View Full Version here: : New member - Need eyepiece advice
08-08-2012, 12:39 AM
Gday everyone. Didn't really want to start two posts so I figured I'd put my into & questions into one.
I live south of the river in perth (Baldivis). I've always been interested in space but never got into astronomy until a couple of months ago. Bought myself a pair of 9x63 binos & I'm hooked! Only had a handful of clear nights (that I've been free at least) since they arrived but I'm really enjoying myself.
Anyway, after many late nights researching telescopes I finally made a decision and ordered a Skywatcher BD 150mm mak-cass. Biggest reason I settled on this was it needed to be portable (most important as I intend to take it camping & my car is already a tetris struggle on trips).
I need some advice on eyepieces, my intent was to buy 2-3 quality plossls but I cannot work out which focal length to go for (I understand how to calculate magnification, but have no practical concept of it in an astronomy sense). I'm only interested in planets & the moon at this stage. Focal length of the mak is 1800mm & has option for both 1.25"/2" EPs.
Also filters, it seems pretty standard to go for a ND filter for the moon, are there good ones and bad ones? Are there any worth while planetary filters to start off with?
I've got about $300-$500 left in the telescope budget after buying the OTA and mount if that helps.
If you managed to get through that essay, thanks!
I'm new to astronomy myself, and recently thought the same questions. First off you ask "are there good ones and bad ones" and the answer is yes, to everything. Good and bad scopes, mounts, filters, eyepieces, cameras, camera lenses etc. Getting glass with the perfect optical qualities is more difficult than glass that's just ok. So deciding on how much quality you can afford is the key.
As for eyepieces I bought myself 8mm and 21mm Baader Hyperions. They are awesome compared to the kit eyepieces that came with my (cheap) scopes. They can be used in both 1.25" and 2" focusers and give a nice wide field of view which I find helpful for finding my way around the sky manually. There is a Baader Hyperion zoom eyepiece (8-24mm I think) which is under $400 and from what I've read its quality is just as good as the individual eyepieces. So a nice zoom like this might be the way to go, it covers pretty much the whole range you'll need and if later on you want to buy one or two ultra high quality single EPs you'll have a better idea of what range you usually use the zoom at.
If you go with single EPs I'd recommend something wide (around 20mm) for larger targets and to help find targets, and something under 10mm for more magnification. The specs for your scope should list the maximum practical magnification, divide your focal length (1,800) by the max magnification and that should give you the smallest EP you should consider.
There are also barlows to throw into the mix. A barlow gives added magnification and generally come in 2x and 3x varieties (but there are others). So with a 2x barlow my 8mm and 21mm can become 4mm and 10.5mm. So getting a high quality barlow you can essentially double your eyepiece collection. So try to look at two eyepiece lengths that when used with a barlow give you a nice even spread of choices. For example getting a 5mm, 10mm and 2x barlow would be a waste because the 10mm would become a 5mm so you don't get any extra flexibility for all the gear.
Not sure on the planetary filter side but it seems a good starting filter to get (I'm saving for mine) is the Astronomik UHC filter to help cut through light polution and help bring out nebulae etc. There are also other filters more specialised but they seem to be of use for smaller subsets of targets (and especially for better astrophotography). The Astronomik UHC seems to be the best first choice all-rounder filter, but perhaps for your scope a O III Group A filter would be a better first choice (I'm sure others will be able to better advise).
08-08-2012, 10:08 AM
:welcome: IIS, and astronomy!
Your 150 Mak is a fine instrument! Along with your binos you have the makings of many, many hours under the stars.
If your budget is upto $500, I recommend the Hyperion range too, :thumbsup:. They are fantastic for their price, all have a 68 degree aparent field of view (AFOV), where plossl's are limited to 52 deg, and ALL have 20mm eye relief, from the 24mm to the 5mm - plossl's as the focal length reduces the eye lens & eye relief reduces to the point that you need to park your eyeball onto an eye lens the size of a pin hole. The eye lens of all Hyperions is a meaty big piece of glass.
