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Ultra Wide Angle Eyepieces on PF-65EDII (1 Viewer)

BinoBoy

Well-known member
I just ordered a Pentax PF-65EDII from BuyDig.com. They've got them for $400 with a 20-60X zoom eyepiece.

http://www.buydig.com/shop/product.aspx?sku=PKPF65EDII

I assume the eyepiece is the XF which doesn't have enough eye relief for me. So, my plan is to resell the zoom and buy some fixed focal length astronomical eyepieces. I ordered a Meade 5000 20mm SWA which has a 68 deg AFOV. They are on sale half off until the end of the month, so it only cost me $70 delivered. Not a big gamble.

In searching on the web, I was surprised to find that you can now get 82 deg and even 100 deg eyepieces. The 100 deg are pretty much out of the question. They are expensive and huge. The 82 deg eyepieces intrigue me though. I'm a binocular nut but fairly new to spotting scopes. An 82 deg AFOV is unheard of in binoculars. However, I've read that not all astronomical eyepieces will work on the Pentax and I'm not sure how to tell which ones are compatible.

I read a glowing review of the Williams Optics 16mm UWAN ehich has an 82 deg AFOV and costs $200. Has anyone tired the WO UWAN or any other 82 deg eyepiece on a PF-65EDII? The review was written in 2006. Are there any more recently released ultrawide eyepieces that are a better deal?

Thanks,
Mark
 
"Meade 5000 20mm SWA. It has a 68 deg view."

u sure? most of that range have 60deg. mind i dunno if 8deg difference would be noticeable!

erm did u notice that meade 5000 UWA eyepieces are 80degree ?
 
The Skies Unlimited website says 68 deg for the Meade 5000 20mm SWA. I am a little confused about these specs, though. In the binoculars forum, the optics experts say that the old method of computing AFOV as mag*FOV is just an approximation and they gave a formula involving trigonometry to give the correct AFOV. For instance, I have a Fujinon Series 2000 7x35 binocular that has an 11 deg FOV. That equates to 77 deg AFOV by the old method but 68 deg by the trigonometric formula. So, I'm wondering which method the eyepiece manufacturers are using.

I noticed that you mentioned the Meade UWA in another thread. Have you actually used it on a Pentax? What do you think of it? There is a thread in this forum named "Ultra Wide Angle Eyepieces" with a link to a PDF on UWAN eyepieces and the reviewer rated the Williams Optics UWAN as better. He didn't say what he didn't like about the Meade except that there was "a lack of attention to detail" in some of the focal lengths, whatever that means.

Thanks,
Mark
 
Those SWA EPs are speced at 68 degrees AFOV. That's measured/designed not calculated.

The big problem with them is they semed to be a scaled (older design, Erfl) so the ER for glasses wearers on the shorter FLs is not good. See edz comments at Cloudy Nights. Unlike say more modern EP designs that have a more constant ER even at shorter FLs (e.g. the Hyperions and similar come to mind). Still if the SWA for $65 has enough ER for you and you like about 20x (it's bright and has a big exit pupil) then you should be happy.

When you do the calculation the accurate results come from theusing the right trig. The other method (AFOV=FOV*magnification) is just an approximation that really works well for FOV < 5 degrees i.e. not so well for modern wide FOV and wide AFOV bins.

I'd be interest to hear how this works for you.
 
Thanks Kevin,

The Meade 20mm SWA came yesterday. The AFOV is awesome, but the eye relief is just a mm or two short. So, I'm going to return it. I'll probably get a Baader Hyperion.

It's hard to imagine what an 82 deg AFOV would be like, much less 100 deg. Can you even see the field stop? 68 deg seems to be all I could want, but I'm tempted to buy an 82 deg just to see what it is like. I've always thought it would be neat to have an AFOV greater than your eye's. People talk about having a nice picture window view. If the AFOV was wide enough it would be like being outside instead of looking through a window.

Mark
 
I think there is less of a win over say 70 degrees for terrestrial views (unless you can pan your eyes around the view). I think the wide field astro guys though do like the bigger views but there's always a trade off.

I find a true wide angle (> 65 degree AFOV) is nice though and is better than say a 60 degree AFOV.

Can you see the field stop ... well there's not much point in paying for the SFOV if you can't. And that comes down to adequate ER and perhaps face shape. I notice more and more with my couple of set of glasses that I'm having problems seeing the whole FOV for AFOV > 60 degrees though it is nice when it works.

Shame about the ER ... are you using that one with glasses or not?
 
Yes, I'm using it with my glasses. The view is pretty impressive without them. If I really jam the eyepiece against my glasses and turn my head just right, I can almost see the field stop. It's not comfortable though.

I saw an ad in one of my photography magazines from Hoodman. They have introduced some funky titanium eyeglass frames that allow the wearer to flip up each eye independently. The idea is that you would flip up one side so that you can look through your camera or scope and still have correction for the other eye for sighting. Unfortunately, the frames are $199 without lenses. So, a Hyperion is cheaper.

http://www.hoodmanusa.com/products.asp?dept=1067

I wish someone would make eyeglass frames that tuck the lenses under your brow as close to your eye as possible. I would love to use my 7x35 11 deg Fujinon 2000's with glasses on.

Mark
 
just bought a wo 16mm uwa ep:

http://www.williamoptics.co.uk/eyepieces.html

Bought it 2nd hand from bloke in oz, so its in the post atmo....

WIll be about 33x in my pf80. SOunds like a cracker of an ep according to the astro lads, but it has low eye relief, so it may get resold(i wear glasses).
I am suprised to find that I dont need my glasses on to get focus with this pentax scope, never owned a scope like that before, the image has always been slightly blurred with my glasses off,.....I dont really understand why this isnt the same with the pf80 as i have mild astigmatism in my right eye. Guess i will have to ask an optician!
In the field it gets annoying fast to be taking glasses on and off tho, and i prefer to not wear contacts.
 
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I'll be interested to hear how they turn out. I first decided on the WO based on a glowing review I read. However, I changed my mind because of the eye relief issue. I settled on the Baader Hyperion as the widest eyepiece with sufficient eye relief. Eye relief specs are notoriously unreliable though. It all depends on where they measure it from.
 
Csn i add something to the meade SWa eyepieces..(and other meade chunky ep's) - i had one for my astro telesocpe and it was a really good ep..the eye relief is a big let down - however if you don't care about its looks you can rip off the massive twist up eyecup to reveal a slender ep whereby you can use all of the eye relief..with that big eyecup which sits quite high on the ep..you are lucky to get about 2/3 of the stated e.r. - cut the twist up cup off & you can use it all
 
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