Your Favourite 2" EP for an 8 x 1220 Dob

[Marty05]

Hi all,
Been lurking for a little while and I now have a question.
I have a 203 x 1200 Bintel Dob (f6), 10 and 25mm 1.25" Plossl ep's.
If I were to buy a 2" EP ( only have enough $$$ for one) what would you more experienced guys suggest and why. What would it do for me that a 1.25" with the same focal length wouldn't?
Thanks.

[raymo]

Get a 2" 30mm 80 degree eyepiece such as Andrews used to sell when I
last looked;[they might very well still sell it]. It will transform your viewing experience. You have to move your head in order to see the whole field of view, like looking through a window. You could get a 2" 2x barlow making it a 15mm for a bit more magnification.
raymo

[Eldest_Sibling]

I have only one 2" eyepiece, a 32mm 70°...

297810

There is also a 38mm 70°, but I would keep to a 32mm and under.

This one is similar or exact, on the inside, the lenses, as my own, and will be fine for an 8" f/6 Newtonian-Dobson...

https://www.sirius-optics.com.au/sirius-2in-70-degree-32mm-eyepiece.html

[mura_gadi]

"What would it do for me that a 1.25" with the same focal length wouldn't?"

Essentially you get a lot wider field of view from a 2" 70/80 degree ep.

Try https://astronomy.tools/calculators/field_of_view/, and plug in your scope and try different ep's. A 1.25" 30/32mm plossl versus the 2" wide fields at 70/80 degrees.


Steve

[The Mekon]

If you want to see what most of these cheap 2" eyepieces offer, I have an ex military 2" Erfle 32mm 70 degree eyepiece you can have for the cost of postage or preferably pick up from my home in Bowral. Most of the wide angle eyepieces on offer are of the Erfle type. I like to call them "awful erfles" If you want a good eyepiece for your 200m Dob, then try a 13mm Nagler. You will be stunned by the difference in views between the Nagler and the supplied eyepieces. I can loan you a 13mm Nagler if you wish.

[wavelandscott]

Before buying any eyepiece, what are you hoping to see or accomplish?

Depending on your intention a 2 inch eyepiece may not be the best “tool” for your task.

There is no special magic in a 2 inch eyepiece and it may not be necessary or appropriate for your intended use.

[gaseous]

Someone else alluded to, the Andrews Communications 30mm GSO Superview is a good wide field 2" eyepiece for the price. If you're looking for something with a bit more magnification, you may consider a Baader 8-24mm zoom, which gets the most use in my 8" dob. Depends on your viewing target preferences to a certain extent, and the Baader zoom is probably 3-4x the price of the GSO 30mm.

[Marty05]

Thanks everyone, some food for thought there.

I guess, being fairly new to this I haven't found my "niche" yet. I'm still at the stage where I want to look at EVERYTHING. Novae, Clusters, planets, moon, sun (I have a solar filter, the type that covers the big end of my 90mm refractor).
I'm sure I will find my sweet spot eventually, or I guess I'll just amass a huge collection of telescopes, eyepieces and filters. (Already have 3 scopes...)

@The Mekon, I'd love to take you up on your offer. I know you refer to them as awful, but it will at least give me an insight on what I'm missing out on with my cheap plossls and it's in the 30mm odd range that was also mentioned in other replies. I'm in Towradgi (Wollongong) so I'll DM you and see what we can work out.

Thanks again..

[Marty05]

Just has a very quick look at zoom eyepieces on line. Wow there's a huge range in quality and price. Seems that you pay for every FOV degree. Probably a fair difference in quality of the optics too.

It does seem like an attractive option though given the many different types of things you could look at. Is there anything in between the Baader and the cheapies? (or is the Baader in between the cheapies and something more expensive).

There's a SVBONY for 90 bucks but 40 to 57 deg.
Celestron is 100 with 40 to 60 deg.
The Baader is around 320 with 50 to 70 deg.

[gaseous]

The Baader Zoom is a pretty well respected eyepiece in the zoom category. I can't comment on the Celestron or SVBony, but I recall someone posting somewhere that the SVBony was actually not a bad little unit for the price. Don't quote me on that though.

[ausastronomer]

How many $$$$$$$$ have you got to spend? If your maximum budget is like $150 then you will be limited to some of the eyepieces recommended so far, which apart from the 13mm Nagler, I would rate as pretty poor.

If your budget is up to say $300 then you can get something a whole lot better than what's been recommended so far, including some excelllent 2nd hand options. If your budget is over $300 then you can get some really nice eyepieces new. Don't be scared to buy high quality eyepieces 2nd hand. Unless they have been badly miss treated, they usually outlast their owners.

If you have a more generous budget 2 eyepieces that perform very well in an 8" dob are the 27mm Televue Panoptic and the APM 30mm UFF. These are a quantum improvement over any budget 30mm 80 degree eyepiece, or eyepieces like the 30mm GSO Superview, both of which I rate as pretty poor in an F6 Newtonian.

Cheers
John B

[Marty05]

Hi John, I was looking around the 200 to 300 mark and could probably stretch a bit on the 300 if the right deal comes along. Working out what to buy with no clear goal on what I want to achieve might be the sticking point.. It maybe better to stick with what I have until that decision is made.

My original 114 x 500 newt came with a 10 and 25mm Kelner. Very poor quality, no coating etc. and also a 2x Barlow of similar quality (or lack of).

Since then I've got a 10 and 25mm plossl, both multi coated. Certainly noticed the difference stepping up to 8" dob with these EP's. Even noticed a big difference with the 114mm.