The one thing about your Mak is how much magnifcation you can use. Being a 6" scope, its highest practical magnification is 300X. Exceed this by much more and the image quality starts to significantly degrade. 350X is also the maximum the atmosphere will allow at the very, very best of times, but mostly around 150X.
The Hyperions range will fit you perfectly. With $500, you can get the 24mm, 13mm, and the 5mm from Australia Telescopes for $159 each (http://www.australiatelescopes.com.au/catalogsearch/result/?q=hyperion) - the cheapest price I've seen in Oz for these. I've got these three EPs and love them to bits. I really only use the 5mm on my 8" dob (800mm focal length), and only sometimes on my C8 as it packs too much magnification in the 8" SCT (2000mm focal length). In your Mak it will give 360X, which is usable, but not too often. You'll find yourself using the 24mm & 13mm most of all. I wouldn't suggest a barlow as the range of magnifcation these three offer makes the barlow redundant. Only puts more glass between you and the universe too.
Filters, nebula filters on a 6" Mak have limited application, just due to the small apperture. You would be best served with a general purpose nebula or light pollution filter, and tops an OIII filter.
Planetary filters, BE CAREFUL! You won't use them too much, so splashing out on half a dozen is not the wisest. Select two or three, and see how you go. Which filter? Have a read of this fantastic Lumicon filter selector chart (http://www.lumicon.com/astronomy-accessories.php?cid=1&cn=Filters). It goes through nebula and planetary filters and their applications. See which filters appeal to you with this info, and then decide.
Which brand? Big lables are very good, but the GSO range is also exceptional for their price. With a 6" Mak, the GSO's would serve you very, very well, :) .
Moon filter, I had a C5, a 5" SCT, and never found the need for a Moon filter with it. Sure the Moon is bright at low power, but not exceptional. I wouldn't bother with a Moon filter with your Mak. I don't even use one with my C8. I could, but when I'm looking at the Moon, I'm not chasing faint galaxies on the same night either. Get my drift?
PS, I've got both 1.25" and 2" barlows, and I've never used them :lol:!
08-08-2012, 07:37 PM
Did a bit of reading around on those Hyperions and they look just the ticket. I'm reluctant to go for a zoom eyepiece as my photography expirence tells me to take a prime lens over a zoom any day of the week (not sure if this is fair comparison but in my head an eyepiece is just a mini photo lens). I'll probably go for the 24mm, the 13mm and an 8mm (start with a more modest zoom & jump up to the 5mm next month if I feel I need it).
Looking at the Hyperions on the baader website, it calls them 'multifunctional modular' eyepieces. It says that you can remove the 1.25mm section for wider fields (one forum post I found refered to this part as a barlow) or add filters & 'extension rings' between the 1.25" & 2" sections to decrease the focal length. Is this gimicky? or can you achieve decent views using such methods?
From what you two have said about planetary/neb filters I'll probably just wait till I've had a few nights through the scope to see if I need them. The three Hyperions will put me close to this months budget anyway.
As for the moon filter, you really dont use one mental?? I've tried a couple of times to look at the moon through my binos and I lasted about 3-5 seconds before walking inside dazed with spots in my eyes. I just assumed the larger aperature of the scope would make it worse. Will the mak with its narrower FOV make it easier to view the moon or am I just soft?
Thanks for your input so far :)
08-08-2012, 08:14 PM
Remember what I said, the Moon IS bright at low power. At high power, the amount of actual Moon you'll be seeing is reduced, and with a proportional reduction in glare. I too get blinded by the Moon, but really only at low power. Have a look at the sketches I do of the Moon. These are all at high power on the most part. The couple I have done of the full Moon did need the use of filters, in which case I used a pair of polarising filters that allow me to regulate how much the image is toned down. I post my sketches here in IIS in the Observational and Visual forum's "sketch the moon night" sticky thread. Have a look. Hopefully it'll inspire you to pick up a pencil and paper too, :D .
