Which eyepiece

[Katie1990]

Hi,

 

I have a skywatcher 200p dob and was hoping someone would be able to recommend an eyepiece with a wide field of view that would help finding objects and observing larger objects like the Pleiades. I have had a look at an explore scientific 30mm with 82° FOV, but was unsure if it would be good with my scope.

 

Thanks

Katie

[Stu]

Welcome to the forum Katie.

The ES 30mm would certainly be a good option if within budget. It would give just on 2 degrees field of view in your scope which would fit the Pleiades in very nicely. I have one and use it in a variety of scopes and find it very good.

[Katie1990]

Thanks for your reply Stu. I was unsure whether it was worth paying that much when my scope was pretty much the same price. But if i ever decide to upgrade it at least id have decent EP's.

[vlaiv]

If looking for something cheaper, that will be a good wide field EP for 200p, take a look at ES68 28mm.

I have that combination (200p+ES68 28mm) and it is marvelous EP in my opinion. Framing on Pleiades might be a bit tight, an you will not be able to fit whole M31 with it, but it gives nice darker background because it is a bit higher mag - exit pupil is around 4.75mm

Here is what it looks like in terms of FOV on Pleiades

https://astronomy.tools/calculators/field_of_view/?fov[]=1|133|||1||&messier=45

Be aware that ES82 30mm is very heavy eyepiece - more than twice the weight ES68 28mm (995g vs 475g) and you may have balancing issues on 200p (need to add a counter weight on back of OTA). I use ES68 26mm on my dob without counter balance and it works ok (needs a bit of tension on ALT control, but otherwise ok).

Alternative to above ES68 28 is a bit larger TFOV / less magnification / larger exit pupil - ES68 34mm (more expensive than ES68 28mm and also heavier at 700g).

 

[Stu]

37 minutes ago, Katie1990 said:

Thanks for your reply Stu. I was unsure whether it was worth paying that much when my scope was pretty much the same price. But if i ever decide to upgrade it at least id have decent EP's.

I certainly think it is good value at the price, and it is well worth looking out for second hand bargains on here or on the AstroBuySell website. Generally speaking, most people look after their kit and you should be able to make a decent saving on new price for something in excellent condition.

Vlaiv is right of course, there are other options out there. Everything is a balance between a range of factors, price, weight, field of view and exit pupil amongst other things.

Exit pupil is a concept worth understanding. It is found either by dividing the aperture of the scope by the magnification given by the eyepiece you are using, or by dividing the focal length of the eyepiece by the focal ratio of your scope. The result is in mm, and represents the diameter of the bundle of light which exits the eyepiece and enters your eye.

So, for the 30mm, you get 30/6 (your scope is f6) = 5mm.

Depending on your age, your pupil dilated to say a maximum of 7mm, reducing as you get older. Using more than this effectively wastes light from the scope. The other effect of larger exit pupils is that the sky can appear washed out under light polluted conditions. Under darker skies and also when using filters, larger exit pupils can be useful. As a finder eyepiece, and for framing larger objects I think the 30mm is very good. You can always add counterweight to the bottom of your scope if needed.

I don't meant to confuse in any way, please do ask if none of that makes sense!

I'm also sure you will get plenty of other useful advice, hopefully from others who use the 30mm ES in 200P dobs.

[Ricochet]

I use a 28mm 82° "Skywatcher" (not actually Skywatcher) Nirvana to get the same framing that you are looking for. This eyepiece was also sold as the William Optics UWAN, and probably under other brands too. As with the 30mm ES82° it is a heavy eyepiece that may require some sort of counterweights. Knowing what I wanted, I watched the classifieds to see if one turned up, and luckily enough, it did.

[bomberbaz]

Another consideration is a 24mm 82 degree ES eyepiece. Its a playoff for weight, cost and field of view. 

First off a little less expensive (50 quid if buying new), fov is still 1.65 in your scope which will still frame pleiades (only 0.4 less then the 30) but maybe of more interest is the weight drops from 1400gm to 870gm making it more manageable. Also worth mentioning is the smaller exit pupil of 4mm which gives a darker background when viewing. 

At the end of the day there is always a play off whatever you go for and all suggestions are worthy on there own merit.

Yes it can be a minefield ??

Steve

[bomberbaz]

Just to throw something else into the melting pot, another worthy consideration is the Nirvana 28mm/82 degree eyepiece.

https://www.365astronomy.com/SkyWatcher-Nirvana-UWA-82-deg-28mm-2-inch-Eyepiece.html

In terms of what it offers it sits bang in the middle of the 24-30mm ES eyepieces (FOV, Weight, exit pupil) however it is quite a bit less expensive than its counterparties at 180 quid.

I have had one, I did like it and it had quite a bit of use. The eye cup took a little getting used to but other than that its well corrected and should perform well in your 200 dob.

Steve

[rwilkey]

Hi Katie, the ES82 30mm would be a very good choice, but it is a heavy beast!  Another recommendation is the SkyWatcher Panaview 32mm (70º AFoV) which is quite light for it's apparent bulk, a stunning eyepiece for its price, razor sharp stars.  This was the first eyepiece I ever bought and I was dead impressed.  Found here: https://www.harrisontelescopes.co.uk/acatalog/skywatcher-panaview-32mm-eyepiece-2.html#tab-3

[Guest]

Hi Katie. I have an Explore Scientific 30 mm 82degree Eyepiece. It does give lovely bright, widefield views. 

[Katie1990]

Thanks guys. Ill have a good look at all your recommendations. ?

[Louis D]

At 30mm, I prefer the 30mm APM UFF.  I compared it to several others in my collection here,  here and here.  Some photos of the eyepieces together:

[vlaiv]

1 hour ago, Louis D said:

I prefer the 30mm APM UFF

That 30mm APM looks sweet - did not know they had this particular focal length of UFF (presumably ultra flat field) series.