focus-test with 17-85 and 50mm/f1.8 // front-focus?

Started Feb 20, 2005 | Discussions thread
Joe11
Regular MemberPosts: 184
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Re: Horrible test. Absolutely horrible.
In reply to hockeynut, Feb 27, 2005

Thank you for your detailed report.

Please have a look to the start message of this thread, there I have discribed the focus points.

I must admit that I'm a beginner to DSLR, but I will get better

All the test chart und bottle pictures are made from a tripod.

Surely, I could have improved the shutter speed, but I didn't want to increase the ISO due to noise. If you print out a higher ISO on a black/white printer, it looks really bad.

The people in the shop understood the problem with the 50mm/1.8 lense.

I repeated it severall times with different conditions. This lense has a front focus, that's for sure. If you compare the new 50mm/1.4 lense pictures, you must admit that these pictures are much better, independant from the lightning conditions.

If a DSLR can't do focus tests on a black and white paper with maximum contrast in bad lightning conditions (repeated several times with same results), we all should all adjust manually. But I think that a DSLR can do better

hockeynut wrote:

I'm amazed. I can't believe how bad these "focus" tests really are.

1/40th of a second? At f1.8? And you're shooting a plant in a
window? What kind of light outside? A full moon? Look at this
picture:
http://www.pbase.com/joe11/image/39969127
I've looked at it three times, and I still can't believe it. Are
you focused on the shadow underneath the leaves?

If you printed this and told them you shot this at 1/40th, f1.8,
handheld with an $80 lens, they'd laugh you at the camera store.

Another one... 1/50th of a second, at f1.8. Can you quit shooting
by candlelight? Can you get some more shutter speed?
http://www.pbase.com/joe11/image/39970016

AF needs light and contrast. These aren't lens/camera tests.
These are challenging conditions. You need to prove to us and
yourself that you have a working camera (and lenses) in GOOD
CONDITIONS FIRST. Start out at f5.6. then F4. Then f2.8. Then
f2. Prove to us that there's NOT going to be an issue with
handholding. Get some shutter speed. If you somehow manage to
stumble across a tripod, make sure that you use a remote, or the 10
second timer to prove that you didn't shake the tripod with your
finger on the shutter.

Frankly, you've not proved anything except that you don't know what
you're doing.
Seriously... who shoots wide open (f1.8) at 1/40th of a second and
gets shots that dark in a window?

Logic. You need to use logic. It's not rocket science. Go
outside on a sunny day. Put a little thought into your test.

This shot:
http://www.pbase.com/joe11/image/40218049

might be the worst of them all. 1/6th of a second? Did you
handhold that shot? That might be the most amazing handheld shot
of them all. I couldn't handhold a shot that good at 1/15th of a
second, much less 1/6th of a second. 1/6 of a second is a LONG,
LONG time. What kind of light is that? A candle?

What is your focus point? If I can take a stab at this... the
center (to me) looks like the gap in the middle of the 4 bottles,
about halfway down the neck.
Can I ask a favor? How about trying your next focus tests on
something other than clear glass? Please.
I see the focus tests on the test chart, and they look ok. But you
used flash. So what did you prove? Really. I'm curious. What do
you think you proved? That at f5.6, with the flash, the 17-85
looks ok. That's about all you proved. Nothing more. Nothing
less. If that's what you set out to prove, you proved it.

Go outdoors. Give up the candles. Give up the moonlit shots.
Real subjects. Real lighting. Logical. Get out a piece of paper.
Plan a test. Start at f8. Remember that you need contrast and
light. Don't try to focus on the "edge" of a subject, if you miss,
you're completely OOF, and you're back to worthless focus tests
again.

Shoot tests at f8, f5.6, f4, f2.8, f2, and f1.8. Get a tripod and
learn to shoot long exposures without wiggling the camera. Or get
some shutter speed.

Sadly, there are other rocket scientists out there sifting through
their rubbish bins, looking for water bottles and a few candles so
that they can duplicate these tests and post, "Me too!"

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