Highest useful magnification

[Nimrodel]

If the highest useful magnification is x145, does that mean it's not any point buying an 4 mm EP?

According to http://www.12dstring.me.uk/fov.htm the magnification will be 225x with a 4 mm EP with my scope watching Jupiter.

[ronin]

Sounds as if you have a 70mm or there abouts scope??? (76mm?)

Say which one it is, as there are difference performance's among scopes. A 70mm ED will go to higher then a 70mm achro.

I would say that if a 70'ish scope then you realistic max is around 100x to 120x,

60x will be fine on Jupiter, 80x nice and 100x equally nice. I have looked at Jupiter with 40x and it was sharp, clear and excellent - that was through a 70mm refractor. You are better going for a good image then a big image.

Your focal length is 900mm, I guess a nice 8mm (BST) eyepiece would be good giving 112x, there are 7mm (X-Cel's) that would give 128x and a 6mm (William Optics) that would deliver 150x.

[Nimrodel]

My scope is a Celestron Astromaster 70EQ. According to Celestron the highest useful magnification for my scope is 165x, not 145x as I wrote first I've got the two EPs that came with the scope (10mm and 20mm) and also a Omni 12,5 mm.

[jambouk]

Max is probably 30-50x per inch.

2.76 inches x 30 = 83x magnification

2.76 x 50 = 138x magnification

So somewhere between the two, depending on the quality of the optics of the scope and the eye pueces, and also the quality of the seeing; if very still seeing, you may get good view with 138x or more.

James

[jambouk]

900 / 10 = 90x magnification

900 / 20 = 45x magnification

900 / 12.5 = 72x magnification

So a good tange of eye pieces there.

James

[ronin]

I would have thought the Omni would have been good on Jupiter at 72x, equally I do not know what the glassware is inside the Omni. The 10mm is generally poor and not sure about the 20mm. The supplied ones tend to be inexpensive Ramsden or Huygens.

Would still say an 8mm and a 12mm of reasonable quality. 12mm for Jupiter (your Omni) and the 8mm later for Saturn.

The problem is saying go buy the BST's (or NED's as they are from TS) means a fair out lay of money and I suspect that two eyepiece could match the scope cost. If you 100% intended to get a bigger better scope then it is worth it as you use them on the next scope.

Plossl's should be good as the scope is slow, f/12.8

Any clubs around you in Norway? Just thinking that trying out someone elses eyepieces would be the easier option.

I suspect that if you went shorter then 8mm then the image is bigger but the quality lesser and that the loss of quality would out weight the bigger image.

[Nimrodel]

Forgot to mention I've got an Omni 2x Barlow as well. I am 100% sure I'll buy a better scope one day, so perhaps I should just go for a 8mm good quality EP now... My dream is to get a bigger and great vision of especially Jupiter, but I suppose it will be poor quality with the scope I have right now..

I live on the countryside so there isn't any astronomy clubs very close to my home.

[RikM]

I rarely use more than 90x with my 70mm scope. Occasionally 128x but never more than that.

Manufacturers tend to quote big numbers for magnification because new purchasers are likely to think higher numbers = better, so I buy that one. With experience you find out that the view through the telescope rarely matches the claims on paper. There are too many variables and the manufacturers assume everything is perfect for their calculations.

[Nimrodel]

I see... you don't have any photos you've taken with your 70mm scope do you? Could have been interesting so see what is really possible.

[RikM]

Photos taken through a telescope don't tell you anything about how the view will look through a eyepiece. A camera gathers a lot more light and can be further improved in post processing.

The best place to get an idea what things will actually look like with your own eyes is our sketching section. I can't post a link from this tablet but if you look at the bottom of the imaging section you will find it.

One thing I have learned about planets is that they always look very small in the eyepiece.

[Nimrodel]

Yes, I understand that and for the EPs question it's for my own viewing I may jumped out of the topic a little bit when asking for photos taken through a 70mm scope - but am quite interested in that as well I love taking photos and would be happy to see any photos taken with a camera attached to a scope with the same size as mine.