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DSOs


prasadka

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Folks

After seeing a clear night I took my etx 90 PE out. I thought the alignment was succesful, when my scope pointed at Jupiter succesfully.

I then tried looking at some of the DSOs but could only see faint stars. I tried in particular to look at the ring nebula, dumbbell nebula and the hercules cluster.

I could see only very faint stars.

1. Is it asking a bit too much of my etx 90PE if i want to look at these objects?

2. Will it help if I used a bigger/smaller eyepiece? ( I currently have the default 26mm plossl.)

3. Can some one help me with a list of DSOs, that I can realistically view wiht my modest set up?

Regards,

Prasad

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It might be a cross between the light pollution of Ipswich

and the lack of aperture in your scope mate.

Using a stronger eyepiece won't do you any good if you have a small scope and are in the vicinity of light pollution...

Don't get me wrong

Your scope is a good scope and when used within its capabilities it will perform quite well.

As for a list of DSO's i will leave that to someone that knows just how bad your light pollution is down there...

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Hi. Prasad,

I sneaked off to find out a bit about your scope, as I knew nothing about it.

It is a lovely little unit, and just as Jamie has told you, under good seeing it will perform well within the parameters of it's design.

The main ingredient of any telescope is the lens or mirror. That is the light collecter if you like. The larger that is, the more light is delivered to your eye. When you have a bright object, the better you can magnify it, using higher power eyepieces.

Unfortunately, most deep sky objects are quite faint, therefore it takes a faitly large aperture to collect enough of their light to be able to see them fairly well. It is a fact that the mirror in you ETX90, together with the central obstruction that is the secondary mirror, is not suitable for many of the deep sky objects you wish to see. I hope you don't feel too disappointed, but only the brighter objects will be suitable targets for your scope. If you are very keen to see DSO's well, I think you should consider perhaps getting yourself a Dobsonian telescope,of 8 inch aperture, at f5. Your ETX, is a very nice little unit with a lot of nice features, but in simple terms it lacks light gathering power.

Cheers Prasad.

Ron.

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As stated before , i have a holiday home by the Orwell in Ipswich, the skies there are a dream from where i now live in basildon, ring neb and dumbell are high enough up to avoid the light pollution, and that is not to bad believe me at ipswich,

You must remember, that viewing faint nebs is Yes down to the kind of skies you have , but i can see the ring and dumbell from my home and also ipswich. its a matter of practise ,but having said that , with whats said before, a lot of DSOs are very faint and rather large ,Planetary nebs can be picked out , but a good light gathering scope of 8 inches would be agood starting point for such observation.

Rog

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Thanks folks for the responses.. In short it looks like i need a bigger scope and I am not ready for it yet :D. Let me live with what I have then.

Anyways, I was told by some one that the ring nebula and the dumbbell Nebula will look like bright pretty stars. Will it help if I enhanced this with a better eyepiece?

Will I be able to get any detail with my current set up if I took a few photos and stacked them up?

Regards,

Prasad

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stepping into imaging is a different matter, once again it all cost ,not sure what you have at the moment to be able to grab images, if its just viewing then camera,s like the mintron are good starters these little camera,s are delighful enabling you to view DSOs on your tv or pc, but once again they are pricey,i know its darn annoying when you cant see things , but we have to get real and say once again , bigger scope more light gathering , look out for second hand stuff , it can be picked up very cheap.

Rog

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Thanks.. Perhaps, a second hand scope with a mount and drive under 200£, is that realistic? probably an 6" or 8" reflector?

Where do I begin? Any clues on websites?

I will probably add an autotracker sometime later in life.

Regards,

Prasad

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You need inky black skies and good "Seeing" for nebula and make sure your eyes are dark adapted..At least 20 mins.

Low to medium power eyepieces with a large apature scope are usually best for these targets..

Keep the high power ep's for the planets..

You can get nebula filters to help improve the view..

If you suffer from a little light pollution then a LP filter may help...But at the end of the day aperture will be your best friend..If you can get an 8" Newtonian and a half decent mount like KK suggests your laughing..

See the image below. this is what you would see with you ETX and the 26mm EP..You would probably only see a very small smudge in the center of your EP in very good conditions.

Greg

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Hi

When my old ETX 90 actually worked the view of DSO's was quite disappointing even on very clear nights. I had to use a lot of averted vision! On the other hand the view of planets was superb. So much so that I have removed the OTA from the fork mount and have mounted it on my 8" Newtonian.

The optics are fantastic but it just doesn't gather enough light for most DSO's in my experience.

JV

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Prasadka, I use a scope similar to your although a little bit bigger, these objects are difficult to see but possible. One thing you might try (if you already haven't) is to make use of the spiral search facility. Via the key pad select an object and press goto as normal. After it has beeped press the goto button again and the system will start an automatic search look carefully while it is doing this and you might see some of the objects you are looking for pop into the field of view.

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Just to add my voice here. Don't know about yous skies, unfortunately. But I'm affraid chaps here are right about the aperture. I see only fairly faint blobs with my 102 frac, and it is a bit of challenge finding smaller ones. I watched the Ring nebula quite a few times, and was not able to see the proper shape. One of the culprits is the LP, of course, but the small aperture won't give you much of DSO's..

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That was real good advise.. So, my plan is,

1. Use my 90mm scope until I get to night skies, know my way around the heavens. Take pictures of planets and the moon, if possible migrate to solar viewing

2. When I get good enough at (1) above, buy an 8" reflector or even better a 12" reflector with a good enough mount and drive and then practise using it.

3. When I get good enough, piggy back the 90mm meade OTA on the reflector for deep sky photography.

Sounds like a 3 year or a four year plan to me. But I think a the patience wont hurt, the DSOs are not going to go away :D

Regards,

Prasasd

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Given dark skies your scope should be capable of showing you these objects although you would need more aperture to see them well.

With the Ring Nebula, too little magnification can mean you overlook it as a faint, slightly fuzzy star. At 50x or so it's non-stellar nature becomes obvious. The Dumbell and M13 are clearly very different from stars even at low magnification and you will not miss them even in a 90mm scope.

Even bright nebulae and galaxies are hard or impossible to spot if there is any moonlight, streetlights or twilight in the sky - especially in smaller scopes.

This SGL thread might help:

http://stargazerslounge.com/index.php?topic=10704.0

There are some links in it to sites that have images of how DSO's actually look through scopes visually.

John

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Hi Prasadka,

I've got the ETX105-PE version of the scope and it's performance on fuzzies is unfortunately the same as yours. I'm afraid it really is a case of needing much more aperture to see these faint objects well, or indeed at all. It never bothered me much as it's still a cracking little scope for planetary work and star clusters, etc and works fine with my LPI webcam. The only nebula I could see in any detail was the Orion nebula, and only because it's by far the brightest around. Now I'm getting a bit more ambitious I'm going to invest in an 8" or 10" version to get some galaxies and nebulae under my belt. It's more money but there's no substitute for cubes, as the racers say.

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Yep.. I seem to get the picture and this is what i have decided too. Wait and do some planetary work and if possible work with the constellations, then move on in life to the DSOs. So, succesfully shelved the DSOs for now.

Cheers,

Prasad

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