Problem with lens

[Mick Rog]

Newbie and absolute beginner with this type of equipment, took me an age to set up the equitorial mount after finally watching You Tube I managed . I've also set up the little view finder up pointing at a distant object.

 

My problem is the lenses. It came with a Barlow 3X lens (a tube about 6 inches long) a Plossl  25 mm AF 40* and a Plossl 6.5mm AF 50* (I haven't a clue what any of this means).

When i put the Barlow and the 25mm lens I can focus in, had a really good look at the moon and Jupiter (although I was somewhat disappointed with the level of magnification), but when I put the 6.5mm lens on I simply cannot see anything other than a blur, no matter what I do. Is it possible that it is faulty?

Advice in idiot proof language greatly appreciated.

[steppenwolf]

I'd put the Barlow lens to one side for now and get to know your new gear with it out of the equation. You don't say what the telescope is but a 3 x Barlow lens on a 6.5mm eyepiece will give the effect of using a 2.2mm eyepiece and, except under exceptional conditions, I'd expect this to be rather hard work!

What is the telescope?

[Mick Rog]

Just now, steppenwolf said:

I'd put the Barlow lens to one side for now and get to know your new gear with it out of the equation. You don't say what the telescope is but a 3 x Barlow lens on a 6.5mm eyepiece will give the effect of using a 2.2mm eyepiece and, except under exceptional conditions, I'd expect this to be rather hard work!

What is the telescope?

Visionary Mira Ceti 150 1400

[Mick Rog]

I've tried every combination, cannot focus or see anything through the 6.5mm lens

[steppenwolf]

Your telescope has an apparent focal length of 1400mm - I say apparent as there is already a built in image amplifier lens in the focuser in what is known as a Bird-Jones system. This type of instrument does not take high magnification well so I would recommend that you don't use the 6.5mm eyepiece for now as that will yield a magnification of x215 which is pretty high for a telescope mounted on your particular mount. Is the Barlow lens definitely x3 and not x2? If it is x2 then this would be fine with the 25mm eyepiece. I would try and borrow a 10mm eyepiece from someone and give that a try and if it works for you, buy something similar.

[ronin]

Half recognise that scope from another post, just a different name/brand.

Ignore the barlow and drop just the 25mm into the focuser, then locate something as you have found the moon is very convenient for this.

The barlow and the 25mm should be usable, not good I suspect. The barlow and the 6.5mm is too much magnification.

In terms of what you see nothing is generally "big". The one that is, Andromeda, is too big. Weird world.

The 25 and 6.5 on the eyepieces refers to the focal length of the eyepiece.

As magnification = scope focal length /Eyepiece focal length you have 1400/25 = 56x, and 1400/6.5 = 215x: Which does not match with the scope description. ????

Little puzzled by the 1400mm focal length of the scope, it doesn't look long enough. So have questions about it, basically the scope design.

I do not think the 6.5mm will turn out to be of much use, too high in magnification. You will likely have to look at purchasing a couple of basioc additional eyepieces, plossl type I suggest about 10mm, 15mm and maybe 25mm or 30mm (I reaslise you have a 25 at present but consider the other 2).

If the scope is the design I suspect then you could find that the barlow is of limited use, you may end up with simply too much (poor) glass in the optical path. Hence a suggestion to use individual eyepieces.

[Mick Rog]

Yes the Barlow lens is 3X. My wife bought it for me (the whole package) when seeing it recommended on the BBC Stargazing website. It's looking like a poor recommendation at the moment.

Like I said, I had the Barlow 3X and the 25mm one on together and we looked at Jupiter and could JUST make out the bands and see the four moons, but i expected it to be somewhat larger and clearer. 

Will the 6.5mm lens be of no use? And can any of you learned people recommend where I can get better quality lenses from?

Many thanks.

[steppenwolf]

The 12.5 or 10mm version from this web page would be a worthwhile choice but I really wouldn't recommend going for a smaller focal length than 10mm which as already stated, rules out the 6.5mm you already have.

[ronin]

Your barlow and eyepiece make in effect a 8.33mm eyepiece (should be the scope focal length that is altered but easier to talk in terms of the eyepiece). That would give 168x magnification. In reality Jupiter should be fairly big at that magnification.

From my experience I find that the assumption is that magnification makes it better. It doesn't. I have seen Jupiters bands clear, distinct and sharp at 40x - just under 1/4 of what you tried and so a fair big smaller. But in a different and smaller scope.

If you could you would I suspect get a better view at around the 80x mark. An eyepieces of around 17mm to 18mm. Catch is that youare unable with the items so far to achieve anything in that area. A 15mm plossl also seems a fair option, 93x but even that may be a bit high.

