westmarch

Hi there, The cap method is simple and always gets you into the general ball park. The acid test is to check it, then your laser collimation, against a real star. This is a good guide to star testing: https://popastro.com/documents/PA_jan-mar2009_p12-13_telescopetopics_startesting.pdf Good Luck John

Star hopping and the sense of elation when your target slides into view is one of the things that makes you say, “YES!”, in a dark and empty dark sky site. IMHO John

But would Gallileo and his telescope have been taken seriously if he had this to contend with?

As has been said previously, dobs are not really suitable for AP. In visual astronomy you compensate for the faintness of an object by increasing the aperture - this collects more light and focuses it on your retina, thereby making it appear brighter. You see in real time the photons being collected. In AP the camera sensor simply collects light for longer through long exposure - aperture is therefore less critical. This long collection of photons is averaged into an image with software. To do this, you need to track the movement of the object incredibly accurately or it will be blurred. This is why in AP the mount is so important and it usually needs a secondary guide telescope to aid in tracking . I would echo what others have said and advise you to go to a local astronomy club viewing session. You will often get a chance to try out different scopes in local sky conditions and get a chance to make a more informed choice between types of scopes if not actual models. John

If you can get to a dark sky site then you will be amazed at how many faint and distant objects, unobservable from a light polluted city site, become visible. This is as true for any size of visual telescope as it is for naked eye observing. The less light pollution, the darker the sky, allowing fainter, more distant objects and detail to stand out. If you are going to observe from your back yard and there is little light pollution then you are indeed fortunate. If however you are like most of us then getting a scope to a dark site needs factoring in. A schmidt cassegrain is one way to combine aperture with reduced overall size (although it often means more expense and can be as heavy as a comparable dob). A truss dob can be another way of reducing size while obtaining the maximum portable aperture. As with life, compromises, compromises. John

Clearly and concisely put. John

Hi there, can’t tell you how much I envy your dark sky opportunities. You may find this site helps: https://telescopius.com You can input the objects you are interested in, the times you want to observe and it will show you the best objects for your locality and email you before each new moon to remind you. Enjoy your scope and dark skies. John

Hi David, welcome to the forum. Clear skies. John

David makes a valid point here. There is always human variability but the transition from night vision (using the rods in the retina which only see contrast) to the start of colour vision (using the cones which respond to colour) occurs somewhere between starlight and moonlight. DSOs tend towards the dimmer end of starlight. A good general article is here: http://www.yorku.ca/eye/sensit.htm A much more detailed article on the human eye and optics with some fascinating insights (pun unintended) is here: https://www.olympus-lifescience.com/en/microscope-resource/primer/lightandcolor/humanvisionintro/ John

If you attach one end of a heavy chain to the back end and the other sitting on the turntable, more of the weight comes into play at low elevations and much less at higher elevation. John

Looks great Mark. What sort of component weight are we talking about? I would be interested in your view on the additional detail visible in M13 over your 16”. John

Although I like the online version, I struggled with the IOS version of Stellarium and, like Stu, opted for Sky Safari as being much more configurable. Having said that, on Wednesday night, I got bored with Jupiter wobbling around and tried to see how many of the Saturnian moons I could spot. I managed one - Titan, despite being able to identify fainter surrounding stars, I could not positively identify any of the other moons. I must admit though that everything beyond Mag 10 was dancing in and out of view with the poor seeing and light pollution from Leeds. John

Backpack arrived today. Excellent buy and I can confirm Philip’s assessment of the quality and the thickness of the padding - more than up to the job. Thanks again for the heads up John

Thanks Philip, I have an ETX90EC that, like you, I use on holiday trips. This looks much better than my current cobbled together arrangement of holdall and foam. Item ordered, great price. John

Hi there, welcome to the forum. I’ve been studying Yorkshire clouds for years, you are in good company. John