More on Canon Rebel XT noise at high ISO - 2 main new data points

Today David Dyer-Bennet commented courteously on the subject
at hand

All Things Mopar writes:

Today G.T. commented courteously on the subject at hand

Known issue on Digital Rebel and Rebel XTs. Use + EC.

What means "+ EC"? Don't know it, didn't get anything
Googling, can't find it in the manual (unless I've blind).
I know what EV is...

He means "use exposure compensation to add (that's the "+"
part) exposure". I don't think his notation is widely used
for that, I just understand it because it's the obvious
workaround for the problem (I'm not very into relying on
the auto exposure of my cameras anyway).

I got that only partially when it was first mentioned, figured
it out on my own later, and got even more knowledgable
yesterday with the camera/flash combo and both user manuals, I
was doing both the camera and flash EC somewhat incorrectly
due to lack of experience with a new toy.

David, you and the others aren't going to tell me that I
should have been instantly capable of use of these techniques
on a camera I wasn't fully trained on at the time I made the
comments I did, are you? If you are, I congratulate you also
on being able to leap up from newbie to expert on your fav
camera(s) to the point where your very first images are
perfect.

Again, for all the lurkers here, I much more highly value the
experience and judgment of people with identical or very
similar equipment to mine, shooting pictures in identical or
similar challenging situations, and at similar points climbing
the learning curve of a new piece of hardware - than I am of
people who spew theory. I understand the theory, but I am
still learning how to put my understanding into practice.

It looks like my Rebel is a keeper, but I will take one more
shot at the WPC museum tomorrow with my latest knowledge to
verify that exposure and noise are acceptable before my
carriage turns into a pumpkin at 9:00 tomorrow night (i.e, at
the end of my 10 day money back guarantee).

--
ATM, aka Jerry

"I disagree with what you say, but I will defend to the death
your right to say it." - Evelyn Beatrice Hall under the
pseudonym Stephen G. Tallentyre

All Things Mopar wrote:

With all that as a proviso, if you still want me to post my
images, here's some NG choices:

alt.binaries.photos
alt.binaries.amp
alt.binaries.paint-shop-pro (where I posted previously, not a
good place)

Wherever, just say where and put a flag in the subject such as [ATM350]
so we can find them. I suggest that you post the photos you were having
trouble with as well as the new and improved. OTOH, if you believe
you're out of the woods on this issue, don't go to any particular
trouble. [We reopen tomorrow, so I'll not have as much time for this...]

Cheers,
Alan
--
-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm
-- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm
-- [SI] gallery & rulz: http://www.pbase.com/shootin
-- e-meil: Remove FreeLunch.

Maybe also look at turning down the contrast so that highlights don't
blow as quick making underexposure less necessary. Then just look at the
LCD review & make sure you get a few blinking blown highlights. If
nothing blown you can boost the EC. Of course then that requires post
processing where you do want more contrast & shooting raw is the next
step. BTW, shooting raw actually shows more noise but more detail too,
and less posterization. Shooting raw with just a few blinking
highlights, you'll be able to recover those also.

All Things Mopar wrote:
Today Paul Furman commented courteously on the subject at
hand


So underexposure seems to be the problem. Look at changing
the metering to a narrower central area so that bright
reflections don't throw off the metering.


Paul, please don't take one small part of a much longer
epistle out-of-context to where it looms very large.

As is well known by everyone with even a modicum of digital
experience, including me, severe underexposre leads to high
noise. Some EVFs, like my old Nikon 5700, got noisy with just
a stop or two under, even at ISO 100.

What I'm saying is that the Rebel XT noise at /any/ given ISO
is proportional to underexposure, again as is well-known, and
that I tend to get mild-to-moderate and sometimes severe
underexposure due to excessive flash pulse reflection off some
part of the car and/or something like a sign in the
foreground.

This does /not/ mean that /all/ of my flash pics are under,
they aren't. About 1/3 are OK +/- 1 f/stop, another 1/3 are
over +1/under -2 stops, the rest are under 3,4,5 f/stops. It
depends. Without being able to easily post cropped examples
here, it is difficult to explain.


I also wonder whether it might be better to shoot full 8MP
images and batch reduce them, instead of letting the camera
downsample.


