A load of silly Questions

cc · #1 21-08-2005, 02:34 PM

Hi All

Am a newbie at this, so here goes.

I just purchased a Bushmaster 675 se60900 refractor scope
It apparently comes with no assembly instructions, I think I got it right in the end.
However I am concerned with the accessories, as I know nothing about them
it comes with 3 eyepieces a 40mm, 12.5mm, and 4mm. It also comes with a barlow 3xlens and a 1.5 Erecting eyepiece and moon filter, also a 5x24mm viewfinder I also found another triangle type viewfinder which has a larger opening and my lenses are too small tio fit it.
I have worked out that the lower the lens mm the closer the vision, but what is with the barlow lens, if I put the 4mm lens in that does it then increase the vision by 3x? and what is the little green moon filter.

Do you think with this scope and acces it is possible to see Saturns rings and see Jupiters cloud belts and surface features, the box it camre in shows terrific pictures of these and indicates that this is possible.

Thanks in advance

CC

[1ponders] (Paul) · #2 21-08-2005, 02:58 PM

I'll start with the good news CC. Yes you will be able to see Saturns rings and the belts of Jupiter and 4 moons of Jupiter. I gather by 60900 that the scope has a 60mm objective and is around 900mm long. If that's the case then you will be pushing it to see real detail. The Barlow increases your telescope focal length ie: 900mm becomes 2700mm. This effectively triple the magnification power of your eyepieces. magnification = telescope FL / Eyepiece FL. SO a 900mm scope with a 40mm lens will give you 22.5 times magnification.

The bad news is you will never see views like they show on the box. For starters except for Jupiter, Saturn and some particularly colourful stars, everything you see will be black and white and shades of grey. Plus you will never be able to get the magnification stated on the box and still be able to see anything. That 675 X mag is using the 4mm lens with the 3X barlow. I would be very surprised if you well be able to see anything clearly even with just the 4mm lens. Your apperture is just too small. As a general rule, for relatively good optic the you multiply the diameter of your objective (in inches) by 50 to get the maximum resolving power. Therefore the most mag that is useful to you is around 125X.

It will probably be an ok scope for terrestrial viewing, the moon, and on fair to good nights, Jupiter and Saturn, but if you really want to look at the heavens above then you need to have either a scope with a shorter Focal Length to give wider fields of view or a scope with more aperture.

How long have you had the scope and what sort of mount is it on?

rumples riot · #3 21-08-2005, 02:58 PM

Well, I will try to address each question.

1. a barlow lens will increase your focal length of your scope by the factor shown. So in your case it will increase your focal length by three times. I think this will in your case be 900mm x 3 =2700mm. Now this would be ok if you were to use say the 40mm but not the 12.5 or 4 mm. Your scope does not have the capacity to sustain such high magnification. This is because 2700 / 40 = 67.5x whereas 2700/4 = 675 x. The image will break down and be useless to you. So use your barlow with this scope and EP's of say 25-40mm range. So in answer to you next question the answer is no the image will not be multiplied by 3x. Just the focal length. A good rule of thumb for any scope and its resolving power is to say 40-50x for each inch of objective. In your case you have a 60mm objective which is my memory serves is 2.5 inches. This would mean magnifications of 100-150x are realistic for your scope. The advertised 675 times is possible but will not give a very good image and quite frankly is a lie.

2. The green moon filter can be screwed into the bottom of your EP's and used to view the moon. As the moon nears its full apparition each month it becomes brighter and brighter. When viewing the moon use the filter to reduce the amount of glare and ease the strain on your eyes. Without it you will find that when you look away from the EP you will not be able to see in the dark at all. A moon filter will help reduce this and make it easier to see away from the EP.

3. As to using this scope for viewing Saturn and Jupiters cloud belts. This scope will be very limited as to what you will see. However, I would think that you will see a very small set of rings on Saturn and I do mean small. Jupiter will show two belts and will be a similar size. Unfortunately this scope is only really a spotting scope. However, it is a start to your determination as to whether you want to get really involved in this hobby.

