Need advice with new scope! :s

[milkyjoe]

I've recently purchased a Sky-Watcher Startravel 102 telescope from FLO, which I am very happy with, but I am a little concerned that I cannot seem to find any dso's to look at!!

Tonight the skies were clear where I live so I relished at the opportunity to do some viewing. I managed to align the scope to polaris using my latitude and mount controls, then I located m31 in andromeda using the free stellarium software on my laptop and adjusted the scope to match the co-ordinates. I looked into the supplied 25mm ep using a tal 2x barlow, but all I could see was a very faint smudge (I'm positive I was looking at the correct object). I also tried a new 10mm super plossl, but the view was even worse; I attempted to locate m51 to do a comparison but gave up in the end as I couldn't find it, should it of been below alkaid in ursa major??

I am doing something wrong as I was under the impression this scope is capable of 'seeing' dso's or could I have duff eps/diagonal/barlow or is it because I only have a 4" fefractor?? Will I ever be able to view any dso's clearly?

I did manage some more very good views of Jupier, but I could barely make out any detail (would a filter help?).

Any advice/tips would be most welcome.

Richard.

[brantuk]

Nothing wrong there Richard - to see it any clearer you need more aperture - even then it's still a smudge - 12" and above you may begin to see some faint structure.

To make it look good in larger a scope I use a 40mm Wide ange ep (currently a WO Swan) and averted vision helps too. To see it like the pictures posted in the forum requires long exposure photography.

[drewedgar]

Hi Richard, I think you may struggle seeing most dso's with a refactor. The smudge you saw was most likely Andromeda. You should get some clusters though.

Ive never used a sw startravel so i may be very wrong.

Drew

[Rui]

Hi Richard.

First thing you must do is: When you look thru any scope, forget all those nice color puctures of nebulae and galaxies. Not even the Hubble Telescope would show it visually.

Second: Adjust your expectations. While your scope will show you fantastic detail in the Moon, nice detail in Jupiter, the globe and the Cassini Division on Saturn (once the rings open a bit more, next year), all galaxies, nebulae and globular clusters will look rather faint and fuzzy. Even a lot of star clusters will be dim, especially if you observe from suburban skies, as it is most usual nowadays.

But sometimes the real treat is to find that particular object, and to realize that we can actually look at it from such an enormous distance and to understand what we are looking at.

don't give up. Keep reading astronomy stuff and keep using your scope. The more you use it, the more you can see. In fact, a trained eye is able to see more than a begginer can imagine.

Clear skies.

Rui

[Capricorn]

The 102 isn't big but will show some DSO's.

Is the scope pointed towards the DSO or at the DSO. They are not big and you have to get the things in the field of view. Therefore is the scope and finder aligned accurately?

Light pollution. How much? M51 is mag 8, if you are in mag 6 skies then it is invisible.

If you try to magnify then the image gets DIM. DSO's are called "faint fuzzies". Now this may surprise you but thay are FAINT and FUZZY. As in not very bright and generally not well defined. If you go from 25x to 50x then it gets 4x dimmer, as it was dim to start with you may not see anything.

Many of the Messier DSO's are clusters, the Pleaides are visible by eye and with 8x42 binoculars you can see others. So the 102 should be OK on clusters.

Get a list of Messier objects and do a sort by magnitude, then start on the brightest. Alternatively visit:

The Astronomical League

OR

Royal Astrononomical Society of Canada - Observing | Certificates

The astroleague site has several sections, you just have to find them, locate and download the simple Messier observation list and start there. The RASC site has a more general observation list but worthwhile looking at..

M31 is a faint smudge, it is a faint smudge through a 10 inch. None have colour, just grey, lots of grey. M31 is big, too big to be seen in the 102 in one go.

Not sure of the separation (~4 deg) between Alkaid and M51 but from what I can see I suspect that it is outside your view if you centred on Alkaid. The plossel will have ~50 deg and the mag would have been ~50 with the 10mm so field of view = 1 deg.

You chose a fast scope and fast scopes need better eyepieces. Although some say otherwise the majority say the above.

