Hyperion 8mil and 24mil quick first light.

[thing]

Received these from Steve yesterday and against all normal behaviour of the weather after a new purchase it was actually crystal clear here. First impressions were 'Wow these are a bit big' especially the 8mil, but they look extremely well built and come in a nice leatherette pouch inside a sturdy box. Anyway, I aligned the scope while it was still twilight and put the F5 8" Newt on first. I thought I would try the 8mil first on Saturn being as it's nice and bright even at dusk. I focused in and wow, 6 moons straight away and Cassini division clearly visible. This at x125. I x2 barlowed it and lost a couple of the dimmer moons but it was still nice and clear. The 68 degree field of view is magnificent, you actually have to move your eye to look in the corners. I didn't notice any coma to speak of. I then swapped it for my 5mil planetary to compare. The 5mil is very crisp but it wasn't as bright as the Hyperion, quite noticeably. I lost another moon with the 5mil. I tried a couple of doubles, Eta Cas and Mizar and they were beautifully crisp and clear.

It was getting dark by then so I swapped for the 24 mil and it's 1.6 field of view, which is exactly the same as my 40mil plosl so i thought comparing the two would be interesting. I swung over to M45 but was disappointed to find a lot of coma on the brighter stars. Slightly refocusing the central stars helped a bit but you shouldn't have to be doing that. Field of view again was magnificent. I swapped for the 40 mil plosl and it was like looking down a tunnel, albeit with no coma. It was also far less bright than the Hyperion. I reckon the FOV through the 40mil (40 degrees) was about where the good spot on the Hyperion was. I tried the Auriga clusters next and the coma wasn't as apparent on the much dimmer stars, quite acceptable really. It obviously shows up much more on brighter stars. That aside, I was extremely impressed with the FOV, and I know folk go on about 82mil Naglers and the like but I can't see how you could make much use of the extra unless you really moved your eyes and head. I've never looked through one so I may be talking rubbish. Apart from the coma at the outer edges on bright stars it was brighter and sharper than the plosl.

I then tried both eyepieces in an F8 120mil achromat. Apart from the views being dimmer, there was no noticeable coma (through my 52 year old knackered eyes) at all on the 24mil. The 8 mil was again superb on Saturn and doubles, barlowed it did start to dim off but I was at x240 probably reaching the edge of what the scope is sensibly capable of.

To sum up, the 8mil is a staggeringly good buy with the discount from FLO, the 24mil in a slower scope is equally as good, but be aware that in a fast scope you will see the dreaded comets on brighter subjects.

[Milamber]

To sum up, the 8mil is a staggeringly good buy with the discount from FLO, the 24mil in a slower scope is equally as good, but be aware that in a fast scope you will see the dreaded comets on brighter subjects.

Umm, no, you won't see the "comets" unless... both EP's are excellent but they *will* show up any deficiencies in your optical train, as shown above.

Arthur

[Kaptain Klevtsov]

Well Arthur, is there a cure for this, or perhaps even a reason? Not being a visual type dude I wonder about these EP reports and how they relate to the imaging world. Would we be discussing a curvature of the focal plane with the Newt. which is causing the comatic aberration, or a mismatch between the fast optics and the Hyperion?

I've been meaning to investigate why the Newt's suffer "inherent coma" so that I can get round to buying a Parracor or Baader MPCC if necessary for my setups, so any pearls of wisdom would be appreciated.

I don't pretend to understand these eyepiece discussions as I don't tend to use them, but I'm intrigued now. The eyepiece has to cope with what the mirror or lens or whatever is in front of it plonks down as an image, suspended in thin air, to look at. Now the magic bit comes in. Some EPs cope with any old curved plane, or flat plane of an image, but others don't. The legendary Naglers cope with a curved focal plane or a flat one, and the Hyperions cope nearly with lots of the same.

I'm puzzled now, why some Ep's don't care what the image curvature is that they're looking at, while others spit their dummy at the least bit of discomfort. How does this work then? Anybody know, or is it magic?

Kaptain Klevtsov

[GazOC]

Thats not strictly right KK. A f4 ish Newt will show coma in ANY eyepiece (even Pan and Nags), generally more so as the true field of view increases. A 35mm Nagler or Pan will still need a paracorr at f4 to be coma free, just less so than cheaper eyepieces.

