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robertm

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About robertm

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  1. Thanks Gus. I’ll see if I can find someone who has one spare. Robert
  2. Would be grateful if anyone could help. The issue I have is that the handset firmware update only ever gets to no more than 1.00% complete before it fails; usually it's between 0.04 and 0.40%. Another issue is that I have is that it takes two attempts to retrieve the Hand Controller version as the first fails to connect. Not sure what I'm doing wrong here, could be a school boy error who knows. I've powered up the handset so it goes into firmware update mode (V1.7 firmware updater on the handset). The firmware is the latest downloaded SW (03.39.03) as is the PC firmware loader (V3.3). I've tried all sorts of baud rates, handshakes and buffer/timeout values but the failures always seem to be at random percentages. The handset is a V3 which was at V3.27 and I'm using the SW handset to DB9 cable and a Startech FDDI DB9 to USB adaptor plugged directly into a PC USB port (tried a hub and that made no difference). Anyone have any ideas ? Many thanks Robert
  3. I'm also building my first using the same wireless All Sky Camera Indestructables instructions by Thomas. I quite like the way it runs continuously but only takes images during the night based on the longitude and latitude. Robert
  4. I've been following the Cloudy Nights thread on this and it seems like the original work was done by a guy called Rick Kellogg a few years ago. He wrote a paper with examples and code in which he expressed a hope that it would be taken up by makers of guide programs; this could be just co-incidence of course but PoleMaster does seem to follow the original work quite closely. Here's a link to the original paper: http://www.syracuse-astro.org/pdf/2012_August_R_Kellogg_Electronic_Polar_Alignment_Scope.pdf Quite an interesting read I found. Robert I'm singing in the rainJust singing in the rainWhat a glorious feelingI'm h.... sorry it must be the weather
  5. I think this is where experience comes in. A lot of lenses look superb for terrestrial but as soon as you look at the bright pinpricks that are stars then that's where you see astigmatism, coma and chromatic aberration rear themselves. The last thing you want is a compromised image before processing even starts (that's my personal opinion).
  6. The main reason for stopping down is to avoid use of the glass around the edge where lens design is most compromised. I'm afraid the trade off is to make the lens a bit slower but that depends what the use is. The 200L II is definitely good for f/3.2 narrowband but for broadband (I.e. luminance) then I suspect the f/4 that has already been mentioned is where the sweet spot is. One thing to note is that at f/4 you are only using 200/4 = 50mm of aperture and that's within a knat's of a 48mm threaded filter. Also if you use a threaded filter then, as well as the f/4 stop, you won't be troubled with awful diffraction spikes. I've not used the 70-200 so can't comment. One new lens of mine is that Samyang 35mm f/1.4, live view with the A7s is absolutely astonishing. It does need to be stopped down a tad to around f/2 for that sensor size but an APS camera might be able to use it opened up a bit more. I've had a few bad samples (sent back to Amazon) so you need to take a critical look to make sure the aberrations are symmetrical. Robert
  7. An interesting topic, this is exactly what I went through a few years ago. My images were taken with Baader 7nm filters and I feel they worked well at f/2.8. I think the shift in band pass was still well within the filter profile. You may also want to consider filter size and how large the sensor is as well as filter to sensor spacing. As others have mentioned getting a filter wheel into the equation may be a challenge but I gave up with adding an oag. The light path is so narrow that any prism will affect the image even if you could fit it in. An alternative is to go with larger format lenses but demand by people who think they need them has pushed up prices massively over the years.... sigh ! If you're worried about over sampling then consider dithering and drizzle stacking as that might help. Something else I've done is doubling the image size before stacking, that can work quite well. Robert
  8. If you want to even consider using it wide open then it has to be well collimated (check for centred vignetting). If it's out, then because it's a professional lens, you can send it back to Canon (UK branch is Enfield I think) free in the first year for adjustment. It's very good at f/2.8 with an 8300 sensor equipped camera but I found that f/3.2 produced outstanding images (in narrow band) if you can get it focussed accurately enough; the edge stars will be squiffy if you don't ! https://www.flickr.com/photos/29673723@N04/5007278823/in/album-72157624216353110/ The next is full size unbinned showing how good it is at the edges: https://www.flickr.com/photos/29673723@N04/4238477498/sizes/o/ There are other examples there but it really is a top lens ! Hope that helps Robert
  9. It's not quite as simple as that. Unfortunately Nikon also seem to do some clipping of the black point which makes full calibration a bit of a challenge. There is a thread on my local society web site where someone has been doing some in depth analysis if you're interested http://forum.orpingt...hp?topic=8917.0
  10. Just to add. Make sure the guider sub has focus when you change the screen stretch to medium.
  11. I've not seen any problems like this when using Maxim but you could try setting the screen stretch to medium which should show guide stars. If that fails then take a single guider exposure, ensuring that you can see stars, then double click on one of the stars to select it then click track (I know it should automatically do it but doesn't always get the ideal star). I would also change the track box size to something like 32x32 or 64x64 temporarily to make sure the star hasn't already drifted outside the 16x16 box. Robert
  12. Nope you're not the only one ! I had the same problem with a C11 and the orange dovetail but I used a couple of tiny aluminium wedges so it did work eventually. Was a shock when I first tightened the knobs though as it arrived about two days before I was to take it on holiday ! The gap on mine was about a millimeter after fully tightening it down. Robert
  13. Sounds like you're having a wonderful time with that mount Olly and creating more than a bit of jealousy I can tell you Regarding the Tak. I always used Chucks Temma Driver with Maxim. It's certainly the best thing that happened to the Temma II and makes the Sky controlled telescope look like hard work. BW Robert
  14. Hi, Just seen this. The off center screw does act as the location lug for the secondary to stop it rotating. This secondary collimation has had my attention for a while now but I think I finally cracked it. The rotation is very critical and I found the only way of accurately setting it was using a camera and checking for even illumination and equal vignetting in the corners. For fine adjustment I rotated the whole corrector assembly within the confines of the OTA screw holes. Even a millimeter can make a difference ! Start with the threaded secondary holes central in the ota holes (they are a few mm larger in diameter. This is a quote from my OAS thread on the subject. The results did look good but bad weather and guiding has thwarted further checks so far. Link to the saga here: Help - How to correctly collimate a Newtonian... with a twist Hope that helps Robert
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