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Posts posted by John
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Magnification: focal length of scope divided by focal length of eyepiece
Exit pupil: focal length of eyepiece divided by focal ratio of scope = exit pupil diameter in mm.
Focal ratio: focal length of scope divided by diameter of primary mirror or objective lens = focal ratio, expressed as F/5, F/7 etc, etc
True field of view = Apparent field of view of eyepiece (eg: 50 degrees) divided by the magnification that it gives in a particular scope = the true field of view in degrees (how much sky is shown).
I think I've got those right
Hope it helps a bit !
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how much did those cost you? im a total beginner and that big fat green one made me drool.....
Too much probably, although most of them were bought used
Quite a lot of the low power, very wide angle eyepieces are pretty fat, and heavy - they seem to need big lumps of glass in them to do their stuff.
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Another approach, simple and functional, a £4.99 plastic component box from Maplins. Works perfectly well for regular sized eyepieces.
I like Japanese volcano tops:
Nice set Simon
I like those classic orthoscopics too
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Great review Mr Spock - thanks for posting it
I'd heard from several sources that the C9.25's were something a bit special and yours seems to underline those rumours. I believe their specification differs slightly from the other Celestron SCT's - is that correct ?
To be able to use 300x plus with ease under UK skies shows that the scope is a top performer.
If I were thinking of moving to a SCT, I think the C9.25 would be at the top of my list
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So, to get a slightly larger view of Jupiter, I would need a 2x barlow and to complement my range a 18mm EP...At the moment I have a 9mm and 25mm EP that came along with my scope....
Yes, the 2x barlow would turn the 9mm into an effective 4.5mm.
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Pressed into John?
I now have the small Maplins case and was wondering how some people have got the 'tight fit' around their Eps?
I lay the item in question on the foam to see which cubes need to be depressed. I then, as tight a spossible around the item, break the cubes free, in a block, down to a depth of a couple of inches or so. You should then be able to press the item down onto the cube block, which will then depress forming a hollow for the item. The foam points in the lid hold the item in place and over a little time, the depression becomes established. When you want to move things around you can always pull the cube chunks back up and they will, with a bit of fidlding, go back to their original place, more or less.
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Your Celestron collection is a good deal bigger than what I started out with (a 10mm, 26mm celestron Plossl, and a Vixen "silver top" 36mm Plossl). I thoroughly enjoyed observing with them. Yours should give you very good views.
This was my collection a few years back - and I was dead pleased with it :
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What a great set
Interesting that you still have a place for the 2 TV plossl's in there - but they are really great eyepieces as are the Nagler zooms.
When I move away from the "black and green" it will be towards Pentax XW's - the only EP's I've tried which surpassed (only by a tiny bit mind) my TV's
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Reading this thread has inspired me to get a case for my eyepieces so far I only have 1 that came with telescope and I have one ordered and a barlow.
As this thread is old, Where would I get a case like this with foam?
I got mine from Maplins - it was around £15 I think. It has that cube-cut foam which is easy to pluck out as needed or, as I do, to push down into indentations in which the eyepieces sit. There is foam in the lid as well to keep the eyepieces in place when the case is shut.
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Niiicccceeeeeee!!!!!
I'm just wondering what your doing with the eye lens caps? I've seen a few people do this but I fold my eyecups down and the TV cap fits nice and snug. I just tested this method on my 13 ethos and its dead wobbly. Each to their own though.
They are snugger with the eye cups folded down but I didn't want to fiddle about near the eye lens in the dark so I keep mine up (as I use them when viewing) and the indentations in the foam seem to keep the caps in place. The 20mm T5 Nagler eye end cap is the worst offender for falling off too easiliy !.
I might try and store them folded down for a while and see how it goes though - thanks for the suggestion
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These do tend to fill up faster than expected...
And change their contents rather rapidly as well - I'm rather shocked to find that I've only one eyepiece left of the 9 I posted a picture of on 14 January this year
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Fascinating looking scope - thanks for posting the pics
It looks rather similar in style and finish to my Intes mak-newtonian - functional but very well engineered. The coatings on my corrector are purple as well !.
The (V) symbol does mean Vixen I believe - nice quality eyepieces in their day.
Good idea about changing the mount - the aluminum tripod will shake somewhat I would think with a 6kg OTA on board.