Likely others will disagree but I have yet to see any magazine or similar site say a scope is not worth getting. Perhaps they should. If the scope is a Bird-Jones design, which has been suggested and I tend to agree then you are better to forget high magnifications. Also all claims are inaccurate anyway. The description implies 504x is possible, my view is that you could spend £20,000 on a scope and never get even close to 504x magnification. Will point out that just about all observing is done at magnifications of 80x and often less, even 100x is not overly common.

The problem of a Bird-Jones is that the principle is sound and is used on professional scopes, but the intermediate lens on the systems it is used on is individually designed for the scope and then it is positioned accurately (withing less then 1mm location I expect). On scopes like these sold to us the least expensive item is used that sort of acts like a barlow and positioning is more a case of where to glue it in.

Your scope should be OK at low to medium powers. But I still suggest individual eyepieces just to reduce to number of bits in there.

[Putaendo Patrick]

Sky at Night magazine don't tend to rubbish the telescopes they review, after all their manufacturers and sellers supply an important advertising revenue.

In this review http://www.skyatnightmagazine.com/review/telescopes/visionary-mira-ceti-150-1400  there were some repeated misgivings about the ability of this scope to achieve higher magnifications. "The supplied 25mm and 6.5mm eyepieces give magnifications of 56x and 215x, but the latter produced quite soft, fuzzy views." and "the Mira Ceti still offers acceptable views of a range of subjects as long as you don’t push the magnification too high".

Reading between the lines, it would seem the 6.5mm EP is both a poor performer and too high a magnification for this particular scope.

 

[steppenwolf]

Quote

Sky at Night magazine don't tend to rubbish the telescopes they review, after all their manufacturers and sellers supply an important advertising revenue.

Absolute nonsense - I do wish people wouldn't peddle this rubbish! As a regular independent contributor to the magazine you mention, I don't give a fig whether the manufacturer is an advertiser or not, it literally has no bearing on my income at all! The key to magazine reviews is to read the full text, you'll soon see where we are coming from as clearly shown in your quoted example above.

A prime example that proves my point is Stephen Tonkin's review of the Celestron UpClose G2 binoculars in this month's issue. Another example is my own review of the William Optics GTF-81 telescope some time ago. Both William Optics and Celestron feature in advertisements in the magazine.

[Charic]

I was going to ask whether its a Jones-Bird or Bird-Jones,  I may wait a little? Ooops, to late?
Similarly I've seen folk get confused over the difference between a Newtonian and a  Dobsonian.

 

[Waldemar]

3 hours ago, Mick Rog said:

Newbie and absolute beginner with this type of equipment, took me an age to set up the equitorial mount after finally watching You Tube I managed . I've also set up the little view finder up pointing at a distant object.

 

My problem is the lenses. It came with a Barlow 3X lens (a tube about 6 inches long) a Plossl  25 mm AF 40* and a Plossl 6.5mm AF 50* (I haven't a clue what any of this means).

When i put the Barlow and the 25mm lens I can focus in, had a really good look at the moon and Jupiter (although I was somewhat disappointed with the level of magnification), but when I put the 6.5mm lens on I simply cannot see anything other than a blur, no matter what I do. Is it possible that it is faulty?

Advice in idiot proof language greatly appreciated.

You say you are an absolute beginner, so take into consideration that observing through a telescope takes time to be learned.  It is not something that comes natural...

The longer and more often you observe the more you will start to see. An observers trick to see more is to use your periferal view, not looking straight at what you want to see, but slightly off target.
In the beginning that is quite odd, but your brain learns fast and you will start to see more detail then when you look straight at it.

[Cornelius Varley]

41 minutes ago, Charic said:

I was going to ask whether its a Jones-Bird or Bird-Jones,  I may wait a little? Ooops, to late?
Similarly I've seen folk get confused over the difference between a Newtonian and a  Dobsonian.

 

Some say Jones-Bird, others Bird-Jones. I believe the correct way around is Jones-Bird.

[Charic]

Cheers. Wiki says Jones-Bird,  but nothing more on the man! 

[Putaendo Patrick]

1 hour ago, steppenwolf said:

As a regular independent contributor to the magazine you mention, I don't give a fig whether the manufacturer is an advertiser or not, it literally has no bearing on my income at all!

Thank you, Steve, for the reassurance!

I've worked off and on in several areas of magazine journalism for many year, but never related to astronomy, and unfortunately many "reviews" are promotional rather than objective in a surprisingly large number of publications. So it's very good news that Sky at Night has not lowered itself to this level.

 

[Cosmic Geoff]

The previous posts give a bad vibe about the Mira Ceti.

The traditional way of testing a telescope is to see how good it is at splitting close double stars. I suggest that Mick starts doing this, as it will achieve several goals: he'll learn how to find things in the night sky, he'll get used to handling the telescope and its eyepieces, and he'll find out how bad it actually is.  Also he could think what he'd like for his 2nd telescope.

