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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?
I need the combined brains and experience of SGL please, I'm stuck!!
I've been an astronomer for 30+ years and have had several Skywatcher telescopes over time, including my current EQ6-Pro for about 10 years. This is largely irrelevant to my post, except that I hope to convey that I'm not a total novice to getting telescopes to work as they should...although I feel like I am today.
I recently picked up a very battered early-version EQ6 with 10" reflector, cheap. It hadn't been looked after well and when I first fired it up...it didn't fire up at all. No life. I noticed that the power supply wasn't suitable as it only had a 0.5A output. So after digging out a spare one from the cupboard outputting 12V 1.25A, the Synscan chirped into life.
My first attempt to slew the mount was met with a horrible grinding noise and refusal to move. Needless to say, I didn't do that again. Clearly the motor/gear train was seized. So a quick look on the internet brought up the amazing website posted by Astro Baby, with step by step instructions on how to strip and rebuild an EQ5 or EQ6 mount. This kept me entertained for a couple of nights, followed by a lovely smooth running mount slewing in RA and DEC as it should. Many thanks Astro Baby!
Last night was the first clear night, so I took the mount out, popped the 10" scope on (had a full respray, new finder, new focuser and laser collimation), and awaited the fall of darkness. Here comes the rub.
I roughly aligned the mount on Polaris, not bothering too much for this first test. The Synscan controller is (unfortunately) running Version 2.05, which is one of the early versions that are not flash upgradable. Although I didn't realise this until after I had downloaded all of the upgrade files from OVL's website. ?
When I picked the first alignment star (Capella, rising nicely in the north-east sky), the mount did something completely unexpected and slewed around to east of the meridian and pointed somewhere in the direction of Alcor! What the ...? After several unsuccessful attempts at carrying out an alignment, I gave up and looked online for any similar problems. I've checked and confirmed all of the following things are correct:
Location - yep as per my Cumbria coordinates Date - yep in the right format (mm/dd/yyyy) that good old confusing American format Time - yep I tried with BST and without BST (not really expecting any significant difference) Made sure the mount was in the "parked" position (weights down, scope pointing towards Polaris) before turning the mount on Tried all sorts of initial alignment stars, but none of them were in the right area of the sky at all Unfortunately, I haven't been able to find anything on the web that offers a solution.
I did wonder if I've done something during the disassembly of the mount - but I know the mount doesn't have encoders on it. I didn't see anything that looked like a counter of any kind?
I don't think it can be anything to do with the power supply...surely that couldn't introduce such a wild error in pointing? It's like the handset has no idea where it is.
Any help would be much appreciated. This was going to be a second mount for me, but at this rate it's going to go on the scrap heap.
I did think about buying a V3 handset, but didn't want to commit another £120 in case it's something in the mount itself that's the problem.
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 .