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Eyepiece recommendations for a 200/900mm newtonian? Considering the baader zoom or individual eyepieces around the same price.


ONIKKINEN
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I keep reading about this notion that fast telescopes require some sort of different types of eyepiece to work well, for instance the explore scientific 68 degree ones say they work well at f5 and above, which my scope is not. Actually my scope is more like f4.2 with the TS maxfield 0.95 coma corrector so worse for this case. Are some eyepieces really so picky about this? I would assume if i pay more than plössl-type money for an eyepiece it would work with mine, but i could be wrong.

I have 3 eyepieces at the moment, all Omegon branded. Omegon Cronus 7 and 9mm (i think 60 degree) and an Omegon flatfield 19mm 65 degree. I think the flatfield is like any other "apm clone" out there as it looks identical to many others from other brands. I also have a good quality 2.5x barlow to extend the range.

What i know i am missing is the extremes and something in the middle. Maybe a 5mm for planets and close ups of the Moon and a 25-30mm wider field eyepiece for rich fields and making it easier to find stuff? Also what i could get is the hyperion zoom eyepiece which sounds very convenient, but lacks the wide fields because of the narrower field of view in the lower power range. Also i keep reading of this "fixed focal length eyepieces are better" type of thing compared to zoom eyepieces.

I am woefully under educated on visual stuff because for some reason visual always had a backseat for my telescopes. Last night i had a great time at the eyepiece with no cameras involved so i am looking to complement that with kit that seems missing from my setup. The budget would be somewhere around the price of the hyperion zoom plus or minus a bit since its not an exact number. I realize i could get just 1 great eyepiece, 1 zoom eyepiece or a few decent ones but i have no idea which ones are the best bang for my buck.

 

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5 hours ago, ONIKKINEN said:

I keep reading about this notion that fast telescopes require some sort of different types of eyepiece to work well, for instance the explore scientific 68 degree ones say they work well at f5 and above, which my scope is not. Actually my scope is more like f4.2 with the TS maxfield 0.95 coma corrector so worse for this case. Are some eyepieces really so picky about this? I would assume if i pay more than plössl-type money for an eyepiece it would work with mine, but i could be wrong.

I have 3 eyepieces at the moment, all Omegon branded. Omegon Cronus 7 and 9mm (i think 60 degree) and an Omegon flatfield 19mm 65 degree. I think the flatfield is like any other "apm clone" out there as it looks identical to many others from other brands. I also have a good quality 2.5x barlow to extend the range.

What i know i am missing is the extremes and something in the middle. Maybe a 5mm for planets and close ups of the Moon and a 25-30mm wider field eyepiece for rich fields and making it easier to find stuff? Also what i could get is the hyperion zoom eyepiece which sounds very convenient, but lacks the wide fields because of the narrower field of view in the lower power range. Also i keep reading of this "fixed focal length eyepieces are better" type of thing compared to zoom eyepieces.

I am woefully under educated on visual stuff because for some reason visual always had a backseat for my telescopes. Last night i had a great time at the eyepiece with no cameras involved so i am looking to complement that with kit that seems missing from my setup. The budget would be somewhere around the price of the hyperion zoom plus or minus a bit since its not an exact number. I realize i could get just 1 great eyepiece, 1 zoom eyepiece or a few decent ones but i have no idea which ones are the best bang for my buck.

 

The assumption that paying more money means the eyepieces will work at a faster f/ratio is a false one.

Eyepieces have to be designed to not yield astigmatism in the outer field at f/4, and very few eyepieces are.

This is one of TeleVue's claims to fame.  I would also add Pentax, Nikon, Leica, and Zeiss to that list.

So far, very few Chinese eyepieces make that list.  The APM XWAs do well at f/4 (and the other brand names for the same eyepieces).

The APM 30mm Ultra Flat field is also a good performer at f/4.

 

Every eyepiece design has a "critical f/ratio" below which edge of field astigmatism increases.  Explore Scientific has not really aimed their designs at the f/3-f/5 market

except the 92° series, which does work quite well in faster f/ratios.  The Orion LHDs also work fine at faster f/ratios.

