I just got one of my Back to the Future items delivered to me, a 12.5mm Orthoscopic EP, manufactured by Kokusai Kohki of Japan. I had been wanting to get one for awhile to test it out and see if all the hype about orthos was true, and so I had been scanning the Cloudy Nights classifieds for a few months in hopes that one would turn up at a decent price. It finally did.
Back when I was observing as a teenager over 30 years ago, orthos were no big deal. They were relatively standard EPs that you would get with your scope, a step up from the Modified Achromatics that Meade would provide with the telescope. MA is just Meade’s fancy name for a three-element Kellner. Orthos have four elements, but didn’t do anything to improve the AFOV.
Lo and behold, after coming back into the hobby 30 years later, apparently the Orthoscopic EP is revered as providing the sharpest views available, especially on solar system objects. Who knew that I had been the proud owner of the top-of-the-line EP when I was a kid?
I had been particularly waiting for one in the KK line, because I could semi-justify buying it. Ideally, I would have wanted something in the 10mm range, because 154x would provide me with reasonably high power on the planets and would still be usable in less-than-ideal atmospheric conditions, while providing me with reasonable eye relief. However, I already have two EPs at 10mm, and another at 9.7mm, and two more at 9mm and 8mm So, no, I couldn’t justify getting another 10mm EP.
But 12.5mm? Well, to quote the Wizard of Oz, that’s a horse of another color. It would be smack in-between all the 10s and the 15mm I have. And at 123x, it would almost be a reasonably high power. Plus, it would have a generous 10mm of eye relief, and I could Barlow it to get 6.25mm and 246x if the conditions were right. Right? Sold!
Which brand of ortho to get? It seems that most orthos are made in the same factory in Japan. The Baader orthos appealed to me, but they recently switched up their line to only offer a 10mm ortho, when they used to offer one at 12mm. I wanted to get one of the more modern “HD” orthos anyway. I know those two letters are nothing but marketing hype, but still, I figure that a newer model has improvements that older models don’t have.
So, I take the telescope out, first for some solar. And yes, it was clear, even though it was only the day after I got the EP in the mail. Screw you again, astronomer’s curse! Well, the new EP did not disappoint. Views of the sun were very sharp. Kinda like this:
And, no, I didn’t take this one. But that’s what the view through the KK Fujiyama ortho looked like on May 10, especially that large sunspot group to the right of center. Any of those large sunspots is bigger than the entire earth.
That night, it was Jupiter and Saturn’s turn. Jupiter looked great, but the seeing wasn’t as good as it could have been; although the GRS was transiting, it was nowhere to be seen, even with the Moon & SkyGlow filter. Just the little notch out of the equatorial band, which I was quite used to seeing. But the bands themselves looked good and detailed, and I could easily see a third band on the north half. The 123x from the 12.5mm might have been just a little light on the magnification to see the GRS, though, so I Barlowed it to get to 246x. The EP took Barlowing very well, and the detail was all still there, but still no GRS.
I also compared it to some of the other eyepieces I have. The ortho clearly bested not only the 10mm Orion Sirius Plossl, but also the 10mm Celestron Luminos. In fact, it became very clear why the Luminos was not a planetary eyepiece. Oh, it’s still a good EP, don’t get me wrong. But it’s definitely nowhere near as sharp as an ortho.
I switched over to Saturn. I was sure I was seeing the Cassini Division for the first time, but really only with averted vision. That’s definitely an accomplishment, though – I can now finally say I’ve seen the rings of Saturn. I also saw what looked like a differentiation in banding on the globe itself. Unfortunately, Saturn still being only 25 degrees above the horizon did not help. It’ll be just a little higher in a couple of weeks.
I tried for M4 again, but it was still invisible. I’ve since read that it has very low surface brightness that is easily washed out by the slightest light pollution. Unfortunately, this means that the chance I had last month when I went out observing around 3am when Saturn was at 31 degrees altitude and light pollution was at an absolute minimum is about the best chance I’m going to get to see it unless I head south. Waaay south. Like South Carolina south. I really do need to get this scope out of the City.
My brother has a “big number” birthday coming up, and he has a strong interest in astronomy, partially as a reflection of my own. So I’ve decided to fan the flames of interest and get him his first scope.
I initially thought about getting him the aptly named Celestron FirstScope. This is a short-tube, wide-field f/4 3-inch reflector, with a spherical mirror cemented to the bottom of a foot-long tube. My cousin had bought one a year and a half ago, and I looked through it at the moon with him and his kids. I was impressed – the view actually wasn’t bad, even though the scope itself was practically a toy.
It doesn’t come with a finder of any kind, and I couldn’t wrestle Jupiter into the scope that night. It’s just 40 bucks, and because of that it comes with dreaded Huygenian eyepieces. Dreaded because of their poor visual quality and very limited apparent field of view of only 35 degrees or so. You have to buy an accessory package for an extra $15 to get a finder – and two other terrible Huygenian EPs, for a total of four. But that night I used my 4mm Plossl to deliver 75x and serve up a nice-sized moon.
But a definite big step up from that is the Cometron FirstScope. For just 10 dollars more than the regular FirstScope, it already comes with the finder attached, so that is a big savings right there. Plus, it comes with Kellners, perfectly acceptable EPs, and a very big step up from the Huygenians. This was sounding better and better.
After asking about the scope on Cloudy Nights, I began to feel cheap. 50 bucks for a big birthday like this was definitely cheap, even if I am unemployed. Although the Cometron would provide nice wide-field views, it would only be able to get him 15x and 30x out of the box, and that’s about what Galileo had. I’d like to think that in 400 years, we’ve come a little further than that. I decided to up the ante and go for something much better.
I decided on the Orion SpaceProbe 3 instead, for $120 with tax. Fortunately, I did just receive a $150 Amazon gift card from using my Citibank rewards credit card, so this is both free money AND a nice gift. Although still a 3-inch spherical mirror, it is a much longer focal ratio and length – f/9.2, 700mm, which means a couple of things. First, and most importantly for an uncoordinated numbnuts like me, that collimation will not be a problem for him – and collimation is possible with this scope, as the mirror is not cemented in. This is important, because I can’t really help him too much on the collimation front, so the less necessary it is to collimate the thing, the better for everyone concerned. At least there are YouTube videos he can watch.
With that nice long focal ratio, I have been told that if you can see anything through it, it’s collimated well enough. Going along with that, coma becomes significantly less of a problem at the high focal ratio of f/9.2 as opposed to at f/5 or f/4. Coma is where the stars at the edge of the field of view get distorted and start to look like seagulls, which is a problem for all low focal ratio reflectors – like the Cometron, but also like any dobsonian 10 inches or larger. Collimation becomes key to getting good views from your scope.
Second, with the longer focal length, it’ll deliver higher magnifications immediately. Sure, the higher powers come at the sacrifice of a smaller true field of view, but it comes with two Kellners, a 25mm and a 10mm, that will give him 28x and 70x right out of the box. And the 25mm will still give him 1.8 degrees TFOV, which is plenty.
The tripod looks halfway decent, and since he likes to go camping in remote locations without picnic tables, he could take this along with him and use it as is. It comes in both an alt-az and an equatorial version. I decided on the alt-az because it would be simpler for him to just point and look; I’ve always found working with an eq mount to be a fight against the scope to point it.
He should get the scope by the weekend. I hope he likes it! If he does, I have a 6mm Kellner that has now become obsolete for me, due to my Barlowing my 12.5mm ortho. I can mail it to him so he can get up to 117x, close to the maximum magnification of the scope, and a nice jump up from 70x. I also hope to have a full report on it from him on the scope in a few weeks. Stay tuned.