Pentax XF 12mm vs Baader Hyperion 13mm

[M.]

Ok, so I need to fill the void between eyepieces.

 

I currently have 

 

Hyperion 10mm (200x magnification)

 

Nirvana 16mm (125x magnification)

 

I'm looking for something between the two, like a 12mm or 13mm.

 

Which one out of the two do you think is better option, they are similar in price bracket £100 for the hyperion and £120 for the Pentax.

Edited July 7, 2015 by M__

[Tweedledee]

Let's look at the numbers including the field of view.

If you got the Pentax XF 12mm 60 degree eyepiece, the view you would get would have almost exactly the same FOV as in the 10mm 68 degree Hyperion you currently have but at a lower magnification.

Pentax 12mm 60 degree gives 167x with a FOV of 0.36 degrees
Hyperion 10mm 68 degree gives 200x with a FOV of 0.34 degrees

Therefore the view would be effectively the same, 0.36d or 0.34d, but you'd be looking at it through a smaller window at lower magnification in the Pentax.

Therefore, out of the two eps you mention I think the Hyperion 13mm would get used more since it would give 154x with a FOV of 0.44 degrees.

This FOV would fit better between your two current eyepieces. Your Nirvana 16mm 82 degree at 125x will have a 0.66 degree FOV

Your scope being a relatively long F10, is very forgiving on eyepiece quality, so most eyepieces unless they are really cheap and poor quality should give you an excellent well corrected view.

I would also suggest that you are missing out at the moment on the much wider fields of view that your SCT is capable of providing. Think about something like a Williams Optics SWAN 33mm 72 degree eyepiece which is a little below your budget. This type of eyepiece will give you 61x with a 1.2 degree field of view and a larger and brighter 3.4mm exit pupil. This eyepiece will not excel on planets, but should give really spectacular wiews of larger star clusters, nebulae and galaxies since it will frame them much better. Other wide field alternatives could be the Skywatcher Panaview or better still the Aero in the 30mm to 40mm range. Of course these are 2" eyepieces and may require you to also invest in a bigger visual back and diagonal, but will really open up your SCT and give lovely wide views that you can only achieve with 2" eyepieces.
 

[Tweedledee]

Another possibly cheaper method for you to achieve wide fields of view could be to get an F6.3 Reducer/Corrector which is ideal for visual or AP. These can usually be picked up very cheaply on ABS.

 

This would effectively double your eyepiece range.

 

Your 16mm Nirvana would then provide 79x with a nice large FOV of 1.04 degrees.

 

Just a thought

[M.]

Thanks a lot Pete, that has certainly cleared things up for me.

[M.]

I think I'm off to rother valley optics to have a look at the two eyepieces today.

[M.]

I decided on the Hyperion 13mm as it fits in with my current set well. I had a chat with the lad at the shop and he was also quick to recommend the Hyperion too. I was impressed with the 10mm versions larger sight glass, so though I'd stick with the same recipe as such.

[Doc]

Good choice.