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SW 130PDS/HEQ5 based AP setup - advice wanted!


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Morning all!

Here's a rough precis of my planned setup (for mixed AP - DSO and basic planetary... I'll get a 9.25 SCT in a few years for proper planetary!):
- SW 130PDS
- SW HEQ5 Pro
- ZWO ASI224MC
- ZWO Mini Finder Guider & ASI120MM Mini Guidescope Package
- ZWO EAF & Hand Controller
- Baader MkIII Coma Corrector
- Celestron 2 x Barlow - any recommendations?
- Planning to automate as much as I can through an Astroberry or laptop.

My questions/unknowns:
- The 130PDS has a back-focus of 55mm; I believe the 224MC has a back focus of 12.5mm ish? I assume I'll need spacers to achieve the appropriate distance?
- Are there any issues with using a Coma Corrector in conjunction with a Barlow?
- IR Cut Filters - are they useful for colour cameras?
- How important/valuable is an EAF and Guidescope at this (early) stage in learning AP? If you had to pick one now, what would you pick?
- Is the ASI224MC the best camera for my needs at this time? Should I be looking at Mono cameras with a filter wheel to begin with?

Looking forward to hearing your advice!

All the best,

Matt

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Although the 130pds is cheap and can do the job, I'd go with a small refractor to start with. Its simpler to use but will cost more.

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I like the organized way you have put together a list if kit that should work together. Most of us just accumulate kit as and when it becomes available cheaply and then regret it when it won't all work together....I'm in that category!

Looking at your post count, you are possibly new to the hobby. Assuming you are just starting AP, I'd be inclined to keep things as simple as possible. There is a lot to learn (both hardware and software) and it's probably best to stick to the essentials. Getting some success early on with simple kit is a good motivator to keep going up the rather steep learning curve and avoid wasting the all-to-few good nights we get in this country. Poor nights are good for testing out guiding and practising mount alignment.

I'd avoid "niche" kit and stick to to popular commonly available stuff simply because there is a wealth of experience out there to help you out. 

The usual advice is to concentrate first on the mount and guiding, rather than the imaging scope. The HEQ5 is a good choice for small scopes. The logic is that you will probably keep the mount for a long time while swapping out the scope as tastes change. Not sure if aa HEQ5 will handle a C9.25 though...worth a check. The SCT might need an EQ6 level mount.

Personally I'd ditch the EAF for the moment...manual focusing with a Bahtinov mask is a simple enough procedure.

Earl's comment about the SW 130PDS is very valid. In skilled hands it's an absolute giantkiller but you need to be able to collimate it, and diffraction spikes are not to everyone's taste. The traditional way in is a SW ED80 refractor with a flattener..it's reliable every time you take it out. It's almost a rite of passage when starting AP. I would guess you are more likely to keep the ED80 as a second scope than the 130PDS, as and when you get the Celestron 9.25. 

At this sort of focal length you will need to guide. A guidescope is fine..but possibly better suited to a refractor imaging scope. Reflectors can have mirror slop which the guidescope can't correct for. Newtonians often use an off-axis guider (OAG) for this reason, but the OAG generally offers a smaller choice of guide stars compared to a guidescope. 

There is quite a lot of merit in buying kit secondhand. At least if something does not work out you can shift it on without too much of a loss. Sticking to this site and ABS I've not had many problems.

And the best of luck....!

Edited by rl
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Very nice setup. Here are a few pointers:

- you have listed ASI224 and separate guide camera. This leads me to think that you are planing on imaging DSOs with ASI224?

This will give you extremely small FOV. Here, look at M42, Orion's nebula:

image.png.fb00fa47d40b057242df7296733fedec.png

You'll be able to capture only central part of it.

I would suggest that instead above you get the following: Keep ASI224 as dual role camera. It is good planetary camera and can be used as guide camera. Don't worry about color vs mono thing for guiding - color cameras guide equally well and you'll have no issues with color camera and your guide scope. Get DSLR or mirrorless type camera for imaging (even second hand one).

Look what APS-C sized chip gives you on that scope:

image.png.aaed2d4b01ef81988970497b44114c61.png

Much nicer field of view.

1 hour ago, OctiCups said:

- The 130PDS has a back-focus of 55mm; I believe the 224MC has a back focus of 12.5mm ish? I assume I'll need spacers to achieve the appropriate distance?

Probably not. There is focuser to compensate 30-40mm of optical path with its range of motion.

With newtonians it is better for focuser to be somewhat more racked out. When it is racked in - it can block a bit of light and create diffraction artifacts in image.

image.png.470016fbd231b4566032a9b3126d1a89.png

image.png.9be009e40a50d6bb5ba5dd1916630890.png

Left star with diffraction artifacts, right normal looking star

1 hour ago, OctiCups said:

- Are there any issues with using a Coma Corrector in conjunction with a Barlow?

No need to combine the two if you are using barlow for say planetary. If you are using scope for planetary - keep planet in center of the FOV. Coma is not present there and you won't need coma corrector.

If you are doing Lunar imaging - you can then calculate how much of sensor you can use with coma free field. There is formula to calculate how much of the central field is coma free depending on F/ratio of the scope. You then set ROI on your camera if necessary (on ASI224 it probably won't even be necessary as sensor is very small).

