Can You Reccommend An ACCESSORY?

[lw24]

Hi,

I have recently purchased my first telescope (Skywatcher Startravel 120 on an AZ3 mount), and am really enjoying it. So far the only accessories I have purchased are a book (Turn Left at Orion) and a Moon Filter.

My birthday is fast approaching, and I would like to get one or maybe two accessories (max budget around £30 each (if i get two) or £60 for one).

Could you reccomend some accessories?

I would like to make my telescope a bit better for planetary observations, and generally, if you think a new eyepiece would be good (I have 10mm and 25mm which give me 26x and 76x magnification) then please say.

Cheers!

Clear Skies!

[Kai]

I would look at a 2x Barlow as it will in essence give you 2 more eyepieces (at 52 and 152 x magnification) it will give you the option of upping the magnification if conditions allow.

[Orion_the_Hunter]

I second the Barlow

[Doc]

A TAL x2 barlow would double your eepiece collection. Or a selection of coloured filters for planetary use.

[John]

Another vote for the barlow here. It might reduce the chromatic abberation a bit as well which does get in the way of good planetary performance with a fast achromat otherwise.

[RobH]

I don't second the barlow!!

I have the same scope, and if you try to push the magnification on planets you don't get anywhere due to the significant chromatic abberation caused by the low F ratio achromatic lens. A magnification of x60 (this is what you get with your 10mm EP, not x76) is about as far as you can push this scope.

With mine, I find the best views I get are with a 30mm 2 inch eyepiece....big bright widefield views. 2 inch eyepieces are a joy to look through.....I'd get one of these.

Cheers

Rob

[swamp thing]

I don't second the barlow!!

I have the same scope, and if you try to push the magnification on planets you don't get anywhere due to the significant chromatic abberation caused by the low F ratio achromatic lens. A magnification of x60 (this is what you get with your 10mm EP, not x76) is about as far as you can push this scope.

With mine, I find the best views I get are with a 30mm 2 inch eyepiece....big bright widefield views. 2 inch eyepieces are a joy to look through.....I'd get one of these.

Cheers

Rob

That's unusual Rob I am not a frac person but I always thought lengthening the focal ratio (Which is what your Barlow is doing) would reduce CA.

I thought that was why all the old fracs had such long f lengths.

Puzzled

Steve

[Capricorn]

You have not doubled the focal length of the objective by adding a barlow. You have simply put another eyepiece in the path which doubles the image size formed by the objective. So the chromatic abberation of the objective is still present and can get boosted by the balow.

If you wanted to have a greater magnification then look at a couple of planetary's, say 6 or 7mm and a 12mm.

Problem is that the scope is an achro and none of the maximum magnification statements seem to take into account the fundimentals of the scope. All seem to say 2xObjective.

On that basis an APO triplet, an ED doublet and a achro all can perform the same. However it is obvious they don't.

How about a SWAN for wider views? Trouble is that they are not great on f/5 scopes, the WO's state F/6 and longer.

[JKB]

I vote for good warm fingerless gloves and a Philips SPC880 with nosepiece

[swamp thing]

Cheers for that Capricorn.

I thought the Barlow altered the focal length of the scope but what your saying is if the CA is already there it won't help.

Regards Steve

[John]

Cheers for that Capricorn.

I thought the Barlow altered the focal length of the scope but what your saying is if the CA is already there it won't help.

Regards Steve

I thought the same Steve so I've learned from this thread as well - thanks RobH and Capricorn

Maybe a nice 2" widefield eyepiece to play to the scopes strengths would be a better bet then.

[lw24]

Right, so you reccomend a 2x Barlow and/or a 2inch eyepiece (30mm?) for widefield views?

Suprised nobodys mentioned any of these:

Baader Semi Apo <--- To reduce CA

Baader UHC-S Nebula Filter / Sky-Watcher OIII Narrowband Filter <--- Makes Nebulae easier to see (I think)

Any comments on these?

Also want to check this.

My eyepieces are 1.25" (I think), and therefore would I need a 1.25" filter and barlow lens? Or would I be able to use a 2" filter and barlow?

Cheers!

[JamesF]

Doesn't the ST120/AZ3 only have a 1.25" diagonal?

With the ST80 and ST102 I find the biggest problem with CA is on the moon and a moon filter makes it far less noticeable. When the seeing has been iffy I've noticed it on the planets, but last night I had a stunning view of Saturn without CA making a mess of it. OTOH I do find that more contrast would be nice when hunting nebulae, but I don't know if a UHC filter is the best solution. Perhaps someone could offer an opinion?

