Pairing Parks Gold Series & Antares Elite for binoviewing feasible?

[janoskiss (Steve H)]

Question for those in the know (ausastronomer I am thinking in your direction):

How similar are the Parks GS-5 25mm and the Antares Elite 25mm?

More specifically: are they close enough to be paired up in a binoviewer? Or will the differences in coatings (I assume Parks is superior) or other subtle differences make them unsuitable for this application?

[MortonH]

Interesting question, Steve.

Over the past few weeks I've been researching and collecting a few oldies, including some ULtrascopics and Ultimas. According to many (most?) posts I've read they are "the same". Whether this is true or just assumption I don't know for sure.

As well as possible minor differences between brands, do you know if there were multiple runs of either eyepiece? If so there could have been differences between runs.

For example, see Matt's recent ad about two Tak 24mm LE's that were different in height by 1mm:

http://www.iceinspace.com.au/forum/s...d.php?t=142811

[janoskiss (Steve H)]

Difference in height is not really a major concern (binoviewers can adjust for that, or a small spacer sleeve can be placed on one EP).

Small differences in focal length would be the worst. But I assume these EPs all use precisely figured identical lenses.

So really the main concern I have is about the coatings. The Elites are multicoated (MC) but not fully-MC (FMC) like the Parks GS. (They're still very good EPs and can't complain about transmission or contrast.) I also have a 35mm Ultima which is also FMC and has a very apparently different coloured coating to the Elites, i.e., when you look at the lens, not through it.

I don't have identical focal lenghts of any two variants so I can't make a direct comparison. That's why I'm asking if I'll get headaches like some folks in old school 3D cinemas where you wore red-blue glasses.

[ausastronomer (John Bambury)]

Hi Steve,

I don't really know the answer to that and I wouldn't want to speculate when someone else's money is involved. I can give you some information which may help you make a decision.

I have used both eyepieces but at different times and over 10 years ago. I liked them both a lot and they are very high quality eyepieces with excellent transmission, sharpness and contrast. Using them at different times I can't remember exactly how matched in performance they were. All of the focal lengths in both series are excellent. You can also add the Celestron Ultimas and Orion Ultrascopics into the mix, as well as the Meade Series 4000 5 element plossls.

I've never had access to any of the technical data regarding any of the variants so I don't know what the coating / glass type specifications were for each variant. The question is, even if there were, would it matter? I don't know, but I do know that the human eye / brain has an excellent ability to compensate for minor optical variations, like field curvature, so very small differences may not be noticeable at all. These eyepieces were produced over many years and there is just as high a probability that 2 of the same eyepieces from the same series, manufactured at different times, have slight variations in coatings / glass type. Again I don't know if it would matter.

I would certainly be giving it a try as you can always re sell one of these if it doesnt work without losing money as they are sought frequently on the used market. However, all that having been said, notwithstanding that different branded eyepieces worked perfectly well, my CDO (OCD but I also need the letters in order) would have me searching the used eyepiece market so I could match them up.

Cheers
John B

[janoskiss (Steve H)]

Thanks John! I do very much like my two Elites. I must be getting old because I can't be bothered with bulky and heavy wide-field EPs any more. I find a 60 deg AFOV plenty. The Pentax XF 8.5mm serves me well there. And given their great performance and convenient size and weight, even at "just" 50-degrees the Elites are a pleasure to use.

The other similar EP I have is not an Ultima (like I incorrectly stated earlier) but an Orion Ultrascopic 35mm. It's pushing the exit pupil for me a bit in an f/4.9 but it's a nice TFOV regardless and in the old f/10 Intes Mak (which only has a 1.25" focusser), it's just what the doctor ordered.

I'll give the Parks Gold Series + Antares Elite pair-up a go. Main reason I am asking about the GS and not the other similar line-ups is that AEC have the 25mm and 15mm for very decent prices (esp. considering the poor $AU-$US exchange rate atm) and I happen to have the Elites in the same focal lengths. (I must say I hate the name "Elite" but you know, whatever ... )

[janoskiss (Steve H)]

I received a Parks Gold Series 25mm thanks to a fellow IIS member. The lens assembly and coatings (the reflections' pattern, colours & intensities) appear virtually identical to the Antares Elite 25mm. The lens edges are better blackened and the barrel is also more of a matte black and the internal baffle looks like it might be more effective on the Antares. These differences are minor and I expect these two EPs to perform the same in practice. I have not had a chance to look through the Parks GS yet.

It's interesting to note that the Parks GS EPs are spec'd as being fully multi-coated, while the Antares Elites are "just" multi-coated. Yet the coatings appear virtually identical (if anything, the Antares reflections appear a smidgen darker; but I'd be surprised if they did not come out of the same factory).

The Parks tend to command higher prices second hand (and also new, when the Antares were available new), yet the Antares appears to be an incrementally better made EP. (A likely explanation is that the Parks I got might be a few years older than the Antares.)

For binoviewing, the main difference is a 1-2mm longer barrel on the Parks, which I'm sure can be accommodated using the dioptre adjustment of the BV.

Yet to receive a BV. I ended up getting this one with 1.8x and 3.0x correctors (and self-centring EP holders); a Chinese FMC 20-ish mm CA unit sold under the Arcturus brand name:
https://www.cameraconcepts.com/store...roductid=17542
Unfortunately there was nothing like this available in Australia for anywhere near this price. ($AU280 for the kit incl. shipping. I did try hard to buy local. Not just by Internet search but also contacting and discussing with several dealers I know to be competent, reliable and trustworthy, notably Claude Voarino @ AEC and Matt Lovell @ Astronomy & Telescopes.)