There are many reasons why one may want to back up raw files rather than letting the camera convert and save a single JPEG rendition of raw image data. Having trouble seeing the information in the viewfinder should not be part of it.
Your EOS Digital rebel / 300D has a "Diopter adjustment" dial in 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 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 allowing you to see clearly at a distance of one meter is less than "+2 dioptres", the adjustment wheel of your camera offers the same benefits without you having to wear your glasses. reading when you watch. in the viewfinder .¹
I wear corrective lenses for about 7 or 8 years. I am currently over 50 years old. I've been using readers for at least a decade. My right eye, which is normally the one I use for the viewfinder, has a prescription of -2.75 diopters.
If I shoot with contact lenses, which I wear by default, I use reading glasses of about +2.0 diopters. I let them slide a little on my nose and I can very well see the controls and LCDs at normal holding positions.
When I hold the viewfinder in the eye, I look over the reading glasses and into the viewfinder. Setting the camera's diopter adjustment dial to a maximum of +1.0 diopter is sufficient to ensure that the viewfinder information is perfectly clear.¹ Once everything is composed, I often remove the drives and I shoot without them. I buy a lot of my t-shirts and polos with pockets on the front just to have a convenient place to put the drives. Otherwise, I'm just suspending a headset at the collar.
In the rare cases where I wear glasses while I'm taking pictures, I adjust the diopter setting of the camera roughly around the "centered" setting of -1 diopter and look through the glasses in the viewfinder. The wider viewfinders of the cameras that I use (mainly a Canon EOS 5D Mark III and 7D Mark II) are certainly handy with glasses. Smaller viewfinders, which tend to have shorter eye relief, make it much more difficult to see the entire viewfinder when wearing glasses.
¹ Do not forget that the apparent distance of the information displayed in the viewfinder, as well as the apparent distance from the focus screen, is about one meter to the "neutral" setting of -1 diopter for the vast majority of SLRs (analog and digital). ). This makes the focus in infinity (and the information in the viewfinder) seem to be one meter in front of the eye. In the Canon system, the nominal value of an adapter or the movement of the "dioptric adjustment dial" corresponds to the net effect of the viewfinder -1 and the correction applied. Thus, the +1 setting includes a correction of +2 diopters, changing the eyepiece from a "neutral" value of -1 to a corrected +1 diopter value. Other camera systems also have a "neutral" setting of -1 diopter, but a label correction indicates the number of steps of this neutral setting -1 provided by the correction. Thus, Canon offers additional correction adapters for diopters of +1, 0, -2 and -3, but no diopter correction adapter of -1. The addition of 0 diopters moves the eyepiece centered from its native value from -1 to 0. Other camera makers call it a +1 diopter corrector. A Canon -1 diopter adapter would do nothing because it would leave an eyepiece already centered at -1 diopter remaining centered at -1 diopter. Douglas Kerr discusses this in more detail.