JamesF
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Posts posted by JamesF
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4 minutes ago, Ouroboros said:
Incidentally @gilesco on the KStars download page you linked what are the MD5 and SHA256 files? I didn’t download them before and yet my set up seems to work without them so what are they?
They're just two different forms of checksum so you can ensure that the file has been downloaded correctly and not corrupted or hacked.
James
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Usually it's me that forgets the clocks are changing :D
James
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1 minute ago, gilesco said:
The one thing that's keeping my frustration at bay... is the weather... that is, if anything arrived I could not use it, just some basic setup preparation and then look to the rain to stop.
It was too grey and dark here today to even be able to see what the weather was like.
James
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35 minutes ago, Ken82 said:
I don’t see any point complaining about delivery times especially during the current economic climate. Virtually every industry that relies on imports has been affected.
Just try and get some plasterboard during April or may and you’ll know what I mean !
You're not kidding. We've been absolutely crucified by prices for some stuff for our barn conversion this year. "White goods" have been an absolute nightmare and the prices just seem to keep going up.
Mind you, our builder told us he knew someone who had driven a 300-mile round trip to get six bags of plaster that cost him twice as much as he'd have paid this time last year because it was that or not finish a job.
It's not just down to the C-word causing manufacturing and delivery issues either. I was looking to order some seeds earlier this week and the supplier whose website I was looking at had a message up saying that because of the B-word and in particular uncertainty over supply and regulations their garlic supplier has stopped dealing in it so they have none to sell this season.
I suspect it is going to take quite some time before things are back to anything vaguely resembling what passed for normal, say, eighteen months ago. Until then I think a very hefty dollop of patience is going to be required when trying to source pretty much anything with a dependency on imported goods and materials. Frustrating as that is, sometimes I can't help wondering if it's actually not such a bad thing...
James
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Indeed. Absolutely stunning.
James
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Thanks. That sounds like it might be worth a try.
James
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I've used zip ties before now, but I've known other people use weights attached to magnets.
James
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2 hours ago, Marvin Jenkins said:
Is it just me or are there just too many circles in this photo? There is supposed to be a telescope in there somewhere but I cannot see it. 😳
I did wonder about that when I looked back at this photo
Fortunately we have a different tablecloth now.
James
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35 minutes ago, ollypenrice said:
In my understanding it has to demosaic first because colour must be attributed according to the Bayer pattern of that particular chip. If it aligned on the stars first the alignment would ignore the Bayer matrix and would stack a red pixel onto a blue onto a green, etc etc, and the colour information would be lost.
A good point. I'm clearly out of practice with all this OSC stuff :)
James
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I seem to recall that when I did mine I set the OTA up on a tabletop and then went around the front end, trying to align my eye with the optical axis, about a metre or so in front of the OTA. If you're not even close, I think you see reflections of the mirrors drifting off towards the edges of the OTA and you need to adjust the collimation to bring them into line with the optical axis.
I feel certain I also used a collimation cap for some purpose or other, but it was such a long time ago I'm afraid the reason escapes me for the moment. Things are so bad these days that if I can remember what I did last week I count it as a bonus, to be honest :)
James
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My Mak has similarly gone "gold" in places. In fact I think the corrector cell is partly gold and partly black where the end cap was in place but it doesn't completely cover the anodised area. That particular OTA used to spend a lot of time outdoors on sunny days for white light solar viewing and imaging and I've always assumed that was what caused it.
James
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I'm assuming you're using the standard finder shoe on the Mak and that is offset to one side of the OTA to mount the Evoguide?
I think I'd be tempted to add a bit more weight to the other side of the OTA to balance it out, to be honest. Or you can probably add the weight elsewhere if it would be more convenient.
The alternative is probably to add a second shoe to the OTA in line with the axis so the weight of the guider is balanced when placed in it.
James
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4 minutes ago, Erling G-P said:
Quite puzzled here - why would the f-ratio have any influence on how a filter performs?
The filter is an optical element of the imaging train. Light refracts through it. And at the relatively steep angles of incidence occurring at small f-ratios perhaps that results in focusing/bloating issues as well as light loss due to the greater amount of material through which the light has to travel?
James
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Just now, Pixies said:
I assume then, if I tighten it up when I screw the end cap back, I will then no longer be able to 'tighten' the collimation screws, as there is no slack left to adjust.
I assume that's partly what the seal is there for. If you screw up the back until the seal is nipped in place but not completely squashed, it will deform a little further during collimation, but hopefully stay in place. I guess if you start with the "pull" collimation screws as far out as feels safe and then refit the back you'll probably only ever be tightening the back against the seal rather than loosening it, if you see what I mean.
