Info about Magnification

[Atharv Salwekar]

I am still amateur observer. I have a 130Eq Astromaster, Provided with 10mm and 20mm eyepieces(650mm focal length). I would Like to know which eyepiece should i use for view Saturn (rings). I also want to see deep sky objects. I am planning to take my telescope in a remote place at around 25 march(less light polluted sky) So before that I want advice on which eyepiece should i buy.

 

Thanking in Anticipation 

[laudropb]

Hello and a warm welcome to the SGL. I would suggest that you look at the post “Eyepieces-the very least you will need “ which is in the Getting Started sub forum. As to specific makes of eyepiece you have to give your budget before we can make any suggestions.

[Charic]

3 hours ago, Atharv Salwekar said:

.......I would Like to know which eyepiece should I use........

The mathematics behind a telescopes magnification is to take the focal length of the telescope and divide that by the focal length of the eyepiece.

The focal length of your scope is 650mm therefore providing  you with 65x magnification from your 10mm eyepiece and 32.6x magnification from your 20mm eyepiece.

Starting with your 20mm, this will give you a lower power / magnification and a wider field of view. Anything shorter than 20mm will provide a sequentially  higher power with a narrower field of view and anything larger /longer than 20mm the obverse.

I always start with low power, working my way to the higher powers depending on the seeing conditions, until the image is displayed at its best without distortion/blur. I find lower powers often provide the sharper cleaner images, even if the eyepiece focal lengths are close, say an 8mm and 12mm, the longer 12mm will/should provide the better detail, depending on the seeing conditions and the quality of your telescopes setup and its ability to capture light and provide a solid detailed image.

Beyond that, its just about finding a suitable eyepiece that works well for you ( concerning eye relief and field of view )  and your budget as indicated by laudropb. Its not always the case that the more you spend on an eyepiece the better the final image, you may well spend over £400 on a premium eyepiece only to have the setup or seeing conditions let you down, whereas a £20 eyepiece (believe it or not ) can produce just as good an image , dependent again on setup and conditions. 

 

[Apollo_95]

I have a similar set up - skywatcher 130P heritage. 650mm focal length scope that came with 10 & 25mm eyepieces. I observed Saturn approx Aug/Sept time last year. The 25mm didn't give much detail with 26x mag but I had more joy with the 10mm with 65x mag. It was quite small but I could make out the outline of Saturn & the rings but not the individual rings. I've recently purchased 8mm BST Starguider EP to improve my vision when next viewing Saturn & Jupiter. From what I've read an EP of 5-8mm will be needed to get good vision of Saturn/Jupiter with my scope so you will prob be the same