Mandy D

No, you need to reduce your exposure dramatically to capture Jupiter's bands. You won't get any of the moons in a photo that shows detail on the planet.

5 minutes ago, gorann said:

PS. My only point is that pink is far from magenta but is white light with a red bias. Magenta is purple so red light mixed with blue. As @vlaiv states then there are many shades of red, blue and green, so there are many shades of pink and purple.

"There are many shades of pink ..." <--- You have stated it here, yourself. Magenta is one of those shades. It is a very deep and saturated pink and was the simplest example I could produce at short notice. The major point I am making is that whte does not have a wavelength associated with it, so does not appear in the spectrum, even though such spectrum can be produced from white light, which is the proof of it's composition. Vlaid has it nailed as human construct, but even that is not the full story.

30 minutes ago, gorann said:

And I now mixed red with 50% white in Photoshop and got what I this is pink:

What you have actually done is to mix white (which is 33% red, 33% green and 33% blue) with an additional 50% red, because the white is a balanced mix of red, green and blue. You cannot carry out your analysis in the way you are attempting to. White does not have a solitary wavelength associated with it, whereas red, blue and green can and do.

7 minutes ago, gorann said:

I disagree Mandy and think you are mixing up pink with purple (=magenta). In my world pink is a pale red colour and Wiki says "Pink is the colour of a namesake flower that is a pale tint of red. It was first used as a color name in the late 17th century." Here is what "pure pink" looks like in a colour scheme:

 

 

Magenta is definitively not purple. It is a very deep pink. If you add 100% blue, 100% red and 75% green you will have a softer pink, more like the example you produced.

Anyway, my point is that you make white light and secondary colours by mixing coloured lights, not the other way around.

3 hours ago, Acrab67 said:

Hello,

I have detected that the tube significantly loses collimation depending on the inclination of the tube. Presumably it is due to the lack of rigidity of the optical tube, since it is made of excessively thin aluminum. Has anyone solved this problem in any way without changing the tube itself? Thank you.

I have been advised that OOUK tubes tend to flex and are best avoided for that reason. The mirrors, however, are amongst the best mass produced units you can find. I have a similar problem with my Skywatcher 300PDS, which definitely suffers from significant tube flexure. My fix for it is to buy two more tube rings, making four in total, installing them over a significant part of the tube length, evenly spaced and brace them with aluminium struts, one or both of which could be long Losmandy dovetails. The 31" in the link below is what I have in mind:

https://www.rothervalleyoptics.co.uk/adm-losmandy-d-series-universal-bars-various-sizes.html

2 hours ago, gorann said:

Is not pink a mix of red and white light? Maybe your discharge lamp also produces some more broadband light that is mixed in with the Ha. 656 nm is near the middle of the red part of the spectrum.

No, pink (magenta) is the result of mixing red and blue light. White is the result of mixing red, blue and green.

Moon halo and Jupiter next to church spire.

Single image, 2023 11 25, 20:36. Nikon D800, 14 mm prime lens, f/2.8, 12.1 s, ISO-400. All processing in GIMP.

@buddyaderholt Yes, definitely use the timer function as it will really help to reduce contact induced vibrations.

Are there no instructions with it? Which bits are you struggling with? Your question is too open ended and you need to tell us more so that we can help.

28 minutes ago, Starfazed said:

Hmm, when scope shopping I looked at all the collimation videos I could find, which only confused me all the more. For now I'm increasingly glad that I went for a reflector that claims not to need collimation and doesn't have an adjustable primary, though if I bite the bullet later for anything bigger than 150mm I'm going to have to figure it out some day!

Yeah, most of the collimation tutorials are very confusing and contain stuff that the beginner does not want or need. So, getting a collimation-free scope as your starting point was a good idea even though basic collimation is so easy to perform once you are doing it. The first time I attempted it on a Skywatcher 200P it took me literally no more than ten minutes with a primary mirror that was so far out I couldn't see anything. Just get a good Cheshire eyepiece and forget all the laser doodads. The first time you collimate, I would not bother with the secondary, which is supposed to be the first step and simply focus on the primary, which is where you will get most benefit for the least effort. Don't let fear of collimation put you off upgrading when you are ready to.

@Venla I would not recommend the clamp in your link or any other clamp where the screws act directly on the dovetail as it will mark and damage the metal. The one I suggested earlier has brass wedges to clamp the dovetail and is one of the best and cheapest I have found. Although it is branded RVO in my link, it is available from FLO and other suppliers under different brands. My Skywatcher Skytee 2 came with a couple of clamps and I immediately replaced them with the one I suggested.

https://www.rothervalleyoptics.co.uk/rvo-mini-vixen-style-clamp.html

There are others which will work with a Vixen dovetail. All you need to do is make sure that both clamp and dovetail are Vixen compatible. Most clamps are universal and will fit most mounts. Any Vixen dovetail should work with the rings on your telescope, although as someone else mentioned, you may have to drill the holes in the clamp to a bigger size, but that is unlikely.

Here is another, lower cost version, with a single clamping screw and wedge.

https://www.firstlightoptics.com/dovetails-saddles-clamps/astro-essentials-mini-vixen-style-dovetail-clamp.html

4 minutes ago, Venla said:

Thanks for all the advice! I don't think I'm able to buy the HEQ5 or even the EQ5 because my budget for this is about 750€. I'm a little confused about the dovetail, though. Does it have to be a specific brand, like Skywatcher because I'm going to buy a Skywatcher mount? And how can I be sure that the dovetail will be the right one for the mount and the tube rings?

£750 will comfortably get you a used EQ5 class mount.

