Canon 40D image noise

[StuartR]

Re: Canon 40D image noise

I'm not too impressed with this Auto ISO malarkey Stuart, it seems that in most cases it wants to select ISO 400 as a minimum unless overexposure is going to occur.

I find it hard to believe however that you can't select ISO 100 manually on the 40D The 2 forerunners to it that I've owned all did it OK which is more than could be said for equiv Nikons which had a minimum ISO of 200

Seeing as most of my day job is about writing software to automate processes (albeit not in photography but a LOT more complex than the ISO, shutter speed, aperture relationship here) I'm going to have to say that I'm generally pro this automation malarkey

I mean, in theory, automated ISO settings should be easy to program, probably far easier than face recognition for example, which is becoming increasingly more common on compact cameras. However Canon don't seem to have done a brilliant job on the 40D - unless ISO100 & 200 are no better than 400 of course!

It should be simple to automate the ISO AND give photographers a number of parameterisation options - like setting the minimum and / or maximum limits or full manual.

I'll check my old 350D tomorrow as I'm with my brother who bought it (I have to look at his 1,500 pictures taken with it in Canada recently ). I can't remember what the ISO options were on that.

I really can't set 100 on my 40D although the manual clearly states I should be able to..

[StuartR]

Re: Canon 40D image noise - ISO100 mystery - the answer

It came to me all of a sudden about half an hour ago from some dark corner of my mind whilst eating dinner. Although quite how chicken and ISO met in my mind I'm not sure...

There's a custom function "Highlight Tone Priority" on the 40D and if you switch it on then ISO100 is no longer available. Turn it off and it is.

So there you have it, mystery solved. I was right and wrong at the same time.

Now, is it better to leave highlight tone priority on and be limited to ISO200 or switch it off to get ISO100? Answers on a postcard please....

[Stephen]

Re: Canon 40D image noise - ISO100 mystery - the answer

It came to me all of a sudden about half an hour ago from some dark corner of my mind whilst eating dinner. Although quite how chicken and ISO met in my mind I'm not sure...

There's a custom function "Highlight Tone Priority" on the 40D and if you switch it on then ISO100 is no longer available. Turn it off and it is.

So there you have it, mystery solved. I was right and wrong at the same time.

Now, is it better to leave highlight tone priority on and be limited to ISO200 or switch it off to get ISO100? Answers on a postcard please....

Mmmm I'm not sure I understand the purpose of this function
Glad you sorted it out though Stuart, I'd never have come up with that solution

[Patrick]

Re: Canon 40D image noise - related question for other 40D users

Hi Patrick

The only settings I normally use are P and Av, sometimes A-DEP. IIRC I've never used the creative settings - I've been behind a camera long enough (just over 40 years) to understand the basics despite the use of P and auto ISO. I also use the "underexpose by one stop" rule for some landscapes following advice that I think came from this forum - probably either Stephen or yourself - and this does seem to work well - I certainly get better exposed skies in most cases.

However, I find "P" normally works quite well so I'm happy to go with it and drop back to Av or, very rarely ,Tv (I don't seem to shoot many subjects where shutter speed is the primary factor) or even M as necessary. The trouble with P of course is that you can (well I do) lose track of what aperture & shutter speed combination the camera is setting and therefore get some, on the face of it, odd results - like my duck shot at the top of the post. The other issue with P, now that I've RTM, is that auto ISO has a lower limit of 400 which is why the exposure ended up as it did.

I've currently set my ISO to 200 which appears to be the lowest I can set - if you can set 100 on your 40D I'd like to understand why I can't (except in the 3 user modes as mentioned earlier).

Cheers

Stuart

Sorry if I was trying to teach you to suck eggs Stuart, but I do stand by the advice.

It is true to say you have brought my attention to something about the 40D I hadn't noticed and that is 200 ISO is the lowest it will go, the 10D goes down to a 100 but not the 40D. Strange that.

For Stephens benefit the highlight alert is supposed to extend the dynamic range by up to a stop, I have not used it myself but report say it can lead to some strange results, perhaps one is increased noise. Food for thought and testing Stuart.

Patrick

[StuartR]

Re: Canon 40D image noise - related question for other 40D users

Sorry if I was trying to teach you to suck eggs Stuart, but I do stand by the advice.

It is true to say you have brought my attention to something about the 40D I hadn't noticed and that is 200 ISO is the lowest it will go, the 10D goes down to a 100 but not the 40D. Strange that.

For Stephens benefit the highlight alert is supposed to extend the dynamic range by up to a stop, I have not used it myself but report say it can lead to some strange results, perhaps one is increased noise. Food for thought and testing Stuart.

Patrick

Food for though indeed...

No offence taken m8! Nothing wrong with the advice!

I read on some American wedding forums a while back that the Highlight Tone Priority facility is apparently much liked by wedding photographers because it helps with the white dress / black suit exposure issue. Perhaps I'll switch it back on when I next do a wedding

Doesn't look like I'll get a chance to do any testing this weekend, we're "down home" in Kent tomorrow but the weather doesn't look good and we have a pretty tight schedule anyway. I'm giving my brother my old 70-300mm IS while we're there though, so I guess he might want to go out for half an hour if the rain stops and we can get a pass from the women-folk

He lives with a couple of miles of Dover docks and the Castle and either would be a good test subject.