Jump to content

A question for the eye docs regarding contact lenses and focusing


Recommended Posts

Advertisement (gone after registration)

In trying to get closer to the viewfinder and see all of the 35mm frame lines I went to my opthalmologist to have contacts fitted and got corrected to "20/20." I'm 47 so do need reading glasses and was given a pair of +2.00 to use when I had my contacts on and which allow me to read easily.

 

Last night when trying to focus at about 2 meters with my contacts on, the target still seemed just a little blurry. I tried across the room and didn''t feel that I could focus as easily as I remember using glasses. I used my M9-P without a VF magnifier and my MM with a 1.4 VF magnifier and both felt this way.

 

When I put on my +2 reading glasses for the closer subjects, the VF seemed more in focus. This defeats the whole purpose of using contacts.

 

This morning, using my regular glasses, both near and far focusing was easy; but I saw less through the VF.

 

Is there any explaination of why contacts don't work as well? I've also noticed that I can't read the LCD menu or see the aperture selection clearly on the lenses without putting on the reading glasses so apparently contacts are out for now.

  • Like 1
Link to post
Share on other sites

In trying to get closer to the viewfinder and see all of the 35mm frame lines I went to my opthalmologist to have contacts fitted and got corrected to "20/20."

 

Perhaps the contacts compromise to everyday 'walking around' use, or were just made wrong. Someone can tell us if there is a virtual distance to the RF patch. (Frame line accuracy is 2m, but the patch?) I think there is because I wear tri-focals and use the middle distance lens to make the patch image sharp. Far distance lens is not as good, and close lens is no good at all.

 

Dunno. I await an answer, too.

Link to post
Share on other sites

Your contacts are prescribed to correct your distance vision. Objects closer to you are not going to be as clear. Also, there is a slight focus demand put on your eyes when looking through the RF which makes it a little less clear for you with your contacts. If, your contacts are under corrected it could also cause a problem with the RF. Be sure your doctor pushed the full plus prescription on you for your contacts. It is normal as we age to have trouble using the RF because, we can not focus our eyes. Some members find that adding a diopter correction helps. But, there is no substitute for having a visual sytem that can accommodate (focus).

  • Like 1
Link to post
Share on other sites

Someone can tell us if there is a virtual distance to the RF patch. (Frame line accuracy is 2m, but the patch?)

 

2m, coincidentally, as the FAQ tells us. BTW, the frame lines for the MM and the M9-P, which the OP references, are not set for 2m (they are set for 1m); that's only for the M8.2 (or upgraded M8) and the new M.

 

 

Jeff

Edited by Jeff S
Link to post
Share on other sites

The rangefinder itself is set at -0.5 diopters, which means you have to accommodate + 0.5 diopters at least to see far distance. Most likely the best choice would be to add a +1.00 diopter lens to your viewfinder to focus distance and mid-range. You can test this in a basic way by putting on a pair of +1.00 readers and looking through the rangefinder.

  • Like 1
Link to post
Share on other sites

Guest borge

Contacts will never give a visual correction as good as spectacles.

You don't control how the contacts stay on your eyes.

 

It is much easier to obtain much sharper visual results with spectacles than with contacts.

 

I have been using both for many many years. My vision is great with contacts but details "pop" much more with spectacles - both of which are corrected properly for my eyes.

 

If you have astigmatism that is even more difficult to correct properly with contacts as the contacts themself "float around" on your eyeball but to correct astigmatism 100% they need to sit on the eye 100% correctly - which is rarely the case...

Link to post
Share on other sites

Advertisement (gone after registration)

In trying to get closer to the viewfinder and see all of the 35mm frame lines I went to my opthalmologist to have contacts fitted and got corrected to "20/20." I'm 47 so do need reading glasses and was given a pair of +2.00 to use when I had my contacts on and which allow me to read easily.

 

Last night when trying to focus at about 2 meters with my contacts on, the target still seemed just a little blurry. I tried across the room and didn''t feel that I could focus as easily as I remember using glasses. I used my M9-P without a VF magnifier and my MM with a 1.4 VF magnifier and both felt this way.

 

When I put on my +2 reading glasses for the closer subjects, the VF seemed more in focus. This defeats the whole purpose of using contacts.

 

This morning, using my regular glasses, both near and far focusing was easy; but I saw less through the VF.

 

Is there any explaination of why contacts don't work as well? I've also noticed that I can't read the LCD menu or see the aperture selection clearly on the lenses without putting on the reading glasses so apparently contacts are out for now.

 

Which is why I use a magnifier with a variable dioptre setting on the M/M9......

 

The difference between 1-2m and infinity is approximately 1/4 of a turn and I have the points marked on the adjustment.

 

No other method will correct for your vision exactly at all distances .....

