Using new Canon 20D, a little disappointed, maybe diopter setting.

I just upgraded from a Canon 300D to a 20D, and I am a little

frustrated with the fuzzyness of my images when I manually focus

using my 50mm 1.4 USM. I have read where many rant about how they

feel that they got a bad copy of a camera or a lens, which I suspect

is wrong because I don't think Canon could survive with that kind of

reputation. Nevertheless, when I set my camera for auto focus and A-

DEP my images are a lot shaper and more to my liking. I am not a

professional photographer, so I am not as knowledgeable as many of

you are. Granted, I am setting my camera on a tripod, using the

smallest aperture setting possible, 100-200 ISO, focusing to the

point where I think my image is razor sharp, yet still after I have

downloaded my images on to my computer, they are crap. I am

wondering if perhaps I have my diopter off. The Canon manual is very

vague about the diopter and I am not sure how to adjust it properly,

or if this is even the reason why I am not producing sharp images. I

was having the same problem with my 300D, so I suspect now more than

ever that "I" am the problem. I can't figure it out what I am doing

wrong however. I produced razor sharp images with my range finder

cameras and didn't have any problems when I was using a Nikon

Coolpix 5000 on digital images. I glance through the photos on

TreckEarth and it just kills me that so many are making prized razor

sharp images with their 300D and 20D cameras. Any advice or

suggestions on what I am doing wrong would be greatly

appreciated.

i had the same problem with the 20d i had. i think it is just inherent with that camera. the

pictures do for some reason get better as you get used to the camera. for now shoot in raw

and apply the necessary sharpening post-capture.

<p>The dioptric adjustment knob adjusts the viewfinder optics, which sit between your eye and the focusing screen. It affects how sharply you can see the contents of the viewfinder (both the image itself and the other information such as shutter speed) by allowing you to match the viewfinder optics to your own near- or far-sightedness. It doesn't affect the AF system or how sharp the image recorded on the sensor is (other than by affecting your ability to tell whether or not you've focused accurately when using MF).</p>

 

<p>You say AF gives you very sharp results. Try this: use AF to lock onto a subject. Now, without touching the lens' focus ring, adjust the dioptric correction knob until you find the point at which everything in the viewfinder (the image itself and the other information) appears at its sharpest, without your eyes feeling strained. That's the best view you'll get from the viewfinder.</p>

 

<p>If you still can't MF accurately after that, it's not the dioptric correction knob's fault; it's likely that you're discovering what a lot of other people have found: the standard focusing screens on many AF SLRs, and in particular on DSLRs with APS-C-sized sensors, are not designed with ease of MF as a primary consideration. Rangefinders make it pretty easy due to their split-image system. Manual-focus cameras tend to have focus aids such as split-image microprisms in the centre of the viewfinder screen. Officially, the 20D does not support any focusing screen but the one that's built into it; unofficially, there are third-party screens (some of which have been discussed here before) which may help when trying to focus manually.</p>

 

<p>Another thing to keep in mind is that the dioptric correction can only adjust for simple near- and far-sightedness. It can't fix other eye defects such as astigmatism, so some people simply have to wear glasses in order to see the viewfinder contents properly. And that tends to cause another issue; many people (myself included) find that it is difficult or impossible to see the entire viewfinder when wearing glasses.</p>

Charles, manual focus is "iffy" without the aid of a split screen type device that used to be standard on our manual film cameras. Such aids are available from after market companies, if you do a search you will find much discussion on the topic. On the other hand, I've been happy with the AF of my 20D although, like yourself, I wish MF was easier. Good luck.

What Steve said.

 

My vision is no longer perfect; I need low power (1.25) reading glasses on occasion. I set the diopter adjustment on my 20D (and my 10D before it) by using AF on a bright clear subject (through a fast prime), then adjusting the diopter until the image in the VF reached its sharpest. That way, I never need to wear glasses when shooting, and it has the added benefit of my wife leaving my camera alone, because she doesn't want to fuss with changing the diopter setting.

 

The only time I use MF is when I'm shooting macro, and I'm selecting my desired (and unavoidably narrow) plane of focus.

It's the camera. There's nothing mechanically wrong with it, just that it really wasn't designed with manual focus usage in mind. My XT is worse in this regard, with the little tunnel vision viewfinder and no focusing aids at all.

