It's been several years since I used my Canon DSLR. During that time my vision requires eyeglasses for reading print within normal reading range. This obviously necessitates putting the glasses on to make external settings on the camera body, and the then removing the glasses to use the view window. A few repetitions of this procedure would drive me over the brink. My question is: Would using camera RAW afford enough additional exposure latitude to simply use auto-exposure and then make necessary adjustments in Photoshop with RAW?

  • Which Canon DSLR? What are typical settings you're changing? What types of photos? Do you have a few examples? – xiota Apr 30 '19 at 18:16
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    The Canon Digital Rebel (an oldie but goodie). Admittedly, its microscopic rear display window presents its own set of problems that even reading eyeglasses won't totally correct. So it looks like I'll have to use the "Braille" method, counting/memorizing dial clicks, etc. Thanks to all who provided input. – BRIAN HELLER Apr 30 '19 at 18:31

There are plenty of reasons why one might want to save raw files rather than allowing the camera to convert and save only one JPEG interpretation of the raw image data. Having trouble seeing the information in the viewfinder should not be one of them.

Your EOS Digital rebel/300D has a 'Diopter Adjust' wheel on the upper right corner of the viewfinder which should allow you to adjust the diopter value of the eyepiece by +/-2 diopters. The apparent distance of the viewfinder as seen through the eyepiece when the adjustment wheel is centered should be about one meter (3.25 feet). If the "power" of your reading glasses that allow you to see things clearly at one meter away is lower than "+2 diopters", then the adjustment wheel on your camera can provide the same benefit without having to wear your reading glasses when looking through the viewfinder.¹

I have worn corrective lenses since about age 7 or 8. I'm currently well over 50 years old. I've been using readers for at least the last decade. My right eye, which is normally the one I use for the viewfinder, has a prescription of -2.75 diopters.

If shooting with contact lenses, which is what I wear by default, I use reading glasses with around +2.0 diopters. I let them slide down my nose a bit and can see the controls and LCD screens just fine at normal holding positions.

When holding the viewfinder to my eye I look over the top of the reading glasses and into the viewfinder. The camera's maximum +1.0 diopter setting on the viewfinder diopter adjustment wheel is just enough for the viewfinder information to be in sharp focus for me.¹ Once I get everything dialed in, I'll often remove the readers and shoot without them. I buy a lot of my T-shirts and Polos with front pockets just so I'll have a convenient place to put the readers. If not, I just hang one earpiece over the collar.

On the rare occasion when I wear prescription eyeglasses while shooting, I adjust the camera's diopter adjustment to somewhere right around the -1 diopter "centered" setting and look through the glasses into the viewfinder. The larger viewfinders of the cameras I use (primarily a Canon EOS 5D Mark III and 7D Mark II) certainly come in handy with eyeglasses. Smaller viewfinders, which tend to have shorter eye relief, make it much more difficult to get close enough to see the entire viewfinder when wearing glasses.

¹ Keep in mind that the apparent distance of the information displayed in the viewfinder, along with the apparent distance of the focusing screen, is about one meter at the "neutral" setting of -1 diopter for the vast majority of SLRs (analog and digital). This makes infinity focus (and the information in the viewfinder) appear to be one meter in front of the eye. In the Canon system, the rating of an add-on adapter or movement of the 'Diopter adjust dial' is the net effect of the -1 viewfinder and the correction applied. Thus the +1 setting includes +2 diopters of correction, moving the eyepiece from a "neutral" value of -1 to a corrected value +1 diopters. Other camera systems also have a "neutral" setting of -1 diopter, but label correction as how many steps away from that neutral -1 setting the correction is providing. Thus Canon offers add-on corrective adapters for +1, 0, -2, and -3 diopters, but no -1 diopter corrective adapter. The 0 diopter add-on moves the centered eyepiece from it's native -1 to 0. Other camera makers refer to this as a +1 diopter corrector. A Canon -1 diopter adapter would do nothing, since it would leave an eyepiece already centered at -1 diopter remaining centered at -1 diopter. Douglas Kerr covers this in greater detail in this paper.


Putting camera setting to auto will make good exposure. But you will loose the ability to set camera depend of your needs. For example if you take photo of wildlife you will need fast shutter speed. And camera in auto do not know it and will try to balance between aperture, speed and ISO. You will not be able to set RAW if you try to use basic modes (portrait, macro, landscape)
I can provide you one possible solution I use (I also use glasses). Try to remember the position of the settings and train yourself to change and manipulate them more by memory (instead of vision). And take photos without glasses, use dioptric correction of viewfinder

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    Thanks, Romeo. Good points. I do very little "action" photography, so in most cases rapid motion wouldn't present a problem. Given that, would you say that RAW would provide the additional latitude necessary to yield a good+ photo in most cases (obviously with the required tinkering)? – BRIAN HELLER Apr 30 '19 at 18:13
  • @BRIANHELLER, RAW file by itself is just a base. After taking photo you should seat and start to edit it. And I give action photography as example, you will prefer to manage the aperture to get shallow or deep field of view, also to manage speed, aperture and ISO to make night photo and so on :) – Romeo Ninov Apr 30 '19 at 18:18
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    I've produced some surprisingly good photos with my iPhone w/HR - even with its obvious drawbacks. It's just been TOO EASY AND CONVENIENT. Again, thanks for your input. Time to sharpen my self-discipline ;-) – BRIAN HELLER Apr 30 '19 at 18:38

Actually it's possible to use the viewfinder with eyeglasses. Even sunglasses. You may adjust dioptric in the viewfinder too, if your eye can't focus on it.

Sadly, using RAW won't help you to recover an underexposed, or overexposed photo. Every pixel in the left or the right of the histogram is lost information, and no computation can recover it.

If you want to shoot in auto, it will work fine on most scenarios. But when it doesn't, you may use exposure compensation and set the light meter to the left (or right) to expose less (or more). Then look at the histogram if there is lost information.

You may try aperture priority in order to control depth of field in your photos. It's almost as easy to use as full-auto. Both full-auto and aperture priority works reasonably well on most scenarios, if you use exposure compensation when histogram shows lost information.

  • The cumulative value of suggestions from all has provided needed encouragement. Now it's a matter of mind over body. Thanks again. – BRIAN HELLER Apr 30 '19 at 18:44

Cameras are pretty good at automatic exposure these days as that does not involve all that much of decision-making. What you may want to think of, however, is cameras offering "post-focus". Basically they do a short 4K video through all focusing planes and then you (or someone else) can pick the correct focus from that sequence afterwards. Takes considerable storage, of course, but you delay decisions.

With regard to delaying exposure decisions, most cameras offer "exposure bracketing" these days, taking (usually) three photographs at different exposure settings. Doesn't work with flash, even though some camera/flash combinations actually do offer "flash bracketing".

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