The Hyperions can be altered with the use of tuning rings. But these signifcantly alter the focal plane of the eyepiece, so unless you are using a Mak or SCT, your scope won't have enough travel in its focuser to make use of this unique feature. As an example I can only use these rings with my big dob only by piggybacking a couple of extension tubes infront of the EP, which adversly affects the balance of my scope, :(. The rings do work, just not practical with my dob.
The term "barlow" on the Hyperions isn't quite right. The lens they use is another design, whose name just escapes me. Only the 24mm doesn't make use of the extra removeable field lens. Removing the field lens does alter the focal length of the EP. However, the ability to use the altered lens depends on the optical design of your scope, and varies from EP to EP. Only trial and error will tell you if the altered EP matches your scope. I can't help as I don't have a scope like yours. By the same token, I don't see the point of altering my EPs as the range I have serves me fine like they are.
These Hyperions can also be used for afocal photography by using an adapter that threads over the eyelens and then couples to your camera. They really are modular.
08-08-2012, 09:24 PM
With an aperture of 150mm, your scope limiting magnification will be around 300x maximum under very good to excellent viewing condition. But for most night, 150x is the more practical limit. For the moon, because it is so bright, you can push the mag higher.
I have a 200mm Meade sct and I have not been able to use it higher then 300x. even though they say, you can use it up to 400x.Most nights viewing is done at 200x and below.
The Hyperions are good but you should also consider Explore Scientific ep.You may want to consider the ES 8.8mm and the 18mm 82D eyepieces.The 8.8mm will gives a mag of x205 while the 18mm mag will be 100x as the focal of your scope is 1800mm.
There is a lot of buzz on the ES eps at the moment I think VTI sells them for $99.95 and $149.95. Their web site is on vtioptics.com.au
The thing I like about these ES are the huge 82 afov and they are practically water proof!
08-08-2012, 09:57 PM
Wonderful sketches mental! I'll definately give sketching a go once my kit arrives. Its going to take a lot of practice tho, I havent picked up a pencil for anything but technical drawing since junior high school art class! I had not even ventured that far into the forums yet, I definately have a few late nights of reading ahead of me.
Hey Richard :) Those ES eps look good too and very well priced. Unfortunately you're about 30 mins too late, just placed my order on the hyperions. I'll definately concider them when I'm looking to expand.
As for the baaders, I settled on 8mm, 13mm & 21mm. This gives me 225x, 138x & 85x respectively. Now I just have to play the waiting game, plenty of time to play with my binos and learn more constelations.
Thanks again everyone, I learnt a lot tonight. I appreciate the time taken for the detailed responses :)
Shame you didn't search enough, by all accounts the Hyperion Zoom IS as good as the primes so you could have saved a bucket of money. The general "zooms are bad compared to primes" rule that has become ingrained with photography these days is always a comparison of lenses with different apertures. An f2.8 zoom and f2.8 prime at the same focal length are typically very close in image quality, particularly across the middle of the shot. Any image loss tend to be in the corners. The Hyperion Zoom IS comparable to its primes from the various comparisons/reviews I found.
I've got both a Baader 2.2x barlow plus a set of Baader extension rings as well and I find the extension rings give me a slightly better image (tiny bit more contrast, tiny bit less chromatic effects on the edge of the moon) than the barlow. But my scope (only a 114mm newtonian) responds better at highest magnification with the barlow than with the extensions.
I was initially disappointed with my scopes viewing quality and was convinced they were badly aligned and no matter how must adjustments I made (trying various techniques) I still ended up with odd shaped stars and Mars. I took a gamble on the Hyperions and suddenly everything was clear, sharp and the right shape! It was the poor kit eyepieces that were failing me and I gave up on astronomy for a while because of it. The Hyperions transformed both scopes into very usable equipment and I still enjoy it more every time I look through them. I hope you find they transform your scope beyond your expectations too!
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