 

I'd suggest a little experiment. Photograph a yard stick or tape rule almost end-on. Set the camera on aperture priority and open the lens wide to f1.4. Shoot with AF first, and confirm that the point of focus is indeed sharpest. Shoot a few more using manual focus; I'll bet the actual point of focus wanders a bit from frame to frame.

 

By the way, shooting at f22 100-200ISO will cause two problems. First, all else equal, you would have lost quite a bit of sharpness to diffraction; your 50mm f1.4 is probably sharpest at f5.6. Second, you're shutter speed is probably down to the 1/15sec range. Mirror vibrations will also noticeably reduce sharpness; use the custom functions to set mirror lockup, or mirror pre-fire.

<em>using the smallest aperture setting possible</em>

<p>

Bad idea. See <a href="http://www.bobatkins.com/photography/technical/diffraction.html">http://www.bobatkins.com/photography/technical/diffraction.html</a>

<p>

Diffraction will destroy image sharpness at f22 and smaller with a small sensor camera.

<p>

Try f5.6 or f8.

<p>

I regularly use MF on my 20D and I have no problem. You just have to do it right. If the marks on the screen are as sharp as you can get them, you have the dipoter set right.

I almost always use MF with the 20D. However at first it was hard to know if

the picture was actually in focus. After a few weeks i got used the small

viewfinder and now i dont have any problems focusing my pictures. I'd say if

you're shooting wide open it will be signifcantly more difficult than if you you

stop down. I would also try changing the diopter setting after you auto-focus

on something and seeing which setting looks the best to you.

 

Good Luck,

Doug

Thanks for the advice. I will put many of your suggestions to practice. Mirror lockup has so far proven to help my handheld shots immensely. I need to go over the AF more in my manual and learn to program it more to my needs. I didn't think pro's used auto focus much, but why shouldn't they if it were reliable. To tell you all how dumb I can be, I never knew I should take my glasses off when focusing the diopter. (You mean I did not have to wear my glasses through all of those shots!) Well, I am learning. I use to think I was pretty smart...DUH! On second note, if any of you have never ventured on Treckearth.com I highly recommend that you glance through it. If you hit Gallery, then click on Category, then select Camera, and find Canon 20D, you can see what many can do with this camera. It's absolutely breathtaking!

"...I almost always use MF with the 20D..."

 

Why? My 20d's AF is better than any other camera I used. Try changing your AF to the * button (on of the custom settings) - this way you get the best of both worlds and your shutter becomes only a shutter, just like a MF camera. Works for me.

Try using only the center AF point for focus, that should solve your problem. That way the camera doesnt pick out some other area to focus on, only the center point.

To adjust diopter, turn AF off and adjust lens to minimum focus, or even take lens off camera. Touch shutter release button to light up central focusing sensor, adjust diopter until lighted sensor comes into sharp focus. I hope this helps.

"Brian P. Bower , may 04, 2006; 01:34 p.m.

To adjust diopter... Touch shutter release button to light up central focusing sensor, adjust diopter until lighted sensor comes into sharp focus."

 

Superb idea Brian! Never thought of using the "red dot" to adjust diopter - far simpler and more accurate that trying to view a screen image.

Another hint that may help: whenever checking image sharpness, be it focusing the lens itself, or in this case the red dot-diopter adjustment - move the focusing knob/ring rather quickly back and forth... instead of trying to "creep up on" that sharp focus point. By going well past each side the sharpest point, the point of maximum sharpness is a bit easier to recognize.

Charles,

 

My 20D is front focussing when I manual focus. It is really easy to see if I use a wide and focus on newspaper or magazine print.

 

My understanding of the diopter is that it adjusts for best focus of the screen. Since the screen is a matte finish and not an aerial image the diopter will not correct the focus error if any visible on the screen.

 

I know my 20D is front focusing also because AF just about always gives sharp photos but the image looks defocussed. If I move the focus more towards infinty after AF focus it looks focussed in the viewfinder but ends up backfocussed after shooting.

 

I believe I have a focus screen / viefinder registration issue. It has already been to Canon once and they said it was within specification. My understanding of the big corporations is these days they have deadlines and targets and don't have the time or expertise to fix these things properly.

 

The comparitive quality of these things is lower than it was 30 years ago.