Some questions about lenses

[Ritzycat]

When I purchased my NexStar 6SE a few years ago, it came with a free case of  Zhumell lens & filters.

In here I have 6mm, 4mm, 12.5m and 32.5m lenses in adition to the 25mm I already have.

There is also a set of 7 filters in here and a Barlow lens. I think I understand that I use different lenses for different magnifications, but what do I use these filters for???

I have:

Polarizing Filter #3,

Filter No. 82A,

Filter No. 12

Filter No. 23A

Filter No. 56

Filter No. 21

Crystalview Moon Filter.

http://www.zhumell.com/eyepiecesfilters/

That first case

When I read their website, it says it came with a manual to explain when each filter should be used. I have since lost that manual. I assume the Crystalview Moon Filter is to be used when viewing the moon. 

I also have a 2x barlow lens. Not sure what that is used for either? Does it double the magnification? When I tried using it to view Jupiter, it made the planet pretty blurry. Is that an inherent effect of using the lens, or do I just need to clean it up?

Thanks!

[Charic]

Hi  Ritzycat..........check this out http://www.project-nightflight.net/color_planetary_filters_small_telescopes.pdf

this one too........http://agenaastro.com/choosing-a-color-planetary-filter.html this giving a chart to make selection slightly easier.

[rory]

The x2 Barlow lens doubles the magnification of a particular eyepiece . You insert the eyepiece into the Barlow and the Barlow into the focuser.

So a 10mm eyepiece effectively becomes a 5mm eyepiece.

Chances are if Jupiter was blurry, probably bad viewing conditions , and over magnification. If you used the Barlow with a high mag eyepiece you'd push the scope beyond it's limit .

Can't comment much on the colour filters , but from what I gather some can help bring out details on certain planets . But I don't think they are used by many , although I could be very wrong .

Helpful formulas for telescopes .

http://www.chuckhawks.com/telescope_formulas.htm

[Ritzycat]

If you used the Barlow with a high mag eyepiece you'd push the scope beyond it's limit .

Sounds about right... I had first said to myself "oo, if I put this barlow lens on the 4mm lens I will REALLY see Jupiter!" suppose it's not that simple. 

On Celestron's website Nexstar 6SE has a highest useful magnification of 354x... exactly how much magnification do I get from using 25mm lens, or a 12.5mm lens?

Hi  Ritzycat..........check this out http://www.project-n..._telescopes.pdf

 

this one too........http://agenaastro.co...ary-filter.html this giving a chart to make selection slightly easier.

 

Excellent, very helpful resource! I think when I'm out tonight, I'll try a few on and see for myself what each one of them does.

[Dave In Vermont]

This will give you several articles on filters and their best usages:

http://www.prairieastronomyclub.org/?s=Filter

Very good site - well worth exploring.

Clear Skies,

Dave

[rory]

Great links for you there .

The way I had it explained to me regarding magnification was imagine magnifying a photograph , at some stage it becomes blurry or pixelated . Your Simply trying to make the collected photons bigger and spreading the out .

Not a very scientific explanation but it helped me understand . With my old 8" newt I used to use around x 200 most of the time in Jupiter.

[Mr Spock]

The 6SE has a focal length of 1500mm. Divided that by the eyepiece focal length to get magnification. So:

32.5mm = x46

25mm = x60

12.5mm = x120

6mm = x250

4mm = x375

Given that most nights seeing conditions limit magnification to around x200 for sharp images, the 4mm is far too powerful for your scope and the 6mm could be used in really good seeing conditions. You will never get to use the 4mm

Using the Barlow to increase the magnification by x2  will make things worse. With the eyepices you have, you don't need it. To use the 4mm and a x2 Barlow giving x750 you would need the Hubble telescope to make use of it!

My recommendation would be to buy a good quality 8mm eyepiece. This will give you x188 and will be perfect for most nights and will reveal the finest detail on Jupiter. If the conditions are really good then you could move up to the 6mm.

As a general rule, I think x1 per mm gived the best balance in terms of detail and contrast. So for a 150mm scope that will be x150. With larger scopes this will be limited by seeing conditions. I use my 235mm scope at x235 on planets more often than any other magnification.

With 32.5mm, 25mm, 12.5mm, 8mm and 6mm you will have all bases covered.

[bomberbaz]

Ref filters, i do use colour filters, green, yellow and blue, sometimes a red. No idea of the numbers but i find they help tweak out differing details of the planets and moon. Yellow is the best but blue and green both have there uses. Jupiter is great fun to exoeriment with on filters. The moon responds very well to filters also and because the percieved light varies with eavh filter you see detail slightly differently through each one. Start on the moon and have a play with them, the results will be surprising.

[RichM63]

Hi, first off they are EyePieces or EPs not lenses. (they contain multiple lenses) Pedant over.

On Celestron's website Nexstar 6SE has a highest useful magnification of 354x... exactly how much magnification do I get from using 25mm lens, or a 12.5mm lens?

To answer this for any OTA or EP combination try out this little calculator.

EP_Calc_v2.xlsx

[Ritzycat]

Thank you for that calculator? What of units should I use for aperture and focal length?

[Ritzycat]

Oops. Didn't mean to make my first sentence a question - wanted to correct that so I don't look like a smarty pants

[John]

Thank you for that calculator? What of units should I use for aperture and focal length?

I believe its millimeters for that calculator.

[Uhwaz]

http://www.12dstring.me.uk/fov.htm
one of my favourites

[LukeSkywatcher]

As Mr.Spock (I seriously doubt his real name is Michael) said, get yourself a good 8mm eyepiece for observing the planets. A 4mm ep is asking too much of the scope. A 6mm will be ok but really on nights when the conditions (atmospheric) are really 100% bang on brilliant (that really is only on a very rare night).

Filters (coloured) are designed to drag out details on planets. Ive never had much luck with them and gave mine away. The Moon filter you have does exactly what it says on the tin. Its designed to mainly cut down on the brightness of the moon.