Brutha

Yes, second that, keep camera level when doing the panorama, it just needs to be able to see the horizon (or top of buildings!)

If you have a 3D printer and fancy a bit of DIY, you could try building one of these:

https://openastrotech.com/

I have the structure built, and am working on the electronics now.

You get goto with the basic electronics, then with Astroberry and a RPi4 you’d get platesolving and other stuff too!

I bought the Starsense for my 8SE, and love it, much faster to get going than before!

I thought about the gps, but since I only use the scope from the garden it’s a bit pointless, it would only supply the date and time, and that is quick to enter anyway.

2 minutes ago, Nikolas74 said:

Exactly was my problem because it's not very easy to find marks for North since all the buildings I see towards North don't make this easy. 

I download also to my phone a similar app that is like a compass etc and can take a picture with bearings... NORTH is what I care about, so I will try this out and make a mark, and then I will rotate my landscape accordingly to match it with the picture from the app. 

Thanks very much... 

You probably don't need to get this massively accurate I think. Even if you can figure out from a map the bearing of your balcony, this might be enough.

On 04/01/2021 at 18:53, Nikolas74 said:

Since I live in a flat I do most of my imaging from my balcony... I purposely choose a top floor because of my astrophotography passion in order to have a decent field of view, but my balcony has walls on one side and on top. 

So I decided to bring to Stellarium my own landscape and my FOV so I can know exactly which targets are on sight and at what time. 

I have done some reading and watch videos but I still have a couple of questions before I begin and hopefully some people from here could help! 

a) how should I take my photo... Me standing straight levelled with horizon or placing my camera on a tripod and place it like a telescope looking up in the sky towards North? 

b) the famous cardinal points and the line angle_rotatez= in the ini file... Is there a secret of finding this number easy in order to match cardinal points to my photo or the only way is by trial and error....? 

Thanks for reading

Nikolas. 

Do you have any land marks that you can measure the bearing to on e.g. google earth or peak finder? I used Peakfinder to establish the accurate bearing to a nearby hill in the picture, then it was fairly straight forward. Some further info here, but irritating missing the image they are referring to:

http://stellarium.sourceforge.net/wiki/index.php/Landscape_Rotation

Hehe, funnily enough I have *finally* managed to get some decent weather to use my 8SE over the last few nights, and have been starting my "messier twitching" list.

I was rather surprised to find M1 quite nicely visible; although to be fair it was just a faint patch of light!

Thanks Malcolm, some good reassurance there! Also, the purple aluminium mount top is very snazzy!

13 hours ago, michael8554 said:

I was assuming that even in Alt/Az mode, the 8SE needs an accurate "Home Position", probably level and pointing true north ?

Michael

Yes, should be more or less level (although it seems pretty tolerant and doesn’t need to be exact). The azimuth of the mount doesn’t seem to have any effect; if you are doing the usual alignment based on bright stars, it simply works out where it is pointing in the process.

With starsense you start with the scope pointed roughly east and level, and it moves around taking 3/4 images and plate solving to get the orientation. 

My first telescope was a skywatcher 127 maksutov; this was “tracking only” with no goto functionality - indeed, this needed to be aligned with true north to make it work. Although later I bought a WiFi adapter that turned it into a goto scope, and this removed the need for the alignment to north.

2 hours ago, michael8554 said:

Then presumably you have plans to adapt the top plate to take the 8SE, and to provide Az adjustment ?

Michael

Yes, correct. The holes for the 8SE mount screws are actually pretty simple, seems to be 3 3/8" holes on a 3" radius (I know I have to be careful with the length of them!).

For Azimuth adjustment; you mean in future for an EQ mount? Yes, was aware of that, hence the two plate design; would need to rework the lower plate a little along the lines of this I think, which gives 20 degrees of Az adjustment: https://www.pierplates.com/products_8510.html

Hi Michael,

Thanks - good question; no, just using the original mount (alt-az) for now I think.

BUT... ideally I leave the option open to switch to a EQ mount at some point in the future if I fancy doing it.

Cheers

Brutha

Hi All,

So, it seems that a pier is a good idea for my 8SE, so my planning is now continuing. The idea is to follow the basic plan from here: Sky at Night home made pier - see basic plan pics below.

The basic idea is filling a drainage pipe with concrete. I'd be grateful for any thoughts on the following questions:

• I'll try and get 200mm drainage pipe - I don't know if this is overkill though, would 160mm be ok if I can't get 200mm?
• I'll use the "two plate" approach I think, since it's simpler to make with just drilling some plates. Can I use e.g. 10mm aluminium plate for the two plates? (which I could potentially machine with the MPCNC machine I am currently building). Or should it be steel?
• Any other things to consider? I have seen people suggesting this approach might be prone to vibration?

Thanks!

Brutha

8 hours ago, vlaiv said:

Creality Ender 3 V2

(simple enough, right? )

 

Yep, I would second that as a general beginner 3D printer too! Easier build than the ender 2 I had before.

Thanks both! I think I shall start making some prep for this then, looks like it could be the summer project for next year!

Hi all,

Since manoeuvring my 8se out of the back door on its tripod can be a bit of a pain, and I have plenty of space in the garden, I’m thinking of building a concrete pier for it. Apart from convenience, I am thinking it might help the vibrations a bit.

BUT - we get some horrific weather here (strong winds, rain etc!), so I would have to keep the telescope inside the house on the mount, then take it outside and bolt it on each time I use it.