In any case - don't combine CC and Barlow. If you really need to - there are hybrid options, coma correctors with amplification effect or barlow that has coma correction included

1 hour ago, OctiCups said:

- IR Cut Filters - are they useful for colour cameras?

Yes, if camera has only AR coated window. It is more useful when working with refractors as those don't focus IR properly. With mirrored systems it only ensures that you can get accurate color (you have to calibrate color to get accurate color)

 

1 hour ago, OctiCups said:

- How important/valuable is an EAF and Guidescope at this (early) stage in learning AP? If you had to pick one now, what would you pick?

Guide scope. You can easily focus by hand but guiding by hand is pain :D

1 hour ago, OctiCups said:

- Is the ASI224MC the best camera for my needs at this time? Should I be looking at Mono cameras with a filter wheel to begin with?

Best camera would be something with larger sensor - like DSLR or mirrorless (for DSO, for planetary ASI224 is the best and it is also good for guiding).

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1 hour ago, OctiCups said:

- Celestron 2 x Barlow - any recommendations?

I forgot that bit. Best F/ratio for ASI224 is around F/15 for planetary. That means that you need barlow around x3.

Most barlows can reach that magnification because magnification varies with barlow to sensor distance.

Specifically, you might want to look at this barlow lens if it will fit the budget (it's a bit pricy):

https://www.teleskop-express.de/shop/product_info.php/info/p5662_APM-Comacorrected-1-25--ED-Barlow-Element-2-7x---photo---visual.html

That is coma correcting barlow that is natively close to x3. It is also very good barlow element.

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Okay, thanks for al the advice; I had anticipated that people might suggest going for a Newtonian as a first scope for AP might be a touch difficult.

I’ve been looking at a couple of refractors - the Explore Scientific ED80, a Williams Optics Zenithstar 73 or the SkyWatcher Evostar 80ED. Any thoughts?

Ref the imaging camera, I have a Sony a6000 - would that be effective? What other cheaper (ebay auction type) DSLRs would make a good option? Canon EOS 600/750D?

And I’m all for 2nd hand purchases!

I’ll ditch the EAF in favour of a Bahtinov Mask for now.

Thanks for the great guidance so far!

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Out of these 3 refractors you listed I'd go for the SW 80ED with the matching flattener. It's very popular as the first scope into ap so should you run into any issues helps could be easily found.

Your Sony a6000 should be fine. It's a mirrorless so make sure you check its flange distance and get the right extension tubes for the spacing. An astro-modded Canon 550D or 600D would be a good alternative. The removal of the LPF#1 filter would really help with emission type nebulae and again massive userbase for support if needed.

Edited by KP82
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57 minutes ago, OctiCups said:

I’ve been looking at a couple of refractors - the Explore Scientific ED80, a Williams Optics Zenithstar 73 or the SkyWatcher Evostar 80ED. Any thoughts?

If you plan on doing both planetary and DSO imaging than you better look at getting two scopes. 80mm or smaller refractor will quickly run out of steam for planetary.

Maybe look into 6" F/8 newtonian as planetary imaging scope until you get SCT to replace it? That is probably the cheapest 6" planetary imaging scope that you can purchase and also - probably one of the best.

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9 hours ago, vlaiv said:

If you plan on doing both planetary and DSO imaging than you better look at getting two scopes. 80mm or smaller refractor will quickly run out of steam for planetary.

Yup, I plan on buying a 2nd hand SCT of at least 8” or more for planetary. They come up regularly on eBay etc so I’ll give it a few years and then add one to the arsenal!

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I'm in a somewhat similar position to you (I have a 130P-DS arriving tomorrow - also my first proper scope). My plan is to use it in alt-az for getting my bearings, and visually to begin with on bigger brighter targets to get the hang of the scope and especially collimating it before moving up to a full size motorised EQ mount.

Obviously I don't have any words of wisdom to share but I'll hopefully have some beginner level feedback on that scope once we have some clear nights over this side of the country.

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I was seduced by the very lengthy 130pds thread on this site and bought it as my first imaging scope, along with an asi224 and an HEQ5. I've never regretted this for a moment- the 130 performs very well. Don't be afraid of collimation: if you invest in a collimator of some sort, it's a pretty easy process- certainly not more difficult than many of the other things you need to learn for imaging. 

For the first 18 months I used it in 2 ways- either with the asi224 doing short exposure/high gain style unguided imaging. In these examples you can see the narrow field of view that @vlaivwas taking about:

482466133_M27TheDumbell.jpg.2debc75075e3af40414fcbb6f5d8a81a.jpg

765263115_M57TheRingNebula.thumb.jpg.8d57639a11695be79c978e1617b63519.jpg

Or with a modified 600d and coma corrector, with the asi224 as a guider, giving a much wider field of view:

1376430160_M33_181111_v3(2).thumb.jpg.b920d3fb21fa629077d9f49593d404e4.jpg

490578953_M42HaRGB190221RW.thumb.jpg.5c5a3dbe032e9f13d4e3bbc89c99b8b4.jpg

Both of these were taken in my first year, so you can see it does perform in novice hands. I've now got an asi1600mm and the 130 handles that really nicely too!

@vlaiv was also right in my view about using a different scope for planetary and lunar- I picked up a cheap 200p and use it with the asi224 and a 3.2x Barlow and that also performs well- although it's right on the limit for an HEQ5.

 

Edited by Whistlin Bob
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