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SmokeyJoe

What do I need for PA with sharp cap?

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I have always had a problem with PA, increasing health problems make it almost impossible to glance through the PA scope now. I got so frustrated that my newt has been in its box in the spare room for the last 18 months.  Big birthday coming up and the boss has approved a SW ED 80 DS pro,  (AP is is the direction for me)  so I need to get this PA problem sorted.   So I was happy to find that you can PA using PHD or Sharp cap. 

Problem is I don't have a guiding set-up.  Budget is quite tight, about 200 quid which I was intending to spend on a second hand cannon D450 or similar for actually taking the images. Can't afford that and  a guide cam which  am only going to use for PA.    I already have an Opticstar px-35c planetary cam but I suspect this is not up to the job (640*480) and it is cooled so not sure about hanging it off of the back of my SW finder.

So can I use my current camera and finder ( with appropriate adapter)?

Is there any way to PA through the main OTA using a DSLR?

If I have to buy an astro camera (ZWO ASI120 MC-S is within my budget) can I do this through the OTA or do need to attach it to my finder scope for PA and then move it to the OTA for imaging?

Is there another solution within my budget?

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SharpCap recommends about 200mm FL for PA.     How I get around this is that I use a 1.25inch  0.5x Focal reducer screwed to the end of my 120MC  ( the camera nose piece has a screw thread inside the barrel).     This transforms my imaging scope ( ususually an Equinox 80  FL=500mm )  into a 250mm finder.   Make sure you have a good Northerly aspect both East and West of Polaris.   The alignment routine requires rotating the scope about the Polar Axis and it's frustrating to have one side all  located and plate solved, but then have a frame full of roof/tree/streetlight on the other side.

Sharpcap works a treat with this for me, so much better than using any reticules built into the polar axis.   Once done,  do the star alignment routine, don't trip over the tripod legs... ;)  and off you go.

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I have used an old Canon FD lens (tele 100-200) which worked fine attached to the Orig ASI120mm. A good quality Canon (or other) FD lens goes for about £20 and then you just need  an adapter (canon FD to C/CS-type) £20.

Then I had an Xmas present of QHY Mini Guide Scope and used that with ASI120mm but together with a new camera blows your budget - just - £250. Unless you go 2nd hand and save some pennies 🙂

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On 27/01/2019 at 11:10, Craney said:

Make sure you have a good Northerly aspect both East and West of Polaris.

This could be a problem, I live on a modern housing estate, houses all around apart from to the East and there are trees in that direction!

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Hi,

I used to make Polar Aligning using drift align. Having a License for SharpCap I decided to give it a try and I ahve to say I like it due to its simplicity.

I use either my ASI 1600MM Pro or my ASI 071MC Pro with a 630mm focal length telescope. Yesterday I made a polar align and I got this result. Look at the image.

A prior guiding confirmed my Polar Align was good.

OK the values do jump but at an average that is more or less what I got. The iOptron CEM 120EC2 has a very good adjustment in Altitude as well as Azimuth ad as my mounts are nearly perfect levelled it is even easier.

Rainer

sharpcap_pa.JPG

Edited by Rainer

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Sharpcap is really good,  quick method of PA...

You can buy an adapter for converting your finder into a guider..I used this method with my 80ed and preferred it over what I have now..

Take it you can see Polaris?  If not you will have to drift align so will need a decent view to the south and either the east or west

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Thanks all for your advice, will definitely be getting a subscription to sharpcap when my new scope arrives.

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You can still follow the PA alignment process in the older (non subscription) V2.9 SharpCap.

 

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