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Visual Improvements to Images


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Hi all.

Firstly, I am a "newbie" to all of this so hope my query isn't too stupid! I'm also new to forums and Blogging so this could end up anywhere!!

I want to try and improve the visual integrity of the planets etc with my newly acquired Celestron 4se and have looked at some Barlow lenses but don't really know what I need.

As an example, I seem to only get a tiny blobby image of Saturn that I can make out that it has rings but they are not in the least bit clear as it appears as just a bit of a blurry line through a blurred dot and I have seen images from other people with the same scope that are "way" better, so assume it's my lens configuration. I am on best clarity in terms of the focus of the equipment though.

I have a 25mm Celestron lens that came with the package and have some older lenses including a small apature 6mm lens that {I think}, is the most powerful of the eyepieces available? Am I right there? But these lenses may be rubbish as my old scope was a £50 starter pack 10 years back and I was told I could use the same lenses with this new scope.

Products I have seen:

Celstron Celestron Omni 1.25 in - 2x Barlow Lens

Celestron Ultima 1.25 in - 2x Barlow Lens

These products look very different but the details "seem" to be very similar. I don't know if I need one of them or both of them as I can't get a clear answer from my own research. I also don't know if I am looking at the wrong thing entirely!

Help and guidance appreciated.

Thank you

:D

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The 4SE is quoted at f/13 so with the aperture of 102 means approximately a 1300mm focal length, 1326 by the figures.

I would say that the 6mm eyepiece is too much for the scope. It will be giving 216x magnification, say 220x as I rounded down the focal length a bit.

I know that manufacturers quote 2 times the diameter as the max magnification but you are above that, and that value is usually a case of wishful thinking.

Anyway try Saturn at about 120x, 11mm eyepiece. 120x was one of the best views I have had of Saturn.

A 8mm eyepiece will give around 160-165x which will be easier on the scope to produce as a decent image. And probably the max that you will get realistic quality images from.

As to the quality of the eyepieces you have, cannot say. Under the situation you have given the 6mm will I think always struggle.

Oddly 8mm and 11mm are the 2 smallest in the TV plossl range, these however do not come cheap, £80ish each. Alternatives are something like GSO plossl's or maybe planetary eyepieces (Sky's the Limit or TS).

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Hi Phil and welcome.

I'm relatively new but will have a stab to help out and prove i have been listening.

Fristly, the images you see on hear are NOT what you will see through the eye, they are taken with camera, stacked and processed further.

With the 25mm you will see a small (copnsiderably smaller) than the images shown on here but you should be able to get it pin sharp (focsued), especially as its the Cels 25. You other lenses should be fine to get you started although you might find the 6mm too much (too high mag) to get true focus.

What other eyepieces do you have?

If it's just those two you may want to consider getting a mid range EP such as a 17 or 10. getting a 2x barlow would give a similar effect (mag) when used with the 25mm.

Personally I'd get another EP and worry about the barlow later but you WILL end up buying a barlow at somepoint so you its down to funds i guess.

Wouldn't like to comment two much on the difference between the two Bx2, so i'll leave that to the more experienced members on here.

Justin

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Phil, congrats on your purchase!

I have some maths to help you:-

Max usable magnification = 50 x apperture in inches = 50 x 4 = 200x magnification.

Magnification = focal length (scope)/focal length (eyepiece) = 1325/25 = 53x, or 1325/6 = 220x (slightly above your max mag)

Exit pupil = focal length (eyepiece)/f-ratio = 25/13 = 1.92mm, or 6/13 = 0.46mm...ideally 6mm is the largest possible, and you shouldnt really go below 0.5mm.

As stated above i would get a good 8mm eyepiece, its really a question of price (£50-£500 for an 8mm EP), would give you 166x magnification, and an exit pupil of 0.61mm...which is ideal and really at the end of your usable limit.

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another thing to bear in mind with planetary observing (or really any high power observing) is that the 'seeing' / clarity will wax and wane and sometimes the moments where the focus pings into sharpness (all at the same 'correct' focus point) will be few and far between. you might get say 10 seconds more or less evenly spread over a minute where the image is sharp and the rest varying from mush to quite sharp. once you get a sharp image, don't be tempted to refocus if it then goes blurred. it will come back.

This is the nature of planetary observing and the higher you go in power, the longer you have to wait for the good moments. the brain eventually somehow learns to collate the data and you start seeing more and more detail, or finally a split double, or finally that rille on the moon, the longer you observe.

the above is why imagers using webcams take hundreds/thousands of mini video snaps and then collate all the good ones to get an image that's good.

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Blimey you guys are good! Never had so many responses to a query before so quick. Thanks again...just about to get my GCSE Maths refresher book out!! Here's to a clear sky tonight to test a 12.5mm lens out!

thats the other variable we have NO say over :D

been pretty bad nights the last month...

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