Full Version: Manage / Repair back focus, plus general ruminations about adapting
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I still have my first and only DSLR, an old EOS 10D (no EF-S mount!), and over the years I've basically stopped using it. When I used it, I often had the impression it had a slight back focus. Or front focus? No matter: in any event, it had trouble focusing exactly where I wanted it to. I did a fair bit of manual focusing and auto, and the viewfinder probably contributed because it is awful and small and dark, but there was no affordable alternative back then. And I didn't know much about finders then.


Now, I do want to pick up my photography again, and there are alternatives, and there is some cash to burn. But the 10D is still there, no longer worth much, as bad to use as it's ever been, but call it nostalgia, I can't bring myself to just ditch it. I'd rather keep it as a 'kick-around' body, even if it's only with the EF-S 18-55 whose rear end I cut open so I could mount it on the 10D ;-)


However, the last time I did use it, in 2013, it did give me trouble beside the back focus. Just cutting out on me several times. Might have had something to do with the batteries, which had been mostly just lying around since 2009.


Two new batteries wouldn't break the bank these days, but what is to be done about the focusing trouble? More to the point: can this be adjusted on the body alone or is there work to be done on the lenses as well?


Because there is still some better EF glass than the 18-55 'yoghurt cup', and no matter what system(s) I go for - there will be more, as well as some Metabones adapters. But of course I would want my main cameras to focus correctly with the 'good' lenses.


Which, in turn, opens up a whole other can of worms: What could be done if a prospective MFT and/or Sony body had similar focus trouble with one or more Canon lenses?

Mirrorless cameras do not suffer from front or back focus. 


They use the image sensor also as AF sensor, in contrast to SLRs which use different sensors for AF and capturing the image.  In addition SLRs typically measure the focus with an aperture of f/5.6 (in the geometry of the AF-sensor).  Some SLRs at the higher end have some sensors using an f/2.8.  The use of these slowis apertures can lead to extra issues when the lens is not well corrected regarding spherical aberation (focus shifts with the aperture.


When using EF lenses via e.g. Metabones, focus might be painfully slow on a mirror less, depending on a number of factors.

I Never read or heard that SLRs would close the aperture to measure focus. So far I thought SLRs always measure wide open. How else could they "guarantee" to get in focus pictures with fast lenses?

And Seymour, I would not put any investment into such an outdated body. Put it on a shelf and enjoy your new camera whatever it might be.
SLRs do not close the aperture for AF. The sensors have their own limitation, from their own optics, limiting what they get to f5.6, f4 or f2.8 depending on focus point, sensor design, camera.


The mentioned spherical aberration AF issues do not occur during the AF itself, though. The spherical aberrations the AF "sees" are those from the wide open lens, even if the AF sensor has its own aperture of f5.6 or f2.8. The error occurs with the lens stopping down, shifting the focus plane, when taking the photo/after the AF is done.


Regarding the 10D, it is a very old dog. The user interface is very, very awkward by today's standards, the LCD is very small and low res., the 6mp sensor rather limiting in resolution and noise above ISO 200. The AF issue you see is a combination of lens and camera. No way to predict how other lenses will perform.

No idea why you would want to go get a MFT or Sony mirrorless and expensive metabones adapters, and go Canon lenses. 

Either go mirrorless if you think you will like that (it is not for me...), or go new Canon DSLR. And then buy lenses for the new platform. Any Canon DSLR will have waaaay better AF performance than the old 10D you have.The AF in a 100D or 650D or 700D or 760D is much, much improved compared to that old thing. 


By the way, mirrorless cameras with contrast detect AF can still missfocus, sometimes badly, depending on lens (even native lenses). You still have to check results.


Quote:Mirrorless cameras do not suffer from front or back focus.
Thanks for clearing that up!

Another reason never to go back to mirrors.
Quote:When using EF lenses via e.g. Metabones, focus might be painfully slow on a mirror less, depending on a number of factors.
I am putting a lot of stock into the 2.0 firmware for the A7 II. There are very enthusiastic reports. I was going to delay the full format purchase until next summer or so and get a small MFT system for now, but since Sony improved the co-operation with adapted lenses and definitely addressed the main issue (RAW compression)... why wait?


Quote:The user interface is very, very awkward by today's standards,
I so completely don't care ;-) Call it quirky but I mainly shoot in manual mode. All I ever wanted in the way of 'interface' was a dial for the aperture and a dial for the shutter. And a decent viewfinder <sigh> I hate a camera that tries to be smarter than me or read my mind or something. (Maybe except if it's a compact.) I don't want it to be my personal assistant - I want it to be my personal image taking slave. Carry out my orders, to the letter, and not ask any questions.

Granted, the whole auto ISO thing sounds promising but mainly, I find things like matrix metering and scene modes useless, distracting black boxes. Much too much effort trying to remember what they do exactly when it is so easy to remember what the basic image parameters do.
Quote:6mp sensor rather limiting in resolution and noise above ISO 200.
And yet, in 2003, its high ISO performance and resolution was sufficient to make me give up pushing Kodak Tmax to ISO 3200 ;-) Took a lot of nice pictures with it despite these shortcomings. Sufficient sensor quality for most of what I do is a given in any system these days.
Quote:No idea why you would want to go get a MFT or Sony mirrorless and expensive metabones adapters, and go Canon lenses.
That is easily explained.

I finally want a decent (and of course 100%) viewfinder to work with again.

It is the single most important piece of "user interface" after all. https://luminous-landscape.com/understan...ewfinders/

I find the established brands, and especially Canon, have become complacent and lazy, their DSLR bodies overpriced, underperforming and putting unwarranted restrictions on my creativity.

I need to wear eyeglasses, which I find impractical to remove for shooting (as well as for using binoculars), and Canon viewfinders have consistently underwhelmed me regarding coverage, eye relief and the option to put in different screens. When they cancelled that option on the 5D MkIII, I lost the last remaining vestiges of interest in Canon bodies. The future is mirrorless, configurable, and adaptable.

What I do care about though, among other things, is build and image quality, which is why I like a lot of Canon lenses.

Another thing I do like is the genuine Canon USM with FTM. If you do have to have AF (see below), that is the nicest implementation I have tried so far, as soon as you can transfer the AF start away from the half shutter press and to some other discrete button where it does not get in the way.
Quote:Any Canon DSLR will have waaaay better AF performance than the old 10D you have.
Another thing that I could not care less about ;-) For the things I shoot, I find autofocus to be highly overrated. I'd take a system optimised for manual focus any day of the week over one that is covered in 99 AF sensors but does not give me decent manual focus control.
Quote:You still have to check results.
That goes without saying ;-)


They might use a moving film plane for focus as Contax did. OTOH, why would then then make new lenses unless perhpas they are going to optimize them for digital. I wonder whether it will allow film too?