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Hi! 10 months in & thanks!

gbarnett

By gbarnett
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gbarnett

gbarnett

Posted
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I’ve been lurking on here for over a year now so thought it’s about time I said hello.

I got myself the 8” Skyliner dob for Christmas 2012 and after going through eyepiece hell have since upgraded the stock 10mm to a 11mm ES 82 degree and the stock 25mm to a 24mm Maxvision 68 degree. Also got a 1.25” 2x / 1.5x Revelation barlow. Had the ES 82 & the barlow about 6 mths and only recently got the Maxvision in case they all go over Christmas. The plan was to get the best eyepieces I could afford rather than wanting to upgrade later.

All of the above I’ve done based on advice I’ve read on here so to everyone who posts advice or gives reviews of equipment I am saying a big thanks as you may not only help the person who asked the question but anyone else who may have the same issues or questions.

I'm only ever going to be be a visual observer so a big dob was the way to go and the 8” was my limit price-wise. The dob has also turned out to be realistically the largest manageable size for me with manoevering it through several doorways and a childgate to get it outside – only found this out after I got it though!. I wouldn’t have anything else for a scope now due to the ease of set up and ease of use. I’ve got quite a cramped narrow back yard and the dob fits in very well.

I chose the 11mm ES82 due to the large FOV to avoid too much nudging for planets and the moon with the manual dob. Also due to the near 2mm exit pupil and large FOV I thought it would be good for DSOs.

I chose the 24mm Maxvision 68 degree based on the price! and the reviews on here. If not for this I would have gone for the 24mm 68 degree ES which would have been about £60 dearer. The eyecup will take a bit of getting used to! I was considering the 24mm 82 degree Maxvision but opted for the 68 degree as I have a 1.25” 2 / 1.5 Revelation barlow so this gives me the option to use the 1.5x element to get a 16mm focal length and makes the Maxvision even more of a bargain. The 2x barlow is redundant with the 24mm as it duplicates my 11mm.

So I’ve worked out this gives me:

24mm (50 x) : 1.36 AFOV : 4mm exit pupil.

16mm (75 x) : 0.90 AFOV : 2.66mm EP.

12mm (100 x) : 0.68 AFOV : 2mm EP (redundant).

11mm (109 x) : 0.75 AFOV : 1.83mm EP.

7.33mm (163 x) : 0.50 AFOV : 1.22 EP.

5.5mm (218 x) : 0.37 AFOV : 1.09 EP.

I think that will do me for a good while as it is a good spread. I don’t think I want to go any longer in FL than 24mm as my viewing location is quite light polluted. I may well try to push the mag higher for the moon though.

I’ve downloaded Stellarium and it’s great for having a quick look to check what is viewable and have a play around with eyepiece configurations. I’ve got a southern view from my back yard which is quite restricted and Stellarium is great for checking what will be viewable at certain times. I’ve spent around 12 months now trying to learn the constellations and navigate my way around the sky. I’m getting there. It has felt like some nights there are too many stars and others there aren’t enough – mostly none at all due to the cloud!

I’ve also been attempting to make my own Cheshire collimator from the cardboard tube from rolls of foil, milk bottle lids and bits of cotton. I’ve had some unsuccessful prototypes so far but its been interesting and fun do do and each rubbish one I’ve made is helping me to improve my design to make one close to the real thing.

My next steps are to get a Telrad to save my back! and maybe a 2.5x barlow for the moon. Also the Baader solar film is on my list to make a solar filter at some point.

I’ve not really done much observing over summer so am looking forward to the dark winter nights.

Clear skies!

Graham.

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Crebles

Crebles

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Posted

Hi and welcome to a fellow 8" Skyliner owner. Looks like we've a similar level of experience.

For what it's worth, find attached (hopefully) a document I came up with when researching eyepieces.

plotting mag vs EP focal length, I realised that the magnification draws an exponential curve - showing minimal change (diminishing returns?) in the longer focal length eyepieces (25mm plus), but far more sensitivity in magnitude with the 'shorter' length (3,-10mm) eyepieces. Not a linear realationship (straight line graph) as I'd assumed early on in my eyepiece research.

Ive never seen described it graphically before - so I offer it here in case its of interest or use. You seem to be someone else who's given a good deal of careful thought to which eyepieces to buy - I know I can't afford to get it wrong!

Kind regards,

Eyepiece magnifications in our 8inch and 12inch scopes.xlsx

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