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Medium powered EP.. Which one??


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I would like to know what is a good medium powered, wide angle EP for my scope. I am aware that some people like the 24mm and 32mm Panoptics. But I am also aware of the magnification calculation of focal length/EP = Magnification. I am assuming that most people will have between 1500mm and 2000mm focal length tubes. My scope has a focal length of only 1200mm. This is quite short for a Dob. My question is should I be looking more towards the 16-19mm EP range to emulate the same magnifications of a larger Focal Length Dob with a 24-32mm range EP? Or am I missing the point completely. I want a wide angle EP to look at DSOs.

Thank you, xmal

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hi Xmal

both of my scopes are 1600mm focal length and I have the 24mm and 35mm Panoptics. They are both outstanding eyepieces.

in my scopes they give magnifications of 1600 divided by 24 = 67x and 1600 divided by 35 = 46x. To get the same view in your scope you would need eyepieces with 1200 divided by 67 = 18mm and divided by 46 = 26mm. The view would be the same (ignoring more/less light through aperture) assuming you had 68 degree field eyepieces like the Panoptics.

I like the range my eyepieces give me

35mm = 46x

24mm = 67x

13mm = 123x

11mm = 145x

8mm = 200x

6-3mm zoom = 267x - 533x

If you work out the same sort of ranges for your scope using the above calculations you wont go far wrong - some people are happy with less eyepieces and they will more or less cover the same sort of thing. Consider both magnification and field of view though as sometimes the FOV can overlap. Other things like eye relief etc are more personal.

Edited by Moonshane
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hi Xmal

both of my scopes are 1600mm focal length and I have the 24mm and 35mm Panoptics. They are both outstanding eyepieces.

in my scopes they give magnifications of 1600 divided by 24 = 67x and 1600 divided by 35 = 46x. To get the same view in your scope you would need eyepieces with 1200 divided by 67 = 18mm and divided by 46 = 26mm. The view would be the same (ignoring more/less light through aperture) assuming you had 68 degree field eyepieces like the Panoptics.

I like the range my eyepieces give me

35mm = 46x

24mm = 67x

13mm = 123x

11mm = 145x

8mm = 200x

6-3mm zoom = 267x - 533x

If you work out the same sort of ranges for your scope using the above calculations you wont go far wrong - some people are happy with less eyepieces and they will more or less cover the same sort of thing. Consider both magnification and field of view though as sometimes the FOV can overlap. Other things like eye relief etc are more personal.

That's the confirmation I needed. By my calculations I needed a 19mm and 25mm, so what you say confirms that. I got a 7mm WO UWAN the other day to get close and personal, but I would like medium powered EP for DSOs with long eye relief. I am guessing the 19mm Panoptic would be right up my street. Any other EPs do you know that might fit the bill?

xmal

Edited by xmal
typo
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My 10" newtonian is 1200mm in focal length - it's a popular focal length actually as 6" F/8 and 8" F/6 scopes are also 1200mm.

I use the following focal length eyepieces:

31mm = 39x

20mm = 60x

13mm = 92x

8mm = 150x

7mm = 171x

5mm = 240x

3.5mm = 343x (rarely to be honest !)

The medium power ones are the most used, particularly the 13mm which is great for globular clusters, galaxies and, planetary nebulae.

Edited by John
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if you like the 7mm UWAN, you'd be hard pressed to do better than buying the set. with your scope they would give (I think I have got the focal lengths right?)

4mm 300x 7mm 171x 16mm 75x 28mm 43x

note that the 16mm would have the same field as the 19mm Panoptic which I think has tighter eye relief than the UWAN but I might be wrong. The 28mm is a large eyepiece and might upset the balance in your dob but not sure about this.

many say the UWANs are about 95% as good as a Nagler which is no mean feat.

Personally I went for TV but these are no slouch vs TV. you might also consider a 12.5mm Plossl or similar to split the gap between the 7 and the 16mm as sometimes seeing above 150x can be a bit tricky.

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In my signature all the EPs are plossls that came with the scope. The 7mm UWAN is the new EP that I have just bought, but have not updated my signature yet. I like the 25mm, and also the barlowed (x2) view, that is why I think I will like the 13mm that John suggested. It is difficult to make a decision. I would like to go to an Astro club and try a few out, but with work commitments and clear skies coinciding with an astro meeting it is difficult to get to try some kit out and just means I am missing some great viewing from home when the weather does clear up. Kinda like the Tele Vue 13mm, but it looks like the eye relief is not too good on it (12mm)

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is that the 13mm Nagler? if you don't wear specs to observe then the ER is OK - not as bad as it sounds. the 13mm Ethos is better (at everything in my view) at 15mm but expensive.

I agree that you should try and look through a few before you buy if you can

where are you based?

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it's an awesome eyepiece I believe. I bet if you look out there will be others around your area that will be more than willing to show you their eyepieces - I am in Manchester so no help from me unfortunately.

best bet I think with eyepieces is buy the best you can afford, slowly and make sure you buy them for the right reasons. you have an excellent scope so that's a great start!

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TBH, I did like the 7mm UWAN, but I have not had one clear(ish) evening since I got it. I would like an EP with the same Wide FOV but more mid-power hence my my original post. Once I know roughly what is good I can keep my eyes open on the for sale section and see what come my way. I think I am sold on the TV 13mm T6. I must admit I really like the scope- for me it is an ideal size to carry around per ounce of sweat per mm of aperture!!!!!!

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TBH, I did like the 7mm UWAN, but I have not had one clear(ish) evening since I got it. I would like an EP with the same Wide FOV but more mid-power hence my my original post. Once I know roughly what is good I can keep my eyes open on the for sale section and see what come my way. I think I am sold on the TV 13mm T6. I must admit I really like the scope- for me it is an ideal size to carry around per ounce of sweat per mm of aperture!!!!!!

The 1.25" UWAN's have the same eye relief as the T6 Naglers - 12mm. The 16mm UWAN (or the Skywatcher Nirvana) are very nice mid-power eyepieces - their new prices are nearly £100 lower than the 13mm T6 and they offer 90% or more of the performance of Naglers.

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hi mate

someone on another thread has just pointed this out. they are apparently very good.

Meade Series 5000 20mm 1.25 inch Eyepiece SWA 07665 on eBay (end time 06-Oct-10 20:24:29 BST)

Thank you for the heads up on this. I have put in an offer. Can't resist a bargain :D. Thanks for spending my money lol!! This is turning out to be an expensive hobby.

Cheers, xmal

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Thank you for the heads up on this. I have put in an offer. Can't resist a bargain :D. Thanks for spending my money lol!! This is turning out to be an expensive hobby.

Cheers, xmal

hope you didnt offer more than me:D
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no reply yet still 24 hours left though:rolleyes::D

My account says that 4 other people are making an offer and there are at least 10 units left, so we both should be ok :eek:. If you tell me your offer, I'll tell you mine :)

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