Question on 200p Dobsonian

[Mr Green]

I originally sent this too Steve @ Flo but had no response! Hope you guys can help!

I recently purchased the Sky Watcher 200p Dobsonian and I am already thinking of getting a couple of bits to make better use of the scope.

I have found a few DSO’s and these still seemed pretty far away and so want to be able to get a closer look! I do not want to spend too much money and so am thinking of getting the 2x Barlow lense that costs £29 on website. Will magnifying these objects twice over with a Barlow make much of a difference or should I purchase a 5mm lense instead?

I am also contemplating on buying the Skywatcher OIII Filter but want to know if this will make much of a difference in picking up color as I have noticed gray area’s in M36, 38, 42 etc that I assume will be red, green, blue etc with this filter. Also wanted to know what size I need to go for! 1.25mm or 2mm!

Apologies for waffling on but in a nutshell I just want to be able to look at objects in the sky with better magnification and pick up colours to make them look more interesting in the best possible way without spending more than £100.

[russ]

I use a 200P and for the majority of deepsky objects i find an eyepiece in the 12mm-18mm range does a great job. Some objects like a bit more magnification, such as double stars and perhaps the globular clusters (although i find the 12mm @ 100x perfect for these). Maybe worth picking up a good quality workhorse eyepiece in this focal range. The new Paradigm eyepieces are a terrific eyepiece for this work and cost a lot less than the usual suspects (Meade 5000 Plossl, Hyperion).

Just bought an OIII filter myself which i'm looking forward to using. I did have a broadband filter (Orion Ultrablock) before and that did a wonderful job enhancing certain objects (M42, M76, M97, M27 and M57 all responded extremely well to the Ultrablock). Worth noting that you'll never see colour in these deepsky objects. The filters brighten/enhance the view. The OIII will only enhance the views of emission nebulae and most planetary nebulae. I'm hoping the OIII will give me my first glimpse of the Veil Nebula in Cygnus.

Russ

[acey]

A filter won't show colour. You use it to improve contrast on nebulae (e.g. M42) - not galaxies or clusters (eg M36,38) which will only look fainter. To see red in DSOs you need large aperture (20 inches plus) - and a dark sky.

Whether you get 1.25 inch or 2-inch depends on what sort of eyepiece you're going to screw it onto.

Higher magnification makes some DSOs disappear completely, others will show more detail. It will help with clusters.

A Barlow will make things bigger but also possibly fainter or less detailed. Works on some things and not others.

A 5mm Plossl will have a very small lens and will not be particularly comfortable to use. Wide-angle types will be better.

As your scope purchase is recent, I'd suggest waiting a bit and getting more experience with what you've got, before spending more money on glass that might not show you much difference at this stage.

[pvaz]

The eye can't capture the colours as the CCD can. The CCD does long exposures and captures light bands not visible to the human eye. If you go to a dark parking lot at night, you can make out the shape of the cars but it will be hard to make out the colours.

Extra magnification dimmes the objects and may make colour even harder to see. However it does darken the background sky and improves contrast which sometimes helps seeing structure.

I have an OIII filter. It blocks everything except some light bands emitted by some nebula. In other words what it does is suppress all other colours except for a very narrow band. This allows you to see the texture and structure on some targets. It haves a dramatic effect on the veil nebula, for example, but it actually does the opposite of what you want regarding colour. Everything gets a slight green hue caused by the filter, even the stars.

Besides many pictures you see, such as most from the Hubble are originally black and white and they are not intended to actually show the real colours. They use a filter to capture the light emitted by certain types of atoms then they combine this images and give a colour to each type of atom. They are intent to be used as graphics displaying the composition of the photographed object not a real image of what you would see.

[Mr Green]

Thank you for the replies!

Going on what you have all said! Would it benefit me buying a decent 12mm eye piece for example to buying a barlow lense and OIII filter?

I would really like to be able to see more detail in DSO's and so need guidance with what to buy!

I also want to be able to see planets in more detail and so a barlow lense seems to make sense for observing the moon and mars for example! Please corect me if I am totally wrong!

[russ]

A decent 12mm-15mm eyepiece with a 2x barlow is a very good idea. It gives a good medium power (80-100x) eyepiece for DSO's and lunar viewing. But with the barlow gives a spot on magnification (160-200x) for planetary views with your scope. My two most used eyepieces are a 12mm and 18mm Paradigm plus a Celestron Ultima 2x barlow.

Regards

Russ

[Mr Green]

I see that the celestron barlow is quite pricey compared to the skywatcher version. Does it really justify costing 3 times the amount?

I was really hoping that I could spend around £100 max.

What is more important? I am very tempted to get the sky watcher barlow that costs £30 and then spend the rest on a decent eye piece. What eye pieces are recommended within my budget?

[John]

I see that the celestron barlow is quite pricey compared to the skywatcher version. Does it really justify costing 3 times the amount?

I was really hoping that I could spend around £100 max.