John (The Mekon) has kindly given me a 30mm 2" Erfle (Thanks again!) and loaned me a 13mm Nagler. Unfortunately no clear skies on a non work night so far but looking forward to the next night I can do some observing. I imagine both of these EP's will be a step change up on my Plossls.

[ausastronomer]

Definitely try those eyepieces out from John Briggs. The Erfle will be pretty "awful". The 13mm Nagler will be very good and at least you will get your head around what a quality eyepiece does.

Some newcomers have trouble getting their head around the concept that in many cases a high quality eyepiece costs as much as their telescope did. You can find some bargains in the telescope world where the telescopes performance doesn't correlate to it's price. Your 8"/F6 dob is one of those. It is a reasonably cheap telescope but they perform very well and well enough to benefit from quality eyepieces. Unfortunately the same thing rarely happens with eyepieces. Cheap eyepieces are generally pretty poor and you usually get what you pay for. Something to keep in mind is that cheap low quality eyepieces have a very poor resale value, whereas high quality eyepieces will always have a reasonable resale value. A new $150 eyepiece, would be lucky to be worth $30 in 2 years time, because it's an eyepiece no one wants. A high quality eyepiece on the other hand will be worth about 75% of it's new price. If you can buy high quality eyepieces 2nd hand, you can almost get your money back on them. To give you some examples, I bought all of my Pentax XW's new for between $AUD 400 and $AUD 440 with some smart shopping, about 20 years ago. There are 2 currently for sale in the classifieds (a 7mm and a 10mm) for $AUD 380 each. I bought my 27mm Televue Panoptic 2nd hand for $300 about 16 years ago. There is currently one listed in the classifieds for $480.

Hard to know what eyepiece you should buy because you haven't really worked out what you like looking at. Over the next couple of years you should look to aquire some quality eyepieces that you can keep for a long time to come that will also work well if and when you upgrade your scope. In time and as an absolute minimum you will need a 2" low power finder eyepiece about 30mm focal length. Something in the 10mm to 12mm range and something in the 6mm to 8mm range as a starting point. The next one in the list would be something between 16mm and 20mm and something high power around 4mm to 5mm. You could also get a decent barlow which will double up on your 1.25" eyepieces.

Over several decades I've found that my 2 most used eyepieces are ones having a ~2mm exit pupil and one having a ~3mm exit pupil. With my F4.5 to F5 scopes that is ~10mm and ~15mm. From my couple of dozen premium eyepieces my 3 most used eyepieces are the 10mm Pentax XW, 14mm Pentax Xw and 17mm Nagler T4 When combined with a Paracorr which has a 15% amplification factor that ends up at about where I want to be. I find those to easily be the best options for general observing of the brighter DSO's including Galaxies, Globular Clusters, Open Clusters, Emission Nebula and Planetary Nebula.

Some of the best value for money eyepieces at the moment are the APM UFF if you are buying new. If you are looking 2nd hand there are some excellent options including Pentax XL and XW, most things from Televue with a couple of exceptions (eg 22mm Panoptic which is clearly inferior to the 24mm Panoptic), Vixen LVW, Baader Morpheus etc. As I said earlier, don't be scared to buy 2nd hand to start with. That basically allows you to try out the eyepiece for a small rental fee.

Cheers
John B

[mura_gadi]

Hello,

I echo all of what John said, particularly for exit pupil and eye relief as they are prime drives of a "useable" eyepiece. If its not useable its a dust collector...

Getting a better idea of where your interest lies is probably the first priority.

I only have 2 years experience more than you, but I have a few of the standard entry level ep's, Starguider's, TMB the plossl etc and a AMP 30mm 80 degree copy, 30mm Bintel and a pre Panoptic 32mm Televue(the APM copy 30mm I got paired with the 80 degree 15mm for $50, the other 2" 30/32mm were free and in one case deserved to be imo.).

The AMP 30mm 80degree in my goto wide field scanner, but I don't use the full field of view, comfortable eye placements is probably around 70degrees. At f6 the edge stars do get trails, I need to really "faceplant" the eyepiece and look at the edges to notice though. Large wide field 2" ep's can take some time to get the most from the view on offer.

The UFF 30mm is my next upgrade for a wide field, from all reports AMP are doing great ep's atm.

I also have a Vixen LV zoom which is my preferred choice for 25mm and under, due to versatility and the sharpness of the image. Some are a little soft at 8mm which mine is, but no regrets for the views it provides from 10mm-25mm at $200 new.

I was thinking about pairing that with a 2.5 powermate which would give me sharp views between 4mm and 10mm. Your maximum power is generally 50x the inches of the scope reduced to 75%. So a 8"1200 is 300 max power, which is what that combo will give me. Pair that with the UFF 30mm and its a great set for under $1000 that will prove to be very versatile imo.



Steve
If your prepared to try 2nd hand even less, and the Powermate will hold its value very well and I expect the APM 30mm UFF will as well. Exchange the Vixen LV for a Baader MK IV 8-24mm zoom for extra FOV ($345 new).

The wider the FOV the worse the image gets, you then spend a small fortune correcting the image to make the wide field worthwhile. You can save good money on good quality ep's if you avoid the wide field requirement (Sacrebleu!).

That's my two years worth, might be worth less than 2cents though... as they say YMMV.

Ps. for faint nebular and other DSO's you may if using adverted vision see the edge stars, but since I only use about 70degrees of the view, the streaky stars are really known unknown's.