DSO's do not need fast scopes they need aperture, that faint smudge is brighter if you collect 4 times as much light, even brighter if you collect 8x as much. Fast is a photographic term for the image on a film/sensor without an eyepiece in the path.

Think you said that you had decided against a goto so you could find the things yourself. Now you have to find them.

When you swap lens do you refocus? The eyepieces are NOT parfocal so when swapped the image will need to be refocussed again. Something faint and out of focus is invisible. And if there isn't a star in view you don't realise you are out of focus.

Where are you?

A club may be a good option.

[milkyjoe]

Hi guys, many thanks for your comments.

So exposure is the key to getting brighter views, but is only obtainable with astrophotoraphy - I am thinking of buying a webcam as a starting point and seen a Philips SPC900NC on ebay. Is this a good starting point or will I need a GOTO system or motor drive system?

I understand I was not going to see dso's such as nebula, galaxies etc. in fantastic detail, but I was under the impression I might be able to see something! Why do people look at these objects if they can't be seen??

My scope is aligned properly as I far as I know, but one thing I need to do is reset the RA dial because I think I've moved it! I was using the stellarium software last night, looking at co-ordinates of m31 and m51, but I couldn't get the co-ords to match my scope?? I found m31 manually using the constellations and by eye. It's a bit confusing all this RA and DEC business isn't it!? lol

There is quite a lot of light pollution where I live unfortunately and I suppose that won't help much, will it? What about using a light pollution filter? What about using filters for galaxies/nebula/planets... will they help to show any detail? Also, should I change my star diaganol as I've heard that my current SW sd only reflects about 90-95% of light into the ep, but these WO dialectric ones reflect 99%, more light=brighter images, yes?

I currently have 10mm and 25mm ep and 2x all of which were supplied with my scope. I purchased a tal barlow and a 7.5 and a 10mm super plossl ep. You recommend a good ep Capricorn - will that really make a difference to the quality of the objects I'm viewing as I don't want to spend 100's of pounds on new ones??

I've read The Warthogs article about eps, and he suggested an 8, 18, and 25mm eps for an f5 scope. Can anyone recommend any others, such as maybe a 30mm or 40mm for low power maybe a 6 or 12 for medium-high power; will a 3x barlow help viewing the planets or is a 2x good enough?

Thank you.

Richard.

[John]

With deep sky objects, especially galaxies and faint nebulae, you need both really dark skies and aperture to see them as any more than faint misty patches of light. There are a few exceptions, eg: M42 in Orion, but in the main you have to be satisfied with just detecting them with a smaller scope.

Buying expensive eyepieces won't make any difference to the amount of light your scope is gathering - that is determined by the diameter of the objective lens or mirror.

Dobsonian scopes are very popular for DSO's because you get a lot of aperture for your money - if you could get an 8" or 10" dobsonian and can observe under reasonably dark skies you will get much more satisfying views.

I'm not an imager myself however I believe that getting into deep sky imaging can be costly and exacting, although ultimately very rewarding judging by the results I've seen on SGL.

While seeing a faint fuzzy patch of light in a small scope may seem at first a little dissapointing, when you consider what you are actually looking at it takes on more fascination I find. Your scope can show all the Messier objects and many NGC's but it's not easy to be a DSO hunter with a 4" scope !.

[Capricorn]

A 5-10% percent increase in reflected light from a better diagonal isn't going to make any difference to what the eye detects. The eye doesn't operate on the same linear scale. A 100% increase in brightness doesn't appear to be twice as bright to the eye. So you will not tell a small increase of around 5%.

Forget RA/Dec, well forget it until you are very sure you know that it is all set up right and you know what you are doing. Did you take BST into account and your longitude?

Nebula: M8, M20, M16, M17, M27.

Galaxies: M33

Clusters G: M13, M22, M3, M5, M55,

Clusters O: M45, M7, M44, M6, M47, M25, M41, M35, M39, M48

They are the bright ones. Get a list/book. Stop relying on something telling you. What you see on a screen is not what you see in the sky, neither is what you read in a book the same. Screens and books are flat, the sky is curved.

If you try astrophotography then how will you image something that you find it, cannot see it and so don't know if you actually have it in the field of view.