I tried that. Resizing is /not/ one of the culprits as best I
can determine. I understand, though, what you're saying, I
think. You're suggesting that I not allow the camera to do
image damage due to interpolation downward, which may
exacerbate the noise.

On the other hand, though, resizing down correctly in a
competant app such as PSP 9 can and does "compress" some of
the noise out, so I /always/ crop for best composition
horizontally and vertically at full 5.5 MP (specifically, 2496
x 1664) /before/ doing any noise reduction or sharpening, if
necessary.

In my case, my final image size is generally 1280 x 960 or
1400 x 1050, or a different aspect ratio final than 4:3 if the
composition is improved. Since the Rebel XT only saves in 3:2,
I allow about 20-25% more space at one end or both ends of the
viewfinder, and have a PSP "Preset" for 2218 x 1664 so I can
easily put a 4:3 crop rectangle on my image and crop before
further post-processing.

Last night, I spent several hours RTFM for both the camera and
the Canon 430 EX external flash and discovered that I was
incorrectly applying flash "power" or EC (which I discovered
means Exposure Compensation). I shot more tests with both
flash and available light, but haven't had time to evaluate
them.

ATM, check this out:
http://www.edgehill.net/1/?SC=go.php&DIR=Misc/photography/car-iso-1600
Is that similar to what you are getting? That's an ISO 1600 car at night
on a D70 in Basic (low qual) JPEG and RAW (manually adjusted to reduce
noise & sharpened in photoshop at full 6MP crop and a reduced 960
pixel-high version of the raw per your final specifications. Shot at 1/3
second f/5 EC +1. Hand held on the Sigma 12-24 so probably not razor
sharp. Note the blown highlights.

Today Ed Ruf (REPLY to E-MAIL IN SIG!) commented courteously
on the subject at hand

No it's YOUR fault.The firmware in the camera can't adapt,
hopefully you can. You say you don't want Photo 101
lessons, but it seems you need them.

I don't know you and you don't know. So, you should not reach
conclusions based on no facts and unfounded assumptions. For
all you know, I've forgotten more about this then you will
ever be able to learn.

No, I do /not/ want Photo 101 lessons - I took that 45 years
ago. You have not told me a single thing I didn't know, except
that you took my comments and questions out of context so that
you could make yourself look smart and me look stupid. If that
pleases you, then enjoy yourself.

As to the histogram, when it is good, I don't need to play
with it. And, when exposure is very bad, I don't understand
it well enough to help - yet.

Then it's time you learned how to use this tool that's been
available to you all the way back to your 5700. This is
basic digital photo technique. You want to push the
histogram as far right as possible, without having the
right side touch or max out. This ensures you are maxing
out your signal to noise ratio., even if the resulting
photo may look over exposed to you initially. you then have
the max signal to work with.

As to noise reduction, I don't currently own Neat Image,
Noisee Ninja or those, because PSP 9 has 2 very good noise
reduction techniques - EPS for mild noise and DCNR for
severe noise. Don't know what those mean? Then /you/ need
to do some research before lecturing me.

I'm well aware of the noise reduction in PSP. I've used v
5,6,7,8 and gave up at 9, though have used both 9 and 10
demos.I have found Neat Image more to my liking. The demo
is free and will batch process up to ten images as a time,
IIRC. You can also create specific noise profiles based
upon your camera exif info and automatically have those
used as a starting point with automatic fine tuning applied
after that. There are many profiles contributed by users to
start with.

The issue has been, and still is, whether a Canon Rebel XT in
any reasonable use, Programmed Auto, full manual, flash, or
available light, can produce accurately exposed images with
minimum noise. I know how to fix it, and I know how to prevent
it - in general. Again, you've /not/ told me anything I didn't
already know, except what I really need. And, you seem
incapable or unwilling to do that.

And, until I more fully understand /all/ of the various
root causes for underexposure and/or excessive noise, batch
processing down from 8 MP using PSP 9's batch function with
a re-size script isn't going to help, it'll just confuse
the issue for my simple brain.

It is a technique which helps minimize the effects of noise
in your final images. It;'s another tool you need to learn.

That's your opinion again, and you know what they say about
"opinions". You should stop lecturing me when you have no clue
as to what I know and what I don't, and what I have experience
in and what I don't.