What is more important? I am very tempted to get the sky watcher barlow that costs £30 and then spend the rest on a decent eye piece. What eye pieces are recommended within my budget?

If you don't wan't to spend that much you could go for a TAL 2x barlow (£35) which is regarded as the best performing "budget" barlow. If you think about it - at high powers any optical compromises will be emphasised even more - a low quality barlow in between a good scope and a decent eyepiece brings the performance of the whole system down a few notches.

With a very few exceptions (the TAL barlow is one of them) you do get what you pay for with astro optical products.

[Astro_Baby]

Whats the budget for EPs - Personally I would skip the OIII filter. I have an OIII and a UHC and while they are ok as a nice to have I wouldnt place a premium on them.

In a scope 12" or larger they may well work better in an 8" like mine I'd rate them as a luxury and put more money into EPs.

I'd also argue against a Barlow - mine is almost never used and only used at all against planets.

Depends on how much you want to spend on EPs - The Baader Hyperion 13mm is rather nice, I like mine.

I'd also counsel patience and not rushing in to eyepiece purchases until yo have had some time with the scope.

[Mr Green]

I think that I am one of those awkward people that wants everything!

I am happy to spend £100 on an eye piece and might go for the sky watcher barlow as it's only £30 and could invest on a better one in the future!

I really do want to get closer and better views of the moon and also enlarge mars quite considerably!

In terms of dso's, I am quite confused! M42 for example seemed to be small in appearance with the 10mm ep included with the scope! Wouldn't a 12mm for example make it look even smaller?

I think if it came down to it! dso's will keep me interested long term and so would appreciate knowing what size lense to go for and the baader hyperion would be a definite maybe! Just need clarification that less magnification than 10mm would be best when I struggled to see objects at 10mm (seemed far away).

[russ]

I agree with Astrobaby regards the OIII. That can be left until a rainy day when you have money burning a hole.

The Hyperion is nice a eyepiece and a good secondhand proposition but i don't think the Hyperion represents good value anymore. £108 is way too close to the Skywatcher Nirvana, which is far superior. And the new paradigm are every bit as good as the Hyperion but for a third of the price.

I also think a good barlow is an asset. Mine gets plenty of use, every single night i'm out. And there's very little to choose between the view from my 6mm Ortho and the barlowed Paradigm. Except the barlow/Paradigm is far nicer to use.

[pvaz]

I think that I am one of those awkward people that wants everything!

I am happy to spend £100 on an eye piece and might go for the sky watcher barlow as it's only £30 and could invest on a better one in the future!

I really do want to get closer and better views of the moon and also enlarge mars quite considerably!

In terms of dso's, I am quite confused! M42 for example seemed to be small in appearance with the 10mm ep included with the scope! Wouldn't a 12mm for example make it look even smaller?

I think if it came down to it! dso's will keep me interested long term and so would appreciate knowing what size lense to go for and the baader hyperion would be a definite maybe! Just need clarification that less magnification than 10mm would be best when I struggled to see objects at 10mm (seemed far away).

The thing is it's huge about 4x the size of a full moon. The reason why you see it small, is because the brighter area is small. The rest of it gets fainter and fainter. To see the most of it you need darker skies, more aperture and a filter may help.

Do get the high mag, it will be useful for planets, but you'll find out with experience that for DSOs it's almost always the low mags EPs that will give you the best view. M42 is nice to see with any mag. Either low to see the hole thing, or high to split stars in the trapezium and see nebula structure in the central region. Most people end up using 2 EPs for DSOs: a very wide field (around 30mm) a medium (around 15mm) and not very often a high mag (10mm or so) is used for specific targets, such as globular clusters.

You just need to have realistic expectations, you won't see color in any DSO with maybe 1 or 2 exceptions. Unfortunately thats a common misconception caused by bad publicity.

The colour in the pictures is revealed over several hours of exposure and software processing. It's usual to remove filters from the camera so it will capture bands of light invisible to the human eye.

The ones using the hubble palette have "false" colour. See this famous example, known as "Pillars of Creation", and read the description (last paragraph).

[oceanheadted]

I bought at a skywatcher UHC filter, but it doesn't get too many outings. Ditto for a Tal 2x barlow. I find barlows degrade the image compared to a straight eyepiece.

I constantly use my Meade 4000 32mm plossl, which you can pick up for 20-30 pounds second hand. I found a red dot finder (I bought a baader skysurfer III, but a telrad might be a good option) was a huge boon as I didn't get on too well with finderscopes.

There's no substitue for practice though. The more you look the more you see.

[John]

In terms of dso's, I am quite confused! M42 for example seemed to be small in appearance with the 10mm ep included with the scope! Wouldn't a 12mm for example make it look even smaller?

When I first started out I was observing M42 at medium power like you were and I too was not very impressed. The breakthough came when I observed it at much lower power on a dark night - I then realised that I'd only be seeing a small portion of the nebula !.

