
After a bit of a hiatus, I was able to get out again and enjoy new moon/clear skies from a slightly less light-polluted viewing location. ?
For those who have seen my past posts, I'm still using StarLight Live 3.3 with a SX Trius 694 camera, now with SX filter wheel. I alternate between using an 8" SCT and various Borg refractors - these shots are with a 5" Borg, with exposures < 30 s. The combination works well, overall, and SLL controls the filter wheel which makes jumping between L,R,G,B and Halpha filters really easy and fun! The only major issues I have are that (on my Mac) SLL seems unable to run the Trius in anything other than 2x2 binning. I haven't been able to get a PC to test whether this is only a Mac related issue, though others have apparently been able to use this camera in all the various binning modes via SLL windows. I also have focus/framing problems if exposure time is set to 1s (camera drops out and SLL freezes up). To facilitate not having to refocus, everything was shot through either an L filter, R+G+B filters, or Halpha filter (all Astronomik 1.25", in a single filter wheel). It generally worked really well, but occasionally I would switch colour filters to do a composite and SLL would stop stacking and I've had to start my colour composite from the start again. But a fantastic feature of SLL!
Enjoy the shots - these (and others not posted) were all taken over a few hours time in the early morning. I love how much - and how quickly! - you can view with EAA!