[thing]

To sum up, the 8mil is a staggeringly good buy with the discount from FLO, the 24mil in a slower scope is equally as good, but be aware that in a fast scope you will see the dreaded comets on brighter subjects.

Umm, no, you won't see the "comets" unless... both EP's are excellent but they *will* show up any deficiencies in your optical train, as shown above.

Arthur

No deficiences in the optical train, unless you figure in non adjustables like the profile of the mirror. I'm pretty [removed word] about things like collimation etc.

[thing]

To sum up, the 8mil is a staggeringly good buy with the discount from FLO, the 24mil in a slower scope is equally as good, but be aware that in a fast scope you will see the dreaded comets on brighter subjects.

Umm, no, you won't see the "comets" unless... both EP's are excellent but they *will* show up any deficiencies in your optical train, as shown above.

Arthur

No deficiences in the optical train, unless you figure in non adjustables like the profile of the mirror. I'm pretty [removed word] about things like collimation etc. The scope showed a perfect star test, because even though I collimated before the eyepiece test, I wanted to make doubly sure.

[thing]

Oops, finger trouble with the quotes again

[jgs001]

Thing, thanks for the review. I've been thinking about adding one of the longer FL Hyperions and you've helped me decide.

[Macavity]

...I've been thinking about adding one of the longer FL Hyperions and you've helped me decide.

G'wan then - The suspense is killing? (Nice REVIEW too, BTW!) Indeed, it seems hard to criticise the 8mm. And, FWIW, I liked the 24mm more than I expected too. Albeit of "simpler" design, it seems to continue the general progression in quality of the series. A good alternative to the 21mm. And, if the truth be told, with a 29mm fieldstop, it is hard to tell (TFoV-wise) from the 31mm Aspheric - At twice the cost. But the latter may have it's qualities too...

[Kaptain Klevtsov]

Thats not strictly right KK. A f4 ish Newt will show coma in ANY eyepiece (even Pan and Nags), generally more so as the true field of view increases. A 35mm Nagler or Pan will still need a paracorr at f4 to be coma free, just less so than cheaper eyepieces.

Hence the puzzlement. I'm interested in how come an expensive eyepiece can cope with the long focal ratio and the short focal ratio. I was expecting that the short focal ratio 'scope would be suited to some eyepieces, which in turn wouldn't work well in long focal ratio 'scopes. This being down to the differences (whatever they are) in the aerial image that the eyepiece looks at. The differences could be curvature of the focal plane, or something else, I'm guessing here.

So the cure for fast Newts. would be the paracorr then, and would that work with the more budget eyepieces?

Kaptain Klevtsov

[ringz]

the main difference between fast and slow scopes isn't curvature of field, it's the steepness of the angle of the cone of light entering the eyepiece.

For some reason it's much harder to design an eyepiece to cope with the cone of light coming from a fast optic.

Could it be like the reason it's much easier to focus a slow scope than it is a fast scope?

--

Martyn

[thing]

Has anyone or does anyone use a paracorr? Are they worth the purchase? Steve has them up for £80 I think which is the price and a bit of another Hyperion.

[jgs001]

...I've been thinking about adding one of the longer FL Hyperions and you've helped me decide.

G'wan then - The suspense is killing?

The answer is .... Yes... I'm going to get one, the 24mm.

[Starflyer]

I've just received an 8mm this morning from FLO (excellent service Steve) - ooh it does look nice I have a 17mm already and that is a total joy to use.

It's a pressy from SWMBO, but I have a moral dilemma - do I sneak a quick look over the next couple of nights or let her wrap it up tonight (Birthday's nearly 3 weeks away)

Cheers,

Ian

[Sam]

I've just received an 8mm this morning from FLO (excellent service Steve) - ooh it does look nice I have a 17mm already and that is a total joy to use.

It's a pressy from SWMBO, but I have a moral dilemma - do I sneak a quick look over the next couple of nights or let her wrap it up tonight (Birthday's nearly 3 weeks away)

Cheers,

Ian

go on... have a sneaky look... we won't tell.