Upgrading 2" eyepiece on my 8" Dob focal rate f5.9

[Martin63]

I bought my first "real" telescope two years ago. It's a Orion Skyquest Dob.

My first upgrade was a 16mm Explore Scientific eyepiece, I am happy with it

Now that I know I want to continue this hobby I am willing to spend more money and I am looking to replace the 35mm 2" eyepiece that came with my scope. 

I want to be able to use this eyepiece to scan the sky and help find messier objects.  My location is moderately light polluted.

I was looking at  a TELE VUE 35MM PANOPTIC EYEPIECE.

This cost as much as I paid for my scope, what are your thoughts and any recommendations would be appreciated. 

Thanks!

[Ruud]

The Panoptic is expensive, but it is a high quality eyepiece that performs well at even very fast focal ratios. The ES 68° line isn't bad either. In an f/5.9 telescope an ES 68 might be as good as the Panoptic.

Have you looked at used eyepieces yet? There could well be a bargain waiting for you there.

 

Edited September 11, 2020 by Ruud

[Dippy]

3 hours ago, Martin63 said:

I bought my first "real" telescope two years ago. It's a Orion Skyquest Dob.

My first upgrade was a 16mm Explore Scientific eyepiece, I am happy with it

Now that I know I want to continue this hobby I am willing to spend more money and I am looking to replace the 35mm 2" eyepiece that came with my scope. 

I want to be able to use this eyepiece to scan the sky and help find messier objects.  My location is moderately light polluted.

I was looking at  a TELE VUE 35MM PANOPTIC EYEPIECE.

This cost as much as I paid for my scope, what are your thoughts and any recommendations would be appreciated. 

Thanks!

Because the Dobsonian is non tracking, you need an eyepiece  which keeps the target longest in the field of view. That means going for the widest possible field of view, ie 100 degrees. Ruling out the expensive Televue Ethos, your next best choices are APM HDC or Skywatcher/OVL Myriads. I have all three kinds. For widest possible field of view you can get the APM HDC 20 and 13mm which has provided me with incredible 3D Spacewalk experiences. Unfortunately the Skywatcher 20 and 9mm are out of stock since 2018. So your best luck for planetary (short focal length) eyepieces are Pentax XW 3.5, 5mm or 7mm, TeleVue Delos And Baader Morpheus 6.5mm. I use the Skywatcher/ OVL Myriad 3.5mm successfully on Mars these days on a refractor, but I have not used it on my Dobsonian. You can also use TeleVue Nagler 31mm type 5 for your wide angle views, but the price is twice of the APM, even second hand ones.

Edited September 11, 2020 by Dippy

[Rob_UK_SE]

2 hours ago, Martin63 said:

I bought my first "real" telescope two years ago. It's a Orion Skyquest Dob.

My first upgrade was a 16mm Explore Scientific eyepiece, I am happy with it

Now that I know I want to continue this hobby I am willing to spend more money and I am looking to replace the 35mm 2" eyepiece that came with my scope. 

I want to be able to use this eyepiece to scan the sky and help find messier objects.  My location is moderately light polluted.

I was looking at  a TELE VUE 35MM PANOPTIC EYEPIECE.

This cost as much as I paid for my scope, what are your thoughts and any recommendations would be appreciated. 

Thanks!

Given your telescope’s focal ratio is f5.9, the resulting exit pupil from a 35mm Panoptic would (amusingly) also be 5.9mm. This would be ok, but contrast would certainly improve with a slightly smaller exit pupil under general conditions. I like to use a 4mm(ish) exit pupil for low power views with my dob. I also found the eye relief a little too long on the 35mm pan. However, it is easier to hold your eye in the correct position when using Tele Vue’s eyeguard extender too (might just be my eyes though!). 

My recommendations would be to look into either the 30mm APM ultra flat or 30mm Pentax XW (currently very competitively priced by 365 Astronomy) rather than the 35mm pan. Both of these result in an exit pupil of just over 5mm and have 70(ish) degree fields of view. Other low power options include the APM 20mm XWA (100 degrees) and 22mm Nagler (82 degrees). These result in 3.4mm and 3.7mm exit pupils respectively. The APM will show more sky, but the eye relief is a bit tighter. The Nagler is the most expensive of the bunch, but would probably yield the best overall views when used from moderately light polluted skies, in my opinion.