 

I've explored many lower-priced eyepieces in scopes of f/3.45-f/5.18 (all coma corrected).  Baader does not make anything appropriate, though they work OK at f/5.1 (f/4.4with Paracorr).

All the older designs: Ramsden, Huygens, Kellner, Plössl, König, Erfle, Abbe Orthoscopic, Monocentric, should be avoided if you are looking for correction to the edge.

 

 

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16 minutes ago, Don Pensack said:

The assumption that paying more money means the eyepieces will work at a faster f/ratio is a false one.

Eyepieces have to be designed to not yield astigmatism in the outer field at f/4, and very few eyepieces are.

This is one of TeleVue's claims to fame.  I would also add Pentax, Nikon, Leica, and Zeiss to that list.

So far, very few Chinese eyepieces make that list.  The APM XWAs do well at f/4 (and the other brand names for the same eyepieces).

The APM 30mm Ultra Flat field is also a good performer at f/4.

 

Every eyepiece design has a "critical f/ratio" below which edge of field astigmatism increases.  Explore Scientific has not really aimed their designs at the f/3-f/5 market

except the 92° series, which does work quite well in faster f/ratios.  The Orion LHDs also work fine at faster f/ratios.

 

I've explored many lower-priced eyepieces in scopes of f/3.45-f/5.18 (all coma corrected).  Baader does not make anything appropriate, though they work OK at f/5.1 (f/4.4with Paracorr).

All the older designs: Ramsden, Huygens, Kellner, Plössl, König, Erfle, Abbe Orthoscopic, Monocentric, should be avoided if you are looking for correction to the edge.

 

 

Looks like all of the good ones are quite expensive, some food for thought... Perhaps i should say that a compromise of "good enough" should be noted and perfect correction to the edge not being necessary.

I wonder if the other APM ultra flat models also work well as i would ideally avoid 2 inch barrel sizes just for simplicity's sake? I would say that my 19mm flat field (an apm clone) works at least decently well to a point where it doesn't bother me.

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Well, at least you have corrected the coma.

However, where eyepieces are concerned:  Inexpensive, well-corrected to the edge, widefield--choose any two.

A fast scope unfortunately requires eyepieces designed for the fast f/ratios, and that does not describe most lower priced eyepieces.

The APM Ultra Flat Fields are a notable exception, though they were designed to yield excellent star images at f/5.  They may not fare as well at f/4, though I know the 30mm does fine.

It would just seem a shame to correct the coma to get better star images and then use eyepieces that have substantial astigmatism in the outer field at that f/ratio.

The APM Ultra Flat Field series is also available under the Meade UHD label, Celestron Ultima Edge, TecnoSky Ultra Flat, Altair Astro Ultra Flat, and Orion Ultra Flat names, and few focal lengths from China under the Svbony label.

That might not be a bad place to start.

Add a good 2X Barlow to cover all the necessary magnifications.

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4 minutes ago, Don Pensack said:

However, where eyepieces are concerned:  Inexpensive, well-corrected to the edge, widefield--choose any two.

Like most things in the hobby, the wallet and the wallet holder disagree on whats best 😁.

I would hate to make a "just fine" decision and have to stick with it so ill probably avoid the more affordable ones for now. As i was already considering the Hyperion zoom + maybe one other affordable eyepiece i realize the TV panoptic 24mm would be "just a bit more" (i will pretend its close in cost, although quite a bit more). That would be ideal for me, well made and the widest 1.25 inch eyepiece there is. I hated the idea of buying TeleVue at first, but perhaps that's the direction ill be going anyway... Thanks for the insight!

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I had a look through a BHZ in a Skywatcher 1145p (f4.4) last night to see how it performed. It actually did better than I expected, but astigmatism across the field made finding the correct focus more difficult than with better corrected eyepieces. It was more apparent on brighter stars so with a larger scope I would expect it to be more obvious. In the centre of the field it was slight, but the addition of field curvature made it more apparent towards the edge, but nothing compared to an eyepiece you would traditionally think of as having astigmatism. I should also point out that I do have astigmatism (~0.25-0.5D) in my eye which would have been contributing so a user with a lower value may see better star images. 

