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30mm 1rpd eyepiece quick review

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#1 Digital Don

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Posted 10 July 2005 - 11:24 PM

I recently had the opportunity to obtain a used 1rpd 30mm eyepiece. I was hoping 'rpd' didn't stand for 'really poor design' :foreheadslap:

I've read numerous reviews of this eyepiece and the opinions are all over the map so I had no idea what to expect. But I got it dirt cheap so I figured, what the hey! As it turns out 'rpd' could stand for 'really pretty decent'!

The eyepiece was being used with a Celestron 11 (The Stray Cat) and at f/10, it actually performs quite well. There is some distortion at the outer edge of the field, but the view was no worse than the 32mm TeleVue Wide Field I used to have. The 1rpd has a wider apparent field however (80° vs. 65°). The overall impression viewing objects like The Double Cluster, The Veil, and M-31 was very pleasant.

Six of us - all with many years of experience - had a chance to check out the 1rpd and the general consensus was the eyepiece was "good". I had several offers to purchase it (at my dirt cheap price, of course) that were respectfully declined :lol:

Does the 1rpd 30mm perform as well as a 31mm Nagler? Probably not, especially at the edge using a short focal length telescope. However, even at retail price you could buy more than six of the 1rpd's for the price of one 31mm and I doubt that even the Nagler is six times better. :jawdrop:

If you ever have a chance to check out a 30mm 1rpd, you might be pleasantly surprised especially if you're using a long focus telescope.

Don :usa:

#2 Amalia

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Posted 11 July 2005 - 02:46 AM

rpd = Round Per Day? :question:

Amalia

#3 Lawrence Sayre

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Posted 11 July 2005 - 04:46 AM

The owner of Astrobuffet (I.E. the seller) told me 1rpd stands for: "One revolution per day".

You won't be anywhere near remotely close to as pleased with it at f/5, but a Paracorr does make the view look much better. It accomplishes this three ways. The Paracorr flattens the field, clears up the coma, and clips the AFOV down a bit (the 1rpd having a FS of 44mm, and the Visual Paracorr being designed to just permit the rays of the 42mm FS 31mm Nagler to not clip [or vignette]). The Paracorr can't help with the astigmatism of the 1rpd.

#4 Amalia

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Posted 11 July 2005 - 04:57 AM

:lol:

Thank you, Lawrence, now I can google! :)

Amalia

#5 Jim7728

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Posted 11 July 2005 - 06:01 AM

I've recently purchased the 1rpd for my 102ED F/9 and only got a chance to use it once in my light polluted skys. The view seemed pretty good 95% out,IIRC. I call the eyepiece my pretend 30mm Nagler, since I'll never spend that much money on an eyepiece. Yeah, $380 is the most I'll spend. :shocked:

#6 Penarin

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Posted 11 July 2005 - 11:18 AM

Nice to see the 1rpd getting some love.

For owners of longer focal length scopes, this EP is a fantastic bargain. At f/9, it performs very, very well. No complaints.

We'll see how it does at f/8, once my AR6 OTA shows up :)

#7 Sky Captain

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Posted 11 July 2005 - 11:31 AM

I really like my 1RPD in my Meade 10" f10 and my 6" f8 refractor, lots of value for the price and if it can be had cheaper...even better.

Kerry

#8 LivingNDixie

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Posted 11 July 2005 - 11:34 AM

cheap is good!

#9 Craig

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Posted 11 July 2005 - 12:56 PM

I love mine (BW-Optik branding) in my 8" f/10 but hate it in my f/6 and f/5 setups. On the SCT, I chuckle at how nice and wide the view is for how little money. On the f/6 and f/5 setups I start wondering if any doors in the house need stops.

One very nice benefit to me: the Televue "B" focal group 1.25" with a 2/1.25" adapter from a WO diagonal is pretty close to parfocal with the 1rpd and the adapter removed. It's the small things that count sometimes...

Craig

#10 Lew Zealand

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Posted 11 July 2005 - 04:19 PM

When I have the 8" f/10 SCT out, the 1rpd is my favorite EP to use, especially for all the targets mentioned by Don. My father-in-law was mighty impressed with how much EP and FOV you can buy for $95 for these slower scopes.

I use it on occasion in the 100mm f/6 achromat and the edges of the FOV leave quite a bit to be desired but that isn't the scope I bought the EP for. And it's fun to look at a 20x 4° TFOV in the southern summer sky.

#11 Olivier Biot

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Posted 11 July 2005 - 04:25 PM

On the f/6 and f/5 setups I start wondering if any doors in the house need stops.

:lol:
Never thought about using an eyepiece for a door stop. You don't want to dent your door, do you?

Cheers!

Olivier

#12 Mike B

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Posted 11 July 2005 - 04:36 PM

Yup! I've got the BW Optik version of same- in the f10 SCT it's a definite keeper!... at $100 new it's a steal :ubetcha:
;) mike b

#13 gparkerson

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Posted 11 July 2005 - 07:19 PM

I purchased the BW Optik version for use in a 102mmf10 Vixen achro and am more than pleased with the view through that scope. I use it occasionally in a 10"f5.6 Newt w/Paracorr as a "finder" eyepiece only, as edge performance is marginal at f6.4. I did try it in the f5.6 Newt combined with a 1.5X Proxima Barlow and the combination was surprisingly pleasing and still a bit lighter than a 20mmT2 Nagler. The 1.5X Barlow/Paracorr/BW Optik combo was too unwieldy for serious consideration.

#14 Guest_**DONOTDELETE**_*

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Posted 11 July 2005 - 08:41 PM

Back when I still had an SCT and a 1rpd, I would go out only with that EP a good bit. Super perform for f/8 and above.

#15 Craig

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Posted 11 July 2005 - 10:17 PM

It's odd -- at lower f-ratios, I not only get clear coma, but I also get what I might call asters -- fine lines going out towards the edge. It's not just the two you get with coma or the two coma lines and the blur between them. These are clear lines -- a half dozen or so radiating out from the star towards the edge. Don't know what to call those...

Craig

#16 imjeffp

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Posted 13 July 2005 - 08:59 PM

I like mine for all the reasons everyone else has already given. It's not a Nagler 31, but it's also not $600.

I've found it to be very forgiving on eye position and comfortable to use.

I bought an Astro-Physics 2" visual back (scroll down) to use with it, but careful observation didn't reveal any vignetting with the standard visual back/2" adapter.

If you want to see something ugly, try using it with the 6.3 focal reducer.


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