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The Tele Vue 13mm Ethos, First Impressions

Posted by Trenton Feist   06/25/2007 12:00AM

The Tele Vue 13mm Ethos, First Impressions
Ethos Impressions

Let me first say that this is not going to be a highly technical review of the Ethos but mainly will be what I observed and what my impressions were in using this eyepiece. My experience with the Ethos started Saturday afternoon with some daytime observations using the eyepiece and a Tele Vue 101. Looking through it for the first time is very shocking to say the least. I bent down over the eyepiece and looked through to see the largest field of view I have ever seen in a 13mm. As you look at the center of the image it is virtually impossible to see the edge of the field of view without straining and moving your eye, it was literally like swimming in the field of view. I first started out by looking at a power line that was approximately ¼ mile away. I wanted to check to see how much curvature there was in the field of view.

Understandably there is noticeable radial lens distortion as would be expected with a 100 degree field of view but I did not find it to be more than what would be expected with this type of field of view, in fact it was less than I expected. I also noted that while there was radial distortion there was very little if any pincushion distortion in the field of view. The lens stays sharp to the very edge of the field and after talking with John Rhodes, the Tele Vue rep, they designed the eyepiece to minimize if not eliminate the pincushion distortion and as you all know you cannot fully correct for both and that is what accounts for the radial distortion. I noticed that eye relief was difficult for me at first. When I walked up to the eyepiece the eyecup was folded down and for me to center the image and not have any blacking out I needed the eyecup up and it took me a few seconds to get my eye placed in the best position. Once I adjusted to the eyepiece I didn’t have any other issues with blacking out and observing was very comfortable. I finished out my daytime observations with looking for the consistency across the field of view and was impressed that the image does stay consistently sharp to the edge. The color was nice as well during the day, but I will talk more about that when I discuss the night observations. Physical size of the eyepiece is fairly large coming close to the larger Naglers but weight was actually surprisingly light for the size.
Then it was out the Chamberlin Observatory to test the Ethos under dark skies. The sky was relatively clear but I would say seeing was probably a 5-6 as there was some haze. The first target was the moon and it was amazing. I did notice some lateral color when looking at the moon with the 101 and wasn’t sure if it was the scope or the eyepiece. It was very subtle and didn’t really distract from the viewing experience. We decided to put the eyepiece in a big dob to see if the color was from the scope or the eyepiece and it virtually disappeared making me think that it was a combination of both. I would be interested in hearing if anyone else has noticed lateral color in a Tele Vue 101 with other eyepieces. My guess would be that since Ethos is still a prototype that they will correct that problem before production. Again it was very subtle and only detectible on the moon. Next it was off to some deep sky tests. I went right for M13 and I was blown away. Even in the city you could make out sharp pinpoint stars and the Ethos at 13mm really brought out the detail with the 101. The other nice thing was the increased field of view compared to other 13mm eyepieces out there. Obviously that is the benefit of the Ethos line but I did not see any compromise in contrast to gain the extra degrees in field of view. So I decided to be a little daring and grabbed the 2x Powermate to see if I could get any more out of it. Well to my surprise contrast still proved to be amazing and the added field of view allowed me to frame all of M13 perfectly, try that with a 7-8mm eyepiece of any type!

Next I was off to M81 and M82 and I am sorry to say that seeing was not on my side for this test. I was only able to make out M81 and it was difficult to see due to the haze. I would have no reason to expect that in a good refractor you couldn’t easily frame both M81 and M82 in the 13mm and the contrast of the eyepiece should allow great observation when seeing permits. I then went to M57 to see how the contrast would work with the ring which can be touchy in the city. I was pleasantly surprised to see the Ring jump out of a nicely black sky. You could clearly see the structure of the nebula and color was also visible. I moved the ring from one edge to the other and the color stayed consistent as did the overall detail and sharpness of the image. I then decided to see how well it would do with color in Jupiter. Again the contrast and color was pleasing with the cloud bands being clearly visible and color being detectable. The 4 Galilean moons were pinpoint sharp and bright. Jupiter was not the best test for field of view for the Ethos but I did want to see if the added glass caused any contrast issues which it didn’t and I think contrast may even be better than the 13mm Nagler T6.

So my overall impression…this is a fantastic eyepiece. The color is “cooler” than other Tele Vue eyepieces, and contrast is excellent as is the lack of pincushion distortion. There is a detectable amount of radial distortion but that is to be expected with an eyepiece of this type, (It would be interesting to use a field flattener and see the difference it makes), and there was also a very limited amount of lateral color present when looking at the moon and I do stress limited. This eyepiece will appeal to a wide variety of people looking for the space walk feeling, and let me tell you this eyepiece puts all others to shame if you are looking for that experience. The price point will be the deciding factor for many that already own a wide field eyepiece or two, when I asked John about the price he gave a very scripted answer that Tele Vue won’t let him speculate but that it would not be any less than $300 which would make it more expensive than the 13mm Nagler T6 but that it would not surpass $640 price tag on the 31mm Nagler Type 5. That gives you a good $300 gap to play with but as for my guess, and I stress this is just a guess, somewhere in the $450 range. The reason I think that is it has to be sellable to more people than just those that have the 31mm. This is going to be the first in the series and the way they are going to sell the series will depend on how many people are able to afford the eyepiece and how many people get the chance to experience what they are missing in not having one and that means they need to get the Ethos out there so people can take a look at it. I think the tell tale effect of the Ethos was evident in the reactions given by people looking through it for the first time, I don’t recall anyone not being impressed if not blown away by the vast field of view. My wife looked through and said “holy cow that’s amazing” others said “I feel like I am going to bump my nose on the moon” or “it feels like I am orbiting the moon”. I for one am convinced and will be adding one to my collection when it becomes available this fall. You just can't describe what its like, you have to see it to believe it! It just goes to show that Tele Vue still has some tricks up its sleeve.