Diopter Correction lenses.....the Follow up eye exam

Some may remember my query about correction lenses and my decision to go in for

another eye test. Here were my results.

 

 

Well, went down to the eye doctor and my eye sight has actually greatly improved

over my former -1 diopter. I have actually enter the + 1/2 on my left eye. The

doctor said my main problem now is just astigmatism, a curving of the lens in

the eye, I guess is my dilema. Seems I could get some eye glasses made that

would help, but sure would like something to test with the camera before

spending more on these glasses. I will check with him and see if he might be

able to provide a test lens for my camera (left it at home)

"just astigmatism" is quite problematic if there's much of it. What is the prescription of the eye that you view with (probably your right eye)? There will be a spherical, a cylindrical and an axis figure.

Well, if I am correct in assuming that the OS is my right eye

 

SPH PL CYL -075 Axis 074

Doesn't the "S" in "OS" stand for sinister, Latin for "left"?<br/>OD (oculus dexter) should be your right eye.

LOL, well they could write it in dang english, couldn't they??

 

Here is the OD reading.

 

SPH +0.25 Cyl -1.00 Axis 109

SPH +0.25 Cyl -1.00 Axis 109

 

Spherical of 0.25 is not a lot, but see my comments below about different camera viewfinders. -1.00 of cylindrical is enough to need correction if possible. Read the article on wiki about optical prescriptions at:

 

http://en.wikipedia.org/wiki/Eyeglass_prescription

 

The standard correction lenses sold by camera manufacturers are spherical and correct for near or far sightedness. They have no directional quality, so for example if you turn a camera 90 degrees to take a portrait there will be no difference in the effect of the spherical correction.

 

On the other hand, the cylindrical correction has an orientation, hence the 'axis' measurement. If you had cylindrical correction for your viewfinder and turned the camera 90 degrees it would be worse than no cyl correction. The eyepiece correction would ideally have to be turned back 90 degrees to keep it at the original orientation to the eye. This could be an argument for a square format camera since there is, of course, no need to turn it for portraits IF you need cylindrical correction.

 

Choosing the spherical value is tricky because it needs to be for ideal viewing of a certain distance that depends on the viewfinder system, not infinity which is your optical prescription for 'distance vision'. I think recently there was a post about Bronica viewfinder corrections where they stated that perfect viewing through the viewfinder was at an eye focus distance of something like 3 metres. So for that camera you would need as a correction:

 

1.your distance spherical value

 

2.plus a bit for viewing at 3 metres not infinity

 

3.plus your cylindrical value (in your case it's negative)

 

The value of item 2 is different for different cameras, hence the trial and error approach usually recommended. I have almost no cyl correction and -1.75 spherical for distance vision. For a Leica I need -2, for a Nikon I need -2.75, and for a Mamiya 6 (for which only whole number diopters are available) -1 is better than -2.

Thanks so much for your time and effort on this John. Again I can see the reasoning for Auto Focus!! Lots of info in that link.

I use a 645 format. Mostly my Mamiya for the Recessional shots. The Bronica ETRS is used if it is an outdoors wedding for flash sync reasons. My lack of a wide angle for it does cause me some problems with opting to use it indoors also. Another issue is the way my Stroboframe is set up. My flash sync cord ends up scrunch tight when I go to the Portrait position, some cords will not work at all. I think I can redo the frame to correct that though. Broncia has the sync cord connection on the side of the camera, while Mamiya has it on the front. No issue with that camera. I do find I can see better thru the Bronica, so I may just have to find that wide angel lens. I always thought the reason for seeing better thru the Bronica was the image appeared brighter too me.

I would hate to do it, but glasses could be bought over having multiple diopters being made. I have not gone thru all the info from the link you sent yet, but would glasses, made to my prescription, help me with my Mamiya or as you stated would I still have problems between using Landscape and Portrait modes, when doing my photographs?

"I have not gone thru all the info from the link you sent yet, but would glasses, made to my prescription, help me with my Mamiya or as you stated would I still have problems between using Landscape and Portrait modes, when doing my photographs?"

 

The glasses would help. There would be no difference between portrait and landscape camera positions, because the glasses would stay in the same position relative to your eyes regardless of how the camera was held.

 

Given that you have astigmatism and a camera correction would be somewhat difficult, glasses seem like the obvious solution. I have glasses for distance vision (driving, blackboards etc) but I find it a bit harder to focus compared to the camera diopter (and no glasses, obviously). I don't know if this is because the eye is further away, or that the glasses' distance correction is not quite right for the cameras. But it's very much better than nothing.

>>The glasses would help. There would be no difference between portrait and landscape camera positions, because the glasses would stay in the same position relative to your eyes regardless of how the camera was held.<<

 

Went down and started the process of new glasses. Cheaper in the long run than diopters for 4 cameras. I very much appreciate your help on this matter. Once I get them, around the 25th, I will run some test shots for both my Bronica and Mamiya cameras.