The dovetail just has to bolt to the tube rings, which any will do. You then buy a clamp to go on the mount and that just has to match the dovetail. For smaller telescopes you normally use a vixen dovetail and clamp and for larger ones a Losmandy, which is muchmore expensive.

https://www.rothervalleyoptics.co.uk/rvo-mini-vixen-style-clamp.html

https://www.rothervalleyoptics.co.uk/skywatcher-universal-dovetail-bars.html

The above should work OK together.

15 minutes ago, Bukko said:

Hi Mandy,

Thanks for replying and the suggestion.

Tying in an isolation Tx would be quite a simple thing to do, as I just re-locate the existing L/N wires and run a new length from the MCB to the transformer.

However, I have a series of UPS's in the system now, so effectively they should do the job of an isolation transformer? I am also prone to frequent, short power outages and brownouts, so the UPS's are important to protect the systems from that too.

I am pretty sure my failure had something to do with a differential ground potential between the house and Obby. Everything is permanently connected and so maybe a little more vulnerable. When the strike happened, nothing in the house failed...

Do you think I would still need an isolation Tx, even when using a UPS?

 

Gordon.

A UPS can act as an isolation transformer, but it will depend on the type and how the wiring is connected internally. If it is a line interactive type, it will not be using a transformer when mains is present, only when running from the batteries. With an online UPS, there will generally be two transformers, one feeding the battery charging and the other on the inverter side. The charger transformer also runs the inverter when mains is present, so you have double isoltation. However, they always earth the secondary of the inverter transformer down to the incoming mains earth, so you will have to open up the UPS and break this connection, then make your own connection to the local earth rod network. It can be done, but means messing with the internals of the UPS.

You might want to consider an isolation transformer to do this. You then do not run into the problems highlighted by @Bubbles82. Run a two core cable from the secondary of the isolation transformer to the observatory and make the earth connection at the observatory end, tying down one side of the secondary to it. This, then becomes your neutral.

Google boat shoreline supply as this is a standard way it is done on boats.

I may have a secondhand 3 kVA 230V/230V transformer in an an enclosure with a 13 A socket on the output, if that suits you, but I am in the UK.

@Highburymark I've currently got the 10 nm continuum filter, but so far have had no opportunity to try it out. Once I've got my wedge up and running successfully, I think I'll have to look into this.

@Highburymark Looks impressive, but a bit ouchy on the price (1.25" £179.50), but 2 nm bandwidth is always going to cost. If I ever get any Sun, I might consider buying one.

12 minutes ago, squipper said:

don't know why but today turn it on and the pointing circle is working in the solar mode took a photo of the sun when a plane flew past. on the tablet  looks ok but if i put it on a whats app group there are small squares on the photo . see if it is the same on this site 

 

The image is only 1080 pixels wide. When I click on it and zoom in, it is displayed at more than 1080 pixels, so, you can see pixellation. Your image is slightly out of focus, or you have camera shake, but it's a nice capture. I've taken your image and run it through GIMP. The first thing I did was apply a Gaussian blur of 1.5 x 1.5 which removed the pixellation. I've also cropped it to square and darkened the sky background. Have a look and see what you think.

@ollypenrice I'm simply not going to discus this topic any further with you, as it would appear to be a pointless excersize. I've laid out what is going on and others have taken the time to explain further. There is absolutely no ambiguity regarding what is the bottom (or any other point) of the wheel, with regard to a discussion of the behavoir in the limit.

@Zermelo It can't be put much better than that! Cycloid, that is the word I was trying to think of. Thank you.

10 minutes ago, ollypenrice said:

This is an interesting point. Not being a mathematician, I look at it conceptually. It seems to me that 'the bottom of the tyre' is an elusive concept because it is not defined by any property of the tyre itself (such as a mark) but by the observer who notes that every part of the moving tyre is, at some point, the bottom of the tyre. 'The bottom of the tyre' is defined by its position relative to the road. An observer looking at a car moving east to west will define 'the bottom of the tyre' as the bit touching the road and will also note that that the bit touching the road does move, east to west, which is contrary to your statement that it is not moving at all. For the roadside observer the bottom of the tyre is a point of contact which certainly is moving. 

That seems to me to be the easy bit. The difficult bit is working out exactly what point of observation discovers no movement forward at the bottom of the tyre. I suppose a number of rubber molecules will be able to shout out, very briefly, 'We are now pinned to the road which we know is not moving!'

lly 

Look at a track laying vehcile, what you would likely call a "caterpillar tractor" and you will soon see that the part in contact with the ground is certainly not moving forwards and extrapolate from there. You will find that the top of the track is moving, relative to the ground, at twice the forward speed of the vehicle. Is that clearer for you? Remember, all rotational motion involves constant acceleration, even at uniform angular velocities!

2 minutes ago, Simon Pepper said:

Anyone know if there anything with a bit more focal length my eyes are struggling to see anything here. I think I see a dip, but there is also some cloud there which could have caused it? 

In Thierry's video it dims out slowly, then comes back slowly, as you might expect. I watched it earlier today and the dip is very noticeable, but you may have to watch a few times before you see it.

5 minutes ago, Bongo said:

Hi! Thanks for your reply. Yeah, it really is an aging DSLR - a Nikon D40 - and as far as I know it doesn't have live view. It was languishing unused in a drawer si I thought I'd try to put it to some use. 🙂

Digicam Control supports D40. You should get live view on screen with that. You'll just need a suitable USB cable.

https://digicamcontrol.com/cameras

35 minutes ago, dweller25 said:

She was trying her best

"Hmm, doesn't smell like steak! I hope it's not another one of those telescope thingies!"

Solar wedge and continuum filter arrived today, all perfectly packaged by @Mr Spock.

Just need some sky, now ...

19 minutes ago, dweller25 said:

It smells great, but NO-ONE is licking the lens - you know who you are 🤣

I thought you were going to let them open the box! Looks eager ...

"May contain snow" 🤣