I have this dilemma, being myopic and having to use corrective eyeglasses during birding and astronomy.
First, it's nicer not to have to use eyeglasses. The view without eyeglasses, with the oculars directly against the face is optically better for these reasons:
1) Less ambient light entering
2) Easier to hold firmly and to align both axis
3) No additional 2 surfaces to keep clean
Disadvantages of not using eyeglasses are serious, and what kept me from using binos without eyeglasses.
1) It takes time to take them eyeglasses off and align the binoculars to the eyes. Having to constantly take them off/on and is very annoying, timing consuming and will lead to missed opportunities.
2) Taking off eyeglasses means you have to put them in a secure place so that they don't accidently get crushed or dirty. Given the cost of eyeglasses these days, it's important. This too takes time.
The chief problem with eyeglasses is that the binos are much harder to align properly as there is little to guide one to the proper position, other than trial and error.
This problem is made worse by the fact that some binos, like 10x32 will only work properly with proper placement, and are not forgiving. I suppose 7x42 is more forgiving. I have a 8x42 Trinovid and while it's not that bad, it has to be aligned just right, both horizontally and vertically, to display the right image. I think 8x30 has generally worse ER and is therefore potentially not the best choice for eyeglasses.
I found out that when I need to look at something, I don't take my eyeglasses off. But if I know there is an extended session before me, e.q. astronomy viewing, where I know the object won't change any, I like to use the binos without the eyeglasses. It's much easier not to use eyeglasses during extended sessions.
When I buy binoculars, I have to make sure they have:
(1) sufficient eye relief, at least 16mm and 18mm is even better, so that they are usable with eyeglasses;
(2) sufficient overdrive past infinity as I am so myopic, in order to be able to use binos without eyeglasses, I need about 6D of overdrive.
Leica 8x42 offers great ER of about 16mm but not enough overdrive at only 4D meaning I am unable to use it without eyeglasses. It is however great with eyeglasses. Leica 8x32 is an example that offers none of the above all that well, ER of about 13-14mm, doubtful that it would work for me, and same insufficient overdrive of 4D. Of course these wouldn't be an issue if I had great eyesight.
There are other solutions, like using contact lenses. I cannot wear them for more than about 5-6 hours, so that often, they are not an option and cannot be relied upon.
In short, in real life, I almost always use binos with eyeglasses, 90% of the time. However, the view is clearly better without eyeglasses, with the focus wheel turned all the way clockwise to compensate for myopia, but it's usually impractical.
etc,
Since I was around 8-10 years old I suffer from myopic, and need eyeglasses. I have had many binoculars in my life but about 10 years ago I decided to have only binoculars who provide a satisfying view with eyeglasses. I sold some great binoculars who could not offer that; Vixen Ultima 8x32 and Celestron Ultima 8x56 (the successors of the Ultima 8x56 had better eye relief than my example from early 90:s).
Like you I experienced it's unacceptable to use a binocular and constantly taking off and on the eyeglasses. If I want to see a flying bird it's gone before I make the chance to see it. Looking at the stars I miss the location if I cannot aim with the binocular. Taking off the eyeglasses makes this practically impossible at free hand use.
The myopic is an disadvantage because there are several otherwise excellent binoculars with too short eye relief for eyeglass use (Nikon E models (porro) and Swift 8,5x44 porro are two examples).
One other, as I think you mention, is that the focus span of many binoculars isn't adequate to compensate the myopic at long distance. My new Swarovski SLCnew7x42 is one of the best existing binoculars for eyeglass use. But no doubt about that the image is even better without the eyeglasses! You are completely right here; eyeglasses decrease as well contrast and sharpness. In some occasions I would prefer to use the binocular without the eyeglasses. But I noticed that I can hardly use the Swarovski at long distance without eyeglasses. It's unfortunate that not even these high-end models offer a wider focusing span.
Excuse my faulty english,
Patric
Regarding missed chances with glasses - I just lift them slightly with my left hand as I raise the bins with my right, and I rest them on top of the bins as I view (eyeglasses still on my ears). The eyeglasses need to be fitted a bit loose on the ears to do this. Not the safest handling for the eyeglasses, but I don't think I've ever dropped them. And it's very quick. It's a completely automatic motion for me now and I don't think I miss a thing.
Doesn't help with the myopia however. That's a tough one. Have you tried contacting the manufacturers about this? This must be a design issue they've considered.
If overtravel past infinity solves your problem, you might contact one of the authorized service centers to see if it is in any way possible to custom modify a pair for you. This might sound crazy, but even if there is no adjustable zero point, there might be a chance to do some slight machining to allow overtravel of the focus past infinity... ???? I'm just speculating here. Either the service people or the manufacturers should be able to answer this though (if you can get in contact with the right people anyway).
- Dave