Setting circles

[bomberbaz]

Hello all, trust we are all well and keeping safe.

So I am looking to create an AZ setting circle for my dob to fit onto a levelling adjustable platform. I am doing away with the pushto, not because I don't like it, but an upgrade is planned.

I have read a wealth of posts from various sources with regards to the platform and AZ setting circle. 

However one thing I am finding frustrating is getting a 18" setting circle template. Failing that, a  printer who will accept a smaller template of the setting circle and stretch to my dimensions. The template I have appears to be 12". Not even sure if that is right because I am not sure how templates translate to a printer in terms of dimensions.

Template attached 

Tried digital printing website but they said they couldn't help.

I am probably going about this entirely the wrong way so any help will be very greatly appreciated.

Steve

[vlaiv]

26 minutes ago, bomberbaz said:

The template I have appears to be 12". Not even sure if that is right because I am not sure how templates translate to a printer in terms of dimensions.

I might be wrong but this is how I would try.

Measure how many pixels you have for diameter of template - what ever you want to be 18".

Let's say it is 3000px and you want that to be 18".

Put resolution of printer to 600dpi - that is standard and most printers will happily print that. 18" is therefore 18 * 600 = 10800 points.

You need to enlarge your image by factor of 10800/3000 = x3.6 or 360% in size to match.

If you are going to print it yourself out of smaller bits - just take couple of crops of enlarged image in Photoshop or similar - and print those. Just make sure to tell printer you want 600dpi.

(you can do above with other dpi setting - like 300dpi or 1200dpi - just follow the same math but change the numbers).

[bomberbaz]

16 minutes ago, vlaiv said:

I might be wrong but this is how I would try.

Measure how many pixels you have for diameter of template - what ever you want to be 18".

Let's say it is 3000px and you want that to be 18".

Put resolution of printer to 600dpi - that is standard and most printers will happily print that. 18" is therefore 18 * 600 = 10800 points.

You need to enlarge your image by factor of 10800/3000 = x3.6 or 360% in size to match.

If you are going to print it yourself out of smaller bits - just take couple of crops of enlarged image in Photoshop or similar - and print those. Just make sure to tell printer you want 600dpi.

(you can do above with other dpi setting - like 300dpi or 1200dpi - just follow the same math but change the numbers).

I was fine until here. What programme do i use to enlarge it. I am used to playing with images but when we start getting into the maths side of things, I am not great. x3.6 is easy, if programme allows for it that simple

Edited May 7, 2020 by bomberbaz

[vlaiv]

5 minutes ago, bomberbaz said:

I was fine until here. What programme do i use to enlarge it. I am used to playing with images but when we start getting into the maths side of things, I am not great. x3.6 is easy, if programme allows for it that simple

Most of programs will let you input new size of image as percentage of old - so use 360% in that case.

Mind you - 3.6 is only for 600dpi and 18" if diameter in pixels of settings circles is 3000 - you need to measure it in pixels using measure tool.

What software are you using? You can use something simple as IrfanView to do everything - measure circle diameter and rescale the image.

[bomberbaz]

8 hours ago, vlaiv said:

Most of programs will let you input new size of image as percentage of old - so use 360% in that case.

Mind you - 3.6 is only for 600dpi and 18" if diameter in pixels of settings circles is 3000 - you need to measure it in pixels using measure tool.

What software are you using? You can use something simple as IrfanView to do everything - measure circle diameter and rescale the image.

I will give this a go. All though I might not be the best I do like to play around with software. Only way you learn 

[bomberbaz]

when I searched for irfanview the link took me to pixillion image converter. Anyway I downloaded that and increased the resolution by 525%, was actually very simple. Didn't actually realise the image I had was as small as it was. Anyway, image has took it well with no pixillation and have a quote of £24 from vistaprint online for the image. Hopefully they can fullfill the quote, we shall see. 

Thanks for your help vlaiv, much apprectiated.

Steve

[Allan Meyer]

Take a look at the web site 

        Blocklayer.com

especially the protractor tool.   https://www.blocklayer.com/protractor-print.aspx

and the circle divider tool.      https://www.blocklayer.com/circle-divider.aspx

After you've had some fun with the above trying options and making custom versions,  scroll way down the page to "Diagrams to PDF", and look for the "Printing help" link.  

Example of a Declination setting circle done with above:

 

R.A. setting circle:

Edited November 26, 2020 by Allan Meyer
typos