Hope I have helped.

rumples riot · #4 21-08-2005, 03:04 PM

Paul here is a link for this scope. http://australianoutbacksupplies.com.au/prod825.htm

cc · #5 21-08-2005, 03:12 PM

OK,

I have only had the scope a week, if I cant obtain the images as they suggest on the box then I may request my money back and upgrade to something better.

I paid $149 for that on special, I thought it was pretty cheap thats why I grabbed it. Mind you I was impressed with the moon views.

What do you recommend as far as specs are concerned, as you mentioned aperture and focal sizes seem to be important.

cc

rumples riot · #6 21-08-2005, 03:24 PM

To be perfectly frank, I would go for a 8" dob. Around $400 and will give you more joy and use.

[1ponders] (Paul) · #7 21-08-2005, 03:34 PM

for the 8" Dob. More "bang" for your buck. Much more stable that the tripod your's came with. If you can get your money back go for it. There is nothing wrong with the scope you bought but it will be very limiting in its ability and the mount it is on will drive you nuts. The other issue with that scope is that it uses .925" eyepieces and the standard these days are 1.25" and 2", so you will be hard pressed to find more eyepieces to fit it, let alone good quality eyepieces. You can get a .925" - 1.25" adapter but IMO its not really worth it. In fact if you are limited by funds consider getting a good pair of binoculars and a sturdy camera tripod and binocular adapter. Or just the binoculars. A reasonably good pair of 10X50 (10 times magnification and 50mm objective lenses) will probably cost around the same amount as you have spent. And you will get much more enjoyment out of them than with your current scope.

janoskiss (Steve H) · #8 21-08-2005, 03:47 PM

Line up the finder during the day, and then go out just after sunset and check out Venus and Jupiter. Look west; Venus is the brightest "star" at an altitude of around 25 degrees, and Jupiter is the second brightest at around 50 degrees. Jupiter will look quite small, but you should be able to see its moons and the two largest cloud belts using your 12.5mm eyepiece. Unfortunately you missed Saturn this year, but Mars is coming around.

The 40mm eyepiece is probably too long for the 25mm focuser to give a respectable field of view. The 4mm is likely to be totally useless with 0 eye relief. And unfortunately that 3x barlow is not going to go too well with either eyepiece. With the 12.5mm, it gives you 216x magnification, which is likely more than the scope is capable of, and with the 40mm, it gives about the same magnification as the 12.5mm.

The erecting eyepiece might work with the 40 & 12.5mm, but the image quality will be worse than through the 12.5mm alone.

If you have some old binos, you can pull the eyepieces out of them and use them with your scope. Check out this thread.

cc · #9 21-08-2005, 03:54 PM

What do you guys think of this scope and its specs and price.

Link below

http://cgi.ebay.com.au/5-optrons-900...QQcmdZViewItem

CC

janoskiss (Steve H) · #10 21-08-2005, 04:04 PM

Yes, get a refund if you can. The scope is not worth that much. You can get an excellent pair of binos for the money (or for less). If you really want a scope and you are willing to spend up to $500 (incl. delivery), get the 8" Dob. Biggest aperture per dollar. Big aperture -> more light collecting area -> more brightness -> more things & detail you can see.

If you have something against mirrors (e.g. maintenance, weight, size), AOE are having a sale on refractors. $250 will buy you a much better refractor than the Bushmaster.

janoskiss (Steve H) · #11 21-08-2005, 04:10 PM

Quote:

Originally Posted by cc

What do you guys think of this scope and its specs and price.

It's crap! The whole advert is a big fat lie, designed to suck the unwary in. Stay away from those scopes. In fact, stay away from ebay alltogether! 99+% of scopes on ebay are junk. All new scopes on ebay are junk.

Try these dealers for good budget gear:

http://www.aoe.com.au
http://www.bintelshop.com.au
http://www.andrewscom.com.au

[1ponders] (Paul) · #12 21-08-2005, 04:16 PM

The scope may be ok but that mount and tripod is a nightmare. Way way undersized for anysort of relaxed viewing. I suggest you be very careful buying scopes off ebay. You can get the occasional good one but the majority are simply rip offs. There are good second hand astronomy equipment sites on the net but unfortunately ebay is not one of them.

