SW 200, 150 or 130PDS

[stuplu82]

Hi Guys,

i am a long time lurker of this forum and have read so many articles on these different scopes. I have been working with a Konus 130mm for many years and its been great for observation. As a keen amateur photographer, I now want to start doing astrophotography and I have been looking at the SW PDS range for a few weeks, mainly on the Harrison Telescopes site. They offer complete mounts and OTA's, but what are the best combinations for astrophotography? I have read a lot on here about how great the 130PDS is, but having worked with a 130mm scope, i am keen for a bigger aperture. 

If i go for the 150, what would be the best mount for AP ? same question for a 200. They offer the likes of the 200PDS on a HEQ5 Pro, but would this mount cope with a AP setup. The 150PDS they offer on a EQ3 PRO and EQ5 Pro, no HEQ5 Pro. Would it be better to say buy a 150PDS and a HEQ5 Pro separately, rather than the package they offer? 

So many people differ on what the limitations of a mount are. I have around £1000 budget for mount and OTA and i already have an entry level D3400, which is fine for me and in addition to this budget, I will invest in a guide scope setup as well. 

Any advice would be appreciated. 

 

Stu

[jjosefsen]

I would not recommend an EQ3 especially not with a reflector catching even the faintest of gusts.

The consensus seems to be that an HEQ5 is the minimum, and I would say a 130PDS or 150PDS would be a good fit.

[vlaiv]

Hi, welcome to SGL.

Simple answer: 150PDS or 130PDS + HEQ5 (both scopes will fare well in AP role on that mount - better than 200PDS).

Long answer:

Mount comes first - this is the piece of kit you want to invest the most when doing AP. In your budget range most sensible option would be to go for HEQ5 (belt mod & tuning at some point should be done to it - you can purchase modded or do it your self).

Selection of scope is a bit more complicated as you need to balance couple of things there. You need to figure out what type of targets you are most interested in. You need to understand the resolution and field of view you want to work with (depends on selection of targets but also things must be matched properly to give good results). It also depends on guiding precision you are after. Then there is question of how well it will be carried by the mount.

In my view HEQ5 is capable of holding 8" scope - but I would choose compact OTA rather than F/5 newtonian for that. F/5 newtonian will have length of 1m or there about. That is large arm momentum and wind is going to be an issue in this configuration. I personally use 8" RC on Heq5 and I'm happy with that (although ultimately wish for top tier mount - that shows how important the mount is). I would not recommend this combination for someone starting the AP because of focal length / resolution involved. Short tube scopes with folded design tend to have long focal lengths, or "large zoom" - this means that you need good guiding and good skies and go for smaller targets with such setup.

Focal length should be also matched with camera and pixel size.

6" F/5 scope is light enough, has decent light grasp, focal length of 750mm - that should give you good sampling rate with most DSLRs (no worries about oversampling, and guiding will be adequate). I don't think that 130PDS is bad idea, so you might consider it also - it is fine scope with a bit shorter focal length, less weight so in all should fare better in many aspects of use on HEQ5. It just comes down to preferred target selection - here you might want to have a play with tools designed to show FOV and select between two scopes based on that (or budget, since you will need stuff - like Coma Corrector, adapters, etc ...).

You can check FOV of scope / camera combination here:

https://astronomy.tools/calculators/field_of_view/

(choose imaging mode, select target, scope and camera - you can do comparison by adding multiple choices to display). One thing to remember is that it's far easier to produce wider image with scope that has narrow FOV than it is other way around. If you have wider FOV than you need - you can crop it but resolution stays the same (you will get smaller image with good framing but no resolution increase). If you have narrow FOV and you want to increase it - you can always do Mosaics - multiple shots of different sections that you merge into one image. A bit more involved in processing (you need to stitch your mosaic and do multiple processing for each tile) but you keep original high resolution, get larger image (that you can scale down if you want to) and get wider fov this way.

You will need coma corrector as well - and there is also selection of those, so you need to be wise in your choices. Unfortunately, I don't have enough knowledge nor experience to recommend one model over others. If I were to choose coma corrector for myself, I would need to spend some time researching on the internet (reading reviews, optical performance and such).

Hope this helps

[alacant]

Hi. How about getting the mount - the heaviest you can afford- and using your existing camera mounted on it? Or are perhaps your projected targets beyond what it could capture? You can always add a telescope later.