Astrophotography: EQ6 mount with motors £600, decent APO triplet £1500, DSLR £600. Astrophotography is EXPENSIVE. It is also not easy, people can/will spend years getting it right.

Your comment about the scope being aligned is contradictory. It is aligned, but needing to reset the RA dial means it is not aligned and no co-ordinates matching with the scope means it is not set up.

Have you got/downloaded instructions on setting up an EQ mount?

Was the mount polar aligned with a polar scope?

What is your lat and long, are these set on the mount?

The 10mm that came with the scope is generally considered poor. Using a barlow rarely does anything other then make the viewing worse. It cannot ever make it better. Look at it as the quality of what you see is Good minus the sum of the errors of the components. No component has negative errors, so the more components in the path the worst it gets.

Please don't say that you are using the scope with the erecting prism in? If you are I will find you and shove the scope and prism where the sun don't shine.:eek:

The scope will/should work at ~100 magnification. But not a great deal more. It is a short focus achro. So a 5mm is as small as make sense. You need about 80x for Jupiter, but about 120x for Saturn. Both those are minimum magnification not a magnification to see much detail. Just a small image with some detail. Small = Small.

If you go for anything think about a 30mm for field of view and a 10 or 12mm for a bit of magnification, for more mag then 7mm should allow Jupiter to be seen at 70x. Problem is you are spending money and expecting great things. It won't happen.

You want an eyepiece(s) with decent contrast,

Start looking round and getting information, it is your money. But just because an eyepiece is advertised as planetry doesn't mean much. I have yet to work out what optics go into a planetry eyepiece that don't go into others. No matter what you look at you want sharp and contrating images whether it is a planet or a DSO.

[Space Cowboy]

Imaging Planets and the moon is not expensive. Motor drives for your mount and the webcam you mentioned is all you need. Imaging DSOs is an entirely different animal!

[brantuk]

The SPC900 will give reasonable results for planets. You'd need to get it modified for long exposure if you want to track or image dso's. You will need an EQ mount and RA motor at least in both cases in order to track objects and good polar alignment is essential to prevent star trailing.

That's the easy bit - now you'll have to learn about the software used to align, stack, and process hundreds of frames to get one decent picture.

If you're serious about AP then get "Every Photon Counts" - very good book, and "Turn Left at Orion" to help learn the sky. Stellarium is also good (and free to download).

Cheers

[milkyjoe]

A 5-10% percent increase in reflected light from a better diagonal isn't going to make any difference to what the eye detects. The eye doesn't operate on the same linear scale. A 100% increase in brightness doesn't appear to be twice as bright to the eye. So you will not tell a small increase of around 5%.

So you think I should keep my sw diagonal?

Forget RA/Dec, well forget it until you are very sure you know that it is all set up right and you know what you are doing. Did you take BST into account and your longitude?

No. My instruction manual suggests to polar align my scope using my latitude, which is approx 53m and setting this by unlocking the mount head where the scale runs from 0-90 degrees. Then it tells you to unlock the DEC lock knob and to rotate the telescope tube until the pointer reads 90 deg, then to loosen the azimuth lock knob and rotate the mount horizontally until the RA axis points to roughly to polaris. The manual suggests finding polaris by looking toward cassiopeia and away from the end of the handle of the big dipper, but the easiest way I think is to find merak and dubhe in ursa major and follow a line north-east and you will see polaris on the end of ursa minor.

Nebula: M8, M20, M16, M17, M27.

Galaxies: M33

Clusters G: M13, M22, M3, M5, M55,

Clusters O: M45, M7, M44, M6, M47, M25, M41, M35, M39, M48

They are the bright ones. Get a list/book. Stop relying on something telling you. What you see on a screen is not what you see in the sky, neither is what you read in a book the same. Screens and books are flat, the sky is curved.

I'm using Stellarium, which is very good and takes into account the date and time and where you live and calculates the position of the constellations in the sky. It also accounts for sterographic projection and curves the sky accordingly depending on where you're looking, so yes, my screen is curved!

If you try astrophotography then how will you image something that you find it, cannot see it and so don't know if you actually have it in the field of view.