Edited September 11, 2020 by Rob_UK_SE

[John]

When I had an 8 inch F/5.9 dobsonian, I also had the 22mm Type 4 Nagler and it is a superb eyepiece

Another possibility would be the 28mm Nirvana which is also an 82 degree eyepiece.

 

[johninderby]

Or the TS 28mm version of the UWAN but with a better eyecup arrangment than the flat top UWAN.

https://www.teleskop-express.de/shop/product_info.php/info/p2757_TS-28mm-UWA-82--2--High-Perfomrance-Eyepiece.html

[Martin63]

On 11/09/2020 at 11:03, Rob_UK_SE said:

Given your telescope’s focal ratio is f5.9, the resulting exit pupil from a 35mm Panoptic would (amusingly) also be 5.9mm. This would be ok, but contrast would certainly improve with a slightly smaller exit pupil under general conditions. I like to use a 4mm(ish) exit pupil for low power views with my dob. I also found the eye relief a little too long on the 35mm pan. However, it is easier to hold your eye in the correct position when using Tele Vue’s eyeguard extender too (might just be my eyes though!). 

My recommendations would be to look into either the 30mm APM ultra flat or 30mm Pentax XW (currently very competitively priced by 365 Astronomy) rather than the 35mm pan. Both of these result in an exit pupil of just over 5mm and have 70(ish) degree fields of view. Other low power options include the APM 20mm XWA (100 degrees) and 22mm Nagler (82 degrees). These result in 3.4mm and 3.7mm exit pupils respectively. The APM will show more sky, but the eye relief is a bit tighter. The Nagler is the most expensive of the bunch, but would probably yield the best overall views when used from moderately light polluted skies, in my opinion.

I think I am going to go with the 30mm APM ultra flat 70 degree. The price is right and I want the extra eye relief.

Thank you everyone for the help! 

[John]

12 minutes ago, Martin63 said:

I think I am going to go with the 30mm APM ultra flat 70 degree. The price is right and I want the extra eye relief.

Thank you everyone for the help! 

Will that show you any more sky than your current 35mm 2 inch though ?

[Martin63]

26 minutes ago, John said:

Will that show you any more sky than your current 35mm 2 inch though ?

It is the default one that came with the scope, anything must be better? 

[John]

1 hour ago, Martin63 said:

It is the default one that came with the scope, anything must be better? 

The amount of sky (true field) shown depends on the specifications of the eye piece.

If your goal is to have a sharper view across the field then the upgrade will almost certainly achieve that. If the goal is to also have a wider view then it may not do that, depending on the specifications of your 35mm eyepiece.

 

[Ricochet]

It looks like the supplied eyepiece has a 56° field so the 30mm UFF will have a slightly larger field, 1.75° vs 1.63°. 

[Ally8446]

You will not be disappointed with the APM. I have an OOUK VX10L and the 30mm UFF is superb in it. Crisp and clear to the edge. 

Al

[Louis D]

22 hours ago, John said:

Will that show you any more sky than your current 35mm 2 inch though ?

Let's run the numbers for TFOV:

35mm Orion DeepView: 37mm Field stop (Orion's claim) = 1.77°

30mm APM UFF: 36.4mm FS (my measurement) = 1.74°

30mm ES-82: 42.4mm FS (my measurement) = 2.03°

30mm 80° Wide Field III clone: 44.2mm FS (my measurement) = 2.11°

31mm Nagler T5: 42.0mm FS (Tele Vue specs) = 2.01°

35mm Panoptic: 38.7mm FS (Tele Vue specs) = 1.85°

35mm Aero ED: 44.4mm FS (my measurement) = 2.12°

40mm Meade 5000 SWA (Maxvision SWA): 46mm FS (my measurement) = 2.20°

I have my doubts about Orion's field stop diameter claim because that would imply either a 61° AFOV with little distortion, or large amounts of edge distortion to squeeze in that additional 5° of AFOV at the edges in the claimed 56° AFOV.

The OP has lots of options of varying degrees of edge correction, eye relief, weight, and price to choose from.  My preference would be the 30mm APM UFF to start with.  It may not be much wider, but it will be so much better corrected and will feel much wider with its measured 72° AFOV.  That, and it has very comfortable eye relief.

[John]

Practically any of alternatives would be sharper in the outer parts of the field of view than the stock 35mm eyepiece I would think.

 

[Martin63]

2 hours ago, John said:

Practically any of alternatives would be sharper in the outer parts of the field of view than the stock 35mm eyepiece I would think.

Yeah a significant portion of the edge is blurry.