The scale of these objects in the eyepiece is not clear from photos we see. Some, like M57, the famous Ring Nebula, are very small and really benefit from magnification others (eg: M31 - the Andromeda Galaxy) are so big you can't fit them in the field of your lowest power eyepiece.

Drawings are better in this respect as they give you a better clue as to what the object is actually going to look like.

[Mr Green]

I think that I am almost there!

I will invest the money in a decent ep and then get a half decent barlow in the near future!

What mm ep would be the best choice for a mix of dso's and planets with the barlow lense then coming in?

As I said, around the £100 mark is realistic for me!

Thanks all!

[John]

I have 2 scopes with the same focal length as your 200P dobsonian - 1200mm. I find a 13mm eyepiece a very useful "workhorse" - 92x on it's own and 218x when you get your barlow (assuming it's a 2x one).

[pvaz]

Yeah 13mm on a 1200mm scope is definitely a great combination. 92x is a good mid level mag for DSOs and good initial mag for planets. If you double it you get enough mag to see some features in Mars and more then enough for Jupiter/Saturn/Moon.

[russ]

Knowing what eyepiece to use is a lot like Golf and knowing what club to use for each shot. Choose the wrong club and you'll get somewhere but nothing like you were expecting. But with experience you will learn to choose the right club.

Same with eyepieces. Some objects (M42, M45, M31, Double Cluster) require a big field and a nice low power (26mm-32mm 2") eyepiece to do them justice. While other objects (planetary nebula, Globular clusters, double stars) require a good medium power (12mm-18mm) to do them justice. With experience you'll know what object requires which eyepiece.

Everyone is different and go about this hobby in a different way. You will find your feet and know what works best for you soon enough. I only suggested a 12-13mm as i find this a good workhorse size for the majority of objects i look at. I also have a 32mm 2" 70deg eyepiece that i use for low power widefield vistas. For M42, i find an 18mm 60deg eyepiece frames it beautifully and it looks a knockout in the dob.

The beauty of the barlow is you can have a decent one, like the Tal that John suggested, for a reasonable price and turn your good medium power eyepiece into a reasonable planetary eyepiece.

Russ

[Mr Green]

Thanks to Russ I have the ep dilema sorted and now want to confirm one thing on the barlow lense!

Should I go for the Tal Barlow or Skywatcher deluxe that is £5 cheaper? I am not prepared on spending more than £50 on a barlow at this moment in time and these are both within range!

[Astro_Baby]

Russ - your right about the Hyperions/Nirvanas - I tend to think of Hyperions as still being £70 which was a bargain at the time. At over a ton for a Hyperion your right - the Nirvanas would be better. I got my Hyperions when they were still cheap(ish)

[Mr Green]

Thanks to Russ I have the ep dilema sorted and now want to confirm one thing on the barlow lense!

Should I go for the Tal Barlow or Skywatcher deluxe that is £5 cheaper? I am not prepared on spending more than £50 on a barlow at this moment in time and these are both within range!

Can anyone give an opinion on this question?

[russ]

Russ - your right about the Hyperions/Nirvanas - I tend to think of Hyperions as still being £70 which was a bargain at the time. At over a ton for a Hyperion your right - the Nirvanas would be better. I got my Hyperions when they were still cheap(ish)

Me too, i bought them when they were £69 and they were a stonking deal at the time, in a league of their own. Even when they jumped too £108 it wasn't too bad at the time because there was no real competition except for the Meade 5000 Plossl. But things change and the Hyperion looks a little overpriced now (but still a good eyepiece). And still a good buy secondhand providing the seller isn't too ambitious. My fav Hyperion was the 17mm but i believe the 13mm is considered best by most. My 24mm was a real duffer strangely.

Can anyone give an opinion on this question?

Personally i'd go for the TAL 2x at that price. Although i was pleasently surprised how well the Skywatcher Deluxe worked. But still the TAL 2x.

Regards

Russ

[Astro_Baby]

The 13mm is amazingly good I find whereas the 5mm I dont like too much. It might be my eyeballs that cause the problems with it because other people who have had a look with it say its fine.

The 13mm is sweet though. I have heard the wider angle ones can be a bit 'off' - no idea whay that should be. I paid about £70 for both of mine new before the monster price hike.

[russ]

I never had the 5mm but i found the 8mm wasn't as good as i hoped, certainly not a match for the 13mm or 17mm. Another oddity was my 21mm...it was good but i see a lot of comments saying it's the runt of the littler. Where as i would have gone for the 24mm as the runt of the litter. I think it must come down to QC issues and getting a Friday afternoon job.

Regards

Russ

[Mr Green]

Hi Everyone!

Thanks to everyone for giving there advice and displaying patience with me!

I have purchased a 12mm paradigm ep and also a 5mm Celestron X-cel ep instead of a 2x barlow that I think is a good choice!

I will probably invest in a decent lower mag ep in the near future but hope that the above will get me going with planetary and dso observation!

Thanks again,

Jon