HTH

[david_taurus83]

The 200 will need an EQ6-R or AZEQ6 at a minimum imo. Can be done with an HEQ5 but more suited to a bigger mount. FYI my 200p with all the attachments for AP weighs in at over 12kg.

[stuplu82]

Thanks for the replies, especially the in-depth one from vlaiv. Is the coma corrector absolutely essential for the PDS? I have read other posts saying that they can observe and photograph without it.

I will take all advice on board and I will definitely stretch to the HEQ5. Its deciding upon whether I go for the 130, 150 or 200. I think the 200 will  be too heavy for the mount and to transport around. Edging towards the 150mm I think.

  

[vlaiv]

17 minutes ago, stuplu82 said:

Thanks for the replies, especially the in-depth one from vlaiv. Is the coma corrector absolutely essential for the PDS? I have read other posts saying that they can observe and photograph without it.

I will take all advice on board and I will definitely stretch to the HEQ5. Its deciding upon whether I go for the 130, 150 or 200. I think the 200 will  be too heavy for the mount and to transport around. Edging towards the 150mm I think.

  

CC is needed for newtonian under some circumstances.

For visual I would say that about F/5 is "break point" - so scopes of F/5 and below need it (actually one might say that F/5 benefits from it, while lower needs it) , while scopes F/6 and longer are fine without it. I have F/6 newtonian (8" dob) and I never had any issues with coma. Coma depends on distance from optical axis (it also depends on speed of the scope) - so you need low power wide field eyepiece to get into coma affected zone - but low power eyepiece has low magnification so you can't see coma if it is small like in slow instrument.

With imaging it's again about the speed and about the sensor used. Larger sensor will cover more field and further away from optical axis - worse the coma. So if you are using slow newtonian and very small sensor - you don't need CC. If you use small sensor and medium speed scope, or larger sensor on slow scope - you will spot coma but it's up to you to decide how much of it you can tolerate.

With fast scope and large sensor - it will be painfully obvious and you will need to crop your shots considerably to remove offensive corner stars.

Also note that not all CCs are equal. Some models introduce aberrations like spherical while correcting coma (faster the scope - worse the aberration) - this makes stars in center of the field "soft" - or worse looking than without CC. Edge stars get improved though with all CC (otherwise it would not work its thing and we would not call it coma corrector )

 

[FaDG]

Been there, seen that! 

I'd vote for HEQ5 + SW150pds. 

That's exactly my setup, and i bought the HEQ5 used from a guy that had a lot of trouble with it using a SW 200 newt. It has never, ever given me the least issue, guides under 1arcsec in nights of good seeing. 

So I agree with comments above: mount first and choose Scope accordingly. 

Definitely +1 for Rowan belt mod, it's a major step towards accuracy. 

You'll also look into guiding, so besides ota and camera your mount needs to handle also guidescope and guidecamera: not enough backfocus for off-axis guider.

And, yes, a coma corrector is in order with an APS-C sized sensor, so all in all buy used to stay in your budget. 

But you'll be pleased with the setup. 

Fabio

[dannybgoode]

The 150pds is a really nice scope I have the 150P 750mm focal length one and have just starting imaging with it.

I think the 150 is often overlooked as well. People either go 130 as it’s a very good starter scope without realising that the 150 is just as accessible and not much bigger but with way more light gathering. Or, they get aperture envy and go 200 which for visual often makes sense but a 200 tube is a lot bigger and heavier. 

The 150 is a Goldilocks tune - just right . Don’t discount the 150P 750mm (though not the 1200mm version) if you can find a good one secondhand as I only paid around £75 for mine and it’s given me so much. Easy on the mount and easy to manhandle around. 

As above - concentrate on the mount first. Spend as much as you possibly can on one - no point having a nice scope if it’s on a poor base. 

[FaDG]

Aha, forgot to mention:  while it's True that the 150 (f/5 also in my case) packs a lot of punch for the low money, you must take into account that it might have some assembly and quality check issues. 

You can find more detail (and also a M42 image from Rome, Bortle 9!) in my presentation thread, here:

I'm not saying it WILL happen, but it could... So if buying used try to test it, just to be on the safe side. THEN, had I tested this scope before purchase I wouldn't have bought it, yet after sorting out the mess it IS an excellent sample! 

[stuplu82]

Thanks for all of your comments. I will indeed purchase a cc for the 150PDS, which seems to be what im heading towards. The guidescope i will purchase used, so any advice on that would be great. 

