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New Year - New Scope


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Hi all,

I guess I should start with both an apology and a 'Happy New Year' to all.  The apology is that this question has been asked over and over again (probably) but I can't find the answer anywhere.

I gave away my old Newtonian about 2 years ago as it wasn't getting used; but now I have the time to really focus on the hobby and have decided to re-invest in some new equipment.  As with many amatuers I want it all, and by that I mean that I want to observe visually and have a stab at astrophotography.  I'm not interested in planets other than Jupiter, but only as I want to re-create that first time of seeing the four moons again - it was amazing.

So, i've settled on a Skywatcher EQ6-R mount but as for which scope; that's where I'm struggling.  I've picked 5 and they are;

Skywatcher Explorer 200PDS

Skywatcher Explorer 250PDS

Skywatcher Quattro 250P F/4 

Skywatcher Evostar 120 ED DS Pro

Skywatcher Evostar 80 ED DS Pro

I've put them all into Stellarium and considering an APC sensor camera I seem to be able to fit the Flame and Horse-Head neblulae into a frame, and without much significant difference.  The Pinwheel is better in the Newts but Pleiades only fits with the 80 ED.  Optically they are all fine but I do need a wide field eyepiece for some targets, especially with the 250PDS but Pleiades fills the eyepiece nicely if it's a 31mm (82 deg FOV).

In terms of price the 250PDS is around £500 with a coma corrector and the 250P F/4 close to £1,000 with a coma corrector.

The 120 ED is expensive at around £1,400 considering that I could get a Skywatcher Explorer 190MN for less money (but considerable more weight).

So my question is - Does the 250p F/4 have any significant advantage over the 250PDS; and are the 80 and 120 ED's worth the expense when considering the two newts.

And if you havn't lost the will to live at this stage; would a 190MN have any advantages over the others?

Thank you for taking the time to read this.

Steve

 

 

 

 

 

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I can’t see anyone buying a new ED120 anymore since the price increase when there are better alternatives. The Technosky 125 has better optics and far better build quality.

https://astrograph.net/epages/www_astrograph_net.sf/en_CA/?ObjectPath=/Shops/www_astrograph_net/Products/AGTEC125F78

Edited by johninderby
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I think that it all depends on what you want to image. The ED80 is a wide field scope and good for nebulae. The larger reflectors are good for planetary or galaxy imaging. In terms of colour correction, the ED scopes are ok, but you will get some CA. The reflectors will give good images but will be more 'faff'. I would say the MN190 is somewhere between but does have dew issues and is heavy. For visual use I would say they are all ok but that depends on where you set up and the amount of carrying needed. As a general rule the greater aperture favours visual use.

As stated there are other options. A small triplet APO would be better for imaging (at a price) or a different doublet. Personally I would not try to get a scope to do both. The 200pds can be picked up dirt cheap on the used market which is good for visual and with a new focuser can be used for imaging small DSO's. Add this to an ED80 or similar and it would be a good starting point.

At the end of the day there a loads of options. Look at my signature and you will see what I mean! I'm still deciding🤣

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I'll +1 the commentary above around visual vs imaging. I have a separate visual scope - I briefly had one doing dual duty but DSO AP demands consistency of configuration (e.g. flat calibration frames are invalidated the second that anything rotates or shifts around) and that makes for painful swaps to/from imaging.

I've been imaging with the 200PDS for a long while and it's a great platform but needs some work to be a really solid high-end AP platform - nothing much optically but plenty mechanically. I imagine the 250PDS and Quattro will be similar.

  • Focus - are you going to hand-focus and maintain/monitor? If not, you're going to need a focus motor (not too expensive) and I would strongly strongly recommend replacing the focuser (Baader Steeltrak NT worked great for me, but plenty of other options out there).
  • Baffling/caps - cheap and easy to do, don't forget to at least cap/baffle the primary to avoid light leakage!
  • Guiding - if you intend to do much really deep-sky imaging you'll need to guide, which means an off-axis guider (definitely the preferable option for Newts because the light shares fate with imaging light and so you don't have issues with differential flexure) or piggyback scope. Backfocus can be challenging with DSLRs when you have an OAG in.

The 200PDS is quite a long system - I use a ZWO ASI183MM and that's got a tiny sensor, so is a very narrow FoV system overall. That works for a lot of my imaging work but it's definitely oversampling on the sensor. Have a play with https://astronomy.tools/calculators/ccd_suitability to get a feel for that.

The f/4 is not the scope I'd go for if I wanted a widefield astrograph-style instrument - I'd probably err towards APOs rather than Newtonians. Don't forget you will need coma correction whichever way you go for Newts, and potentially field flatteners for APOs, so budget for that.

Paracorr is the right answer for CC of Newts, in my view, though the GSO CC is also alright by many accounts. All optical chains are only as good as their weakest link, so I wouldn't skimp on the CC - I did and regretted it. Don't forget to also budget something for collimation tools for Newtonians, so at minimum a good laser + reasonable barlow and a Cheshire/Concenter.

