Help me give a good eyepiece review

[MarkVIIIMarc]

I have two new toys, an eyepiece and a 2x Barlow.  Especially the eyepiece I would like to give an in-depth review of but am not sure I am experienced enough to do so.  If you all could give some tips on how you try yours out and what to look for that would be great.

Tonight we have tons of cloud cover to I only had a minute or two of time at the eyepiece.  I noticed:

-The eyepiece focuses nicely in my 1250mm F5 Z10 at 156x magnification and gave a good wide view of Jupiter and its moons.

-When I put in my Zhumell 2x Barlow the lens had a near air tight fit but it does fit and focus even if 312x was a bit beyond seeing conditions tonight as is typical. 

-I found eye relief to be very comfortable without and with the Barlow. 

-Physically looking through a 2" eyepiece is more comfortable for me for some reason (subliminal?).

-My target only ran across my field of view maybe once without thick rain filled clouds obscuring it.  Counting that and when I was zeroing in on it I did not notice any edge aberrations but I didn't have time to really let Jupiter hang near the edge and see if it was less sharp. 

 

For the 2x Barlow I noticed:

-It is a TIGHT fit on both ends.  Sometimes I have to walk away from my scope and into the light to slide or rotate eyepieces or adapters in.  This might be to keep itself and eyepieces centered I assume.

-Not with the 8mm tonight (maybe due to just a short time on target) but with some other eyepieces I get some weird edge brightening.  Like real bright on a crescent if I am off center.  What is the proper term for this?

-It does not seem to reduce brightness much if at all.  My 30mm had beautiful views of Jupiter through the Barlow.

 

I'm hoping to catch the moon later in the week when conditions clear.....I suppose measuring FOV and focus from edge to center against the moon is something to do?  Then my new 8mm is close in magnification to my 9mm so I can compare those.  My 9 is a Zhumell factory eye-piece so I feel like it is more a mystery item than if it were an X-Cel or Omni which people were familiar with. 

[Joe12345]

I still don't think I would be qualified to give a decent review even though I've had over 1 year experience.

If I were you, I would read lots of other reviews of something similar to what you plan to review, then you know what you should be looking for. Also if you see any terms you don't understand, research them a bit.

[DirkSteele]

There is a huge variety of things to look for.  Colour rendition (sometimes easier to assess during daylight hours).  Look for on axis and in particular off-axis aberrations.  Most EPs are great on-axis (but assess how sharp it is compared to others you have used) these days but off-axis is where the money goes.  Try to assess if there is any pin cushion distortion / angular magnification distortion / lateral chromatic aberration / ghosting images (internal reflections can indicating poor stray light control).  Also from the externals, how well made it is, are the coatings dark and smoothly applied?  Assess how easy and EP is to use.  Is there plenty of eye relief, is eye placement critical, fatiguing to use for long periods?  If you have more than once scope, test in all of them.  An EP may be good in a f/10 SCT but might crumble in a f/4 newtonian and its steep light curve.

 

Have a read around other reviews on the web as well and you will see the sorts of things that people assess.  And most crucial, enjoy using your eyepiece!

[LukeSkywatcher]

I tend to leave reviews up to people who know what they mean and are talking about . I certainly dont know what i mean or talk about when it comes to optics. One thing i do know about EP's is that Vixen are brilliant and my favourite brand.

Dont get me wrong. By all means give a review in the review section. Lay it on the line and use the words and terminology you understand. 

[Moonshane]

Unless you are someone with a lot of time and equipment to measure things then it's difficult I feel to give a technically 'scientific review'. Therefore I feel a good description of how you feel about the eyepiece/piece of kit is good enough. After all, most people just use them in the same way you will so your findings will be valid.

I'd recommend you take your time though as often,  prevailing conditions can create negative impressions but over time you'll get a better idea of the characteristics of the kit and especially if you make comparisons with well known kit like the standard eyepieces that come with scopes.

Try a number of different targets, faint ones, bright ones, challenging ones like tight doubles, detailed ones like planetary detail etc etc.

Your way is the right way so don't worry too much. It's all good info. 

[John]

I think the best approach is, as Shane suggests, try the eyepiece out on a wide range of objects, under different viewing conditions and don't be in a hurry to jump to conclusions about how it performs.

If you have other similar focal length eyepieces to compare it with that can be revealing and helpful as can trying the eyepiece in different types of scopes but if you don't have access to these then just jot down how you find it and thats useful as well.

 

[Dave In Vermont]

There was a recent poll of things that could be told about EP's in the process of review that most people had never seen offered in a EP-review. One stood out from a few maybe's. And this was the weight of the EP in question.

It was put foreward as some folks indicated that when they were looking for new EP's to add to their collections, the weight can be a deciding factor. This was due to a few different concerns - ranging at best as both the limitations of the mounts they were using, to the setup being too large for the rest of their gear to reach balance with. No doubt other considerations will arise*. But we all agreed that weight should be listed in a good, all-inclusive review of these most important (and often neglected) end of the optical-pathway.

May this jostle a mind or two -

Dave

* Maybe a new thread: What's your heaviest eyepiece? Hmmm...

 

[Linda]

6 hours ago, Dave In Vermont said:

There was a recent poll of things that could be told about EP's in the process of review that most people had never seen offered in a EP-review. One stood out from a few maybe's. And this was the weight of the EP in question.

And this is also an objectively measurable thing, not depending on the observer's experience or eye quality. Only on your kitchen scales being more or less correct.

I would like to know whether an eyepiece is blackened on the inside of the part that you put into the star diagonal.

Something else that I noticed with my own new eyepiece is that usually, when I increase magnification, the view becomes a bit more blurry. With the new eyepiece however, the view became sharper. I think this means it is in a different league of quality than my 24mm eyepiece, that was the one that gave the sharpest view until then. It also says that it is a lot better than my other eyepieces with almost similar magnification.