I don't often use my barlow (very rarely, in fact), but I do get a lot of use out of the (1.25") 32mm lens in the set of Revelation EPs I recently bought from FLO as the wider view helps when star-hopping. I have pushed the magnification on the ST102 up to around 85x with a 6mm EP and it's fine for splitting multiple stars and actually not too bad on planets when the seeing is good. It's also ok on the moon when trying to see smaller details. Other things I use a lot are a red torch, a pair of binoculars and a box to put all my bits and pieces in. I also used to use a planisphere a fair bit, though now I tend to take the laptop out and work from that.

On the book front, several people have recommended the "Illustrated Guide to Astronomical Wonders" as a sort of "next book on" from TLAO. If you're interested in viewing the Messier objects then there's also O'Meara's Messier Objects book, but that's as likely to leave you sick at how good his seeing must be as anything else.

The one thing I don't have that I'd really like now, and I must sort out some time soon, is a comfortable chair to sit on whilst at the telescope. It is far easier (for me, at least) to sit still than to stand still. Some sort of table to

put kit on and to rest on to make notes is also useful.

James

[RobH]

I think your best idea would be to see if you can borrow a barlow/higher powered EP, and maybe a few of the other bits before investing.

That way, you will know that what you're getting is right for your needs.

What part of the country are you in?

I'm sure there will be some members locally who would help out.

Cheers

Rob

[Mr Spock]

A minus violet filter would be useful to reduce CA.

[John]

It's interesting that a number of the responses to the same query posted on the Cloudnights forum also suggested barlows.

I'm sure RobH and Capricorn are right though, on reflection, a barlow won't improve the colour correction, and is likely to emphasise it more.

An alternative suggestion would be to save the money towards a slower scope that would complement the ST120 by being more optimal for lunar / planetary viewing but work on the same mount - a 127mm maksutov perhaps ?. You would have the best of both worlds then

[great_bear]

You have not doubled the focal length of the objective by adding a barlow. You have simply put another eyepiece in the path which doubles the image size formed by the objective.

You've doubled the effective focal length of the telescope by adding the Barlow - thus doubling the focal ratio and making life a bit easier for eyepieces. However, you're right inasmuch as a fast achromatic objective has already done its CA image damage, and nothing short of a Chromacorr is going to fix that.

[Rossco72]

Fringe killer filter to get best out of your curernt scope. Attach it to the diagonal and forget about it.

[themos]

Another vote for a Philips webcam + adaptor.

[lw24]

Doesn't the ST120/AZ3 only have a 1.25" diagonal?

Yes, it only has a 1.25" diagonal, and this is why I was wondering if I needed 1.25" eyepieces and filters to go with it.

A minus violet filter would be useful to reduce CA.

I haven't used the telescope to the extent where I think I need a minus violet filter yet. When I think I need one, I'll get one.

An alternative suggestion would be to save the money towards a slower scope that would complement the ST120 by being more optimal for lunar / planetary viewing but work on the same mount - a 127mm maksutov perhaps ?

The Skymax 127mm OTA is a bit much for a birthday present to be honest. The Skymax 90 OTA would be more practical.

If I bought a Skymax OTA, would I need some sort of adaptor to mount it onto the AZ3 mount? (I'm guessing tube rings don't work)

Another vote for a Philips webcam + adaptor.

I'm interested in getting into basic astrophotography (nothing serious, just some photos of planets etc). Would a webcam be practical on the AZ3 mount, as I've heard you need an Equatorial mount for astrophotography.

If I was to get a webcam, what one/s would you reccommend?

Thanks for the advice so far, I'll probably ask for some/one of the following:

Startravel Skymax 90 (for planetary viewing)

Barlow 2x (Definately) <--- Please reccommend one

32mm plossl eyepiece (If I think the benefits will be worth it)

Cheers!

[RobH]

You're wasting your money with a barlow and that scope....you have been warned

[lw24]

Right,

I'm interested in getting a barlow and a new eyepiece OR a maksutov cassegrain OTA.

Could you please help me with a few questions on these:

-What barlow would you reccommend (I'm looking at getting a fairly cheap one (no more than £40)

-What eyepiece do you think would contribute best to my current collection (10mm and 25mm (give me 26x and 60x magnification)

-How is the Skywatcher Skymax 90 performance wise on planetary viewings?

Cheers!