Probably best to avoid the 190MN if you want to do more DSO imaging, if you ask me.

Edited by discardedastro
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I agree with @Clarkey, there isnt really a scope that will do both to any good degree. Also you dont mention budget or if you have any experience imaging?

If you've only  a little (or no) imaging experience then I'd not be looking at the 190mn, from what i've read, its a fantastic scope but I wouldnt say its a beginners scope & from what i've heard its pretty demanding when it comes to collimation & with it been a Mak it needs a long cool down period so I'd say its really better suited to a small obsey. You'll probably have seen countless times the old adage that the best scope is the one you'll use the most. Combine an EQ6 R & a 250mm scope & you've a heck of a lot of weight to carry in & out. The EQ6 R plus 250 Quattro come in at 50kg then you need to add on the weight of all your other bits, its not a weight i'd fancy just 'nipping out' with. It might sound ok right now but imaging carrying all that out, setting up & then 20 mins later the sky clouds over & you have to strip it all down & take it back inside, that scenario would get boring pretty quickly for me 😂 For observing only I'd definitely consider a 250mm scope but only a dobsonian which is easier to set up & move around than the other option.

If you look at my signature, I've gone for fairly lightweight (ish) & easy to set up. Budget also played a part with everything coming in at around 3.5k, Thats not including my processing software & a tablet plus a couple of guide books which takes it too around 4k. I'd have thought this is pretty middle ground (Cheap even considering some peoples set ups 😬) but it does everything I need to a standard i'm happy with. 

So really what i'm saying is a big dobsonian for visual & a small refractor with HEQ5 Pro mount, but thats just me. Good luck & keep asking as many questions as you need so you make the right choice the first time around

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18 minutes ago, nephilim said:

The EQ6 R plus 250 Quattro come in at 50kg then you need to add on the weight of all your other bits, its not a weight i'd fancy just 'nipping out' with. It might sound ok right now but imaging carrying all that out, setting up & then 20 mins later the sky clouds over & you have to strip it all down & take it back inside, that scenario would get boring pretty quickly for me

100% fantastic point. If you've got space and security to allow it, a Telegizmos scope cover is a hugely worthwhile invesment - my EQ6-R and 200PDS live outside, fully set up with cameras + computers + optics, 24/7/365 and setup is 5 minutes and shutdown the same. The EQ6-R has some bolts that will rust - all the shiny ones are just coated mild steel and the coating will not last - but it's an easy and cheap job to swap those for stainless steel (see my thread below, which is also hopefully helpful in getting to know the EQ6-R, fantastic mount that it is for the money).

For AP, being able to leave stuff in situ rather than having to redo alignment steps and repeat flat frames can make setup and running much simpler, and makes for easier calibration of imagery after the fact.

If you're going to be carting stuff about all the time, A) plan for a Polemaster or similar to make polar alignment less time-consuming and B- consider weight and portability as important as optical quality...

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@discardedastro I'm probably right at the limit of what I really want to be carrying around, setting up & stripping down each session. My imaging area isnt far from the back door & the actual optical part etc (Imaging lens/ camera, guide scope/ camera & Asiair Pro) just goes on & comes off in one go (see image). Then its just the tripod & mount head & associated 'bits'. The tripod, mains electric extension, counterweight goes in the shed nearby, but anymore then I would need a rethink.
I'll probably up grade my mount to an EQ6 R or similar in the next year or so & as an obsey isnt really practical (or affordable) right now, I'd more than likely go down the pier route as its a good option & works well for PA etc, the Telegizmo cover you've linked would be ideal for just the pier, the rest (optical & electrical) would come inside with me.

Your right when you say that 50% is weight/ portability etc. Many people starting with their first scope sometimes dont realise just how big they are until it suddenly arrives at the door & a 250mm scope is not small. I've seen countless posts in the Sales page of people selling up as gear isnt getting used, I realise weather & other commitments will play a part but you can pretty much guarantee that a big percentage of sales will be down to gear just been to big & heavy. Your post looks interesting, i'll have a read through that now.

Steve

217977756_10227269564353241_8877795612223466802_n.jpg

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Hi all,

Lot's of great advice here so many thanks to all.  I had never considered attaching an F2 lens to a CCD/CMOS camera so that is definitely one to consider.  I have both a APC and Full-Frame Canon so I think i'll start with these and a 150mm F/4 to at least investigate the basics and then either commit to an F2 or a small Doublet once I get to grips with it.  I might even try a 40mm F/1.8 on a x2 extender to see what that produces (if anything) but whatever it will allow me to develop slowly.  

I think I will stick with the EQ6-R as it will allow me to expand without having to consider the payload too much.  I've watched a couple of videos featuring a Redcat 51 and a Zenithstart 81 so they may be a reasonable future option, as well as the Technosky 125; so plenty of research to do.

As for general observing I'll go with a Dob - around 250mm.  I'm familiar with colimating my old Skywatcher 130 so that at least doesn't hold too many mysteries 😉.

Kind Regards

Steve

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