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telescope magnification

Need our opinion on a telescope Optics Planet has on sale, go ahead and ask! Post some hints and tips on various telescope brands and configuration.

telescope magnification

Postby opticsplanet.com on Mon Oct 04, 2004 8:15 am

hello i bought a bushnell go to motorized north star and when i use the
> 4mm lense it wont focus its always blurie is there a fine tune on these
> when focusing and when i first received my telescope the barlow lense
> looked bent and the end of it looks burnt/melted in a way could this be
> the problem if so could i get another one i had just bought the
> telescope last fall less than a year old, and its getting sky watching
> season and do i need a rma # thank u very much and i hope u can help me
> with this
Last edited by opticsplanet.com on Wed Oct 06, 2004 6:10 pm, edited 1 time in total.
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Voyageur magnification

Postby opticsplanet.com on Mon Oct 04, 2004 8:17 am

Hi Paul

If you are using the 4mm with a Barlow lens you are at a very high magnification, or nearly 500x. In a telescope as small as one of the NorthStars, a fuzzy image at such a high magnification is normal. Even in a very large and expensive telescope, it is rare to get a sharp image at such high magnification.

My advice for all observing, no matter what the telescope, is to use only as much magnification as needed to view an object satisfactorily. In a telescope like a Northstar you will have your best viewing at magnifications of from 50x to perhaps as high as 140x on nights where the atmosphere provides good seeing conditions. Using more magnification than this will result in fuzzy images in your Northstar.

If your Barlow is bad, you should notice a problem using it with all eyepieces. Still, if you would like to return just the barlow for a replacement and try another one, I would be glad to help. Let me know and I will try to find one for you.

If you have any more questions, don't hesitate to contact me.
----------------------
Your personal optics expert
Joanie (Jne) K
http://www.OpticsPlanet.com
Phone: (888) 263-0356
Fax: (847) 574-6820
opticsplanet.com
Site Admin
 
Posts: 4044
Joined: Tue Sep 23, 2003 11:18 am
Location: Prospect Heighs, IL

Maximum Magnification

Postby Mark on Fri Mar 04, 2005 2:09 pm

Given Focal Length of 900m and width of 4 1/2 inches. The maximum usable magnification if about 50 times with Width, i.e. 4.5 x 50x = 225x. But realistically you should expect less.

If you use the 20mm with the 3x barrows, then you'll be at 135x. Otherwise your 4mm will give you 225x.
Mark