Inexpensive EP 26-30 for Binoviewer?

Started by rolandlinda3, 11/17/2004 01:33AM
Posted 11/17/2004 01:33AM Opening Post
We have groups looking through a Denk II binoviewer quite a bit and we need a fairly wide angle with low power set. At the same time, we don't want to break the bank or have lots of newbies handling an expensive set. Someone recommended Ganymede optics; another Antares W70s. Any one had good experience with something between 26mm and 30mm?

We did have one set of plossls but the distortion was noticeable and the pieces uncomfortable to the eyes -- you had to be exactly the right distance from the glass or you could not see worth a hoot.

I am glad for any good reports...

Roland Beard
site: www.christworksministries.org
blog: www.rolandlinda3.wordpress.com
Posted 11/17/2004 04:30AM | Edited 11/17/2004 04:30AM #1
I recently purchased a pair of the 30mm Rini eyepieces from Ganymede Optics for public star party use with my binoviewer. Very large eye lenses with good eye relief. While I have only used them once, I was surprised at how well they performed, considering their $29 cost. Not bad at f/5. I would need more opportunities before I could give a more elaborate review.

The only item of note was that I had to keep my eyes on axis of they would black out, which was probably more noticable because they do not come with rubber eyecups. So I just ordered a pair from Scope Stuff to see if it helps keep my head better positioned.
Posted 11/26/2004 07:09AM #2
I found 2 user reports on RINI 30mm MPLs. I got a pair based on the reports and then did a test tonight. In short, I like them and would buy them again. For higher magnification, I also still like my 14 mm Antares w70s. If you are looking for inexpensive EPs for a binoviewer or want one of these as a single, feel free to read my report. Roland

__________

Observing: Nov 25

Weather: Clear, light breeze, temperature: 32 F
Sky conditions: poor due to bright moon near zenith
Scope: 12.5” F4.5 Dob with EQ platform; cold-soaked for 1 hour
Test: Denk II Binoviewers with low cost eyepieces--Rini 30mm, Meade SPL 26, Antares W70 14 m--to compare brightness, field of view, and ease of use
(also used single 22m Televue Panoptic for FOV comparison and contrast)
Objects: Saturn & moons, Orion’s Belt, Orion, & Moon (near full)
Observing time: 2330 EDT for 70 minutes

Summary: The Rini EPs were very good with respect to brightness and ease of use. I did not find any serious distortion for objects near the edge of the FOV. Their field of view (FOV) is about 50% better than the Meade 26mm SPLs and deliver better contrast and brightness. For more magnification, the 14mm Antares delivered very good brightness and were also easy to use. For the price ($65 including shipping), the Rini 30mm pair is our choice for lower cost EPs with decent performance that provide very good field of view. For more magnification, the 14 mm Antares W70s, which are also not expensive, also perform well.

One note: when I ordered the Rini EPs, I had sent a note saying that I was going to use them in a binoviewer. When they were sent, the ticket said the pair had been “matched”, which indicates to me that someone takes the time to make sure the pair truly is a matched set. I did not have to adjust the diopters on the Denk IIs to get good performance so whatever they did to check them apparently works.

Details:

I used the 22 mm 2”/1.25” Panoptic to adjust my TELRAD and check the condition of the optics before starting with the Denk II and OCS combination. I focused the 22mm on Saturn, where I could also see 2 moons very close to the planet but they were also very faint. If I was slightly out of focus, the moons would disappear. This made a good initial checkpoint for my binoviewer testing with the pairs of optics. I viewed Saturn with the Rini 30s and the Meade 26s. I could still focus and see the two faint moons quickly but the Rini 30s had about 1/3 larger FOV and the moons and local stars were brighter. The Rini 30s were comfortable to use and eye relief was good.

I went to Orion’s belt and found the same results. I also compared the double (Mintaka) using the Rini 30s, the Meade 26s, and the single 22 Panoptic. Again, the FOV, brightness, and ease of use of the Rini EPs was a noticeable improvement over the Meade 26mm. I did notice that differences in star color were more easily detectable with the 22 Panoptic than the Rini 30s with the binoviewer, but I presume this is due to ½ the amount of light going to each eye with the binoviewer setup.

In viewing Orion (M42) I used all three pairs of optics with the Denk IIs as well as the 22 mm Panoptic (single EP). In short, the 26s were OK, the 30s were much better, and the 22 Panoptic was a nice change but near as fun as using the Denk II binoviewer. I then looked at the structure of Orion and found that I was seeing as much structure with 30mm Rini pair as the 22 Panoptic single EP. I also compared the Rini 30s with a 2X Barlow and the Antares 14 mm pair without a Barlow. I found it easier to change the two EPs rather than pull the whole binoviewer to add a Barlow. Furthermore, I got better brightness and contrast with the pair of 14s.

The last object I looked at (for obvious reasons) was the moon. I am not really fond of looking at a full moon but I knew it would be a good FOV comparison. I like having an EP (single) or pair with the bino-viewers that permits me to see the whole moon in the FOV. This also means we can see (with the proper filters, of course) the whole sun in a FOV. The Rini 30s accomplish that task very well. The Meade SPL 26s cannot quite get the moon in the FOV and the detail is not as good.

Roland Beard
site: www.christworksministries.org
blog: www.rolandlinda3.wordpress.com