Posts Made By: Rod Kaufman

Joe,
I find the pentax models work quite well in my Discovery 12.5" F-5 and in my astrosystems 16" F4.5 dob. Excellent contrast and virtually no distortion with the 10.5 mm model in both scopes.I don't know why you experienced a problem with the 14mm unit;that is weird.
At any rate, it's good to see a post on eyepieces in the eyepiece forum, compared to what I've been reading recently...

Vito,
I have the pro-optic 6mm widefield eyepiece and I feel it reveals very good color rendition in Saturn's globe in my astrosystems 16" F4.5 dob. The edges are soft but not terrible. I think the naglers would have a much better corrected edge and a wider field as well. I did compare my 6mm pro-optic widefield with my UO 6mm ortho and I think the ortho is a tad sharper but the color rendition was more accurate in the pro-optic eyepiece.Just a side note: I have a speers-waler 10mm eyepiece with a 75 degree or greater field of view and you can position Saturn at the extreme edge and visualize the divisions in the ring structure. Not too many eyepieces have that kind of edge sharpness with a wide field of view.

James,
I agree with Jeff. It seems like you have astigmatism from an overly tightened mirror clip. I am not sure of the means by which your mirror is held in the cell but make sure the clips or retainers or screws do not impinge upon the mirror. Lining the mirror clips with cork sheeting will prevent the problem of the mirror shifting around if you are concerned about excessive play between the mirror and it's retainer.

I have some comments regarding the application of various eyepieces relative to performance issues on the planets.
Over many nights of observations on Jupiter and Saturn with a Discovery 12.5" dob and an 16" Astrosystems dob, I attempted to discern subtle differences in performance among the eyepieces in my collection.
I have general comments that may be of benefit to some amateurs, First, I am convinced that a battery of eyepieces are necessary to obtain the maximum amount of detail, color variation,and resolution. However,cost effectiveness is an important issue as expensive eyepieces do not necessarily equate to the best performing eyepieces. After re-reading the cloudy nights review on planetary eyepieces and reflecting back on my recent experiences, I have recognised that some relatively inexpensive eyepieces can outperform more expensive units on specific details on the planets. For example, I found that my seibert 7mm eyepiece gave the best overall resolution on the rings of Saturn as compared to my pentax XL, UO ortho and ultima eyepieces. The difference was not subtle but rather obvious. I found that a 7mm pro-optic eyepiece gave the best color rendition on the globe of Saturn with the Pentax unit close but not as good. The overall contrast between the rings of Saturn and the globe was best in the pentax and UO orthos, giving that nice optical snap every amateur loves to see. The ultimas were also very favorable in this regard.On Jupiter, the differences were apparent but more subtle. I found the pentax eyepiece and the UO orthos to give highly resolved details of the belts, bands and festoons. Color variation was more difficult to discern but the pro-optic widefield 7mm unit and the pentax XL were quite close with perhaps the pentax revealing the best color fidelity. The ultimas were also good in this regard,and also quite good in resolution but not quite as good in revealing subtle color variations.
I would like to read comments from other amateurs who have applied a variety of eyepieces in the observation of the aforementioned planets over many hours with similar instruments. Perhaps some kind of a consensus of opinion or at least a trend of recommenmded use of eyepieces for various surface details may start to be realized. Up to now, it's been pretty much, "this eyepiece is better than another". It just doesn't work that way, in my opinion.

Jay,
I have a JMI mini-max on one of my dobs. The most frequent causes of "encoder error" in my experience are: 1.Low battery--a 9 volt lasts about three full observing nights of about 8 hours per night or less and it's "encoder error" on the scroll line. 2. Faulty cable--most likely at the encoder pin connections. Try a new cable with a new connector. 3. Make sure your unit is set to the proper mount and not on dob or alt/azimuth setting. 4. There may be a bad encoder. I would check the battery, pin connectors and encoder settings on the max and then call JMI and ask to speak to the tech. She walked me through a procedure over the phone and we identified a bad pin connector as a cause of encoder error when I encountered the problem a few years ago. My unit has worked fine after installing a new cable. I hope this helps.

Mike,
I have a Seibert wide-angle eyepiece in a similiar focal length and a 7mm unit and I have experienced good visual performance with both eyepieces. Why don't you send your eyepiece back to Seibert and take advantage of his 30 day momey-back guarantee?

Mike,
Nifty-looking unit. Is the mirror cell commercially available or is it your own design? What is the weight of the main components?

Roman,
I have a 23mm Axiom eyepiece that I use regularly in my 16" f4.5 Astrosystems dob. The edge exhibits significant astigmatism and curvature of the field at a short focal length. However, the on-axis performance is superb and typical of the ultima line of eyepieces. It is particularly useful for planetary observations when atmospheric conditions are less than optimal and during twilight. I also have a fine view of the veil nebula in this eyepiece with a lumicon oxygen filter.

Dan, While I have not done a direct comparison, I do own the Speers 10mm and 14mm units. The 10mm Speers eyepiece has very good edge correction while the 14mm benefits from my 1.25" paracor in my F4.5 16" dob. Both eyepieces, however, deliver excellent images given their widefield of view. I haven't used the 18mm Speers but it appears to have poor reviews due to aberrations such as astigmatism. I would not purchase the 18mm unit for use in my fast dobs. I think the best corrected eyepieces I have used are the moderate to low focal length pentax XL eyepieces which have no distortion in my F4.5 dob despite their 65 degree apparent field of view.

Gregg, I would also expect the 18mm ortho to out-perform the Meade eyepieces. I also have a 18mm UO ortho with normal multi-coatings and my impression is that it is clearly better than the meade eyepieces in my collection. I have used the aforementioned eyepieces in a variety of scopes including my 12.5" Discovery dob and a 16" dob. I also used it in a meade 10" schmidt-cass I used to own. It's possible you got a dud and I would return it and try another one.