Why so negative??

Astrophotography: EQ6 mount with motors £600, decent APO triplet £1500, DSLR £600. Astrophotography is EXPENSIVE. It is also not easy, people can/will spend years getting it right.

Yes, I agree. Astrophotography the proper way is very expensive, but there are other ways to capture images such as using a webcam and a computer.

Your comment about the scope being aligned is contradictory. It is aligned, but needing to reset the RA dial means it is not aligned and no co-ordinates matching with the scope means it is not set up.

What I meant was because I accidentally moved the RA axis dial, I am not sure where it is supposed to point in relation to indicator pin?! (remember, I am new to astronomy so I don't know what I'm doing fully, but I'm trying to learn).

Have you got/downloaded instructions on setting up an EQ mount?

Was the mount polar aligned with a polar scope?

What is your lat and long, are these set on the mount?

See above.

The 10mm that came with the scope is generally considered poor. Using a barlow rarely does anything other then make the viewing worse. It cannot ever make it better. Look at it as the quality of what you see is Good minus the sum of the errors of the components. No component has negative errors, so the more components in the path the worst it gets.

I've replaced it with a 10mm super plossl. What I was wondering was that would more expensive eps with more sophisticated lenses in be worth the money, and would they make any noticeable difference to my views?

Please don't say that you are using the scope with the erecting prism in? If you are I will find you and shove the scope and prism where the sun don't shine.

What is an 'erecting prism', the ota came with a lens and that's as much as I know!?

The scope will/should work at ~100 magnification. But not a great deal more. It is a short focus achro. So a 5mm is as small as make sense. You need about 80x for Jupiter, but about 120x for Saturn. Both those are minimum magnification not a magnification to see much detail. Just a small image with some detail. Small = Small.

OK. So I'll need a 12.5mm ep with my tal 2x barlow then to view jupiter properly, ccording to your specs.

If you go for anything think about a 30mm for field of view and a 10 or 12mm for a bit of magnification, for more mag then 7mm should allow Jupiter to be seen at 70x. Problem is you are spending money and expecting great things. It won't happen.

I bought a 7.5mm super plossl, but could do with a 30mm, and no, I'm not expecting great things, just would be nice to see a bit more detail, but filters might help me there, such as a contrast booster and/or a pollution filter and maybe a fringe killer.

You want an eyepiece(s) with decent contrast,

Do you have any in mind?

Start looking round and getting information, it is your money. But just because an eyepiece is advertised as planetry doesn't mean much. I have yet to work out what optics go into a planetry eyepiece that don't go into others. No matter what you look at you want sharp and contrating images whether it is a planet or a DSO.

Thanks.

Richard.

[John]

Hi Richard,

At the end of the day a 102mm is a small aperture scope for deep sky objects and no filters, expensive eyepiece or diagonal upgrade is going to change that.

My 10" scope does not show detail in many deep sky objects and I'm using eyepieces that cost £400 apiece new.

For nebulae you might see some benefits from using a UHC filter (eg: the Baader UHC-S) but they don't improve the views of galaxies - for that you need dark skies and / or larger aperture.

If you can get your scope to a dark sky site you might be surprised at the improvement - my 6" refractor, at a dark sky site, matched the views that my 10" gives from my moderately light polluted back garden.

There is also a viewing technique called averted vision which can help with faint objects - basically this means observing the object out of the corner of your eye, where the the eye is more sensitive to light.

[TheThing]

There seems to be a lot of negative comments here - not encouraging to a beginner!

A Barlow will makes views better! Otherwise why would they be sold/used?!? They have to be used in the right context though - lunar and planetary? Helpful. DSOs - perhaps not ALWAYS, but sometimes.

The 102 is small by modern standards, but in the past astronomer have used smaller. SPM often used and still uses a 3".

Get a copy of Turn Left at Orion for starters. Upgrade the 10mm for something a bit better and maybe add a Tal x2 Barlow. A light pollution filter might help as well. Seben do a good one fairly cheaply as do SW. (Seben make poor reflectors but good refractors, EPs and filters):

[Ogri]

You can get very enjoyable views from eyepieces that are not particularly expensive.

