Vixen 2x Barlow

[cjmarsh81]

I have just noticed myastroshop now has a Vixen 2x Barlow for $49. It seems too cheap for a decent barlow, however I thought Vixen made good quality optics. Does anyone have an opinion on these?

[matt]

Is probably an acceptable "budget" barlow?

As in all things astronomical, you generally get what you pay for.

That's not meant to be a put-down, simply a truism which I've noticed.

It really does come down to your expectations. I can recommend you pick up the phone and give MyAstroShop a call.

Very helpful and very straight shooting:)

[davidpretorius]

hey, i have series 500 ep's and a cheap 2.4x barlow. i still like em and use em. I also have a $300 powermate 5x for imaging and for being silly and looking thru.

I doubt very much myastroshop would sell anything that is crap, so I would say, get something around this $$. Get out and start looking at the sky and then is say by xmas, look at getting something special. You could still sell that barlow for say $35 or $40 if you look after it as there are always noobies coming on the scene.

[matt]

As you know Dave, I'm a Vixen EP owner and have bought plenty of stuff (from scopes to accessories) from MyAstroShop. There was never any inference that this particular item is crap, or the vendor would trade in such equipment.

I'm not saying you're accusing me of that, by the way. I just want it on the record that that was not my intention with the advice I gave.

Like I said, this would certainly be a good "budget" barlow. Affordable and will do the job. I'm not knocking affordable gear. Just putting it in the context of my experience so far.

I still think it's worth picking up the phone. There's no harm in talking:)

Don't just rush into a purchase coz someone says "that'll do you for now".

[Starkler]

I have to agree here and choosing a barlow isnt the place where you want to be economising. Buy a poor barlow and every eyepiece you put in it will be degraded, even top shelf ones.
Buy a good barlow and you'll keep it forever.

Cheaper barlows usually have poor coatings, resulting in excess light scatter and reflections. For an analogy, think of the difference in driving at night with a dirty windscreen with oncomming headlights as compared to a clean one.

[davidpretorius]

sorry, no inference to your posts or thoughts matt, sorry if it reads that way. I have talked on the phone to myastronshop and i am very impressed that he sells what he would use!!

ie "i do not think he would sell crap" I won't say catergorically he won't , but i trust him!

yes definately pick up the phone and have a chat.

also, don't agonise over this and waste viewing time. I have suffered the old what should i buy , should i go a nagler etc etc

at the end of the day, even if you have series 500's, a collimated scope, then your viewing is still very good. it may not be the best, but gee it is still beautiful up there in the sky.

Yes don't rush in, but don't take all year agonising about what jupiter may look like through a 5mm or 6mm. At the end of the day, a $49 barlow may give you those views you are after now, and even if you have to throw it away in 6 months, i would say that it was a great $49 spent if it enables you to see something you are hanging out to view?

[cjmarsh81]

I have just asked the local shop here where I got my scope to work out a good price for a 5mm Vixen LV eyepiece. He is going to get back to me tomorrow.

Holding off on a barlow for now because the eyepieces I have are not very good. They are clear in the centre and blurry, disfigured and discoloured towards the edge of the eyepiece. If I get a barlow I am simpy magnifying this.

[davidpretorius]

Ok, from my experience over say 2 months, when i could get out and view ie no rain or clouds, I was able to use the 5mm lv vixen and get satisfactory views out of this eyepiece at least 7 or 8 times out of 10.

There were times with mars and jupiter when the seeing was so bad, than even a 12mm or higher would not show anything on the surface.

Make sure your local guy knows the price of myastroshop etc inc freight as these ep's are extremey good value at the moment ie sub $200

[matt]

That's a good choice and about as much mag (200x) as you're likely to need for Jupiter and Saturn without using a barlow.

As Dave says, that should be OK to use most nights.

[janoskiss]

Even cheap plossls should perform quite respectably in your scope. So, here are couple of things to consider before you spend big on more EPs:

1. Have you got collimation sorted out? Do you have a reliable collimating tool?
2. Is the scope properly cooled by the time you are looking through it?; this is hard to answer if you've never seen the difference. When temperature is dropping relatively quickly, the mirror may never get there without a fan.

Pinched mirrors are also not unlikely and easy to fix (see Geoff Starkler's depinch-howto article on this site).

[cjmarsh81]

I am planning on ordering a skywatcher collimation tool shortly. Given up on the laser collimator. No-one, and I mean no-one has anything good to say about these things.

[cjmarsh81]

With the cooling of the scope I have noticed when I first set it up things are blurry for a little time. But this does not take too long to go away.

The 10" dob I have is advertised as having a Pyrex primary mirror to reduce the time needed for the mirror to cool without having a fan. Is this really true and I don't need a fan or is it just marketing hype.

[davidpretorius]

i will still get a laser down the track as a backup check for a mechanical test along with the star tests etc.

they seem ok, but not as ou primary source of collimation

[matt]

The thing with the laser is they're not as accurate overall as a cheshire because they're prone to errors in machining of the barrel which inserts into the eyepiece holder and they occasionally go out of collimation themselves!

The cheshire will give you the best result, but a laser is handy for a quick confirmation that collimation is good. They are quite handy for getting the angle of the secondary right.

