Next purchase, might need some advice

[Astro Waves]

Hiya everyone,

So looking towards my next purchase, its not going to be anything too massive but just was a bit unsure really as I'd like both eventually but wasn't sure which way round would be the best. I have sadly moved back into a city (Edinburgh) and its about Bortle 7 (6 in places) and was thinking about the L-extreme to help with the ol' nebulas but also light pollution but then as I'm not guiding and would have to take shorter exposures (I think the longest I've had out the iOptron Sky Guider Pro is about 2/3 minutes), would this be collecting enough data to warrant the filter ooooorrr would it better going for a guide scope first then I would be able to get those longer exposures then work towards the filter? I would also need something to control the guide scope with which bumps up the price again but was taking about getting an old laptop/tablet if I can get PHD2 to work on it. Think that all makes sense, might a be a tad rambly but you get the idea, hah. 

 

Cheers

[discardedastro]

Have you considered tools for polar alignment? Either iPolar if the SGP supports it or a Polemaster.

You should be able to get better exposure times out of the mount if properly aligned. Guiding won't help much if your PA is spot-on. PHD2 doesn't take much grunt so even a Raspberry Pi would do fine on that front if you wanted to go down that route.

I'd definitely focus on getting your subframes "good" in terms of duration and stability before considering filters. An Optolong/IDAS LP filter will certainly help somewhat in 7 skies but not as much as longer exposures will!

[Space Oddities]

The L-eXtreme is very narrow, I believe ~7nm on both OIII and Ha. I'm afraid guiding is mandatory with this filter if you really want to see anything and have round stars.

If you're on a budget, there are alternatives that are less narrow and therefore less effective against light pollution. The L-eNhance is one of them, or the more classic CLS-CCD filters. 

I think an autoguiding system is a good investment to maximize the # of keepers and be able to do narrowband. Between light pollution from the city and the Moon, narrowband can be a life saver   You can also use the guide camera to make your polar alignment very precise, which helps achieving longer subs.

Check out the classifieds section of this forum, as well as sites like AstroBuySell. There are often guide cameras for sell, like this QHY. ZWO, QHY, Altair make good guide cameras that don't cost an arm. As for the guide scope, there are some very cheap options (or here) today that work just fine, especially if you have a lightweight and widefield setup.

Hope that helps!

[Astro Waves]

1 hour ago, discardedastro said:

Have you considered tools for polar alignment? Either iPolar if the SGP supports it or a Polemaster.

You should be able to get better exposure times out of the mount if properly aligned. Guiding won't help much if your PA is spot-on. PHD2 doesn't take much grunt so even a Raspberry Pi would do fine on that front if you wanted to go down that route.

I'd definitely focus on getting your subframes "good" in terms of duration and stability before considering filters. An Optolong/IDAS LP filter will certainly help somewhat in 7 skies but not as much as longer exposures will!

I hadn't thought about polar alignment helpers but now you mention it I might have a look into that. If it doesn't take much doing then I might see if I can find a tablet to run it on to save weight whilst having to cart everything around each time I need to shoot. 

 

1 hour ago, Space Oddities said:

The L-eXtreme is very narrow, I believe ~7nm on both OIII and Ha. I'm afraid guiding is mandatory with this filter if you really want to see anything and have round stars.

If you're on a budget, there are alternatives that are less narrow and therefore less effective against light pollution. The L-eNhance is one of them, or the more classic CLS-CCD filters. 

I think an autoguiding system is a good investment to maximize the # of keepers and be able to do narrowband. Between light pollution from the city and the Moon, narrowband can be a life saver   You can also use the guide camera to make your polar alignment very precise, which helps achieving longer subs.

Check out the classifieds section of this forum, as well as sites like AstroBuySell. There are often guide cameras for sell, like this QHY. ZWO, QHY, Altair make good guide cameras that don't cost an arm. As for the guide scope, there are some very cheap options (or here) today that work just fine, especially if you have a lightweight and widefield setup.

Hope that helps!

Always sadly on a budget. Thanks for the links, I'll have a goosey at them now. 

I kinda thought guiding would be the better way to go at the moment, I know the filter would help pull out more colour etc but the camera is modded so that helps. Thanks for your input on this. 

[PeterCPC]

If you use the L-extreme you will be looking at 5 mins exposures as a minimum I would say.

[discardedastro]

22 hours ago, Astro Waves said:

I hadn't thought about polar alignment helpers but now you mention it I might have a look into that. If it doesn't take much doing then I might see if I can find a tablet to run it on to save weight whilst having to cart everything around each time I need to shoot. 

If you do the guiding setup right it can also (as @Space Oddities said) act as a polar alignment aid. PHD2 has great tools in this regard - a static polar alignment tool which can get you there or thereabouts, and a drift alignment tool for getting the alt/az set just right. This will actually be more accurate than a Polemaster etc in general though if you're shooting reasonably wide fields you don't need to get that close for long exposures - but if you want to shoot narrowband, it'd definitely be the way to go.

[BigMisterP]

23 hours ago, Astro Waves said:

I hadn't thought about polar alignment helpers but now you mention it I might have a look into that. If it doesn't take much doing then I might see if I can find a tablet to run it on to save weight whilst having to cart everything around each time I need to shoot. 

 

Always sadly on a budget. Thanks for the links, I'll have a goosey at them now. 

I kinda thought guiding would be the better way to go at the moment, I know the filter would help pull out more colour etc but the camera is modded so that helps. Thanks for your input on this. 

Unfortunately you’ve not suggested a budget.

Guiding uses very little CPU, neither does scheduling the imaging shots. A simple 2GHz 4-core CPU will do nicely. Circa £140

SharpCap, £10pa, will do the capture and include a polar alignment tool.

Astrotortilla £0, will confirm your image centre

PHD2, £0, also free will do the guiding, follow preparation steps as they make it more accurate yet. This also have polar alignment too.

Photopills, £?, is usefully to get an idea for north using AR in day time so you can identify local landmarks to speed up polar alignment.

Sources:

https://smile.amazon.co.uk/Computer-Windows-Professional-x5-Z8350-Bluetooth/dp/B07MB9TC33/ref=sr_1_13?dchild=1&keywords=stick+pc&qid=1619258271&sr=8-13

https://www.sharpcap.co.uk

https://sourceforge.net/p/astrotortilla/home/Home/

https://openphdguiding.org

Guidescope & camera

https://www.firstlightoptics.com/zwo-accessories/zwo-mini-finder-guider-asi120mm-bundle.html