[FaDG]

For the guidescope there are basically three options:

1) a dedicate guidescope as The AltairAstro 60 f3.8 or the tecnosky equivalent: small and extremely bright. I own one of these and it's great for the 150pds.

2) a widefield refractor, Like an 80/400 or a 70/500. These are available from several manufacturers and, while bulkier, can also be used as grab&go fracs

3) an adapted 50mm finder, where a guidecam can be fitted. Light, small but with shorter focal length and a bit lower grasp due to smaller aperture vs. the 60mm. 

1) and 2) need dedicated rings to be fitted on the ota. 

Personally i have 1) which i use with the newt and 3) for the 72ED on the Star Adventurer, both used with an ASI120MM. 

Fabio

[dannybgoode]

I bought an Altair Astro 60mm guidescope - the v2 with the locking focuser and an Altair Astro AR0130 v2 mono camera. 

The guidescope in particular is very nice. Very well made and the included mounting rings are solidly made. 

Got it all set up tonight and it picks out plenty of stars and seems to talk nicely to PHD. 

Not the cheapest solution but should be perfectly fine for most guiding tasks I am ever likely to need. 

[stuplu82]

Whats your thoughts on the Altair Astro AR0130 v2? do you use it for guiding only?

Whats the general feeling on DSLR photography nowadays? It was always the 'in' thing about 10 years ago, but technology has come such a long way since I was last into it. 

[vlaiv]

32 minutes ago, stuplu82 said:

Whats the general feeling on DSLR photography nowadays? It was always the 'in' thing about 10 years ago, but technology has come such a long way since I was last into it. 

My view on this is that it's a matter of personal preference / budget.

DSLR (even modded one) can be used for daytime photography, and can also be used for astro photography, so it's something that you might use based on that criteria. There is also budget criteria, as most DSLRs (entry/mid level) are cheaper than dedicated astro cameras - but with introduction of new CMOS based astro cameras, this gap is closing fast.

If you can afford it - to me it's no brainer, dedicated cooled astro camera is the way to go. It makes things so much easier, but it does involve a bit different approach - using power source for cooling, using lap top / computer in the field - but it allows for precise calibration and noise levels (with new CMOS sensors) can't compare. Some of these CMOS cameras are in fact same sensors used in DSLR cameras, but with cooling and no "fancy" user-land optimizations - you get raw unaltered data out of them - which is good thing for processing in AP.

[bottletopburly]

A qhy mini guide scope small light and f4.8 I think £120 from modern astronomy  ?

https://www.modernastronomy.com/shop/accessories/qhy-accessories/qhy-miniguidescope-kit/

[dannybgoode]

6 hours ago, stuplu82 said:

Whats your thoughts on the Altair Astro AR0130 v2? do you use it for guiding only?

Whats the general feeling on DSLR photography nowadays? It was always the 'in' thing about 10 years ago, but technology has come such a long way since I was last into it. 

Using it purely as a guidecam. It’s a nice piece of kit. Seems very sensitive and very easy to use. Also comes with a years subscription to SharpCap Pro   

 

[Uranium235]

Personally, I'd go with the 130pds every time, it will be much easier on your guiding and gives you a much more compact setup.

The 200pds imo is too much of a handfull, and takes some tweaking to get if in the right place with a larger sensor. Plus it's quite restrictive in terms of what you can image.

The 150... hmmm it's fl is just a little too long for me. The 130 is 650mm, which is a good spot.

Oh, and in regard to guiding. The 50mm finderguider is the most cost effective. Plus it never fails to find a star.

[vlaiv]

1 minute ago, Uranium235 said:

Personally, I'd go with the 130pds every time, it will be much easier on your guiding and gives you a much more compact setup.

The 200pds imo is too much of a handfull, and takes some tweaking to get if in the right place with a larger sensor. Plus it's quite restrictive in terms of what you can image.

The 150... hmmm it's fl is just a little too long for me. The 130 is 650mm, which is a good spot.

How about 6" F/4 with good CC then? Best of both worlds - 600mm FL and aperture of larger scope

 

[Uranium235]

Lol... isn't f4 asking for trouble? How often do you see perfect corners on a sub f5 newt? ?

Maybe it would suit an experienced Imager,  but probably not someone just starting out.

[dannybgoode]

4 hours ago, Uranium235 said:

Personally, I'd go with the 130pds every time, it will be much easier on your guiding and gives you a much more compact setup.

The 200pds imo is too much of a handfull, and takes some tweaking to get if in the right place with a larger sensor. Plus it's quite restrictive in terms of what you can image.