Once you get the hang of collimation you'll rarely use a laser.

I used to perform collimation in 3 stages.

1: Quick alignment by eye

2: Laser

3: Cheshire.

Now I can pretty much pick it by eye if it's close and finish off with the cheshire.

And of course, then out under the stars to a star test - if the seeing will allow.

Definitely get yourself a combination cheshire/sight tube.:)

But each to his or her own

[cjmarsh81]

This is the one I am looking at getting http://www.myastroshop.com.au/products/details.asp?id=MAS-133

Doesn't actually say the word cheshire anywhere, but I think it is?

[davidpretorius]

looks good, nice and long to make sure your secondary mirror is aligned properly

[cjmarsh81]

Sounds good. Will see if the local guy can order it at the same time as the eyepiece and do me a deal, otherwise I will get it from myastroshop

[janoskiss]

Good choice for the collimating tool, and you are right about pyrex mirrors being quicker to reach usable temperatures. They do not cool faster but they deform less for a given temperature gradient, so they do not need to get as close to equilibrium as ordinary glass.

[ausastronomer]

CJ,

If you haven't ordered the collimation tool yet I would be happy to sell you mine at a good price. Mine is the Synta made 1 that MyAstroShop is selling. It is in perfect condition. I have no use for it as I have the Tectron Tools Collimation Set and an EZ Laser Collimator. I would be happy to sell it for 70% of the new price (whatever that is) plus postage. If your not interested in it I will list it in the buy and sell section.

In respect to your barlow. I will agree 100% with Geoff's comments. Any optical system is only as good as the weakest link. Put a $20 barlow in a $10,000 telescope and you still have a $20 optical system. I don't know the Vixen barlow that MyAstroShop is selling but at that price I would almost bet money that it's made in China and of fair quality only, compared to the premium barlows. I would look for one of the Japanese made 3 element barlows or a TV barlow or Powermate if you can afford them. If your on a budget then the Vixen barlow will be a good option at the lower price level.

CS-John B

[cjmarsh81]

Ausastronomer I have already ordered the collimation tool from myastroshop. Go ahead and list your item in the buy and sell section. Thanks anyway.

[cjmarsh81]

Hello

Since I posted this thread about the 2x Vixen Barlow from myastroshop I have found out more information about it. It is $49 because he is selling it for half price. I spoke to Steve and he said his supplier found excess stock of these in the warehouse so he is selling them cheap.

I did not order it before as I thought it was a $49 barlow. Now I know it is not such a cheap barlow I have decided to get one.

I ordered one yesterday afternoon and I recieved it this morning at 10am. This is the second time I have ordered an item from myastroshop and have to say they are very quick with delivery!

[davidpretorius]

yup he is doing all the right things, customer service is spot on by the sounds of all the feedback!

[cjmarsh81]

Tonight is the first night there has been a gap in the clouds since I got my Barlow. Just looked at the moon with it and the 5mm Vixen at approx 480x magnification. Looks really good. I didn't think i would be able to see the craters so clearly. It is shimmering a bit, but this should go away when it gets a little darker.

I haven't used any other barlow before so I don't have anything to compare it to, but i think this Vixen for $49 is a great buy.

[janoskiss]

At 480x the shimmering never goes away! It just gets less more more severe literally as the wind blows. :P

Barlow sounds good so far. :thumbsup: Pls tell us how it does on other targets when you get the chance to try it out. :)

[cjmarsh81]

will do

[iceman]

The shimmering is due to the seeing! You're lucky you're getting crisp focus at that magnification! :)

[cjmarsh81]

Ok, tried looking at Saturn with the 480x. Nice big oblong blur. Oh well.

The barlow seems to be ok. It does narrow the FOV, but that is to be expected.

The 5mm Vixen LV (240x Mag) has a FOV of 45deg. The 10mm plossl I have is 52deg FOV. When I barlow the plossl to make it 240x mag it has less of a FOV than the Vixen. I suppose this is normal.

I have not seen any degradation in the quality of images, perhaps a little darker but thats it.

[janoskiss]

The narrowing of the field is not normal. A good barlow will preserve the apparent FOV of the EP.

Or are you talking about true FOV? It is quite possible that the barlow magnifies more than 2x, so you get a narrower true field than you would at precisely 2x.

[cjmarsh81]

I don't know exactly what you mean by true FOV. I just mean the actual image I see.

For example, comparing the vixen lv without a barlow which is known to be 45deg, I can see some stars to the edge of the FOV when looking at Saturn that are not visible with the 10mm in the barlow even though the 10mm is meant to be 52deg FOV.

[janoskiss]

true FOV: how many saturns wide?
apparent FOV: how many hand widths at arm's length?

It just sounds like you are getting more than 2x magnification out of the barlow with the EP you're using in it. Can you see the filed stop? (edge of field has a sharp well defined stop)

[cjmarsh81]

I think it was a sharp stop. I have just packed up the scope, I will have another look tomorrow night.

Come to think of it, I think the size of Saturn was a little different with the 5mm and the barlowed 10mm. I do not remember which one was bigger. I will check that also tomorrow.