As a quick grab and go option I thought it was ok, and would use it again, but given the new cost you may expect more from it. 

I also used my Vixen SLVs (4, 6, 9) and I thought they coped very well at f4.4 and would be a good "budget" choice if the 50° field is acceptable to you. The 24mm Panoptic was stunning in the scope from centre to edge and would be an excellent choice if you can afford it, but will likely make you want to upgrade all your existing eyepieces. 

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I was thinking about this a bit more, do i really need the 24mm? I would get a magnification of 35x, compared to the 44x that i get from my existing 19mm that i think is too bright in terms of background. Most often i am observing from Bortle 6-ish or if im up for a quick view at home it would be a typical city sky hellscape of B8+ so a brighter background is not what i really want most of the time. Also, the 63mm secondary mirror giving a 30% obstruction might make an appearance at this low of a power. I think i can see a shadow of sorts with daytime use with the 19mm, so i would assume the effect gets more noticeable at even lower powers.

I could live without having a wider fov as i can see pleiades with the 19mm fully already, so perhaps the panoptic will have to wait. But what i am missing is something between 44x and 93x which is quite a jump. Also, the 9mm that gives 93x doesn't see much use without a barlow as its mostly a Lunar/planetary eyepiece for me. The TeleVue Delite 11mm or 13mm would be right around the missing ranges and from what i can gather vacuuming up from a million threads here and at CN they do work for faster scopes. Also, they are quite a bit cheaper than some of the other televues. 62 degrees sounds just fine, perfectly viewable comfortably and not too low. I should also note that the 0.95x maxfield corrector is not perfect to the edges, so wider fields might not even be that desirable. Choices, choices...

1 hour ago, Ricochet said:

I also used my Vixen SLVs (4, 6, 9) and I thought they coped very well at f4.4 and would be a good "budget" choice if the 50° field is acceptable to you. The 24mm Panoptic was stunning in the scope from centre to edge and would be an excellent choice if you can afford it, but will likely make you want to upgrade all your existing eyepieces. 

I dont mind the lower FOV at all with planetary and Lunar close ups, so i might just grab one of the Vixens for a high power eyepiece since they are quite affordable. The last bit is what i am a tiny bit afraid of, since its happened on other equipment already but i think this is just how this hobby goes 😁.

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Part1 of my purchases has just arrived: APM 24mm ultra flat field 1.25 inch barrel eyepiece. Might be able to test this tonight as the weather is 50/50 right now and every weather service seems to disagree what happens in a few hours.

Part2 was not in the budget anymore since i had to use the money elsewhere, but since FLO is scheming against all the wallets of the northern hemisphere i ended up ordering a Pentax XW 10mm from the current sale 😃.

Still not sure what focal length eyepieces i should have gone with, but if i would never buy anything if i just kept thinking about this, so these are the ones i ended up with. With these i get 35x and 84x, which i think i will be using quite often. TeleVue eyepieces maybe one day, but for now these will do.

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Sounds like you'll do fine with those eyepieces.  You might want to add a 1.25" Barlow to get to higher powers without breaking the bank.  I won't make any used recommendations because I'm sure the Finland used astro market is nowhere near as robust as the one here in the US.  Others on here could probably recommend a current production Barlow of high quality for a decent price.

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1 minute ago, Louis D said:

Sounds like you'll do fine with those eyepieces.  You might want to add a 1.25" Barlow to get to higher powers without breaking the bank.  I won't make any used recommendations because I'm sure the Finland used astro market is nowhere near as robust as the one here in the US.  Others on here could probably recommend a current production Barlow of high quality for a decent price.

Used market does exist, but since the userbase is quite small there usually aren't that many interesting listings. But i do have a TS optics apochromatic 2.5x barlow (https://www.teleskop-express.de/shop/product_info.php/info/p55_TS-Optics-Optics-TSB251-2-5x-Barlow-Lens--1-25-inch---apochromatic-triplet-design.html) .

Performs well, or at least has performed well with any eyepiece in it so far. Also had a shot at imaging the planets with it and cant fault the apparent quality. I am pretty sure its the same as the GSO 2.5x barlow as they look pretty much the same but with a different brand etched to the side.

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