TheSkySearchers-Welcome!

Thinking of buying a wide field eyepiece for my F5 8"/200 mm Newtonian for faint nebulae. Right now I have the stock 30 mm wide field eyepiece that comes with Zhumell telescopes, and a 1.25" 25 mm Celestron stock eyepiece from the 102AZ refractor.

Given the same EP focal length (e.g. 24 mm), is a 2-inch eyepiece inherently better/brighter than a 1.25 inch because more light comes through? I realize TFOV/AFOV, optics design, and eye pupil matter, but is bigger diameter generally better for DSO's?

While I enjoy my Zhumell 30 mm wide field eyepiece a lot, I notice distinct image aberration (off axis astigmatism or coma?) around the outer field. The Celestron 25 mm cheapie has much less distortion in the outer field, but has a smaller field of view and is dimmer than the Z30mm.

2" are not superior to 1.25", they just provide wider field of view. As an example max FOV for 30mm 1.25" EP would be ~50 deg, for 30mm 2" EP you can get ~82 deg. Same power, but wider field.

30mm 2" EP you have is of relatively simple design (Erfle or Konig), they work better in slow scopes, but in fast scope like yours you will see FOV curvature. To address that you will need a better corrected EP, but it takes a lot of glass, so they are large, heavy and expensive.

It is easier to correct narrow field EPs compared to wide fields. As a result simple designs like your 25mm Plossl have flat fields, but narrow 50deg FOV.

Your also need to match EP design to the scope. I believe consensus is that 82 deg EPs are a good match for fast newts like yours. TeleVue Naglers, Explorer Scientific 82 deg, and Meade 5000 UWAs are all good options (lined up from high to low price).

As @Bigzmey said, the only advantage of the 2" format is field of view. If it is a wide field of view that you want, you will find that the eyepieces you want come in the 2" size.

With your scope, the minimum magnification you can effectively use (assuming you have young-ish eyes) is 35mm. A 35mm eyepiece will give you a maximum TFOV/AFOV of 1.5/42 degrees in 1.25", and 2.3/67 degrees in 2".

The image that you look at through the eyepiece is a physical thing that takes up space in the eyepiece barrel. It cannot be wider than the barrel, because any light hitting the sides is gone. So the barrel size is the limiting factor in field of view.

Thank you both, Kathy and Bigzmey.

So the two-inch diameter allows a wider field of view but won't necessarily make faint objects slightly brighter.

Right now all things astronomy seem scarce and pricey, but keeping my eye pupils open wide for a Meade PWA or ES 68-82 wide eyepiece on the used market.

Keep your eyes open for an ES 82° 18mm. That is my go to DSO eyepiece for both my 8” and 12” dobs. Might be a tough find on the used market, but you won’t regret it if you get your hands on one,

The Happy Parrot wrote: ↑Sat Mar 27, 2021 12:24 pm Thank you both, Kathy and Bigzmey.

So the two-inch diameter allows a wider field of view but won't necessarily make faint objects slightly brighter.

Right now all things astronomy seem scarce and pricey, but keeping my eye pupils open wide for a Meade PWA or ES 68-82 wide eyepiece on the used market.

You already have 30mm and 25mm EPs which gives you 6mm and 5mm exit pupil. Your first priority should be to add a couple EPs to cover 3mm and 2mm exit pupils. I would look for 18-20mm and 10-12mm. This would keep you going until you have a chance to pick better quality EPs.

There are a lot of options on used market. ES 82, 68, 62 lines, Meade 5000 UWA, SWA, HD60, Celestron X-Cel LX, Paradigm/Dual ED are all good quality EPs. My first upgrade from stock Plossls was X-Cel LX, it was a noticeable improvement in the FOV, image brightness and quality. I used them for awhile while hunting on used market for better quality EPs.

A two inch eyepiece will not make objects appear brighter, but the wider field of view is great for distended objects such as clusters and nebulae. A great example of this is a view of the Double Cluster in Perseus. With galaxies, which mostly are smaller objects there is no big advantage to a two inch.

2 inch are usually wider FOV than 1.25 but given two eyepiecs in 2 and 1.25 and about the same Focal length you won't see all that much of a difference. but I still prefer the 2 inch ones most of the time.

prowler75 wrote: ↑Sat Mar 27, 2021 3:04 pm Keep your eyes open for an ES 82° 18mm. That is my go to DSO eyepiece for both my 8” and 12” dobs. Might be a tough find on the used market, but you won’t regret it if you get your hands on one,

Interesting suggestion, Craig. I have an ES 16 mm/68 deg., which I really like. Was thinking the 24 mm/68 or 82 would be a good in between step to the 30 mm. Your idea is another possible option as many of these eyepieces are really scarce right now, new and used.

helicon wrote: ↑Sat Mar 27, 2021 6:34 pm A two inch eyepiece will not make objects appear brighter, but the wider field of view is great for distended objects such as clusters and nebulae. A great example of this is a view of the Double Cluster in Perseus. With galaxies, which mostly are smaller objects there is no big advantage to a two inch.

That's exactly what I was curious to know. Thank you, Michael.

Bigzmey wrote: ↑Sat Mar 27, 2021 5:27 pm
You already have 30mm and 25mm EPs which gives you 6mm and 5mm exit pupil. Your first priority should be to add a couple EPs to cover 3mm and 2mm exit pupils. I would look for 18-20mm and 10-12mm. This would keep you going until you have a chance to pick better quality EPs.