Unfortunately I don't get any benefit out of some of them, as the eye relief on shorter plossl's for example, rules them completely out for me.

Frankly, I'd be wary of a 30mm eyepiece in your 'scope. The 500mm fl means you would get a magnification of 16.6 x.

I don't think you would get good comfortable/enjoyable viewing contrast at that magnification to be honest, as I have a Meade 4000 32mm SP and in my ST120 (similar 'scope) at 600mm fl, it gives 18.75 x magnification and even with a Skywatcher Light Pollution Filter fitted (they help the contrast nicely, even if you have no LP), it's struggling.

While there is nothing wrong with that Meade 32mm SP, it just isn't a joy to use in my 'scope, and I'm worried you may have a similar disappointment with yours.

Ignoring my Baader Hyperions (which I get on well with), I have had tremendous viewing enjoyment with a very cheap eyepiece. One of those 1.25" 20mm erfle designs. There's a Skywatcher one at about £25 inc delivery around, and the 66 degree field of view means it's giving roughly the same view as the 32mm SP, but the contrast is far, far better, and the view is decidedly immersive (yes the edge of field resolution could be sharper, but the area I actually look at, is plenty good enough for me and my rubbish eyes).

This 20mm EP gives a magnification in my 'scope, of 30 x. I might be wrong (it wouldn't be the first time *grins*), but I think this area of magnification, with a reasonable field of view (around 65 - 70 deg putting it into the 'super wide angle' class), has a lot to recommend it as a general purpose all rounder eyepiece.

I think far too much is made of specific eyepieces of specific lengths, which all too often ignores the actual magnification they offer with particular 'scopes. For example, I would love a Skywatcher Panaview 32mm or 38mm at some point (or something remarkably similar), but it took a long time for it to dawn on me, that there's no point me getting such an EP, until I have a 'scope where it will offer around 25 x to 35 x magnification. For example, the 38mm would give me 15.79 x magnification in the ST120, but in a 1200mm fl dob, it would give 31.5 x magnification . . . . . . which is the sort of 'scope people have, that rave about the views these eyepieces offer.

Frankly, I'd be better off picking up dads £49.95 15 x 70 binoculars, than putting that £90 worth of 38mm glass into my diagonal . . . . . .

So what would give you a 25 x to 35 x 'ballpark' magnification for a heavily used eyepiece?

Well a 15mm EP would give you 33.33 x magnification, and an 18mm EP would give you 28.77 x magnification.

Personally, I wouldn't use anything longer than 20mm (for 25 x magnification) in your 'scope (obviously you might get on ok with a lower magnification, so it would be worth trying longer length EP's at some point as a 'loaner' from a friend or something).

Another factor is viewing conditions. My 8mm Hyperion gives 75 x magnification in the ST120. That is a very usable magnification when viewing conditions are reasonable.

The Orion Nebula, for instance, looked drop dead gorgeous at that magnification, and when conditions were really good, it Barlow'd to 150 x magnification with no problem at all, still giving a jaw dropping view. In those circumstances, I am confident my 'scope would have managed around 200 x magnification ok.

Bear in mind, viewing conditions can be so poor, that we think something horrible has gone wrong with the 'scope or the eyepieces! Even if things don't look particularly bad with the Mk 1 eyeball.

So don't be put off with comments such as 'It ain't going to be Hubble', as the views stand up for themselves all on their own, and it's really like saying nothing else Michelangelo ever did is worth looking at, other than the Sistine Chapel ceiling.

Plus if Television was even 20% of the quality today that it was in the days of black and white television, I for one would still own a set and be paying for a television licence . . . .

I might be biased, but to me the very best artistic photography, is done in black and white.

You have a very good and usable 'scope in the ST102, with its own particular set of caveats (every 'scope has its own unique issues, mine is about the same in this regard as yours, and I accepted these before I put down the money for the 'scope. I have not been disappointed), and if you work with it (for example, you can get a lot of extra mileage out of it by also using it as a spotting 'scope for terrestrial use - mine is gobsmackingly good at terrestrial with that 20mm 30 x mag EP in it), to its strengths, you should be able to get a lot of very satisfying results with it.