The 150... hmmm it's fl is just a little too long for me. The 130 is 650mm, which is a good spot.

Oh, and in regard to guiding. The 50mm finderguider is the most cost effective. Plus it never fails to find a star.

The 150PDS is only 700mm fl and so much more light gathering than the 130. Would take the extra light over the slightly narrower fib any day

[FaDG]

The 150  is 750 fl and with my 0,95x coma corrector becomes 712 mm, which for me is just right, with perfect stars to the corners. Also, should you use it for moon or planets (you can find a jupiter image in the thread i linked above) the extra 100mm fl come in handy, and I rather found it too short than too long. Actually, I stopped using my ED80 @600mm fl finding the little additional zoom very pleasant (not to mention the difference in light collection power! ) 

Just my Experience, but the HEQ5 does not have any weight  nor balancing issue (i only use one 5,5kg counterweight + another 1.5 kg one), and never had trouble guiding with the 60/224 nor the 50mm finderscope. 

One more point to be taken into account, but please correct me as i'm just speculating here: I think that the secondary mirror size is driven by the sensor vignetting, so I could imagine that the 130 and the 150 share the same one. IF this is the case, couldn't the 150 have a lower obstruction? Or conversely, IF it's not so, could it have lower vignetting? 

@Uranium235, while we have different opinions, I'm fully open to discussion and to  learning: I'm not trying to convince the OP that this is THE BEST setup, just stating that I found it cheap and proficient, and at the moment I can't find a benefit in the 130 other than the marginally lower cost. True enough, I also have a small and light 72/400 Apo for portable, widefield imaging, so I use that as a complement. 

Fabio

[Adam J]

15 hours ago, Uranium235 said:

Lol... isn't f4 asking for trouble? How often do you see perfect corners on a sub f5 newt? ?

Maybe it would suit an experienced Imager,  but probably not someone just starting out.

Yes I agree F4 is asking for trouble....at least if you want nice stars. I expend significant effort on getting good stars but even then every time I change something like rotating the camera its like rolling a dice and sometimes I get a good result sometimes I get a less than perfect result and thats with a perniment setup in an observatory. I am sure that many of the issues would be solved by a Moonlight focuser on my 130PDS but that misses the point of a £170 scope. I think that F4 is left to people who get more enjoyment with tinkering with their equipment than they do form imaging in itself. 

My advice for a beginner in respect to F4 Newtonian is just don't go there until you have at least appreciated the difficulties at F5.  

Adam

[Adam J]

4 hours ago, FaDG said:

The 150  is 750 fl and with my 0,95x coma corrector becomes 712 mm, which for me is just right, with perfect stars to the corners. Also, should you use it for moon or planets (you can find a jupiter image in the thread i linked above) the extra 100mm fl come in handy, and I rather found it too short than too long. Actually, I stopped using my ED80 @600mm fl finding the little additional zoom very pleasant (not to mention the difference in light collection power! ) 

Just my Experience, but the HEQ5 does not have any weight  nor balancing issue (i only use one 5,5kg counterweight + another 1.5 kg one), and never had trouble guiding with the 60/224 nor the 50mm finderscope. 

One more point to be taken into account, but please correct me as i'm just speculating here: I think that the secondary mirror size is driven by the sensor vignetting, so I could imagine that the 130 and the 150 share the same one. IF this is the case, couldn't the 150 have a lower obstruction? Or conversely, IF it's not so, could it have lower vignetting? 

@Uranium235, while we have different opinions, I'm fully open to discussion and to  learning: I'm not trying to convince the OP that this is THE BEST setup, just stating that I found it cheap and proficient, and at the moment I can't find a benefit in the 130 other than the marginally lower cost. True enough, I also have a small and light 72/400 Apo for portable, widefield imaging, so I use that as a complement. 

Fabio

No the 150 has a slightly larger secondary. 

[stuplu82]

There seems to be a fair split on the 130/150 PDS opinons on here. 

I have a 130 Konus which is no use for AP, as its a 1000mm F/8 and it is on a basic EQ2 mount. I will buy the HEQ5 and decide on the OTA later. I guess there isnt going to be too much of a difference visually between the 130 and 150, but the extra light gathering capability is obviously a perk. For an extra £50 I will likely just go for the the 150 and at 750mm, its should be okay for AP. Ideally i would have gone for the 200PDS, but the extra weight would mean a EQ6 which is an extra cost and at 1000mm it prob wont suit a beginner AP like myself.