How low can you get?

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Re: How low can you get?

Postby Aratus » Wed Feb 17, 2016 1:06 pm

Yes, it isn't going to be a cheap addition to my observing arsenal! A decent 2" diagonal + a worthwhile wide-angle eyeiece is going to be a major investment. However, I notice that many 2 inch dielectric diagonals have a 1.25" converting ring, so it would probably make a very slight difference to my other eyepieces too, so I would probably replace my existing diagonal altogether.
I use an 11" Celestron SCT (CPC 1100) on an equatorial wedge, housed in a 2.2m Pulsar observatory. I use a ZWO ASI1600MC and Canon 500D for imaging.
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Re: How low can you get?

Postby Gfamily2 » Wed Feb 17, 2016 2:00 pm

Check the clearance on your mount - a 2" diagonal can be quite a bit deeper than a 1.25" diagonal, so you might find that it will foul the mount if you're observing near the zenith.

This is an issue for me with my Meade LS8 on its single arm Alt-Az mount. With a zero shift focuser between the OTA and the diagonal, I can only get to elevations of about 78 degrees with the larger diagonal.

It's probably not an issue for you, but it's something you may not have thought of.
Scopes: Meade 8" SCT, Skywatcher 127mm Mak, Raffle winner of SW ST80
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Re: How low can you get?

Postby dave.b » Sun Feb 21, 2016 12:22 am

That's called the small print! Buy a bargain and spend more to use it. :-)

In any case a two inch dielectric star diagonal should cost less than a ton. Still a lot more than twenty quid, but you're buying a precision bit of gear to use with all your EP's and possibly cameras.

Make sure you buy the right one with fittings for your telescope. I managed to get a William Optics one with fitting for both my SCT and refractor, but that was some years ago.

You can also get 1.25" dielectric diagonals too.

Dave B.
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Re: How low can you get?

Postby Aratus » Mon Feb 22, 2016 4:58 pm

I can see that this will require a little more outlay than I expected! Still, a dielectric diagonal will give a very slight edge over what I have, and with an adapter I can still use the old 1.25" eyepieces. This does seem to be an reasonable upgrade route. It appears that the 2" eyepieces generally have better eye relief.
I use an 11" Celestron SCT (CPC 1100) on an equatorial wedge, housed in a 2.2m Pulsar observatory. I use a ZWO ASI1600MC and Canon 500D for imaging.
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Re: How low can you get?

Postby Aratus » Fri Mar 04, 2016 11:29 pm

For the record I have pursuaded myself to buy a 32mm 2" eyepiece and a dielectric diagonal.
I'll let everyone know how I get on with it. Thank you for all the help!
I use an 11" Celestron SCT (CPC 1100) on an equatorial wedge, housed in a 2.2m Pulsar observatory. I use a ZWO ASI1600MC and Canon 500D for imaging.
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Re: How low can you get?

Postby Supercooper » Sat Mar 05, 2016 10:13 am

It would be cheaper to buy a telescope that collects a few more percent light. If you had a 150mm reflector but you'd only need a 165mm telescope to collect 10% more light.

That sort of size increase wouldn't cost hundreds and would have resolution benefits too! This seems a little like the boy racers who spend hundreds on their cars and in so doing they're throwing that money down the drain as the value of their car crashes with each modification.

I can see that you might want to have the best light transmission that your telescope can but at what cost? The atmosphere is a much bigger influence than your coatings on seeing.

Just my humble opinion... we astronomers say "Clear skies and good seeing", not "Expensive optics and fancy coatings" :o)

Barry
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Re: How low can you get?

Postby dave.b » Sat Mar 05, 2016 10:54 am

It's a hobby! Budget is a matter of personal preference. What amazes me is those that operate at a significantly higher level of budget to me; meaning I'm on the wrong career path! I won't be buying a £3k CCD any time soon! But having an EP collection that I've built up slowly with a value of something like £700 has been affordable.

Bottom line, we should not impose our own values on others, other than to encourage and nurture everyone in this community.

Dave B.
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How low can you get?

Postby Aratus » Sat Mar 05, 2016 1:46 pm

We are all different, and we all have varied resources. I've had 4 telescopes in my life, and I've had them 10, 9, 15 & 11 (so far) years respectively. Each one has been a significant upgrade when either the old one has broke, or become too frustrating to use. Getting the most out of the current telescope I have is about tweaking and expanding it over the years. It involves spending relatively small amounts of money compared to the initial cost, but it often isn't money I can spend without some thought. Hence the discussion here.

I would agree that monetary philosophy is not a subject for discussion. There does come a time when tweaking a telescope brings little or no satisfaction, but only the particular individual knows when they've reached that point. We cannot decide that for others, or indeed judge others if they decide to get a better telescope when we think they could have got more out of the one they already had.

Personally I feel that I've a long way to go yet before I need to contemplate a new telescope. There will come a time though . . . ;)
I use an 11" Celestron SCT (CPC 1100) on an equatorial wedge, housed in a 2.2m Pulsar observatory. I use a ZWO ASI1600MC and Canon 500D for imaging.
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Re: How low can you get?

Postby dave.b » Sun Mar 06, 2016 5:05 pm

Exactly :-)
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Re: How low can you get?

Postby Supercooper » Wed Mar 09, 2016 6:01 pm

Well said... All anyone can do is advise people about the effects their ideas may have. You can't stop them throwing their money away if they want to, and you can't make them spend it if they don't have it or don't want to.

All I've tried to do is point out that the rewards sometimes arent' worth the expense. What my dad calls 'the difference between expensive and dear'. Something that's 'expensive' is purely that - a lot of money. Something that's 'dear' may cost a lot but is not necessarily worth it, or has an associated sacrifice. I suppose he means that if you buy somthing dear you have paid more than just money.

I also understand that some astronomers get attached to their instruments. That is not something that has happened to me. To me they're just instruments that are always in some way limited and can be bettered. If the right improvement comes along I will jump at it - Always on the look out.

Barry
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Using fab Helios f8 150mm Achromatic Refractor on SkyWatcher EQ5 - enjoing the views!
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