Do Glasses/Contact Lens Affect Focusing?

[eli griggs]

I'm very close sighted, the distance from top of a Hasselblad 500 cm waist level viewer (lightly pressing the WLF top), to the ground glass, which I can focus.

With the magnifier, no way without bifocals and dont even bring up 35mm camera viewfinders, though the Canon F-1 sports finder should be useful enough to do the job, without glasses.

I'm still waiting for my cataract surgery, and will choose good distance vision for the implants, and use close up glasses for those needs.

The fact that I have an very bright focusing screen in the 'Blad helps with the cataracts, but it's only cross hair white etched for focusing and a split ring would be so much better, just from Fifty plus years of experience with other cameras with that focus aid.

By the way, in my first ever practical use of the Hasselblad 500 mirror lockup, I was in North Myrtle Beach, SC. right after getting my first system, and the first night the wind blew out my also new to me, contact lens.

Lucky, the wind blew it onto my jacket, an easy find and I ducked into the pharmacy that was right beside me on that sidewalk, walked to the front counter, and removing viewfinder, popped the mirror in, to assist me rewetting and putting that delicate lens back in place.

The store pharmacist seemed to run the whole place and watched me do this, fascinated with the use of the camera's pop-up mirror and the task I'd used it for.

Just one more fond memory of my Hasselblad history and vision issues.

 

[Sirius Glass]

I'm very close sighted, the distance from top of a Hasselblad 500 cm waist level viewer (lightly pressing the WLF top), to the ground glass, which I can focus.

With the magnifier, no way without bifocals and dont even bring up 35mm camera viewfinders, though the Canon F-1 sports finder should be useful enough to do the job, without glasses.

I'm still waiting for my cataract surgery, and will choose good distance vision for the implants, and use close up glasses for those needs.

The fact that I have an very bright focusing screen in the 'Blad helps with the cataracts, but it's only cross hair white etched for focusing and a split ring would be so much better, just from Fifty plus years of experience with other cameras with that focus aid.

By the way, in my first ever practical use of the Hasselblad 500 mirror lockup, I was in North Myrtle Beach, SC. right after getting my first system, and the first night the wind blew out my also new to me, contact lens.

Lucky, the wind blew it onto my jacket, an easy find and I ducked into the pharmacy that was right beside me on that sidewalk, walked to the front counter, and removing viewfinder, popped the mirror in, to assist me rewetting and putting that delicate lens back in place.

The store pharmacist seemed to run the whole place and watched me do this, fascinated with the use of the camera's pop-up mirror and the task I'd used it for.

Just one more fond memory of my Hasselblad history and vision issues.

After my cataract surgery, the implant has provided my dominate eye with 20/20 vision and good reading vision too. I have been waiting a few months for the other cataract surgery to be done to the second eye. As soon as a surgery suite open up we can start.

 

[eli griggs]

After my cataract surgery, the implant has provided my dominate eye with 20/20 vision and good reading vision too. I have been waiting a few months for the other cataract surgery to be done to the second eye. As soon as a surgery suite open up we can start.

Good Luck!

 

[Sirius Glass]

Good Luck!

I will have the eyes matched. I am waiting as fast as I can.

 

[Pieter12]

I will have the eyes matched. I am waiting as fast as I can.

In contrast to the US, in Canada they will do both eyes at the same time. Don't know about the rest of the world.

 

[MattKing]

In contrast to the US, in Canada they will do both eyes at the same time. Don't know about the rest of the world.

Around here they now usually wait a short period of time - a few days to a few weeks - before doing the second eye.
That gives the opportunity to ensure that there are no complications with the first procedure before operating on the second eye.
Except in the case of people who only need the operation on one eye. They don't do the second "just in case" - they wait until it needs the operation.

 

[Pieter12]

Around here they now usually wait a short period of time - a few days to a few weeks - before doing the second eye.
That gives the opportunity to ensure that there are no complications with the first procedure before operating on the second eye.
Except in the case of people who only need the operation on one eye. They don't do the second "just in case" - they wait until it needs the operation.

I m aware of the U.S. protocol, but cataract surgery is one of the most successful procedures with the least complications. For those who need both eyes done, a cynical mind might think by doing separate operations, doctors, staff and facilities can end up charging more.

