Baader Hyperion 5mm EP for Nexstar 8SE?

[kristalline]

Hi! My bro has a Celestron Nexstar 8SE and I was thinking of getting him an eyepiece as a gift. I was wondering if the Baader Hyperion 5mm eyepiece is a good choice for his telescope, as well as the viewing conditions under the Singapore skies.

Does anybody own this combination and would be willing to share their experience whether this is suitable for viewing planets such as Jupiter, Mars, Saturn? How big will they appear on the eyepiece?

Thanks alot!

[Gary]

Hi Kristalline. Welcome to the forum!

Very thoughtful of you to get an eyepiece gift for your brother. I do not have any experience with a Baader Hyperion 5mm eyepiece. A 5mm eyepiece for the 8SE telescope will give about 400 times magnification, at the limit of the telescope's maximum useful magnification. It is good for viewing planets at such high magnifications but such clear skies will not be common in Singapore.

Perhaps you can let use know what eyepieces he already has so as not to avoid duplication or too similiar of his current eyepiece collection, e.g. getting him a 5mm when he already has a 6mm.

Depending on the magnification and the distance of the planets, the planets usually does not appear too big in a field-of-view, e.g. it will not fill up half or more of the view. Sometimes, depending on the sky clarity, the apparent size may be deliberately made slightly smaller (ie. by lowering the magnification) in return for a sharper and more contrasty view.

If he doesn't already have one, perhaps a zoom eyepiece (e.g. 8mm - 24mm) may be a good idea. If it is available from the astronomical retail store, another option is to give him a voucher which may be more flexible. Then he can decide for himself what astronomical accessory he like and need most.

Hope this is helpful and good luck!

[antares2063]

hi Kristalline,

A view of a planet through a earth-based telescope will never be as large as our own (nearest) moon.

Try playing around with this link , just select Object Data (jupiter) , the telescope , and eyepiece focal length

http://www.telescope-simulator.com/inde ... &Itemid=58

regards,
Junwei

[kristalline]

Hi! Thanks for the replies! That's what I thought. From what I read and in terms of theoretical numbers, the 5mm might seem ok. However, the reality might be different under our skies. He only has a 25mm and 10mm eyepiece. I understand that if he gets a barlow lens, the 10mm can be turned into a 5mm. However, by magnifying the lens, would the image be less crisp, especially around the edges, as compared to a standard 5mm eyepiece?

As for the telescope simulator, would the telescope and eyepiece combination realistically perform according to what is shown on the website?

[antares2063]

The simulator just lets u have an idea of the apparent size of Jupiter when viewing with a 8in SCT f/10 + 5mm , and yeah for planetary views, sky and seeing and the optics quality of the scope plays a part

I guess there's no hard and fast rule ba

[Gary]

Hi! Thanks for the replies! That's what I thought. From what I read and in terms of theoretical numbers, the 5mm might seem ok. However, the reality might be different under our skies. He only has a 25mm and 10mm eyepiece. I understand that if he gets a barlow lens, the 10mm can be turned into a 5mm. However, by magnifying the lens, would the image be less crisp, especially around the edges, as compared to a standard 5mm eyepiece?

As for the telescope simulator, would the telescope and eyepiece combination realistically perform according to what is shown on the website?

When the light path goes through more lens, the image will be dimmer. A lousy low-grade barlow will make the image dimmer and less contrasty. But with a good quality one, the difference may not be visually perceivable. I have been using a made-in-japan Celestron Ultima 2x Barlow for a few years and quite happy with it. If you intend to get one, as usual, please check with a few sources online to have a better idea of how much it cost.

Not all 5mm eyepiece are manufactured the same way and have the same specs (e.g. afov, eye relief, coating). So very generally, all things being the same, whichever setup (5mm vs 10mm+2x barlow) that has the minimum number of lens should give a brighter image (but brighter may not necessarily give higher contrast).

If you do get a quality 2x barlow, you may also try to put it between the telescope visual back and the diagonal of this 8SE SCT to give an apparent 3x barlow effect. With the 25mm eyepiece, it can give a nice 8mm effect which is more useable in typical skies conditions in Singapore for an 8-inch SCT for observing planets. And still enjoy the wider field-of-view of the 25mm compared to the 5mm.

Since 8SE is a tracking telescope and the planets are mostly positioned and view through the center field of view (on-axis), you may not need to worry too much about the edge (off-axis) perfomance of an eyepiece or eyepiece + barlow setup.

In the event your brother decides to do lunar planetary imaging with a webcam or dedicated camera, a barlow can be useful too to give a more satisfactory image scale.

[antares2063]

Since gary suggested a barlow...may i also suggest an eyepiece called orthoscopic / orthos..typically they are very sharp on axis and offer great performance for planets/moon. Price wise is less than 100(usd) .

Just my 2c worth