Author Topic: Newbie Brain Hurts - please simplify (eyepiece/diagonal)  (Read 496 times)

tenpaseper

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Re: Newbie Brain Hurts - please simplify (eyepiece/diagonal)
« Reply #15 on: January 12, 2018, 05:38:03 PM »
Not all glasses wearers are created equal.

If you have a simple refractive error (far sighted, near sighted) you can fix this with the telescope focuser.
Note if you and your wife have a large difference in prescription you will have to refocus when swithching viewers.
If you have astigmatism focusing cannot fix this. Although if you are viewing at high power, astigmatism is not
so bad. A mild astigmatism hurts when viewing wide fields, not moon and planets.

I mention this because I have both near-sightedness and astigmatism. I still don't wear my glasses for the following reasons.
1) you have to keep them clean, you will notice how dirty your glasses are when looking through a scope.
2) It will require you have all eyepieces with long eye relief. The 32mm eyepiece I recommended will work,
  not sure about the 20mm, it might ...
3) I often see the glare from the eyepiece into my glasses, and reverse glare if there are any outside lights near me.

I keep my glasses on a lanyard, so when I am done looking through the eyepiece and need to see the sky again,
they are close.

Greg Quevedo

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Re: Newbie Brain Hurts - please simplify (eyepiece/diagonal)
« Reply #16 on: January 12, 2018, 05:42:28 PM »
I'm assuming you have an 8" LX200 at F/10.

First of all, Jupiter and Saturn are pretty small, and you will want higher magnification for them (Saturn in particular).

You can see everything an 8" F/10 SCT has to show you with a few plossls, a F/6.3 focal reducer/corrector, and a 2X barlow.

Plossls don't have really wide fields, but they give good views and are affordable. In short focal lengths, they have uncomfortably short eye relief, but you can avoid that with a barlow lens. With a 2X barlow, a 20mm plossl becomes an effective 10mm.

A typical set of plossls would be 32mm, 25mm, 20mm, 15mm. With a 2x barlow, you don't need anything shorter. If funds are short, you can skip 25mm plossl at first.

A 32mm plossl is as wide of an eyepiece (in terms of true field) as will fit in a 1.25" eyepiece barrel. If you want even wider fields, you can use the reducer/corrector with either the 32mm or 25mm plossl. The R/C plus the 32mm plossl gives you about as wide of a useful field as can be achieved with an 8" F/10 SCT. It's the brightest field, too, so it is helpful for detecting faint fuzzies, and particularly useful with nebula filters.

For planetary/high power observing use the barlow with the 25, 20, and 15mm plossls for magnifications of approximately 160X, 200X and 270X. Ideally, it would be nice to have an option that gets you a bit higher, but conditions seldom allow for much higher magnification, so it isn't an initial priority. Note that the 15mm plossl likely won't have enough eye relief to use with glasses (the 20mm might be too short too, it depends on many factors).

As far as a diagonal, unless it is defective the stock 1.25" prism should be fine. If your diagonal isn't good, or your scope didn't come with one, I'd go with the Celestron (Celestron 94115-A) if you are on a budget. You can pay a lot more and not get much better performance. (A used older made in Japan version is a good option, too).

A 32mm plossl, a 20mm plossl, and 12, 9, and 6.5mm Meade HD-60s (or equivalent Starguider Dual ED, Paradigm Dual ED, or Celestron X-Cel) is also a great way to go. No barlow necessary, but you'll want the R/C eventually. The HD-60s have good eye relief, but not quite enough to accommodate my glasses.

Beyond that, there are a myriad of options that allow you to spend more money. I have 2" diagonals and 2" eyepieces. I have 68-degree and 82-degree eyepieces. But I could still spend a perfectly wonderful night of observing with my C8, a few plossls, and R/C and a barlow. In fact, for my grab-and-go C5, that is exactly what I use: 32mm, 26mm, 17mm, and 12.5mm plossls, an R/C, and a 1.7x barlow.

Demetrius Bryan

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Re: Newbie Brain Hurts - please simplify (eyepiece/diagonal)
« Reply #17 on: January 13, 2018, 02:34:06 AM »
I have several of the Meade Series 4000 Plossls, and they were my only eyepieces for many years. I never felt I had anything to complain about. As someone who is just getting started in astronomy, I think you are wise to try to start out simply, conserve your budget, learn about your telescope and the sky. There will be plenty of time in the future to upgrade if you wish.

Astronomics, the company that hosts the Cloudy Nights forum, has Meade and Celestron Plossls at very affordable prices. FWIW, mine are the 9.7mm, 26mm, 40mm, and an 18mm wide field, which give a pretty nice range. I do have a Barlow, but I just personally don't use it much. On the Astronomics site, if you're looking at eyepieces and you click on the tab "Tech Details," it will give you info such as eye relief, if that is a concern due to the eyeglasses.

Many people like the zooms, and I just recently bought one myself, but if you've never seen one before, be forewarned, they are gigantic, at least the one I got is. I've only had a chance to use it a couple times, and it seems very nice, but it's going to take some getting used to.