 

[MattKing]

I m aware of the U.S. protocol, but cataract surgery is one of the most successful procedures with the least complications. For those who need both eyes done, a cynical mind might think by doing separate operations, doctors, staff and facilities can end up charging more.

When they do the operations here, they set up the operating theatres for left eye operations on one day, and right eye operations on another day.
All the specialized equipment and personnel are set up and work routines optimized for the eye side that they plan on working on that day.
And they have specialized operating "theatres" that are reserved for use with eye surgery only. Many/most are in public hospitals.
The scheduling is done in such a way that the surgeons and anesthetists and nursing staff do the number of procedures that are indicated, by statistical analysis, to be a practical and efficient number per session.
They usually also make scheduling decisions based on an appropriate mix of patients, making sure not to load too many "vulnerable" patients in any particular session - often people who need cataract surgery are of an age where they have other complicating conditions and/or are on complicating medications.
In our province, cataract surgery for most is included in our publicly funded medical system. As a result, the "insurer" (aka our government funded medical system) is active in negotiations with the association of BC ophthalmologists to arrive at agreed protocols which limit cost - the government's goal - while ensuring reasonable remuneration - the doctors' goal - while ensuring high quality results for the populace - the goal of both.
The annual or so negotiations between the government and the ophthalmologists are apparently "energetic" - ophthalmologists tend to be the medical professionals who bill the highest amount each year to the provincial medical system .

 

[Pieter12]

When they do the operations here, they set up the operating theatres for left eye operations on one day, and right eye operations on another day.
All the specialized equipment and personnel are set up and work routines optimized for the eye side that they plan on working on that day.
And they have specialized operating "theatres" that are reserved for use with eye surgery only. Many/most are in public hospitals.
The scheduling is done in such a way that the surgeons and anesthetists and nursing staff do the number of procedures that are indicated, by statistical analysis, to be a practical and efficient number per session.
They usually also make scheduling decisions based on an appropriate mix of patients, making sure not to load too many "vulnerable" patients in any particular session - often people who need cataract surgery are of an age where they have other complicating conditions and/or are on complicating medications.
In our province, cataract surgery for most is included in our publicly funded medical system. As a result, the "insurer" (aka our government funded medical system) is active in negotiations with the association of BC ophthalmologists to arrive at agreed protocols which limit cost - the government's goal - while ensuring reasonable remuneration - the doctors' goal - while ensuring high quality results for the populace - the goal of both.
The annual or so negotiations between the government and the ophthalmologists are apparently "energetic" - ophthalmologists tend to be the medical professionals who bill the highest amount each year to the provincial medical system .

Maybe but not in Quebec.

 

[Sirius Glass]

In contrast to the US, in Canada they will do both eyes at the same time. Don't know about the rest of the world.

When one eye was done, the other eye's cataract was so immature that the doctor called it "juvenile". That operation was 4 years ago and now the other eye is finally catching up.

 

[Alan Edward Klein]

I'd rather do one at a time just in case.

 

[cowanw]

Hard to get around with both eyes covered for a few days!

 

[Pieter12]

Hard to get around with both eyes covered for a few days!

The eyes do not get covered after surgery. Just dark sunglasses outside because the pupil remains dilated for 12-18 hours.

 

[eli griggs]

I got the impression the VA Doctors intend to do both at once, no intervening period.

 

[Cheshire]

Yes, it can really screw with proper focusing. If you dont agree, please try to focus a range finder without your prescription lenses on. Youll notice the issue fast.

Often times you wont be able to see the double image in the range fidner view finder window if your prescription is off. I had to use that to convince my eye doctor a few years ago that my migraines werent caused by diet. He rechecked my eyes, and i got a major change in prescription.

 

[Doremus Scudder]

Yes, it can really screw with proper focusing. If you dont agree, please try to focus a range finder without your prescription lenses on. Youll notice the issue fast.

Often times you wont be able to see the double image in the range fidner view finder window if your prescription is off. I had to use that to convince my eye doctor a few years ago that my migraines werent caused by diet. He rechecked my eyes, and i got a major change in prescription.

We have to differentiate between 1) not being able to see the focusing screen well because your vision is not properly corrected, e.g., without your glasses on and 2) whether or not wearing glasses changes where the sharpest focus on the focusing screen is perceived.

For #1, yes, not wearing your glasses or wearing the wrong glasses can interfere with focusing simply because you can't see well enough to focus.