Back to the Nikon 8800 and SB-800, when I spent nearly a
week testing that back in April, which you're referring to,
I had not learned full manual nor the most effective EC
techniques before concluding it was not to my needs, and
returned it.

You have repeatedly said you didn't need Photo 101 advice.
Full manual exposure is just this. ll manual exposure with
the 8800 is the same as the 5700 which you used much
longer. Which way do you want it? I'm a clueless digital
newbie, or don't insult me by the inference of your replies
as you have repeated berated David Taylor? You can't have
both.

No, an 8800 is /not/ the same as a 5700. It is within the
samee design family, yes, but there were 2 previous cameras in
between. And, the 8800 was Nikon's first camera with the new
SB-800 that had iTTL, which the 5700 does not have, so that is
what I wanted to test.

Finally, to my 5700. I'm glad to hear that you not only own
one, but that you "dusted it off" and tried it again. I
much more highly value knowledge from someone who has
facts, instead of opinions based on what they've read.

Since my 5700 is now in 4 broken pieces - I fixed it with a
hammer after it died - I can't take any more test images to
prove what I say, but have thousands at the HF and WPC
museum that can easily be examined by looking at the degree
of under exposure and EXIF to get the shooting parameters,
then looking carefully at the car subject and what is in
the foreground that tricked the 5700's AE, which was
determined solely by a little sensor on the pop-up flash.

Learn to use the histogram real time. It's the real tool
you have to maximize signal to noise.

Keep your histogram lessons to yourself. I don't use it and I
don't shoot RAW, so that makes me unworthy of constructive
help, is that your thesis? The idea, before, now, and in the
future, is to be able to /reliably/ produce flash and
available light pictures of /car/ in /museums/. Very large
quantities of pictures. Using basic photography knowledge,
knowledge about the camera and flash operation, and the back
of the camera LCD to make an on-the-spot judgment if the
exposure is or is not OK.

Now I ask instead of assert: Ed, have you personally shot
pictures of /cars/ in museums and dealer showrooms, or more
general subjects in museums? If you have, great, I am all
ears. But if you have not, I suggest that you have no
expertise because you have no direct experience with the
frailties of the car picture biz.

Yes, if you actually got off your ass and looked at any of
the galleries on my website you might actually see "some"
of what I shoot. Additionally, at work I shoot much more
valuable and transient situations than yours. I document
scramjet engine test hardware between tests. I use my own
equipment instead of what's available at work because I can
get better shots with it or more timely shots than using
our professional photogs. The models are near polished
copper in many instances with near polished steel hardware
in the facility. Some parts may be covered in muck from
cooling water. The models are closely enclosed in ducting
around them making it even harder to get a good shot. I
also don't get to go back and do it again, as the testing
environment is quite harsh and the model changes after
every run. The facility is basically a rocket engine on
it's side. All this info is available on my website if YOU
took the time to look before spouting.

I'm not "on my ass", and I'm not going to look at your brag
site. I've quietly watched you expose your "knowedge" for
years, with very little help that is actually on-topic for
whatever /any/ OP wants to know. Again, I ass/u/me that is how
you get your jollies.

Fine by me. I unplonked you, and what do I see? More insults
and zero.zero real-world help. So, back you go, enjoy talking
to yourself again.

--
ATM, aka Jerry

"I disagree with what you say, but I will defend to the death
your right to say it." - Evelyn Beatrice Hall under the
pseudonym Stephen G. Tallentyre

On Mon, 02 Jan 2006 06:16:04 -0600, All Things Mopar
wrote:

Today David Dyer-Bennet commented courteously on the subject
at hand

1) /Both/ camera's, my "defective" one and his "working"
one showed the /same/ amount of noise at /all/ ISO from
100 to 1600 on /all/ 3 of my PCs. Naturally, no noise is
readily apparent until ISO 400 on both cameras.

The problem, then is that your expectations are not being
met.

What *are* you expecting at ISO 1600? Usable photos? Or
crisp, clean, studio-looking photos? Are you expecting
less noise than P&S cameras and a lot less noise than film
that speed has grain? Or are you expecting a lot better
than that? Because "a lot better than that" isn't
available yet.