  • Like 1
Link to post
Share on other sites

The general rule with visual correction is spectacles are clearest, then rigid CLs then soft CLs (assuming all are accurate and giving you the full correction). You mention that you were given CLs to correct to 20/20 but you don't mention whether they were rigid or soft (I assume soft). As Borge mentioned if astigmatism is present in your glasses it may not be corrected with your CLs or it may be incompletely corrected. It is quite possible to give someone 20/20 visual acuity by only correcting the sphere and not the astigmatism present, depending on the quantity and orientation of the astigmatism. But that is not to say the astigmatism is not significant especially for visually demanding tasks. Small degrees of astigmatism and especially "against the rule" and oblique astigmatism can have a huge effect on resultant visual acuity. I have a small bit of ATR astigmatism in each eye and I wouldn't dream of leaving it uncorrected especially if taking photos.

Good quality modern toric soft lenses have complex designs to help stabilise the rotations found in older lenses and visual variations due to rotating lenses are NOT the problem that they used to be.

If you are myopic close up tasks will be more challenging with distance CLs compared to being hyperopic. Neither will be great, especially if you need a +2 add, but being myopic will make near vision more difficult. (Incidently if this is your first time of having an add +2 is quite strong. Could it be that you have been over-minused in your CLs?) That would certainly make any close up task (menu screen/viewfinder/focussing tab/etc) much more difficult.

I am myopic (-2.50) and have a small cyl' in my shooting eye (-0.50 x 90) also +1.50 add. I use toric soft lenses and have no problems focussing an M9/MM (at least not for visual problems!)and can just about make out the screen info at the rear without any extra help.

Regards

Richard

  • Like 3
Link to post
Share on other sites

I am not an expert on this subject, but as you have asked, get it right so you will have enjoyable image making. Otherwise it is a waste to not hit your focus regularly.

 

Personally, I have gone back to wearing my eye glasses and using a Match Technical eye cup (without correction) so I can get my glasses close to seeing the entire frame while not scratching them. Works great now.

Link to post
Share on other sites

A well fitted contact lens will in most cases give better correction than spectacles. There are several reasons why this is true. Glasses do not sit on the corneas and are subject to aberrations that the contact lens is not. This does not take into account the ill fitting contact that "floats around" which was mentioned above - get a new doctor that can fit a contact.

  • Like 1
Link to post
Share on other sites

I was never able to wear contacts. After years I had progressed to bifocals and could not see my alarm clock in the night without them. In 1995 I had laser surgery that corrected my vision for distance. I still use some over the counter reading glasses at times but for the most part use nothing. It sure helped with my camera focusing since I needed nothing to see the viewfinder info anymore. Laser surgery has progressed since mine were done. They can correct for both near and far focusing.

Link to post
Share on other sites

There is no LASIK procedure that will correct for distance and near focusing. There is investigational procedures that will provide both far, intermediate and near zones of ablation of the cornea. But, it should not be very satisfactory due to the optical considerations involved. They will try and sell anything in medicine to the unsuspecting public. There is mono-vision LASIK, though.

  • Like 1
Link to post
Share on other sites

HI There

Well, I'm going to be positive about contacts . . .

I guess I'm in your situation ymc226 (is this what your girlfriends call you? :) )

 

I tried varifocals and have finally got to a compromise which works really well for me and my longsightedness.

 

I wear soft disposable contacts, and I have a +1.75 in my right eye which makes focusing a snap, and a +2.5 in my left eye which makes reading a snap (including the LCD on the back of the camera).

 

I understand it doesn't suit everyone, and it isn't perfect, but for me it means that after 10 years of wearing glasses full time, the last 10 years I haven't - at least, only very occasionally in the theatre or driving at night.

 

My focusing is just fine (Nocti 0.95 wide open in low light no problem). Having got the contacts right it's then just practice.

 

Your optician should be able to tell you about this method - it's common, and as far as I'm concerned it's the complete answer to my longsight problem.

 

All the best

  • Like 3
Link to post
Share on other sites

Contacts will never give a visual correction as good as spectacles.

You don't control how the contacts stay on your eyes.

 

It is much easier to obtain much sharper visual results with spectacles than with contacts.

 

I have been using both for many many years. My vision is great with contacts but details "pop" much more with spectacles - both of which are corrected properly for my eyes.

 

That's interesting - I get exactly the opposite.

 

I'm 8.5 diopters short sighted (glasses prescription), and my vision with spectacles (even with really expensive lenses, I've tried many types) is quite poor - only clear in the very centre of the field, quite distorted, and lots of chromatic aberration towards the frame.

 

But, I can see perfectly with contact lenses. Near, far, centre and peripheral.

 

My vision with glasses is bad enough that I'm reluctant to drive with them on, even though legally, I'm OK to drive. Especially the loss of peripheral vision is a concern.

 

I have no astigmatism, and my eyes are good, other than the short sightedness.

 

- Steve

Link to post
Share on other sites

Guest borge
That's interesting - I get exactly the opposite.

 

I'm 8.5 diopters short sighted (glasses prescription), and my vision with spectacles (even with really expensive lenses, I've tried many types) is quite poor - only clear in the very centre of the field, quite distorted, and lots of chromatic aberration towards the frame.

 

But, I can see perfectly with contact lenses. Near, far, centre and peripheral.