James
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You can blow some of that dust off the mirror now, too
James
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The seal wasn't a ring when I took my 127 Mak apart either. I just put the same seal back when I reassembled it. Seems to be fine :) I can't recall how I kept it in place during reassembly though :(
In my case I think it was the black mounting ring at the bottom of the picture that screwed inside the main tube and the backplate was fixed to that with the "pull" collimation bolts. If yours is wobbly I'd guess that either the collimation bolts have worked loose or the mounting ring needs tightening. Assuming it is constructed the same way as mine of course, which is not necessarily a given.
James
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I printed a PLA mounting for the anemometer and wind vane of my weather station that has been outside since December and it's still looking fine. It is a bit "over-engineered" perhaps, but I really wasn't sure how strong it needed to be. It's not solid: 30% infill, as far as I recall.
James
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46 minutes ago, Paul M said:
I'm now so expert on all things Ubuntu that when an old laptop slid out of a cupboard today during a search for something else I got an Idea..
It's an old (15 years?) Dell Vostro with Vista. It was never a good laptop even when new. I'd intended to throw it back at Dell but they told me it was an RTB warranty and they needed 4 weeks to turn it round. So I suffered with it for years. That showed 'em!!
I threatened to try Linux on it years ago, when SGL was having a big Linux conversion period. I never did, until today. I still have the Ubuntu 20.04 Installation USB stick I created to rebuild Ubu, would it work on an ancient old Windows lappy?? This thing hadn't been booted for years so no idea if it would even power up. It did and I went straight to Bios to set USB as 1st Boot. I was slightly surprised to see it come to life, eventually asking me if I wanted to install to the local disk. I opted for that. Nothing of the old Vista Install was of interest to me so it got blitzed.
It's a slow old machine with 4gig of RAM but it kept soldiering on installing amd64 files. On completion I had a usable machine. I've been playing with it all afternoon. Quite nice it is too. I did the full install (as opposed to the minimum I put on Ubu) and then installed Chrome and Real VNC server.
I am still using (as a wifi gateway in the blobservatory) an old Acer Aspire One (1.6GHz 32-bit Atom CPU, 1.5GB RAM) running an Ubuntu variant called Lubuntu. It's a lighter weight build with a smaller footprint and lower CPU requirements than the standard releases, but it works just fine. I suspect the last release or so have become a bit more porky, but there are other lightweight distributions as well. They're very handy for squeezing a bit more performance out of older hardware.
James
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I don't know. It just doesn't feel right as an explanation to me. I'm not sure if DSS stacks and then demosaics, or demosaics and then stacks. My immediate thought is that it would be better to stack the raw frames as generating the full colour image acts to "smooth out" the data, but I'm not certain. I don't get the bit about SNR either. I'd have to work through the maths to be certain. Perhaps there's a dependency on the stacking method used.
I don't doubt that Mark's arcsinh stretch works, mind. I've used that myself and been happy with the results. The way he implemented it in PS is clever too. I'm not sure I'd have thought of that myself.
James
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13 minutes ago, johninderby said:
I can see no possible response to this other than "wibble".
James
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41 minutes ago, Galen Gilmore said:
isn't a green color cast after debayering normal on the ZWO asi294?
No idea, to be honest. But if it is then my first guess would be that the green photosites are more sensitive or have a wider bandpass than the red or blue ones.
James
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52 minutes ago, vlaiv said:
I think you are overthinking it.
However you explain it
- Moon pulling on water
- Moon making Earth pull less on the water
- Waver just following straight path in bent space time
you are essentially describing the same phenomena.
Perhaps, third option would be "the most precise" explanation - as far as our understanding goes at this point.
I agree that it's the same phenomenon, but I got to the point where I wasn't happy with the simple explanation. It didn't seem to account for what happens in a way that felt sufficiently "thorough". Factoring in the behaviour of the water due to the rotation of the planet for me provides a greater depth of understanding. In fact I might suggest that now I understand it (at some level), whereas before yesterday I would merely be repeating what I had been told was the reason.
James
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39 minutes ago, happy-kat said:
Thanks for that. In fact, double thanks, as doing some of these courses seems like an ideal way to spend some time whilst I don't have much work.
James
Fortunately we have a different tablecloth now.
How do I update KStars/EKOS/INDI?
in Discussions - Software
Posted
Have to admit that I don't know what the preferred method is for checking them on MacOS either.
James