Re: help with manual focus on Rebel XT

Today default commented courteously on the subject at hand

I was wanting longer focal lengths for my Canon Digital
Rebel XT without spending a huge pile more money so I
purchased two methods to compare.

I have 4 lenses for mine, kit lens, 17-40 L zoom, 24-70 L, and
a Sigma 18-125. I have great difficulty getting a decent AF
lock, even after reducing the sampling points to only one in
the center. About 1-2% of what I shoot are just a tad out-of-
focus. And, no, it isn't shake. So, I've learned to take a 2nd
shot with the AF point moved slightly if there is any doubt at
all in my mind. Digital is free, the battery lasts me for over
400 exposures, and alkaline AAs last 200+ in my Canon 430EX
external. Since I shoot either large or medium JPEG, 2 1/2 gig
of memory with me is plenty.

So, I've also experimented with MF as well. But, it is also
problematical and inaccurate for me, quite probably because
the "finder" has no optical focus aide such as split image or
microprism, and is 4 stops dimmer than my old Nikon FTN going
from a 50mm f/1.4 prime to an average f/2.8-5.6 on the Rebel,
depending on lense and zoom focal length used.

Plus, the Rebel's AF/AE system refuses to show me an AE lock
in manual focus mode unless /it/ thinks I've correctly got the
blinking thing in focus. So, if I could get 100.0% AF lock on
auto, why the hell would I try manual? And, if /my/ version is
what I want, good, bad, or indifferent, how can I convince the
Rebel to still do an AE lock? Yes, I've tried the 4 ways that
AE/AF can be set as a custom function by reading/re-
reading/re-reading - RTFM, right? Also experimented, also
talked to my local camera store manager, who is at least
marginally good at this stuff.

So, I posted near the top because I cannot at all help you in
your particular endeavor, except to say that neither of us are
going goofy - or we both already are, but don't know it.

Good luck, and please, please, please post what you finally
find as a good solution, and I will try to duplicate your
success with my lenses and workflow.

1. A 2x teleconvertor to mount to my Canon EF 70-300mm
F4-5.6 IS lens. 2. A Quantaray 500mm F8 mirror lens and
nice solid T-Mount to EOS adaptor. 3. Crop the image and
enlarge.

So far solution 1 is producing slightly better results and
the IS feature does work. However it becomes 140-600mm
F8-11 lens and autofocus doesnt really work so it requires
manual focus.

Solution #2 is nice because it is so light weight and
compact and is actually faster at 500mm F8. However it is
manual focus, fixed aperture, no IS. I can live with those
trade-offs, but I cannot get the focus quite on. The depth
of field is very small so it has to be good.

So far neither of the above is really getting significantly
better results than cropping the image from the 70-300 with
no TC.

In both cases it seems like the focus is always a bit off.
The 70-300 with TC is a bit sharper but still fairly poor.
I am using a tripod and a RS60-E3 remote shutter release.
My suspicion is that I don't have the eyepiece diopter
quite perfectly adjusted and am misfocussing, or that the
focus screen is not perfectly matched in distance as the
image sensor. When the image on the focussing screen looks
sharpest to me, the captured image is still a bit blurred.
I am considering purchasing an eyepiece diopter to try to
get the focussing screen completely sharp since I am at the
end of the range on the camera.

Is there a technique to getting really sharp manual focus
or do I just need more practice?






--
ATM, aka Jerry
.

Relevant Pages

  • Re: help with manual focus on Rebel XT
    ... viewfinder really sharp to be able to manual focus accurately. ... the Rebel's AF/AE system refuses to show me an AE lock ... success with my lenses and workflow. ... The goofy thing might be expecting a sharp image from an inexpensive ...
    (rec.photo.digital.slr-systems)
  • Re: Want to see how bad P&Ss really are?
    ... to point where I want to focus, get a lock, then move to compose ... the camera locks the aperture wide open and adjusts the ... put the camera/lens in manual focus mode but there really is NO ... I wish modern cameras would have a microprism or split image ...
    (rec.photo.digital)
  • Re: help with manual focus on Rebel XT
    ... A Quantaray 500mm F8 mirror lens and nice solid T-Mount to EOS adaptor. ... However it becomes 140-600mm F8-11 lens and autofocus doesnt really work so it requires manual focus. ... I am considering purchasing an eyepiece diopter to try to get the focussing screen completely sharp since I am at the end of the range on the camera. ... Is there a technique to getting really sharp manual focus or do I just need more practice? ...
    (rec.photo.digital.slr-systems)
  • Re: Want to see how bad P&Ss really are?
    ... Stephen Bishop added these comments in the current discussion du ... to point where I want to focus, get a lock, then move to compose ... the camera locks the aperture wide open and adjusts the ... put the camera/lens in manual focus mode but there really is NO ...
    (rec.photo.digital)
  • help with manual focus on Rebel XT
    ... However it is manual focus, fixed aperture, no ... I am considering purchasing an eyepiece diopter to ... Is there a technique to getting really sharp manual focus or do I just need ...
    (rec.photo.digital.slr-systems)