Mick should be prepared to conclude that the telescope is a dog and he should get rid of it at the earliest opportunity and buy a decent one, marital relations permitting.  Maybe he could try sending the Mira Ceti back and ask for a refund. 

A good astronomical telescope should show an 'Airy disk' when looking at a star of moderate brightness with a high enough magnification. It's hard to explain what this is to someone who has never seen it, but look here: https://en.wikipedia.org/wiki/Airy_disk 

In a real, good quality telescope, under good seeing conditions, the disk is very tiny and surrounded by one or more tiny rings.  Brighter stars appear as more of a mess.

If the figures given above are correct, there is something odd about the eyepiece and Barlow line-up.  6.5 mm (1/4 inch) is already a short focal length eyepiece, and combining it with a x3 barlow will give a silly result in any telescope, let alone one with a 1400mm effective focal length.  I have a 2.5mm eyepiece, which in a short-focus f5 telescope gives the highest power that would ever be any use for anything (x400 in this case). Its only use is for splitting close double stars, which is what I got it for. So far, I only managed to try it on the moon, and everything was blurry. 

[John]

I think the scope has limitations in all honesty.

This is from the "Sky at Night" review:

".... the Mira Ceti still offers acceptable views of a range of subjects as long as you don’t push the magnification too high...."

And I think this is a review of the same scope under different branding:

http://www.cloudynights.com/page/articles/cat/user-reviews/telescopes/eq-newtonians-and-dobs/baytronix-150mm-newtonian-r1070

I would stick to low to medium power viewing and enjoy what it can do.

 

[brantuk]

18 hours ago, Mick Rog said:

I was somewhat disappointed with the level of magnification

A lot of newbies express this view - unfortunately this is due to their expectation that viewing through a telescope is all about magnifying stuff. Indeed I was surprised when I first started astronomy to discover that it's more to do with the ability to "see things" rather than just magnifying them.

Of course you have to pick the right scope and lens in order to see stuff - so yes magnification plays a part. But once you learn how to use your instrument and it's accessories and it's limitations, you'll get a lot more out of it. I personally find it's more about "judgement".

You have to judge the seeing conditions, elevation of the object, suitability/capability of the gear, viewing technique, type of object, focal length of the scope, eye piece size, exit pupil, dark adaption, depth of atmosphere, transparency, etc.

I've used many types and sizes of scopes and the parameters are always different for each one - as are the conditions on the day. Remember - "picking the right magnification" isn't the same as "magnifying the object". Hth

[Putaendo Patrick]

16 hours ago, Charic said:

Wiki says Jones-Bird,  but nothing more on the man! 

Two men, in fact!

Robert Thomas Jones was an interesting figure. Started work as a mechanic for an Aerial Circus in the 1920s, then joined NACA (the forerunner of NASA) and worked as a scientist for NASA for many years - his main area, I believe, was aviation aerodynamics for supersonic flight. He became interested in astronomy in the late 1950s and formed a small telescope manufacturing business with his wife in California, the Vega Instrument Company. They only produced some 50 telescopes which are now collector's items - originally they cost as much as a small family car! Jones, it seems, was a talented inventor and craftsman, he also worked on an artificial heart pump and even made a concert-quality violin for his daughter! Jones died in 1999.

His original concept for a "Wide-Field Telescope with Spherical Optics" was published in the September 1957 issue of Sky and Telescope.

https://docs.google.com/a/asemonline.org/viewer?a=v&pid=sites&srcid=YXNlbW9ubGluZS5vcmd8Z3JhbnQtbWFydGluLXMtc2l0ZXxneDoyNjhjOTQyMDVjYWNjYWEx

Jones's idea was further refined by T. Bird, about whom I know nothing, except the improvements were published, I believe, as T. Bird & A. Bowen. "A Compact All Spherical Catadioptric Newtonian Telescope." in Telescope Making 3 (Spring 1979).

 

 

[newbie alert]

You have to understand that barlows,eyepeices are bringing focus down to different points..if the focus point isnt on the same point as where your eye will see it ,it be fuzzy and out of focus..

If your using a 25mm ep with a x3 barlow you are in effect using a 8mm eyepeice....but your barlow to one side..put the highest number eyepeice in and view your target..then use a lower number eyepiece and re focus.. you will get to a point where your seeing condition wont allow you to see the finer details so a higher number is better as it give you a brighter image with more clarity..its not about zooming in and using the highest magnification you can..

[Charic]

1 hour ago, Putaendo Patrick said:

Two men, in fact!

Many thanks.
I thought it was just one person, it makes sense now as to why the names are often altered, be that  Bird Jones or Jones-Bird!
I`ll stick to Jones-Bird, Now where's  my Royce Rolls?