How should eyeglasss wearers focus?

[antshrike]

I've been taking some pics lately with my new Canon A590 hand held through my Kowa 824. They come out pretty good considering they're hand held. I normally focus the scope for my eyes and let the camera do the rest. The other night my wife and I were looking at the full moon through the scope and I found I had to refocus every time she used the scope. She was not wearing eye gasses while I was. So here's my question. Is the in focus view I see though my scope and eye glasses correcting an astigmatism also in focus for the camera? Any thoughts?

[Matt_RTH]

I can't comment on the physics of the issue but I know that with my camera, the scope is slightly out of focus to me when I look in the ep. This was the case with two scopes I've had. Another one was same either way.

I think it has to do with depth of field and the camera's ability to sens the focus of the image when pointed through the scope.

Another issue is that it's just plain to hard to focus under the best , stabilized conditions. So hand held is a significant compromise.

[John P]

I only need glasses for very close work, (not for reading yet) and rarely wear them normally; I've found that the only way I can consistently achieve sharp pics from digiscoping is to focus my scope while wearing my glasses.

I'm still using a CanonA95, which may be significant as it's a similar camera to yours, other cameras may well vary but it's the only one I've used for digiscoping.

[JGobeil]

You have to be extremely careful if you wear PROGRESSIVE lenses. I have these (+2.25 and +1.75) and, to a certain degree, I can compensate for focus problems on a LCD screen by adjusting the viewing angle. This makes it very difficult, if not impossible, to use a LCD screen for focusing.

Fortunately, my DSLR viewfinder can be adjusted for my eyesight and I can avoid wearing glasses when using it. My percentage of keepers has increased substantially now that I use a DSLR instead of a P&S camera.

[antshrike]

Thanks for the replies. The A590's view screen is not that great, so I don't use it for focusing at all. I only check that I'm centered. I'm just hoping that if the view is focused for my eyes (with glasses) that it's also focused for the camera which can use its autofocus. I know it will never be super sharp while I'm doing it hand held.

[Neil]

Thanks for the replies. The A590's view screen is not that great, so I don't use it for focusing at all. I only check that I'm centered. I'm just hoping that if the view is focused for my eyes (with glasses) that it's also focused for the camera which can use its autofocus. I know it will never be super sharp while I'm doing it hand held.

The focus square will go green if it thinks it's in focus. The scope focus has to be very close for the camera to get correct focus. I prefer macro mode as it seems to be more accurate up to half zoom. You can check focus by going into the digital zoom zone and then focusing and then zoom back out again.
The 590 screen is not really good enough to determine accurate focus so best to focus the scope first if you have time.
Neil.

[wings]

I am in the same category as Jules in that I wear progressive bifocals, but here's a new twist: when eyeglass wearers press their faces toward the camera eyepiece I suspect that, for the most part, the eyeglass lens axis is not parallel to the camera eyepiece, i.e., the eyeglass is somewhat slanted away from the eyepiece. Two questions arise:

(1) does this angle-of-eyeglass to camera eyepiece distort focusing, and
(b) for people wearing bifocals, is it OK to focus through the upper part of the eyeglass rather than the lower part, recognizing that the upper part is for far distance and the lower part is for closeness?

Or are these moot points?

[JGobeil]

I am in the same category as Jules in that I wear progressive bifocals, but here's a new twist: when eyeglass wearers press their faces toward the camera eyepiece I suspect that, for the most part, the eyeglass lens axis is not parallel to the camera eyepiece, i.e., the eyeglass is somewhat slanted away from the eyepiece. Two questions arise:

(1) does this angle-of-eyeglass to camera eyepiece distort focusing, and
(b) for people wearing bifocals, is it OK to focus through the upper part of the eyeglass rather than the lower part, recognizing that the upper part is for far distance and the lower part is for closeness?

Or are these moot points?

Interesting questions. Fortunately, I don't need to wear my glasses when using the viewfinder, but I have tried it, so I may venture an answer.

IMO, using the viewfinder with or without glasses is similar since it is quite easy to position your eye and glasses everytime in the same position. Adjust the diopter control carefully for your eyesight by looking at the menu and you're in business. It should behave similarly each time. Having a soft viewfinder eyepiece on which you can rest your glasses will help - a large circular one seems to be the best and you can get them cheaply on eBay (buy a few since they are easy to loose).

I think that the viewing angle is quite perpendicular. Personnaly, I rest the eyeglass on the eyepiece, so I look through the glass right in front of the eye, at a 90 degree angle.

It is not the same when looking at the LCD because it is not really possible to look at it everytime from the same distance and viewing angle through the glasses.

[wings]

Thanks Jules, i'm going to try your technique.

[JGobeil]

Thanks Jules, i'm going to try your technique.

Not much technique there. Just one important thing: adjust the focus on a menu (if available) or on the AF points, not on a picture at infinity - it is much easier and IMO more accurate.