Confused about long eye relief Vixen LV 25mm

[BarneyMaroon (Tony)]

Hi, I bought a 2nd hand Vixen LV25mm "Long eye relief" EP. I bought it because I have an astigmatism and need to wear glasses to see properly.

I don't think the rubber guard folds down (they might, but it would require some father strong squishing and folding), so my eye will be about 35mm from the lens. In my limited understanding, this will restrict my FOV through this EP. Is this right? If so, are these EP's even intended for spectacle wearers.

I have other EP's with foldable rubber guards, my understanding was that a viewer who wore glasses would use these in the folded down position, and non glasses wearers would use them extended.

Which of my assumptions is wrong.
1. 35mm eye position does not restrict FOV, so EP will be just fine
2. Rubber can be folded and I am being too careful
3. This EP is for spectacle wearers.

Thanks

[rrussell1962]

Hi Tony, I've just had a quick go with my LV25mm. With glasses on I cannot see the field stop, so yes the Field of View is restricted. Vixen give the eye relief of the LV25mm as 20mm, so I think having your eye 35mm away from the eye lens is pushing it a bit. If you just hold the eyepiece by the chrome barrel and pull the rubber eye shield it will come off completely.

I think your LV25mm would give you about x80 in your LX90 with an exit pupil of around 2.5mm (assume F10 200mm), my astigmatism is -1.25 in my observing eye and I find that the astigmatism not really noticeable once the exit pupil gets down to that sort of size, but obviously I don't know how bad your astigmatism is.

[BarneyMaroon (Tony)]

Thanks for the input Russel. My astigmatism is -2.25 - I have not found a limit where I don't notice not having them on (but am new so have not explored). I often have kids looking after me, so I think not wearing will lead to more focus changes and I suspect I would not like the on and off again thing.

I would not have realised the cups pull off - thanks. The lenses look pretty exposed to scrapes without the cups, but I will give that a go.

Cheers.

Originally Posted by rrussell1962

Hi Tony, I've just had a quick go with my LV25mm. With glasses on I cannot see the field stop, so yes the Field of View is restricted. Vixen give the eye relief of the LV25mm as 20mm, so I think having your eye 35mm away from the eye lens is pushing it a bit. If you just hold the eyepiece by the chrome barrel and pull the rubber eye shield it will come off completely.

I think your LV25mm would give you about x80 in your LX90 with an exit pupil of around 2.5mm (assume F10 200mm), my astigmatism is -1.25 in my observing eye and I find that the astigmatism not really noticeable once the exit pupil gets down to that sort of size, but obviously I don't know how bad your astigmatism is.

[Wavytone]

Hi Tony,

I had a set of LV's including the 25mm - I sold them a while back when decided to cull my gear, and kept my set of LVW's.

I'm also a full-time wearer of expensive prescription specs with coatings and the works, and like you appreciate long eye relief.

The rubber eyecups on the LV's can be folded down though they are bit stiff. I preferred not to take them off completely because I learnt long ago that anything harder will scratch my specs.

The LVW's have similar eye relief but have shorter and softer eyecups that also fold down or can be easily removed.

You might like to take a look at some of the other eyepieces with ~20mm eye relief too such as TV Radians and the Explore Scientific 68-degree range.

[BarneyMaroon (Tony)]

Thanks for the advice about folding the rubber down. I thought I would tear the quite stiff rubber - but it works fine. These EPs are just great. I really wish I had bought more than the 15 and 25 @$50 each!

[bigjoe (JOSEPH)]

Originally Posted by BarneyMaroon

Thanks for the advice about folding the rubber down. I thought I would tear the quite stiff rubber - but it works fine. These EPs are just great. I really wish I had bought more than the 15 and 25 @$50 each!

Loverly EP'S Tony-Wish I had some still : light , clear, and easy to look through; Lanthanum glass is one reason.

Cheers bigjoe.