Any thoughts on whether this is a worthwhile thing to do? Has anyone done anything similar?

Cheers

Brutha

If you are looking for a DSLR for general use as well, you could look for a cheap 2nd hand Canon 550D (T2i) on EBay, this should come in under your limit I think.

It has the ability to do a 60fps video recording of the central 640x480 portion of the sensor, and i saw some decent planetary images created from that. I tried it with my 8se and a 2x Barlow - was rubbish seeing though and I was learning my way round things so didn’t achieve much! Will try again next time I get a clear night though.

So, have discovered that the OnStep project (an open source goto/tracking mount driver) has the possibility to drive an alt-az mount with a field rotator; I guess this is the way to go for the electronics side of the project!

1 hour ago, Seelive said:

Alignment would still need to be carried out if it isn't (not that different from an eq mount and polar alignment really, just that most spirit levels are designed to be used on horizontal or vertical surfaces).

This is part of my thinking around this: an alt-az tracking mount could be calibrated entirely with software via plate solving (just like the celestron star sense).

1 minute ago, vlaiv said:

Why would you update tracking rate so rarely?

In each iteration - move mount where you think it should be, update its coordinates accordingly and then continue iterating. This should really be millisecond period (depending on resolution of stepper motors).

I have AzGti mount and it has very nice feature - it is called point and track. It does not need alignment in order to be able to do that.

 

This is a good point! I had imagined the Raspberry Pi as the "brains" of the outfit who knows where the scope is pointing, and an Arduino or similar just running the steppers at the speeds it is told to.

But maybe you're right; actually I guess the Arduino can handle both tasks fairly easily - perhaps with stuff like error correction and so on in Raspberry Pi.

15 hours ago, Seelive said:

I'm not sure if there are any equations that will automatically create the desired movements. To correct for a misaligned mount you would need to know the tracking error for an object at the field centre, then knowing that, the field rotation required can be calculated. But if the measured tracking error is not taken at the field centre then the tracking measurement error will also be affected by the field rotation. I'm sure it is possible to solve by iterative methods - but it's Boxing day and the bottle of wine has already been mostly consumed!

I guess the problem can be split into two parts. Part one is to create an alt-az based tracking mount, like that on my telescope for example.

The second part is to calculate the field rotation rate, using my latitude and the altitude and azimuth figures that the mount is pointing to. From here the calculation is:

Rate of field rotation (degrees / hour) = COS(observers latitude) * angular rate of rotation of earth (degrees / hour) * COS (Azimuth in degrees) / COS (Altitude in degrees)

That second bit should be straight forward... BUT I am realising the first part, creating an alt-az based tracking mount is not that trivial! The tracking rates vary depending where you are pointing; so if you simply update the tracking rates e.g. every minute based on where you think the mount is, it will wander off target fairly quickly I suppose.

Of course, the fact that there are loads of alt-az tracking mounts about, and that my Celestron seems to work very well means the problem has been solved before!

I think the Astropy project may be of use here - let's see!

2 hours ago, malc-c said:

I do love all these DIY experiments... but in all honesty would it not be simpler to use an EQ mount, or in the case of a dobsonian, wedge the base !

Oh yes, I'm sure it would be simpler! But this is more of an interesting project to pursue and hopefully learn some stuff along the way - with a very vague chance that I produce something useful in the end!

Hehe, thanks Vitaly! May need to improve my maths skills a little in order to attempt that - but this is probably a good thing!

Edit: maybe I found it in fact - think the equations are here for anyone else looking! http://www.ing.iac.es/~docs/tcs/software/TCS_PAPER_RL.pdf

Hi All,

Somewhat inspired by the Open Astro tracker (that I am currently building) and Astroberry, I'm kicking around the idea of an alt-azimuth version with field derotation (achieving the field rotation by mounting the camera inside a kind of cage made from large "lazy susan" bearings. The idea being that via Astroberry and plate solving I could build something that doesn't need polar alignment.

Whether this proves possible or worthwhile is another question of course, but it's a fun project to plan!

I have the formula for field rotation (deg/hr) based on altitude, azimuth and observers latitude - but I am missing those for altitude and azimuth tracking speed.

Can anyone point me in the right direction?

Thanks!

Brutha

On 24/12/2019 at 09:36, Aramcheck said:

You could also make yourself an astrolabe... https://in-the-sky.org/astrolabe/index.php

Ah, now there's a thought, thanks for that link! I hadn't realised how the astrolabe works, since you hang it from your finger or a hook etc, it doesn't need a horizon to work with, which is handy.

I have actually got a way towards building my 3d printed device already though, I ordered a gyro/accelerometer, and from some initial testing with Arduino I think it will actually be quite accurate - but I will keep the astrolabe as a possible future build!

3 hours ago, joe aguiar said:

I mean theres a formula for the width of one finger with your hand stretched out is a certain degree. Your fist is another and your thumb to your pinky spread out is another degree . Did u learn this formula?

Joejaguar 

Yes, that's the one! For me it was a bit out (I tried it against the moon, where I knew the elevation from Stellarium). I think thumb to pinky was supposed to be 25 degrees if I remember right. No doubt it would be very easy to adjust to my own hand / arm / finger peculiarities!

Thanks, funnily enough I did try the fingers method and it sort of worked, no doubt I could improve the accuracy by calibrating my fingers!

I think I'll try the DIY inclinometer though, there is something satifying about building your own gadgets!