Best of luck with it, maybe take it to a local astro Society meet up, and see if you can ask to try different EP's in it so you can get something similar to suit you?

Hope that helps.

PS these people have the 66 degree wide angle EP's and also the BST Explorer EP's that are supposed to be very good (other than the 25mm I think, which isn't as nice as the shorter ones - others here should be able to comment on them as they have quite a following I believe - yet to try one myself though) http://www.skiesunlimited.co.uk/telescope%20eyepieces.html I think they are away until the end of the month or something though. They also usually do a variant of the Planetary Ep's at decent prices as well, which are also supposed to be good.

[ronin]

The only proviso to be aware of when it comes to field of view is that the field of view you get is not 50 deg or 68 deg or whatever.

The field of view you get is the eyepiece field of view divided by the magnifiction.

So if using a plossl, usually 50 deg, and a magnification of 30x then you have a field of view of 1.66 deg.

[ollypenrice]

You can see a great many DSOs in a 4 inch scope and M31 is much more than a faint smudge from a dark site. Also, ditch that darned computer when you are trying to observe. You need your eyes adapted. People talk about dimming the screen, using red acetate sheets over it and all that. Well, for imaging yes but for visual I recommend paper charts (SkyAtlas 2000 is the one, big and clear) and a red head torch. Failing that use a software planetarium to print paper charts for outside.

I took a similar scope (a 4 inch f5 TeleVue Genesis) to Spain before I moved to a dark site in France and found every Messier galaxy in the Virgo Cluster. From my present site I used the Genesis to show the entire Veil Nebula complex in a single go, using a 2 inch 35mm EP and O111 filter. Likewise it showed the whole Rosette in a 19mm EP with UHC filter. I can still see both those objects in the little 70mm Pronto which I bought when I sold the 4 inch so there is aperture to spare in your case. Now these are high end scopes but performance depends on aperture, in the main.

But, but, all this is from a dark site and that, I think, is where your problem lies.

I would also forget setting circles. I have never used them and prefer a reflex device to get in roughly the right place, then the finder, then a very wide angle EP to close in on the target. The best reflex, in my view, is the Telrad.

DS astrophotography is expensive but I would adjust two things on the post regarding what you need. An EQ5 pro will do fine, the EQ6 is needed for bigger scopes. And you don't need to spend £1500 on an apo. One of the most productive imaging scopes ever made was the humble ED80 and those go second hand for around £300. You can still find them new, I think.

What you need is a dark site and that will reveal all, you'll see. (Literally!)

Olly

[Ags]

Hi milkyjoe. I have a telescope with the same aperture but much longer focal length. I think Capricorn's list of DSOs is a good place to start. I have seen some of the objects on the list and they did look good. I would add M57 to the list of nebulae - it is small but relatively bright, and 'easy' to find as it is near Vega. It is also right overhead at the moment so it is at its best. Catch M13 before it slips any lower in the sky. Once you've found M13, use a high magnification on it - it helps bring out the faint stars.

The human eye can see down to 6th magnitude. A 100mm scope adds a further 6 magnitudes which is an enormous gain. Going up to a 10 inch / 250mm scope only adds another 2 magnitudes! You would need a 25 inch / 625mm scope to add a further 2 magnitudes on top of that. So aperture fever is a losing game...

I think your scope will excell at viewing star clusters and star fields because it has a wide field of view - getting a larger scope also means inevitably smaller fields of view so more aperture is not always an improvement. M33 will look better in your scope than mine because you will have a wider field of view to frame the galaxy, while it barely fits into my telescope's field of view.

One thing I will add is that I see more now than when I first started looking - your eye learns how to see.

And I forgot - don't try to view fuzzy objects on nights with a bright moon. It's an obvious point, but in my experience clear nights always seem to have a full moon, so it's tempting to have a go, but all you see are vague smudges confirming you are looking in the right direction... ;-)

[great_bear]

Most things have been covered by other comments, but Olly's is the central one:

USE A DARK SITE.

Instead of spending money on new gear at this stage, spend it on a weekend away somewhere really dark, when the weather predicts clear skies.