I see what you mean. My current eyepieces are:

30 mm Zhumell Wide 2" stock ep.
25 mm Celestron stock ep (unknown type) 1.25"
16 mm ES 68 deg.
12 mm Agena StarGuider ED (same as Paradigm)
8.8 mm ES 82 deg.
5 mm Meade MWA 100 deg

My main interest are nebulae and galaxies, so I find myself using the 25 mm and 16 mm by far the most. The 5 mm is a favorite for planets with the dob. The 8.8 is brand new, and I've only had a chance to use it on the moon a couple of times. The 12 mm and 30 mm get the least use, but maybe I'm all set and should be content with my mystery Celestron 25 mm eyepiece.

The Happy Parrot wrote: ↑Sun Mar 28, 2021 1:19 am

Bigzmey wrote: ↑Sat Mar 27, 2021 5:27 pm
You already have 30mm and 25mm EPs which gives you 6mm and 5mm exit pupil. Your first priority should be to add a couple EPs to cover 3mm and 2mm exit pupils. I would look for 18-20mm and 10-12mm. This would keep you going until you have a chance to pick better quality EPs.

I see what you mean. My current eyepieces are:

30 mm Zhumell Wide 2" stock ep.
25 mm Celestron stock ep (unknown type) 1.25"
16 mm ES 68 deg.
12 mm Agena StarGuider ED (same as Paradigm)
8.8 mm ES 82 deg.
5 mm Meade MWA 100 deg

My main interest are nebulae and galaxies, so I find myself using the 25 mm and 16 mm by far the most. The 5 mm is a favorite for planets with the dob. The 8.8 is brand new, and I've only had a chance to use it on the moon a couple of times. The 12 mm and 30 mm get the least use, but maybe I'm all set and should be content with my mystery Celestron 25 mm eyepiece.

That changes things. Looks like you are well set just need to upgrade the 25mm EP. I would aim for ES68 24mm, ES82 24mm or Meade 5000 UWA 24mm. However, if used 25mm X-Cel LX, Meade HD60 or StarGuider would come out it would be still good improvement over the stock EP.

Bigzmey wrote: ↑Sun Mar 28, 2021 3:18 am That changes things. Looks like you are well set just need to upgrade the 25mm EP. I would aim for ES68 24mm, ES82 24mm or Meade 5000 UWA 24mm. However, if used 25mm X-Cel LX, Meade HD60 or StarGuider would come out it would be still good improvement over the stock EP.

I think you are right, and I've been looking around, but these eyepieces are rarer than hens teeth these days. I wasn't aware of the Meade HD60, good to know there is another option. The Meade 28 mm MWA sounds interesting too.

The Happy Parrot wrote: ↑Sun Mar 28, 2021 12:24 pm

Bigzmey wrote: ↑Sun Mar 28, 2021 3:18 am That changes things. Looks like you are well set just need to upgrade the 25mm EP. I would aim for ES68 24mm, ES82 24mm or Meade 5000 UWA 24mm. However, if used 25mm X-Cel LX, Meade HD60 or StarGuider would come out it would be still good improvement over the stock EP.

I think you are right, and I've been looking around, but these eyepieces are rarer than hens teeth these days. I wasn't aware of the Meade HD60, good to know there is another option. The Meade 28 mm MWA sounds interesting too.

I did not have any experience with 100deg EPs but if your MWA 8.8mm works nicely then other MWAs are worth considering.

The Happy Parrot wrote: ↑Sat Mar 27, 2021 12:24 pm Thank you both, Kathy and Bigzmey.

So the two-inch diameter allows a wider field of view but won't necessarily make faint objects slightly brighter.

Right now all things astronomy seem scarce and pricey, but keeping my eye pupils open wide for a Meade PWA or ES 68-82 wide eyepiece on the used market.

No, the 2” format is never brighter just because it is bigger. Different coatings could easily explain your experience.

I’m very happy with TV Panoptics in the range of focal length of interest. I also have the stock Zhumell 30 mm and know that the edge fuzzes out in my Z12. The Panoptics work great. Maybe used if pricing is a concern?

notFritzArgelander wrote: ↑Sun Mar 28, 2021 5:19 pm
No, the 2” format is never brighter just because it is bigger. Different coatings could easily explain your experience.

I’m very happy with TV Panoptics in the range of focal length of interest. I also have the stock Zhumell 30 mm and know that the edge fuzzes out in my Z12. The Panoptics work great. Maybe used if pricing is a concern?

Thanks nFA. I've read great things about the TV Panoptics, but they are over my budget. Same for the ES 24 82 degrees and Meade MWA's.

All is well, however, as I ordered the ES 24 mm 68 deg. Still an upgrade for me, and hopefully parfocal with my ES 16 mm. Such is the price difference, that I was able to afford an Astronomik UHC-E filter as well for an added bonus.

Congrats! ES68 24mm is a very nice EP.

Bigzmey wrote: ↑Sun Mar 28, 2021 7:17 pm Congrats! ES68 24mm is a very nice EP.

Thank you for the good advice!

All there is to do now is wait for the packages, and sell some unused inventory in the meantime.

Look first to the FOV. That's what determines barrel diameter. It is possible to have a moderate FOV in a 2-inch barrel. As an example, Baader makes some 68° modular eyepieces that have interchangeable barrels. While at a certain point a wide FOV will require a 2-inch barrel, a 2-inch barrel does not indicate the FOV.

Also, someone above mentioned the ES 18/82, and I second that. I love that eyepiece. It's just the right combination of specifications for lots of targets.

Interesting info about modular eyepieces, I didn't know about that feature, though I have read good things about the Baader Morpheus line.

The ES 18mm/82 does look appealing. That may well be my next upgrade, but first I want to try my 24mm & 16mm/68 eyepiece combo on DSO's for a while, and see how it goes. Looking forward to trying the UHC-E filter as well. I think it will play nice with my relatively small telescopes vs. my Lumicon OIII which I feel is too dark.

Will keep you posted!