I totally understand your brain burn-out. It can be paralyzing. I know it's easier said than done, but try not to over-think it. A few Plossls will get you started very nicely.

ivirlocri

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Re: Newbie Brain Hurts - please simplify (eyepiece/diagonal)
« Reply #18 on: January 13, 2018, 06:42:50 AM »
I imagine you have enough advice by this point. So I'll just congratulate you on your very nice new scope, welcome you to the forums and wish you many happy nights of fine and fun observing!

Eric Ayyagari

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Re: Newbie Brain Hurts - please simplify (eyepiece/diagonal)
« Reply #19 on: January 14, 2018, 12:35:03 AM »
Quote
You could get Plossls but you're probably better off getting Explore Scientific EP's. I recommend the 62* or 68* line of EP's. It turns out that BOTH sizes are ON SALE at OPT!
I gave them a call and double-checked to make sure that the 62 and 68 EP's were the correct FOV for an f/10 SCT and that's what they recommended. The eye relief is excellent, too. 82* would be too much EP for your scope so don't worry about them. All of OPT's (optcorp.com) staff are astronomers so they knew what I was talking about. So, having said that, I'll let you contact them and have them help you pick out the EP's you'll need. I recommend a low power, wide-field EP (24-32MM range), a mid-range EP (10-18MM range) and a high power EP (5-9MM range).
ES stuff is high quality but at prices the rest of us can afford. Check it out. Good luck on your search!

STARKID2U

The Explore Scientific eyepieces are on sale everywhere, not just OPT.

exjeraca

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Re: Newbie Brain Hurts - please simplify (eyepiece/diagonal)
« Reply #20 on: January 14, 2018, 12:36:17 AM »
Quote
You could get Plossls but you're probably better off getting Explore Scientific EP's. I recommend the 62* or 68* line of EP's. It turns out that BOTH sizes are ON SALE at OPT!
I gave them a call and double-checked to make sure that the 62 and 68 EP's were the correct FOV for an f/10 SCT and that's what they recommended. The eye relief is excellent, too. 82* would be too much EP for your scope so don't worry about them. All of OPT's (optcorp.com) staff are astronomers so they knew what I was talking about. So, having said that, I'll let you contact them and have them help you pick out the EP's you'll need. I recommend a low power, wide-field EP (24-32MM range), a mid-range EP (10-18MM range) and a high power EP (5-9MM range).
ES stuff is high quality but at prices the rest of us can afford. Check it out. Good luck on your search!

STARKID2U

First of all, I certainly wouldn't call the eye relief on the 62s or the 68s "excellent." I'm not sure any of the ones below 20mm in focal length are useable with glasses (I can't really use the ES 68 24mm with glasses). For example, the 16mm ES 68 has a scant 11.9mm of relief. The 62 14mm has a mere 10.4mm. That's not any better than plossls.

And I am rather confused as to why you would claim that 82-degree ES eyepieces are "too much" for an SCT. Every ES 82 eyepiece is perfectly usable on an 8" F/10 SCT, save perhaps the 4.7mm (too much magnification). Given the OP wants to keep costs down, they would not be my pick, but for someone who wants 82-degree fields, they are certainly good picks, particularly for an F/10 scope.

liomocharla

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Re: Newbie Brain Hurts - please simplify (eyepiece/diagonal)
« Reply #21 on: January 16, 2018, 11:33:17 PM »
For a starter eyepiece either a 25mm or 32mm plossl, would be a good choice. You can get decent one for around $20 to $25 and they perform well. I absolutely would not recommend a plossl under 25mm. For an inexpensive good diagonal I would recommend a Celestron 1.25 Prism Star Diagonal, around $30 to $40 dollars. Total at most $65.

frenafverbi

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Re: Newbie Brain Hurts - please simplify (eyepiece/diagonal)
« Reply #22 on: January 20, 2018, 02:20:45 PM »
I dislike the "kits" because they usually include several eyepieces that aren't useful.

For most telescopes, two eyepieces is a good way to start. That particular scope would have included just one... a Meade 26mm Plossl (Meade includes that same eyepiece with every telescope they sell... whether you pay $100, or 10,000 ... it comes with the same 26mm eyepiece). Anyway the 26mm on that scope is sort of a "middle of the road" eyepiece... not particularly high magnification and not particularly low either.

For your scope a "low" magnification (wide field) eyepiece would be something in the 35-40mm range (I own a 41mm with my scope).
A "high" power eyepiece would be something in the 10-15mm range (I use a 13mm).

You can see how the 26mm is basically about half-way in between low and high.

You can use any eyepiece that fits... but if the eyepiece is less than 10mm then you'll likely think things are just a bit too much on the fuzzy side to be enjoyable.

Eyepieces for your scope will either have 1.25" diameter barrels or 2" diameter. I'd probably nudge you toward a 2" diagonal since it opens up so many more options for low-power (long focal length) eyepieces. Most eyepieces in the 30-40mm and greater range are probably going to have 2" barrels. Eyepieces with shorter focal lengths (25mm and below) generally only need 1.25" barrels (they make them with 2" barrels as a convenience for people with 2" diagonals... so they don't have to reach for their 1.25" to 2" adapters.)