You can find a suitable place in the UK to go with the help of the light pollution simulator here: need-less light pollution

Remember you *must* observe in *total* darkness, and have been sitting in the dark for the best part of an hour in order to see lots of deep space objects. The moment your eyes are exposed to anything other than the faintest light, you've blown it (your eyes are shot) - and you have to sit in the dark for another hour.

[milkyjoe]

So, it was a full-moon last night and the skies clear again and there was hardly any cloud around, which was nice.

I managed to get a much better look at the moon this time (instead of through my bedroom window!) using my 7.5 and 10mm super plossls and my 25mm stock ep-it looked amazing, and even better with a moon filter! Unfortunately though, after a few mintues of viewing it nearly made me blind in one eye as it was a little too bright if I'm honest!!

I think things are slowly starting to sink in when I'm looking at the sky because I remembered the constellations ursa major (not difficult I know ) and cassiopeia and a few others-it's a start at least! lol

I took another look at the andromeda galaxy again and found it pretty quickly this time round. I tried looking using my peripheral vision instead of directly at it as suggested by another member, that did help quite a bit; I'm still trying to find m51 (the whirpool galaxy) but for the life of me, I cannot!? I scanned a whole section of sky beneath alkaid in ursa major using my 25mm ep, but couldn't find it anywhere... am I using the wrong ep or something?? It doesn't help that I keep having to remember my view is flipped horizontally either! Is there anything I can use to combat this?

One last question: why when I'm looking at the moon does the view through my left eye seem much brighter than using my right?? Could that have something to do with my 'basic' diagonal or are my eyes busted??

Clear skies.

Richard.

[great_bear]

Hi Richard,

In these nights currently, the full moon alone is enough to ruin your vision for seeing Deep Sky objects with your scope - so it's no surprise really that Andromeda is still faint for you. In a couple of weeks when the moon is out of view you will get much better results.

Unfortunately though, after a few mintues of viewing it nearly made me blind in one eye as it was a little too bright if I'm honest!!

One last question: why when I'm looking at the moon does the view through my left eye seem much brighter than using my right??

It's because of that thing you said about "nearly made me blind in one eye". You'll find that if you had been using your left eye to view for more than a few seconds, it would have been your right eye that gave you the brighter view.

Sounds like you could probably do with buying a stronger moon filter!

[SteveP]

Hi Richard

As others have said, a 4" scope is not the best for viewing DSO's. Also, the learning curve with astronomy can be quite steep and getting to grips with how your mount works can create some frustration.

At this stage, I'd be tempted to stick to a small number of brighter objects and use that time to learn more about your mount and your scope. On the basis that you can view M31, have a look at the Double Cluster in Perseus (they're stunning) and if you're out a little later in the night, also have a look at M45 (Pleiades). Also have a look at a couple of double stars. These will help you to understand more about the use of different EP's and your Barlow. I'd recommend Mizar in Ursa Major and Albireo in Cygnus. You might also try and find M27 which is close by but again will look like a faint smudge. All of this will get you more familiar with your equipment before you decide you want to splash the cash some more

HTH

Steve

[TheThing]

4" isn't too small! Remeber that up until a few years ago, a 3" refractor was the weapon of choice! SPM did a lot of his observing with a 3" which he still has and still uses.

[great_bear]

4" isn't too small! Remeber that up until a few years ago, a 3" refractor was the weapon of choice! SPM did a lot of his observing with a 3" which he still has and still uses.

Indeed.

A 10mm eyepiece (for example) will give you an equally bright image in any F5 telescope regardless of aperture - even a 12" Dob won't give you a brighter image for a given eyepiece. All that changes is the magnification achieved.

What this means in practice, is that there is a smaller set of objects worth looking at in a smaller scope, that's all.

[Ogri]

I find a polarising filter a great help too (I really struggle with anything bright, last night was so bright here, I had to pack up and head indoors after about 10 minutes as it was making me dizzy).

As a perspective on relative view brightness, and its impact on contrast, with different length eyepieces related to 'scope focal lengths, I had a thought. This might be obvious to 'old hands', but to us astronomy newbies, I haven't seen it discussed anywhere at all.

