Posts Made By: Rod Kaufman

Any difference with a paracorr on this eyepiece?

I've been considering a 5mm eyepiece as well and I would like to read comments on the two in the above post as well as any comments on the pentax xw and xo models.
I read a recent review of a pentax versus the radian in cloudy nights and the pentax models reportedly did alot better, especially in viewing galaxies. Differences in eyepiece performance are ususally subtle but in the latter case it appeared dramatic.
Any comments on the 5mm pentax xo and/or xw?

Charles,
Some of their eyepieces are made by GSO and some of the focal lengths are reported to be fairly good while others are not. In general, the longer the focal length of your scope, the better for some of these eyepieces.
I think the best unit they sell is not an eyepiece; it's their 2" barlow. I've got one and I've encouraged others to buy it and they've reported excellent results with it in this forum. The ratings of this barlow are also very high on excelsis.com
Some of their larger 2" units in their ultrawide or very wide offerings appear to be the same as the burgess units and the 36mm and 32mm units may be bargains.
I would expect their plossl units to behave as generic plossls that other companies may brand as their own and probably sell for more.

Some additional notes on the 4 and 5mm tests.
Both were conducted independently on Floyd's 14.5" starmaster under conditions of excellent transparency and good seeing.
On the 4mm tests my 4mm vixen 45 degree AFOV eyepiece was a distant third behind the UO ortho and the Burgess eyepiece. The vixen lacked the contrast and clarity of detail that the UO ortho and Burgess units provided throughout the session. I,too, would rate the Burgess unit ahead of the UO ortho relative to contrast and clarity of detail.
On the 5mm units, several things come to mind:
Despite what I've read about the radians being unsuitable for planetary viewing, the contrast and clarity of detail was very good, better than what I saw in the UO ortho. It's throughput was excellent, with a faint star near Jupiter being discerned while it was not evident in the other eyepieces, except for the Pentax unit which afforded the best throughput of the faint star of all of the 5mm eyepieces. The 5mm nagler provided more contrast than the Burgess unit with the belts and bands of Jupiter in sharp relief. I found the pentax 5.2mm unit to provide more of a "pure white" image of Jupiter but without bleaching of the belts, bands, and details of the planet. One can argue the difference in magnification accounted for the perceived differences but it should be noted the pentax unit was tested last and at a time when the planet was low, near the tree line, with a thicker layer of atmosphere to contend with. Even so, the detail was exquisite and more pronounced than what I had seen in any of the other eyepieces.
Finally, a note on the Burgess units: it's my impression that the glass lenses used in these eyepieces seem to have the same appearance as those utilized in a 6mm synta-derived orion expanse unit, with respect to the eyelens and barlow-type unit at the bottom of the eyepiece. I'm not saying the configuration is the same but the appearance of the glass lenses look the same.

I had an opportunity to do some comparos last night at Pinos. I initially compared a 5mm TAK LE eyepiece to Linton's 5.2mmXL on NGC 40, a planetary nebula similar to the Eskimo nebula. I looked for subtle differences between detection of faint, outlying nebulosity as well as detection of faint stars in the field of view. After swapping eyepieces back and forth several times, my impression is there was no appreciable difference beween the two eyepieces, relative to light transmission, contrast and clarity of the image, at least for this particular object.
Clouds moved in for awhile, but I was able to resume observing at 4:00am. I was able to view Saturn at 1500X with Steve Kennedy's 28" reflector. Kennedy put my TAK 5 in his scope and the image was detailed and contrasty. I was able to do a comparo at the opposite end of the parking lot with another reflector with the 5mm TAK and a Pentax 5mm XW on Saturn. I couldn't detect appreciable differences between the two, relative to on and off axis performance with respect to contrast and clarity of image. Both eyepieces were excellent performers.
I feel the choice between the TAK 5m eyepieces and the Pentax models comes down to ergonomics of use and cost. The TAK 5mm offers an AFOV of 50 degrees or so while the pentax units offer considerably more at 65-70 degrees. Eye relief in the pentax models is generous at 20mm while the TAK is adequate at 10mm. Cost is significantly less for the TAK 5mm eyepieces, averaging less than $200.00 new while the pentax XW models are considerably more. Used versions appear frequently on the AM, with the TAK units averaging around $130.00 and the pentax models at more than $200.00. If eye relief and field of view are secondary considerations, I would rate the TAK 5mm as a best buy, based upon lower cost and essentially similar optical performance.

The word on the street is the pending arrival of the next (3rd) generation of the speers waler eyepieces. It seems at least one dealer has a few samples that are currently being evaluated.
I've got the older first generation 10 and 14mm units and the second generation 7.5mm unit. The 10mm unit is sweet and I'll be interested in any improvements upon the design.
It appears at least one vendor (an AM sponsor) has reduced prices on the remaining stock of the second generation units in order to make way for the incoming units.
Progress, progress...

Axioms will not work very well in fast scopes due to off axis aberrations. On-axis views will be very sharp.
I barlow my 23mm axiom in my 16" f4.5 dob and it helps a lot but if you're looking at a DSO, such as the swan nebula, you can use it without the barlow without noticing too much edge distortion. On the other hand, if you're using it to view an open star cluster, use the barlow or you are in for a lot of edge aberrations.

Robert,
Seibert optics has 'em. They should do fairly well with decent eye relief, good correction and a relatively wide field of view.

Mounsey's review on planetary eyepieces states the two are very similar in every regard with a medium glass tone.
I've got the 5mm Tak LE but I feel it's a bit different from ultima line. The eye relief seems a bit more than the ultima but the AFOV is a bit less.

While I haven't used the eyepiece in question, I see Alpine sells a scoptis (sp) 2" 35mm eyepiece that apparently weighs in at well over two pounds and it's relatively inexpensive but it did very well on a cloudynights review (see the link on the Alpine site.)