For #2, no, wearing glasses or using magnifiers will not change where best focus is on the focusing screen.

Best,

Doremus

 

[Alan Edward Klein]

We have to differentiate between 1) not being able to see the focusing screen well because your vision is not properly corrected, e.g., without your glasses on and 2) whether or not wearing glasses changes where the sharpest focus on the focusing screen is perceived.

For #1, yes, not wearing your glasses or wearing the wrong glasses can interfere with focusing simply because you can't see well enough to focus.

For #2, no, wearing glasses or using magnifiers will not change where best focus is on the focusing screen.

Best,

Doremus

I wear progressive eyeglasses. They often are not focused at the optimum angle when I look at things. But I can tell usually when the optimal focus point is reached. Passing that point and returning to it usually works.

 

[Pieter12]

I wear progressive eyeglasses. They often are not focused at the optimum angle when I look at things. But I can tell usually when the optimal focus point is reached. Passing that point and returning to it usually works.

Would removing your glasses and using a proper diopter work?

 

[BMbikerider]

I have worn glasses since the early 90's and I have never had a problem.

 

[Alan Edward Klein]

Would removing your glasses and using a proper diopter work?

With 4x5 that wouldn't work. With eye-level viewfinder cameras, it would work. But then I couldn't see the scene when not looking through the camera. I would have to put my glasses on and off as I switched back and forth, a real annoyance.

 

[Pieter12]

With 4x5 that wouldn't work. With eye-level viewfinder cameras, it would work. But then I couldn't see the scene when not looking through the camera. I would have to put my glasses on and off as I switched back and forth, a real annoyance.

I do it all the time with sunglasses.

 

[Doremus Scudder]

I wear progressive eyeglasses. They often are not focused at the optimum angle when I look at things. But I can tell usually when the optimal focus point is reached. Passing that point and returning to it usually works.

Alan,

I bought a pair of flip-down magnifiers (4x) that attach to the nosepiece of my glasses. I use just glasses for viewing the scene, glasses with flip-down magnifier for general viewing of the ground glass and, for fine focusing, glasses plus flip-down magnifier plus a 5-6x loupe. Never had a problem finding sharp focus.

Maybe a pair of flip-down magnifiers would work for you. Another alternative I use a lot is to keep my progressive glasses on a cord around my neck and a pair of 3-4 diopter reading glasses in a handy pocket. When I need to view the ground glass, the progressives come off and the readers go on.

FWIW, the reading glasses/flip-down magnifiers also help reading the mm scale on my cameras' beds and when setting shutter speed and aperture.

Best,

Doremus

 

[wiltw]

For #2, no, wearing glasses or using magnifiers will not change where best focus is on the focusing screen.

Indeed, while it may be not possible to assess 'best focus' with split screen or microprism in low light low contrast situations, in brighter light and/or more contrasty circumstances even imperfect vision can detect misalignment of split image, or the shimmer in microprism area, and 'best focus' of general groundglass area..

Assessment of 'best focus' on the general groundglass, there can be error. I just set my OM-4 diopter for my left (near) eye and left eye focused in a lower light low contrast part of the house, 7' away from my target. When I switched to my right (distance) eye, it could not detect misaligned split image, nor microprism shimmer, and using the general groundglass surround the assessment of 'best focus' landed on 6' distance (not the 7' measured distance)...my right eye needs + 1.5 or +2 diopter adjustment to see close clearly, and without that it erred in detection of 'best focus' in low light low contrast.

 

[Doremus Scudder]

wiltw,

Your error is likely due to just missing focus. Focusing by eye has an inherent margin of error that gets larger with low light, bad vision, etc. I'm just referring to the image as projected on the ground glass/viewing screen. Your vision (or lack thereof) won't affect the sharpest focus there since it is being projected onto a receiving surface that is not going to be affected by your vision. Getting things as sharp as possible, however, requires good vision and proper magnification. Even then, there is error. That's why auto-focus is better than focusing by eye; it is inherently more accurate.

What is not going to happen is finding two different places for sharp focus, one without glasses and one with.

Best,

Doremus

 

[Sirius Glass]

It all comes down to the lens prescription and how it was filled. I preferred contact lenses to eye glasses. I have had excellent progressive eye glass lenses that worked well with all types of eye glasses. The same with single vision and bifocal lenses. I have one implanted lens from a cataract operation and it works will with any type of camera.