Effectively, a 30mm EP in a 500mm fl 'scope, would roughly equate 'contrast wise' to using a 72mm EP in a 1200mm fl dob, yes?

My 32mm Meade 4000 SP, in my 600mm fl 'scope, roughly equates 'contrast wise' to using a 64mm EP in a 1200mm fl dob.

Which is why in my ST120, that perfectly good 32mm Meade 4000 SP, is absolutely the pits for viewing practicality and enjoyment. The whole field of view is 'brightness swamped', and trashed for contrast.

Would any of you seriously consider using a 72mm or 64mm EP in a Skywatcher 200p dob?

I really doubt it.

To get an equivalent view with equivalent contrast to say a 38mm Skywatcher PanaView (no apologies for mentioning it, as it's this particular EP that set me on the path to learning this) used in a 1200mm fl 'scope, with a 500mm fl 'scope, would take a 15mm/16mm EP. So which EP in that range would give a nice equivalent 70 degree AFOV? It's about finding the right questions to ask, isn't it?

It's the actual fl of the 'scope, and the actual magnification that results (along with its relative 'brightness' which is where aperture comes in), along with an equivalent AFOV and an equivalent eye relief, which determines being able to compare apples to apples. It's all too easy, and far too common, to be comparing apples with oranges, pears, grapefruit, cherries, etc., otherwise.

People new to astronomy, grasping this, can save a bomb on not mis-spending money on EP's, and it can help hugely in determining what 'scope it may be practical for them to get. Depending on the focal length, to improve contrast, it can actually be a decent option to get a smaller objective than a larger one, to reduce light gathering (that does seem to be bordering on heresy, doesn't it?), if it means eyepiece selection becomes highly facilitated for much better contrast. Many say there is no substitute for aperture, I say there is no substitute for contrast (especially, with 'black and white' which is what visual astronomy essentially is). Aperture 'with' contrast therefore, would be 'the Holy Grail'?

And I'm not talking the 'this 'scope can do 633x magnification!' type language here () - it's the low end magnifications that for most users, and perhaps especially beginner astronomers, that seem to be the most crucial. The lower magnifications are the ones that help us find stuff, but to do that, we have to be able to see what we are looking for against the background, which requires that all important contrast.

Below a certain point, magnification wise, and certain apertures, it most certainly is not worth going. Because without contrast, the view is essentially worthless.

For me, with my eyes, and using my ST120 with its 120mm objective lens and 600mm focal length, that cutoff point is somewhere between 25 x magnification and 27 x magnification. The 21mm Hyperion for 28.5 x mag is ok, the 25mm plossl for 24 x mag isn't.

Below that, I am far better off using binoculars (two optical pathways changes things radically at lower magnifications for me).

I don't know if that might be 'controversial' (I certainly have no intention of it being so), but it has surprised me that something that is actually pretty important (perhaps with special regard to new astronomers), doesn't seem to get any mention?

Obviously things like filters can have an important effect on relative contrast too, but even using polarising, LPF, UHC and ND filters, I find that lower magnification cutoff point even seems to prevent the filters having much effect.

Hopefully that's food for thought anyway.

[great_bear]

As a perspective on relative view brightness, and its impact on contrast, with different length eyepieces related to 'scope focal lengths, I had a thought. This might be obvious to 'old hands', but to us astronomy newbies, I haven't seen it discussed anywhere at all.

Effectively, a 30mm EP in a 500mm fl 'scope, would roughly equate 'contrast wise' to using a 72mm EP in a 1200mm fl dob, yes?

My 32mm Meade 4000 SP, in my 600mm fl 'scope, roughly equates 'contrast wise' to using a 64mm EP in a 1200mm fl dob.

Erm... Nope...

You can't do this calculation without considering aperture, which is why Focal Ratio is useful. As I said in my last post, a given EP (e.g. 30mm, as you suggest) is equal contrast-wise (all else being equal*) in any scope of the same focal ratio - irrespective of overall focal length. Doesn't matter if it's a big dob or a tiny little refractor - the brightness is the same.

*in practice, true contrast is wildly different between scopes and is more about quality of build and materials than anything else.