Look forward to a report on the views through it
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hello all first time on the site but wathched the nights sky every clear night i could for years love it any advise on telescopes for rookies thanks
Try posting this in a thread of it's own in this section - you will get plenty of suggestions then
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I have a 10" F/4.8 Orion Optics newtonian optical tube. Normally I use it on an alt-azimuth mount (rather like a Giro) and it's really easy to set up and use - almost a 10" "grab and go" in fact (apart from a bit of cool down time of course).
I put the scope onto my CG5 mount, which has the 2" steel pipe tripod legs, to see how it fared. The mount could handle the scope for visual use fine (the OTA weighs around 10kg which is relatively light for a 10") but, as a package, I found the whole thing very unweildy - the pleasure seemed to have gone right out of it.
I've a 6" refractor which I also use on the same mount but with that you can easily rotate the diagonal to get the eyepiece in a comfortable position - it's just not as simple with the newt unfortunately.
I have a lot of admiration for those who can manage a 10"+ newtonian on an equatorial mount but personally I'll be sticking with dobsonian / alt-azimuth mounts for scopes in that aperture category in future.
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I tried to do that with my C8 when I had it. I was advised that Celestron don't keep records of the serial numbers as well, which was not much help !. Rod Mollise's guide to buying an SCT might be of interest if you have not already seen it (free download):
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The thing is that, generally, additional magnification won't show any more detail -what is needed is time at the eyepiece so that your eye and brain become accustomed to teasing out the detail that is already in the image and seize the fleeting moments of excellent seeing to build the best image that the combination of scope and viewing conditions can deliver.
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Great review of a great finder Shane !.
I've owned both a Telrad and a Quikfinder and liked them both. Because of it's small footprint I think the Quickfinder is suitable for a wider range of scopes. It's lens is slightly less prone to dewing than the Telrad as well I found. Both great finders though.
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hey sorry took so long to get back to you, wasn't feeling too good yesterday and had work today. I measured it tonight, and its 140mm from the dovetail to the ground when fully extended.
Thanks Natalie
Hope you are feeling better now.
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Sounds great Natalie - thanks for the report.
One of the issues I find with many mounts is that they are rather too short, or at least the tripods are rather too short (I'm 6 foot and my back does not like stooping for too long) - I'm wondering how tall the AZ4 is with the tripod extended - say to the dovetail where you mount the scope ?.
I'm glad you got a successful 1st light with it.
John
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Some nebulae are small and tight (eg: M57 - the Ring Nebula) and benefit from higher magnification. Some though are huge and sprawling and will hardly fit in the field of view at very low power with wide angle eyepieces. The Veil Nebula (which has a number of parts) needs a 4 degree true field of view to fit it all in - that's 8x the diameter of the moon. So the answer is to use a magnfication that suits the angular size of the object you are looking at. The apparent size of DSO's is something that the photos don't really help you grasp as there is nothing for scale - some are a lot smaller or larger than you think and for that reason it's easy to miss them altogether sometimes.
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.Any recommendations on makes/models of reasonably priced quality EPs would be appreciated.
Thanks
You get what you pay for with eyepieces but, for your scope, the TAL, Skywatcher, Meade or Celestron plossls will work pretty well.
First Light Optics have a good deal on Skywatcher Plossl's at the moment:
Skywatcher - Skywatcher SP Plossl eyepieces
John
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This was so helpful for me. Reading through my user manual was pretty basic but this thread really cleared some things up.
My Scope is a F/8.6 and came with a 9mm, 25mm and 2x Barlow lens. So from what was posted above it appears that I have the standard high power and low power eye pieces.
Would you all recommened any other sizes?
You might want to post this question in the beginners section as well to get some other views but I'd suggest a 32mm Plossl which will give you nice low power views. With the barlow lens you would have quite a comprehensive range of powers then.
John
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Konosky 200
in Discussions - Scopes / Whole setups
Posted
I used to have a Konusky 150mm F/8 refractor. It was exactly the same as the Skywatcher Evostar 150 refractor, except that the colour scheme was yellow.
I believe that the Konusky 200 is pretty much the same as the Skywatcher 200P:
Reflectors - Skywatcher Explorer 200P EQ5
Except that the yellow (older) Konusky versions have the older style (and more wobbly) aluminum tripod legs.