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07-23-2009, 04:55 PM   #1
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Reduce eye strain (glasses & manual focus)?

Hi everyone,

I'm a newbie who recently started with a *ist DS and several manual lenses.

I wear glasses and do manual focus with a split prism focus screen. I find my left eye would get very tired after shooting for some time (maybe 30 minutes or so) in low light conditions. This would persist for a day. I wear glasses for short-sightedness and look through the viewfinder on the left eye. Most of the time I try to keep both eyes open and relax my eyes, but this is still not natural and I don't always do it.

I've got my diopter adjusted so that everything is nice and sharp in the viewfinder, although I'm not sure if that's the right thing to do.

I also find manual focus difficult to achieve, although I've only got the diagonal split screen for a few days and I'm still very much adjusting to it.

I mainly work with the Super Tak 50mm 1.4.

I think I'll give my eyes a break for a few days.

Any tips would be most appreciated. Thanks!


Last edited by iht; 07-23-2009 at 04:57 PM. Reason: Typo
07-24-2009, 06:40 AM   #2
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QuoteOriginally posted by iht Quote
...Most of the time I try to keep both eyes open and relax my eyes, but this is still not natural and I don't always do it.

I've got my diopter adjusted so that everything is nice and sharp in the viewfinder, although I'm not sure if that's the right thing to do.
Seems you're doing everything right.
I'm not clear if you wear your glasses or not. If the diopter ranges suffices to correct your vision, I think you should avoid wearing them.

Tip1: persist in keeping both eyes open.
Tip1: if possible take some brakes. I think focusing for 30' straight is a long time.
Tip2: consider a magnifier on the viewfinder. It is not to everybody's liking though.
Tip3: are you sure your left eye is your 'best' eye? The best is not always the dominant eye.
07-24-2009, 07:15 AM   #3
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iht: The first thing to do is get your eyes examined. You note that you use glasses for short sightedness. I am assuming that you are younger or would be dealing with bifocals. If you are under 50 your vision can change quite slowly and only noticible after you get a new pair of glasses. I remember going thru this phase in my 20's and 30's. (if you are over 50, have a check for cataracts.) Also, make sure that you are focusing your super tak wide open and then stop down to the desired aperture. Even in dim light f/1.4 ought to provide enough light for most situations. Hope this helps.
07-24-2009, 09:39 AM   #4
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I have the same camera and shoot pretty much the same way, with my left eye and wearing glasses.

First, the diopter should be set so all the numbers in the viewfinder are perfectly sharp. It's easiest to do this with the lens defocused so you only look at the display numbers.

Second, I found significantly less eyestrain with my Katzeye split-prism screen than the stock screen. You can check to make sure the screen is giving you correct focus. Take some close-up test shots of a newspaper at f1.4, at an angle to the page so some text is in focus and some out of focus. Note what lines of text should be in perfect focus according to the split-prism, and what the image shows. If they're different, the screen may be installed wrong.

A viewfinder magnifier might help a bit, but it might not be compatible with your glasses. I use a magnifier but the difference is not very large.

Even when I had eyestrain, it wouldn't last for a day; more like 30 minutes. It sounds like your eyes are trying to make up for a lot. I agree that an eye exam may be in order.

07-24-2009, 01:56 PM   #5
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You can try and use the Viewfinder magnifier as others have suggested for easier focusing in manual : Pentax O-ME53 Viewfinder
07-24-2009, 06:56 PM   #6
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+1 for good, and thorough, eye exam. I would probably have gotten much more back into photo work years sooner if I hadn't been laboring under a repeatedly-incorrect prescription, until I lucked into a really on-the-ball optician, and you sound like you may have similar complaints to mine.

If your eyes and even your glasses (or switching between) are causing strain over time, it's likely they're doing their best to compensate for not-rightness until they just get too tired, and then trying to focus gets to be like trying to hit two moving targets at once.

You may need to go through the whole dilate-and-relax the-eyes routine where you have to wear the cheesy dark shades they give you for a couple of hours. Worked great, though.
07-24-2009, 07:16 PM   #7
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I got the prescription for my better (left) eye from my Optometrist, grazed eBay until I found a matching Pentax SMC Diopter Correction Lens (+2), made a slight shift to the VF diopter and removed my glasses.

The increase in sharpness, range of peripheral vision in the viewfinder and overall pleasantness of the shooting experience was remarkably noticeable - actually shocking the first time I looked through the VF.

I wear lined trifocals.

The only issue is using the LCD, which I cannot do without my glasses, so I either put them back on (if I really need the histogram) or just don't chimp - which makes my photography more intentional and contemplative.
07-24-2009, 07:49 PM   #8
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QuoteOriginally posted by monochrome Quote
I got the prescription for my better (left) eye from my Optometrist, grazed eBay until I found a matching Pentax SMC Diopter Correction Lens (+2), made a slight shift to the VF diopter and removed my glasses.

The increase in sharpness, range of peripheral vision in the viewfinder and overall pleasantness of the shooting experience was remarkably noticeable - actually shocking the first time I looked through the VF.

I wear lined trifocals.

The only issue is using the LCD, which I cannot do without my glasses, so I either put them back on (if I really need the histogram) or just don't chimp - which makes my photography more intentional and contemplative.
Diopters on the finder are much better, too,I'd think, than trying to use your glasses to look through the finder. I just about never do this, anyway, ...I've got a correction set on the built-in and just nudge my glasses aside. (my actual prescription isn't very strong, anyway. ) Could be a neat service/product for those chain optical stores to provide, come to think of it: they'd only have to carry a few sizes of blanks, and all kinds of people have DSLRs these days.

07-26-2009, 06:26 PM   #9
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Thanks everyone for your helpful input.

Maybe this is what I have done: I do wear normal glasses for short-sightedness when using the camera, and I've got the diopter set to the hard right (+1), which means my eyes are getting doubly compensated (glasses + diopter). I guess this explains why everything is sharp - probably way too sharp for my eyes' good!

And yes, I look through the viewfinder on my left eye. I find this to be most natural. And yes, I've got lazy eyes and my left eye is quite a bit better (as in less short-sighted) than my right eye.

OK, I'll use the method 'Just1MoreDave' suggested and adjust the diopter so that the numbers in the viewfield are clear.

From my limited experience, I find it rather inconvenient to have to take off my glasses when using the camera. I suppose you do get a bigger screen without glasses since the eye is closer to the viewfinder, which makes it easier to focus. Is that the theory? I'll try it out again and see if I can work with that.

I'm still unsure about the magnifier. I'll see if the above measures would improve things before I spend any more money on this new hobby!

And yes, I'll book in with an optometrist and see how my eyes are going. It doesn't help that I'm a software engineer looking at an LCD screen for 8 hours, although I've never felt that kind of strain before I started using the camera.

Cheers everyone!!
08-21-2009, 05:38 AM   #10
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The ever widening use of computers led to a marked increase in the reported cases of eyestrain. Still, too few computer users can identify the early symptoms of eyestrain. They stare daily at a lighted monitor, never noticing that their eyes have come under strain.
08-22-2009, 02:28 PM   #11
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QuoteOriginally posted by gabrieljosh Quote
The ever widening use of computers led to a marked increase in the reported cases of eyestrain. Still, too few computer users can identify the early symptoms of eyestrain. They stare daily at a lighted monitor, never noticing that their eyes have come under strain.
This is what either happened to me or actually am getting old..
Got me some glasses that are specially made to filter computer monitor glare and radiation (if it has it).

Welcome to the forums gabrieljosh.
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