1rpd ST80 30mm 2” eyepiece

[Sunshine]

Found his eyepiece in the local classified ads, I would like to expand my eyepiece collection to include a wide 2” when I first use my new dob. Anyone have an opinion about this eyepiece? My dob is f6 1524mm, thanks.

[Rob]

Makes me think along the lines of Moonfish.. I know its not, but wonder if its out the same factory. The Moonfish is good in long F ratio scopes. So if we are talking the same here, you should enjoy it in the f6.. however it will curve at the edge (outer 20%)

Rob

[Louis D]

If you can pick one up for $50 to $70 used, it's a pretty good deal.  After all, they're only $71.60 shipped directly from China (at least to the US).  I have the Agena Astro version with a screw-off eye cup and removeable barlow to convert it to a 20mm eyepiece.

I compared it to my 27mm Panoptic, 30mm APM UFF, and 30mm ES-82 in an 8" f/6 Dob here and here.  I refer to it as the 30mm Wide Scan III clone.  It's the one second from the left below.

[John]

The design (which is available in a number of brandings) will show astigmatism (seagull shaped stars around the field edges) in scopes of F/8 and faster. They seem to work well enough at F/10 and slower so are more at home in SCT's and Mak's

 

[Sunshine]

2 hours ago, John said:

The design (which is available in a number of brandings) will show astigmatism (seagull shaped stars around the field edges) in scopes of F/8 and faster. They seem to work well enough at F/10 and slower so are more at home in SCT's and Mak's

 

Well that answers my question, I didn’t spend a small fortune on a good dob to see seagull shaped stars lol.

thanks to all.

[John]

You might find that a 70 degree 2 inch eyepiece is a better bet. It's not showing quite as much field of view but that also means that what you do see should be better defined.

[Louis D]

2 hours ago, Sunshine said:

Well that answers my question, I didn’t spend a small fortune on a good dob to see seagull shaped stars lol.

thanks to all.

Then give up 7 to 10 degrees AFOV (depending on what is being measured) and get the 30mm APM Ultra Flat Field.  It is reviewed in the same group and is near perfection at f/6 from edge to edge.

The 31mm Nagler T5 is another, though heavier and more expensive, option.

[Sunshine]

1 hour ago, Louis D said:

Then give up 7 to 10 degrees AFOV (depending on what is being measured) and get the 30mm APM Ultra Flat Field.  It is reviewed in the same group and is near perfection at f/6 from edge to edge.

 The 31mm Nagler T5 is another, though heavier and more expensive, option.

Brilliant thanks! I’ll look into the APM’s I hear they’re great.