I "expected" to see little or no noise at ISO 400, some noise
at 800, and noise, but controllable noise on a properly
exposed image at ISO 1600. Where'd I get that? On
dpreview.com, from my fav camera store manager who's much more
knowedable about why a DSLR is a lower noise solution than
even an expensive EVF, from rec.photo.digital, and in this NG.

Popular Photography magazine characterized the Rebel XT noise
level at 1600 ISO as unacceptable.
-Rich

In message ,
Rich wrote:

Popular Photography magazine characterized the Rebel XT noise
level at 1600 ISO as unacceptable.

What did they do; shoot a black frame and then use histogram
equalization?
--


John P Sheehy

All Things Mopar wrote:

No, I do /not/ want Photo 101 lessons

You keep saying that, yet your posts repeatedly demonstrate that this is
exactly what you need.

I'm not sure why you find that thought to be so insulting. We all needed
that at some point or other, and I don't think anyone here minds helping
with it.

It is clear that what you need is to learn to properly expose a digital
photograph -- which is not the same thing as properly exposing film.

--
Jeremy |

wrote:

Popular Photography magazine characterized the Rebel XT noise
level at 1600 ISO as unacceptable.

What did they do; shoot a black frame and then use histogram
equalization?

They probably shot JPEGs using the LCD review to judge "proper" exposure.
Or even just blindly relying on auto-exposure.

I think we know by now how seriously to take magazine "reviews"...

--
Jeremy |

Today Paul Furman commented courteously on the subject at
hand

Maybe also look at turning down the contrast so that
highlights don't blow as quick making underexposure less
necessary. Then just look at the LCD review & make sure you
get a few blinking blown highlights. If nothing blown you
can boost the EC. Of course then that requires post
processing where you do want more contrast & shooting raw
is the next step. BTW, shooting raw actually shows more
noise but more detail too, and less posterization. Shooting
raw with just a few blinking highlights, you'll be able to
recover those also.

Thanks, Paul. What you talk about here is in a group of up to
5 different processing parameters, two are fixed and three I
can vary. The settable functions are contrast, sharpness,
saturation, color, and something else, but I get the idea.
I've ran some very quickie tests varying contrast and
sharpness and my images look best at the default for what is
called Parameter 1, which is one step more contrasty and one
step more sharpness than "neutral".

The issue really isn't blown out highlights, they're more of
an annoyance. Across the full dynamic range from white to
black, museums are a tough row to hoe because you're exposing
for the subject - the car for me - the foreground blows out,
and the far background goes dark.

I mentioned that I was at the Henry Ford Museum on Saturday.
It is /very/ large and has locomotives, 100 cars, airplanes,
giant stationary steam engines, steam and gas powered farm
impplenents, early Edison electrical stuff (in fact, an entire
Edison generating station), and tons of "Americana". While
there are non-permanent walls so the place doesn't look like
stuff piled into a warehouse, there really isn't anything to
bounce flash off to either side, nothing generally behind the
car, and no ceiling.

So, naturally, the part of the car that is spot on for
exposure is noise-free, shadows have some noise and the dark,
red-yellow color cast from no flash light on the far walls,
makes them get noisy from sheer underexposure. It is the
extremely large dynamic range couple with uneven light across
a car shot at an angle, besides the reflection stuff, that
makes museum car photos so difficult.

I think all the way around, I need to idle down the discussion
on noise now because it has gotten out-of-hand and out-of-
proportion to its importance. I alluded earlier to learning
enough that I can get an exposure no more than 1 stop under,
maybe a tad more, and adjust all that stuff in PSP later
rather than doing it blindly in the camera where I really
can't see it that well. It is also best if I set a "use it as
often as I can" set of "defaults" for the museum du jour,
rather than try to manipulate a half-dozen parameters, where
the combinations and permutations get to where nobody can
track them.

Suffice to say that I have proven to myself in at least a
controlled environment that I can get low-to-moderate noise
even at ISO 1600, which /does/ fit with my expectations.

--
ATM, aka Jerry

"I disagree with what you say, but I will defend to the death
your right to say it." - Evelyn Beatrice Hall under the
pseudonym Stephen G. Tallentyre