 

My vision with glasses is bad enough that I'm reluctant to drive with them on, even though legally, I'm OK to drive. Especially the loss of peripheral vision is a concern.

 

I have no astigmatism, and my eyes are good, other than the short sightedness.

 

- Steve

 

For all I know it might be the astigmatism that causes it. I have -1.50 and -1.00 astigmatism on my left eye and -1.00 and -1.00 astigmatism on my right eye.

 

Ironically, when corrected, my left eye (which is the worst uncorrected) has much better vision than my right eye as well. Maybe I should visit yet another optician and get more opinions. My last optician tried to overcorrect me several times and I had to change the glasses in my spectacles three times due to over correction.

Link to post
Share on other sites

A well fitted contact lens will in most cases give better correction than spectacles

"Better Correction" is different things to different people. Many CL wearers prefer their vision through CLs compared to glasses (less distortion, less chromatic aberrations, wider field of view, etc) but clinically they often do not reach the same level of visual acuity that they get with accurate glasses. Both high contrast and especially low contrast visual acuity will be better with glasses. Looking through a hydrated membrane (soft lens) coated in tears does not help your low contrast sensitivity.

With spectacle lenses that are now correcting high order aberrations too this difference can be even more marked.

However many people feel that this benefit is outweighed by the advantages of the bigger field of view, less distortion, more natural vision that they get with CLs.

Nicer way of seeing the world? Undoubtedly CLs are a nicer way of seeing the world, but in the majority of cases I believe spectacles give sharper and clearer acuity, albeit with other disadvantages.

Richard

  • Like 1
Link to post
Share on other sites

Nicer way of seeing the world? Undoubtedly CLs are a nicer way of seeing the world, but in the majority of cases I believe spectacles give sharper and clearer acuity, albeit with other disadvantages.

Richard

 

HI Richard

I'm sure you're right - the best answer is to keep perfect vision throughout your life (wouldn't it be nice).

I realise that I get clearer sight through my varifocals - but from a practical point of view my lopsided CL give me much more flexibility (and less neck ache trying to read the top of big screens!).

 

all the best

Link to post
Share on other sites

Guest borge
"Better Correction" is different things to different people. Many CL wearers prefer their vision through CLs compared to glasses (less distortion, less chromatic aberrations, wider field of view, etc) but clinically they often do not reach the same level of visual acuity that they get with accurate glasses. Both high contrast and especially low contrast visual acuity will be better with glasses. Looking through a hydrated membrane (soft lens) coated in tears does not help your low contrast sensitivity.

With spectacle lenses that are now correcting high order aberrations too this difference can be even more marked.

However many people feel that this benefit is outweighed by the advantages of the bigger field of view, less distortion, more natural vision that they get with CLs.

Nicer way of seeing the world? Undoubtedly CLs are a nicer way of seeing the world, but in the majority of cases I believe spectacles give sharper and clearer acuity, albeit with other disadvantages.

Richard

 

That is my exact experience as well. Glasses provide much more clarity and acuity. Although I had problems with the distortions and perspective changes in the beginning (everything looks a bit smaller - but changing to a lower index glass helped a bit). My soft CL's provide the same visual correction - but - compared to glasses, it's like looking at an unsharpened image, while the glasses are sharpened images. The soft CL's provide much less contrast as well.

 

My vision is perfectly fine with both but after getting used to glasses I really prefer them for pure visual quality. But the soft and disposable CL's are essential for the summertime (sunglasses). I have tried sunglasses with correction and never got comfortable with them, and I also tried the latest Rodenstock ColorMatiq IQ self-tinting lenses and I returned them - They did not provide the "sunglasses" effect at all, the difference was barely visible under bright sunlight. And they kept their tint even far into the afternoon when it was dark... Horrible product.

 

When using my 35mm I have to use my CL's. My glasses only works with 50mm framelines (and above).

Link to post
Share on other sites

HI There

Well, I'm going to be positive about contacts . . .

I guess I'm in your situation ymc226 (is this what your girlfriends call you? :) )

 

I tried varifocals and have finally got to a compromise which works really well for me and my longsightedness.

 

I wear soft disposable contacts, and I have a +1.75 in my right eye which makes focusing a snap, and a +2.5 in my left eye which makes reading a snap (including the LCD on the back of the camera).

 

I understand it doesn't suit everyone, and it isn't perfect, but for me it means that after 10 years of wearing glasses full time, the last 10 years I haven't - at least, only very occasionally in the theatre or driving at night.

 

My focusing is just fine (Nocti 0.95 wide open in low light no problem). Having got the contacts right it's then just practice.

 

Your optician should be able to tell you about this method - it's common, and as far as I'm concerned it's the complete answer to my longsight problem.

 

All the best

 

I'm not sure my situation is the same as yours. I'm +7.00 in both eyes and corrected with contacts, I'm basically blind at reading distances, more so than with glasses.

 

I'll go back and speak with my ophthalmologist but I think he knows what he's doing; he authors texts for medical students. Maybe I'll look into the Walter Rx eyepiece as brought up in another thread.

 

Regards,

 

Lawrence

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...