Brandon Belknap

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Re: Newbie Brain Hurts - please simplify (eyepiece/diagonal)
« Reply #23 on: January 23, 2018, 02:49:05 PM »
And here's one of the things that made my brain hurt - in the photography world, the higher the number on a lens, the greater the magnification. A 10mm lens would be a fisheye, while an 800mm lens would be a serious telephoto. Now I start reading all of the posts about eyepieces, and it looks like the larger the number, the lower the magnification.

This is why I ask the questions....

tingranseattters

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Re: Newbie Brain Hurts - please simplify (eyepiece/diagonal)
« Reply #24 on: January 23, 2018, 03:36:56 PM »
Looking through the classifieds, I see "made in Japan" as part of the description often. Are the Japanese-made versions of a particular optic better?

corloconre

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Re: Newbie Brain Hurts - please simplify (eyepiece/diagonal)
« Reply #25 on: January 23, 2018, 03:39:25 PM »
Quote
And here's one of the things that made my brain hurt - in the photography world, the higher the number on a lens, the greater the magnification. A 10mm lens would be a fisheye, while an 800mm lens would be a serious telephoto. Now I start reading all of the posts about eyepieces, and it looks like the larger the number, the lower the magnification.

This is why I ask the questions....

I’m pretty new also. Remember magnification is focal length / eyepiece diameter.

Alex Strouth

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Re: Newbie Brain Hurts - please simplify (eyepiece/diagonal)
« Reply #26 on: January 25, 2018, 05:31:46 PM »
Quote
Looking through the classifieds, I see "made in Japan" as part of the description often. Are the Japanese-made versions of a particular optic better?

Not necessarily because they're Japanese made, but usually because they were manufactured at a time where you could get excellent manufacturing standards from Japan at a market price people were willing to pay.

Currently what matters is how much the vendor is willing to pay for X quality at Y consistency. My Explore Scientific 92 degree eyepiece is as good or better than any TeleVue from Japan or Taiwan that I've looked through, and it comes from China. But it also costs a lot more than many TeleVue eyepieces. So its quality is not so much a factor of *where* it was manufactured, but how much money was thrown at ensuring exceptionally high quality.

But that wasn't always the case either. Older eyepieces made in Japan are a better bet for quality than elsewhere. Today, that's not necessarily the case.

Stanley Edwards

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Re: Newbie Brain Hurts - please simplify (eyepiece/diagonal)
« Reply #27 on: January 25, 2018, 08:42:04 PM »
Quote
And here's one of the things that made my brain hurt - in the photography world, the higher the number on a lens, the greater the magnification. A 10mm lens would be a fisheye, while an 800mm lens would be a serious telephoto. Now I start reading all of the posts about eyepieces, and it looks like the larger the number, the lower the magnification.

This is why I ask the questions....

It still works that way with telescopes. The longer the focal length of the telescope, the more magnification. Think of the eyepiece as the camera (or at least part of the camera).

You have a scope with a 2032mm focal length. If you had the 10" F/10 model, your focal length would be 25% longer, and so would your magnifications. If you buy a 500mm refractor, you'll get 1/4 the magnification with the same eyepiece.

The telescope projects an image at the focal plane just like your camera does. Only instead of having your camera sensor at the focal plane, you have the fieldstop of an eyepiece. Changing eyepieces is like changing cameras with different sizes sensors. Let's say you put a 200mm lens on a full-frame Nikon DSLR and take a picture. Then you take that same lens an put it on an APS-C-sized sensor camera. Now you get 1.5X more magnification (1.6X for Canon), because the sensor is smaller. Now place it on a Nikon 1 body (with adapter), and you get 3X more magnification.

The longer the eyepiece, the bigger the fieldstop (assuming the design is scaled). So a longer focal length eyepiece yields a bigger field of view (less magnification), just like a larger sensor means a bigger field and less magnification.

buddderpdrivla

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Re: Newbie Brain Hurts - please simplify (eyepiece/diagonal)
« Reply #28 on: January 30, 2018, 11:31:59 PM »
Quote
Quote

And here's one of the things that made my brain hurt - in the photography world, the higher the number on a lens, the greater the magnification. A 10mm lens would be a fisheye, while an 800mm lens would be a serious telephoto. Now I start reading all of the posts about eyepieces, and it looks like the larger the number, the lower the magnification.

This is why I ask the questions....

I’m pretty new also. Remember magnification is focal length / eyepiece diameter.
No, magnification is focal length of telescope / focal length of eyepiece.

Malcolm Verano

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Re: Newbie Brain Hurts - please simplify (eyepiece/diagonal)
« Reply #29 on: January 31, 2018, 02:47:17 AM »
Quote
Ditto.
Find someone selling the basic eyepiece kit from Meade or Celestron used either here or on AM (many post the same ad on both).

"AM" is a new abbreviation to me (I'm a ham radio operator. Right now, to me it means "Amplitude Modulation".) What is that?