Cheap EPs for a 10" f/5 Dob

So here are the parameters: 1) 10" f/5 Hardin DSH, 2) price range of <$50 per EP 3) casual observing of lunar, planets, and brighter DSOs.

My preference is for a generous FOV, but I'm willing to compromise on that somewhat for better edge performance in this price range. I do like larger eye lens and reasonable eye relief (good for kids, and neighbors). Lastly, I'd like a parfocal set of 4 in the 5mm, 9mm, 15mm, 20mm range.

What would you recommend? Right now I'm leaning towards the GSO SuperViews, or the Orion Expanses.

Thanks,
Dave

You may also want to consider the antares ultra-wideview eyepieces available through scopestuff and other vendors. I am not sure if they are parfocal but they will do reasonably well in your scope although they will exhibit some degradation at the edges. The 8.6mm does fairly well in my hardin 10" F-5 dob. FYI: I just had my review of the hardin dob posted in the review section of the astromart.

I think you'd have to buy one of these eyepieces and test for yourself how much the edge performance bothers you. I haven't tried this particular combination of scope/eyepieces (maybe others can chime in), but my experience and reading would lead me to avoid cheap widefields entirely with an f/5 scope. Maybe spend a little more on a low and medium power eyepiece and get a 2x Barlow for higher powers? The Orion Stratus seem to be substantially better WRT edge performance, but cost about $120.

If I were to pay attention to only your first line, I'd have to say Plossls or Orthoscopics. With the eye relief caveat, I'd say get a nice barlow for the higher powers instead of individual eyepieces. Adding widefield to the equation just won't add up for me, personally.

Dave:

I have an OPT StarHunter 10 which was made by GSO, essentially the same scope as you have. I have used a variety of eyepieces in this scope, including Orthos, Plossls, Ultima's, Parks GSO, Urfles, and various TV eyepieces including the old Widefields and original Naglers.... These are all good eyepieces in the right scope but at F5 many of them cannot handle the steep light cone and are getting ugly as one gets away from the center of the FOV.

More money will buy better performing eyepieces but if you are looking for decent performance without spending much, I highly recommend the Scopestuff 9mm Widefield. These are apparently the same eyepiece as the Orion Expanse and these do a very nice job IMHO in an F5 Newtonian. Better than any eyepiece I have tried other than the TV stuff, right now it sits in my case between a 15mm TV Widefield and a 7mm Nagler, it fits in nicely. These eyepieces have barlow front section that helps make them sharper towards the edge.

As far as a longer focal length eyepiece, the 15mm is a reasonable choice though not ideal. It is not so sharp at the edge but when used with a barlow provides a 7.5mm effective focal and of course is sharper.

It is my understanding that the Antares WF's are essentially the same eyepiece but with a different barrel design and maybe better coatings.

In the end you will want to get some better eyepieces but these worked for me and provided reasonable enjoyable widefields of view.

If you want to bump up your price range, I think the Naglers and Panoptics are the best choice for an F5 scope. At some point you will migrate towards these, so in the long run the best move from a financial standpoint is to buy the TeleVue stuff now used on Astromart and avoid the intermediate steps and expenses. I think you can find series 1 Naglers in the shorter focal lengths for around $100 and Naglers are rated to be used down to F4, something no other eyepiece can claim.

But hey, get that 9mm widefield from Scopestuff, it's amazing for the money.

Jon

Hi Dave,
At $50 per EP you are going to find it difficult to get wide field EPs that will not have very soft outer FOV in an f/5.
I would suggest getting something with a good 50-52° FVO that is sharp edge to edge. The part of the FOV that is usable is about the same as a 70° FOV EP with poor performance. Something like the Ultrascopic for instance at 52° FOV. http://www.astromart.com/classifieds/details.asp?classified_id=363974
Like these for $50 each. 7.5-10-15-25mm f/l.
The Celestron Ultima series is found at similar prices and are the same EPs basically.
But if you want the wide FOV, I would suggest you either save up and buy one good one at a time. We have all wanted a cheap, wide FOV EP, but they just don't seem to be around. They are either cheap or they are good, but not both.
Also, most EPs have eye relief that is about 80% of their f/l. So a 7.5mm is going to be a little tight. A 5mm is even tighter.
Good Plossls are over looked and under rated EPs too. They are also about 52° FOV, but a good one is sharp, flat fielded and eye relief is as stated, around 80% of the f/l.
Quality and usability is subjective of course and opinions may vary. But I find a soft view that is wide is not as pleasing as a narrower view that is crisp.

My 2 cents is that you'll have a lot more satisfaction with 2 quality eyepieces and a Barlow than you'll have with a case full of cheap eyepieces.
--
Mike