Realistically if you want to go for an Equatorial mount then the minimum sized one would be an EQ3 or EQ4. Look at the mounts on this page. http://www.andrewscom.com.au/site-section-10.htm The Guan Sheng GS-300 and SkyWatcher 102X1000EQ3 are both on EQ3 mounts. Compare them with the EQ2 further up the page. There is no comparison when it comes to stability. If you are seriously looking at an equatorial set up IMO these are the minimum mounts you should consider. Anything smaller, unless its carrying a much smaller scope will drive you to distraction with wobbling and vibration. And even with the socpes that are on these EQ3s there will still be movement.

If you don't mind me asking, what sort of limit were you looking at as far as cost goes. If we know more maybe we can direct you to a scope to suit your needs. Also what sort of things are you wanting to look at?

Miaplacidus (Brian) · #13 21-08-2005, 04:17 PM

The golden path to cost-effective enlightenment: first get 7x50 or 10x50 binoculars plus a star atlas (Bright Star Atlas), subscribe to a mag, join your local astronomy club, look through as many different scopes as you can. Then, when it's time to buy a scope, chances are you'll be best served by buying a dob.

wavelandscott (Scott) · #14 21-08-2005, 05:17 PM

As mentioned above, while this scope will work (with some limitations) you will probably not see Saturn and Jupiter look like they do on the box...although the moon should be pretty good...

I would encourage you to try and attend a viewing night and/or contact someone from the forum who lives close to you so that you can see some of the different options in terms of scopes available...

Before you select a scope, I always think that it is good to have an idea of what you want to see first...that will help determine what type of scope is right for you...

Depending on how you want to use it, the Bushmaster may be the right scope for you...many people have started with very similar scopes and used them for some time before moving on to bigger and better...again, this is a personal thing...

Many of the members of this forum are die hard Dobsonian Reflector owner/fans (myself included)...but, there are many other good types of scope available...it is all in what you are interested in looking at...

Good Luck!

cc · #15 21-08-2005, 05:24 PM

As I said, I have only just started this week, I suppose I was looking at around $500, I am really annoyed that the box the bushmaster comes in is full of large colour pics of Jupiter and Saturn, and I cant get the images they say u can on that scope

davidpretorius · #16 21-08-2005, 05:39 PM

hey newbie,

hi from a 1 month old newbie

there is one other guy that i know of in hobart.

there are four of us in launceston. do you come to lton often? no probs organising a look at some 8" dobs and my 10" dob. get to see first hand.

i have listed my costs as my signature. i had a budget of $1300, to include some imaging stuff.

8" dob with a few eyepieces is the way to go, and then ask the forum what to buy next.

janoskiss (Steve H) · #17 21-08-2005, 06:58 PM

CC, Sorry for your disappointment. Here is a "buying your first scope" guide, definitely worth a read: http://astronomy.trilobytes.com.au/scope.htm
Prices have come down since that was written but otherwise all the info is relevant.

cc · #18 21-08-2005, 07:37 PM

Thanks.
I will have a read of that.
Im not sure whether I was expecting too much from this scope, but the images on the box appear to be highly misleading, or maybe they can be produced on this scope if you know what you are doing.

CC

Miaplacidus (Brian) · #19 21-08-2005, 08:28 PM

Oh, didn't realize you were in Hobart. I seem to be in the strange situation of owning most versions of beginner scopes presently (might write a comparison article soon), so PM me and we can organize a time for you to come round if you like. That is, if you choose to get a refund and if they let you. Where did you get it, BTW?

The Astronomical Society of Tasmania's website is http://ast.n3.net They have a viewing night at Mt Canopus 8.30 every Friday night, beginners welcome (they usually wheel out the 12.5 Discovery dob).

Cheers, Brian.

janoskiss (Steve H) · #20 21-08-2005, 08:59 PM

Quote:

Originally Posted by cc

Im not sure whether I was expecting too much from this scope, but the images on the box appear to be highly misleading, or maybe they can be produced on this scope if you know what you are doing.

Not unless the picture of Saturn on the box looks like this:

http://members.optusnet.com.au/~jano...-refractor.png

And even that would be quite an achievement for a small scope.