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Hello everyone, 

I have an 8" Skywatcher 200p (f5) OTA on a NEQ6 Pro mount. I have been practicing taking prime focus photos with my Canon 750D, but come to a problem where I can't seem to get longer than 20-30 second exposures before my stars start looking elongated and needless ti say the target moves off screen after about 2+ hours. As I'm in australia polar aligning has been a major pain. My question - if I was to fork out half a grand for the polemaster and finally be able ti achieve an accurate polar alignment, would that solve my photographing woes or will that not be enough to achieve better tracking and I should EITHER / AND ? invest in an autoguiding setup? If so can you offer any advice on what to look for? I have 0 knowledge on autoguiding and feel overwhelmed with the choices- can I get anything or does it depend on what setup i have? What would you recommend for mine? Thank you very much!

Simona

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Simona I’m not an expert on this but you should be able to achieve way better than 30 s exposures with an unguided NEQ6. I have yet to get a guiding setup for my AZ NEQ and I can easily get 60s possibly more with a good polar align. Ultimately we will both need a guiding setup to push exposure time but I’m waiting until I gain more experience  with the camera and processing. Remember as well that guiding will not compensate for a gross error in alignment so you need to get your alignment issues sorted first else you will be wasting your money. An alternative to PoleMaster (which is really good bye the way) is Sharpcap and it is free. Of course you would need a suitable camera but you could find a cheap second hand camera I guess which may also be suitable for guiding later. Sharpcap provides the software solution for polar alignment similar to PolMaster. If I were you I would try to persist in getting your alignment sorted first maybe try get help from a local group. Good luck with it but certainly your mount is good  and is capable of better.

 

Jim

Edited by saac
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Hi, Simona.

Firstly, accurate polar alignment (however it is achieved) is essential for good long-exposure pictures. Personally, I struggled for years (literally) before the purchase of a polemaster reduced it to a simple 5-min exercise - but I have Polaris on hand - don't know about using it with the southern sky.

Secondly, trailing is not just a matter of poor polar alignment, but also of a thing called periodic error. Basically, because no gearing system can be perfect, small errors in the gears translate to relative movements of the mount, even if it is perfectly aligned. Typically the NEQ6 has a pe of about 30". The question now becomes how many pixels this takes you across, which is all to do with the focal length you are imaging with (long focal length=more pixels) and the camera you are using (smaller pixels=more pixels). If this trailing is kept below the visual threshold of the finished image, then you get away with it. If not, your stars will trail.

The bottom line is that, to get top-quality images, you will need to get into guiding at some point. It looks horrendously complicated, but a good starting point is having a look at a program called PHD2. Like all the best astro software it is free and it does everything you need for guiding.

HTH

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22 minutes ago, Demonperformer said:

Hi, Simona.

Firstly, accurate polar alignment (however it is achieved) is essential for good long-exposure pictures. Personally, I struggled for years (literally) before the purchase of a polemaster reduced it to a simple 5-min exercise - but I have Polaris on hand - don't know about using it with the southern sky.

Secondly, trailing is not just a matter of poor polar alignment, but also of a thing called periodic error. Basically, because no gearing system can be perfect, small errors in the gears translate to relative movements of the mount, even if it is perfectly aligned. Typically the NEQ6 has a pe of about 30". The question now becomes how many pixels this takes you across, which is all to do with the focal length you are imaging with (long focal length=more pixels) and the camera you are using (smaller pixels=more pixels). If this trailing is kept below the visual threshold of the finished image, then you get away with it. If not, your stars will trail.

The bottom line is that, to get top-quality images, you will need to get into guiding at some point. It looks horrendously complicated, but a good starting point is having a look at a program called PHD2. Like all the best astro software it is free and it does everything you need for guiding.

HTH

Thank you for taking the time to respond, I  really appreciate it. What should I look for in an autoguiding setup? Do you have any recommendations for products? I feel like a fish out of water and not sure where to find this information. I'm not sure if there are compatibility issues with setups etc. 

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38 minutes ago, saac said:

 

Thank you for responding :) I'm glad ti hear my mount should be able to perform better. Ithink I'm pretty decided on getting the polemaster for alignment based on feedback :)

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There are a number of ways to polar align. There's PoleMaster if you're happy to pay for it (I'm not!) and there's Sharpcap which is free if you d/l the older 2.9 version. Both these require the pole is visible to you. The latter requires a guidescope and guide camera which you would need for autoguiding anyway so it's a better use of money to go for the latter option. Your scope has 1m (?) focal length so a 60mm guidescope with 240mm of FL and a camera with small 3um pixels would work well.

Your Synscan handset has a built-in PA process which will get you to within 5' to 10' accuracy which is good enough for autoguiding (if you guide Dec in one direction). The nice thing about this is that you don't need to be able to see the pole, which is handy for me from certain parts of my garden.

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3 hours ago, simona said:

Thank you for responding :) I'm glad ti hear my mount should be able to perform better. Ithink I'm pretty decided on getting the polemaster for alignment based on feedback :)

Simona, if you do decide to go down that route you won't be disappointing I and many others have found PoleMaster to be an excellent bit of kit. It's one of those rare bits of equipment that just works. Once I have my mount aligned I then use the PoleMaster camera as an electronic finder so I'm still getting some use out of it. Take a look at Sharpcap as well because that too is an excellent (and free) piece of software.

 

Jim 

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Save your money and try PHD2's new polar alignment tools first. I wrote these initially due to the problems of polar aligning in the southern hemisphere due to the absence of a bright pole star.

Instead, invest in a guide camera and scope. You can use these with PHD2 for both guiding and polar alignment.

Edited by kens
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Tricky one. You are imaging at 1000mm focal length so borderline OAG (off axis guider) territory but you probably wont have enough backfocus for the DSLR.

Given the pixel size of your camera you'll be wanting a guide scope with a focal length of at least 200mm. So that rules out the usual finder/guiders (which I don't like particularly anyway).

In a similar setup I used a ST80 with ASi120MM-S camera. These days I would probably go with the ASI290MM Mini (note the Mini suffix). The ST80 is a touch heavy and a bit of overkill. But I also use mine for wide field photography - its not super quality being an achromat and quite a bit of spherical aberration but its ok and certainly fine as a guide scope. Another guide scope option would be the ZWO 60280 which would be much lighter but I have not used one myself. 

I'm assuming you would buy from the likes of Bintel and they stock the above items. You should also head over to Ice In Space. Its a predominantly Aussie forum and there is a good selection of second hand gear in the classifieds.

You may need some other bits and pieces to attach the guide scope to your OTA.

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The ASI290MM Mini is a great guide camera and i highly recommend if its within your budget, its more expensive than the ASI120, but you get what you pay for (much, much better sensitivity than my GPCAM2). I use to guide with the ST80 and invariably struggled to get a good guide star, but since i switched to the 290 mini i have plenty to choose from.

 

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