Newbie question about eyepieces for 2 scopes [Archive]

Karren

21-10-2007, 12:29 AM

Hi,

I have recently purchased 2 Skywatcher 8" dobs second hand (I live in 2 different places and didn't want to transport my scope around all the time). One is a 1200mm f6 and one is a 1000mm f5. Being second hand they came with an assortment of scrappy eyepieces I am not entirely happy with. I would like to purchase some nice reasonable quality but not frightenly expensive set of eyepieces and a barlow. My budget would be best limited to $50 to $150 each (terribly restrictive, I know). At the moment I am mainly interested in planets, but I know that will change as I get more confident finding things. I also need the eyepieces to be suitable for both scopes (I am not sure how much difference the different focal lengths will make).

I realise that this is an overwhelmingly large question and also a matter of taste, but any assistance you guys would be willing to offer would be greatly appreciated.

Thanks and kind regards,

Karren.

citivolus

21-10-2007, 02:34 AM

Hi Karren.

You will get 20% higher magnification in the 200mm f/6 than in the 200mm f/5. The brightness difference between the two scopes will be on the borderline of visibility, so realistically you likely won't notice much difference between them at all.

For planetary I would suggest a 6mm and a 2x barlow. This will give you reasonable numbers for your aperture, and allow you to push up your magnification in good seeing. A 20mm on top of that would be good for globular clusters, galaxies, and the like, giving you 20mm, 10mm, 6mm, and 3mm focal lengths.

As for designs of eyepieces, for planetary you don't really benefit much from wide field, so to keep the price down you could go with Plossls, just don't expect much eye relief. A 5 or 6mm will run around $90-150, depending on brand and quality. Something in the 15-20mm range will cost about the same. A basic 2x barlow will cost about $110-140. As a low cost example, if you purchased the Meade 4000 series, $290 would get you two eyepieces and the barlow. You can go cheaper with Plossls with non-brand name eyepieces, but every step down in price is a gamble of a drop in quality too.

You can spend more on eyepieces if you want wide field, but your budget doesn't really give much room for that unless you get a good deal used. You can spend less on the barlow, but I am not certain as to the pedegree of a $50 barlow, such as the one from Bintel. I am sure there are people here who can comment.

If you can push your eyepiece budget just a tad, you could go to something like the Vixen LV series:

http://www.myastroshop.com.au/products/vixen-ep.asp

These are nice for the extended eye relief, which is good if you need to wear glasses due to strong astigmatism like I have. $500 would get you a barlow and two eyepieces, potentially giving you a usable range of 3mm through 20mm.

If you live on the edge and feel like importing your own, OPT has a sale on the Baader Hyperion eyepieces for $99 USD each until Christmas. Just keep in mind you wouldn't have local dealer support if you went that route, and any warranty issues would be that much harder to work out. $300 US ($330 AU) would get you two of those eyepieces and a barlow, including shipping. I have not used the Hyperion eyepieces personally, but have heard good things about them here. OPT will also mail packages, if the courier prices scare you.

In the future you would likely want to add some wide angle eyepieces, as well as something in the 32mm or so focal length range if it doesn't vignette too badly on your scopes. However, these eyepieces would at least get you started.

Another suggested inexpensive accessory is a 1.25" variable polarising filter. They don't cost much, but if you ever want to point either of those scopes at the moon, they will save your optic nerve.

Regards,
Eric