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Andrews 2" UW30mm 80 degree
Submitted: Thursday, 7th April 2005 by Mark Hodson
andrews2inchuw30mm-1.jpg

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The Andrews 2" UW30mm 80 degree

This eyepiece goes by several names depending in which country you buy it, but it is a BW-Optik 30mm.

I had been debating with myself for a while as to whether I would get this eyepiece or not as I had only just received the 42mm GSO. The apparent field of view difference between the two designs meant not a lot of difference only a magnification gain for a similar actual FOV.

A recent favorable review in the Sky and Space magazine gave me the push and so here is my opinion on this budget wide field eyepiece.

 

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Simulated view of eyepiece on Pleiades & checked on scope

The picture on the right is a simulation of the fields of view between the 30mm 80 deg and the 42mm 65degree in my 12.5” f6 scope.

The program used is Starry Nights and the object is Pleiades. This was tested in the scope and proved to be about right.

The outer red circle is the actual field of view of the 42mm and the inner circle is the 30mm; remember though the 42mm gives a lower magnification not shown in the simulation.

 

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Comparative size and helical screw plastic eyepiece case

This is a large eyepiece as seen in the picture on the left, and weighs 570grams so balancing and focuser weight handling have to be taken into consideration.

The top element is 38mm in diameter and the bottom 45mm.

It is a five element design and is not considered to be an Erfle.

 

andrews2inchuw30mm-4.jpg

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Eye cap and deep greenish blue coatings

Coatings appeared deep greenish blue and are fully multicoated.

Eye relief while good for non eyeglass wearers does require removing the eye cap to use glasses. The cap appears about the right height when your eye is placed up against it and I measured the relief to be about 16-18mm where you were able to see the entire FOV.

You do need to look around to see the entire field of view and gives that falling into the eyepiece experience.

I did not experience any of the blacking out or kidney bean affects common in wide field eyepieces but this a personal thing and differs between viewers.

Internal reflection and ghosts were non existent.

 

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Shiny bits

The bottom of the barrel appears to be the field stop, and if while looking through the eyepiece not on a scope, you unscrew the chrome barrel extension you will notice the you can see the inside of the barrel turning.

The blackening does not appear as black as my other eyepieces and the bottom area where the filter would go was not blackened at all.

This gave a slight yellowing at the very edge of the view, but was virtually eliminated by re-blackening the whole inside of the barrel with optical black.

 

Testing

Scopes used were an F6 Eq Newtonian, an F5 Dobsonian and an 80mm f7.5 ED refractor. Objects viewed included 47Tuc, Pleiades, Orion nebula and Sirius.

First thing noticed was the edge sharpness which was evidently clearer in the f6 and even more so in the refractor.

The sea gull shape of the stars was quite pronounced in the f5 from about 75% out towards the edge. This is a result of coma in a Newtonian design and is worse the faster the focal ratio. I would not use this eyepiece in scope faster than F5, but then this depends on what your tolerance is on this aberration. Faster focal ratios are more demanding on eyepieces and so this has to be taken into consideration when considering one of these.

The refractor shows no such aberrations.

Daylight testing with the refractor on a building several hundred yards away showed little curvature in straight vertical and horizontal lines.

This eyepiece has turned my 80mmx600mm refractor into a high quality 20x finder scope with a 4 degree true field of view approaching that of my 11x80 binoculars ; simple awesome.

I find the eyepiece quite acceptable in the F6 Newtonian sharp to about 85% of the way out and usable in the F5. I now find myself grabbing this eyepiece first when observing and simple enjoy the wide views.

I also tried using a 2x Barlow and a 4x Powermate giving the equivalent of a 15mm and a 7.5mm eyepiece respectively in the F5 and F6 Newtonians.

The Barlow while usable was not a match for the Powermate and eyepiece combination.

Graeme, the owner of the F5 newt and I agreed that it provided the best views of the globular clusters with out changing the characteristics of the eyepieces. It reduced edge distortions to a level where you have to really look to see them and then only on the very edge.

My main concerns and improvements would be the black used to coat the internal surfaces and the lack of a positive locking area in the way of a groove in the chrome barrel. I think for such a heavy eyepiece this should have been mandatory and would not add much to an eyepiece.

I will be machining this in myself as I don’t want the heartache of seeing my eyepiece hitting mother earth.

I think that for AU$149 this eyepiece is a real bargain and this appears to be the consensus in various forums. It does not look quite as flash as my 42mm GSO but it’s the performance that counts and I feel that for the budget conscious of us or for those who don’t want to use their Naglers at star parties you can’t go to wrong with one of these.

Please feel free to give comments or ask questions in the forum.

Mark Hodson

Review by Mark HodsonDiscuss this review at the IceInSpace Forums.
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