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Old Aug 10, 2006, 12:04 AM   #1
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I am new to digital and am pretty well versed in film. I have a Nikon F100 and a few very good lenses. Would ISO relate to ASA in film?

I did not want to hijack the previous thread so I started this one. Ads said in that thread, some good cameras will show noise at say 1600 when some point and shoot cameras will show it at 200.

I am asking as I was looking at theNikon F200 and the comparible Canon models. I do have Nikon lenses though. So where it says in somne reviews that the F200 will start to show noise over ISO 400, what kind of lighting conditions would this be? Is this a cloudy day, or is it pretty dark? Would this noise show up in a 5x7 digital print? Are they nitpicking at that point? Also, can the darkness issue be gotten around somewhat by the choice of lenses and shutter speed and aperature? For instance, I have a Nikon 50mm 1.4 lense. This is a fast lens. Will this allow more shooting under 400 ISO?

I appreciate if someone could shed some light on this subject. No pun intended.

Thanks- Ken


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Old Aug 10, 2006, 12:51 AM   #2
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At 5x7 print size, noise will be a very minor issue with any dSLR used up to ISO 1600. Even with the "notoriously noisy" Olympus E-300, I've printed A4 size (8x10) prints of ISO 1600 shots after the judious use of a noise-reduction program like Noiseware or Neatimage. Noise can also be used to advantage with certain types of photography, especially b/w.

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Old Aug 10, 2006, 1:56 AM   #3
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High asa film has large grains, increasing the chance of correct exposure for each grain at the cost of resolution - larger grains mean fewer of them on a given area of film. When you look too closely you start seeing the actual grain rather than the picture. Digital cameras have resolutions fixed by the circuitry of their sensors and mimic high asa by amplifying the signal they get. The resolution stays the same but each individual pixel has a lower chance of being exposed correctly.
Basically the more photons that hit a photosite during an exposure the more accurately the sensor can get the correct level for that site. Suppose you have 5 pixels and with the exposure time you have at ISO100 you expect 64 photons to hit each (Idon't know the actual numbers but the principal still holds). Photons are random creatures so in fact you get 60, 61, 65, 64, 69. Ok, not much difference so you get smooth colour. Now do the same exposure at ISO 1600. You will have one sixteenth the exposure time and so expect to get 4 photons at each site and the camera will amplify the signal by 16 to get up to the correct level of light. Instead of 4 photons each you get 3,4,4,3,6. Amplified up this gives 48,64,64,48,96 and so you won't get smooth colour at all. This manifests itself as noise in your picture. At ISO6400 you would get 0,1 or 2 (with a small chance of more) photons per site, and at this level the noise is basically so bad your picture might look like static on the tv. It's not so simple as this, but you get the idea.
To reduce noise you need more photons per pixel site. You can do this by having bigger pixel sites (and hence bigger sensors to maintain the same resolution) by exposing each pixel for longer, or a combination of the two. Dslrs have much larger pixels than nearly all point and shoots and so have much less noise at a given iso.
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Old Aug 10, 2006, 3:49 AM   #4
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"Would ISO relate to ASA in film?" ISO and ASA are essentially the same scale. The old ASA was an American standard and it became ISO, an international standard about 20 years ago, and apply to both film and digital sensors.

I presume you are an old fart like me who remembers Plus-X at ASA 125, Tri-X at ASA 400 and Kodacrome II at ASA 25. These would now berated at ISO 125, ISO 400 and ISO 25. I still find myself saying ASA when I really mean ISO.


HighASA (ISO) in film meantmore grain. High ISOin digital cameras results in more noise. Remember the film term "pushing"?- to underexpose and compensate by overdeveloping? Just as grain increased athigh EI (exposure index), noise increase with high ISO.

ASA, pushing, EI- terms not heard often in the digitalage. I feel old.





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Old Aug 10, 2006, 10:07 AM   #5
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Thanks allfor the answers. So basically with film, I use 200 ASA and realrely ever use 400. So can I safely say in looking at a camera such as the Nikon D200 and shooting at ISO200, this should cover thre vast amounbt of daylight shooting even into as the sun goes down? I should get great pics from that camera and at those light levels?

So when are peoplt shooting at 800, 1600, 3200?

Thanks- Ken


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Old Aug 10, 2006, 12:22 PM   #6
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ken6217 wrote:
Quote:
Thanks allfor the answers. So basically with film, I use 200 ASA and realrely ever use 400. So can I safely say in looking at a camera such as the Nikon D200 and shooting at ISO200, this should cover thre vast amounbt of daylight shooting even into as the sun goes down? I should get great pics from that camera and at those light levels?

So when are peoplt shooting at 800, 1600, 3200?

Thanks- Ken

Yes that's true. You should get roughly the same exposure with digital at a given aperture, shutter speed and ISO setting as you would with film. Maybe not EXACT exposure but very close. So, if you just use 200 speed film you won't use higher ISO speeds on a digital assuming you shoot the exact same type of stuff in the same situations.

Where the ISO 800, 1600 and 3200 comes into play is the following conditions:

1. Low light non-flash. Even with a wide aperture lens, say a 1.8 a person may need to use ISO 800 or 1600 to get a fast enough shutter speed to hand-hold the camera. For instance I took an available light shot of my wife with our niece last night - ISO 800, f2.0 and shutter speed of 1/30 - if I had dropped my ISO down to 400 a speed of 1/15 becomes difficult to hand-hold.

2. Sports - I shoot a lot of sports and in general you need shutter speeds over 1/500 of a second. When I shoot HS football under the lights I use a 2.8 lens, ISO 3200 and get shutter speeds between 1/320 and 1/640 by the end of the year. If I was using only ISO 400, that 1/320 shutter speed would drop to 1/40 - too slow to even hand hold much less stop action.

3. Wildlife - much like sports you want to freeze action - even if it's just feather's blowing in wind - now that typically won't take you into the realm of ISO 3200 but could easily require ISO 800.
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Old Aug 10, 2006, 4:11 PM   #7
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Quote:
ASA, pushing, EI- terms not heard often in the digitalage. I feel old.

You are NOT alone
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Old Aug 10, 2006, 6:49 PM   #8
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John,

I forgot to mention that as well. I haven't that term pushing ASA in a long time. Not since the days of TRI X.

Out of curiousity, dslr to you use and how did the shots come out in the shooting scenarios that you mentioned above without post production software? Would you say it is close to film?

My issue right now is that I am looking at a Canon 30D and a Nikon D200 and trying to decide. I like the Nikon but am afraid of the comments about noise over ISO 400. Are they nitpicking or is there an issue. Also when I hear that film is equal to about 20 megapixel I wonder how well these two dslr's will do. Also not that I doubt I will enlarge over 8x10.

Thanks much for your help.

Ken


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Old Aug 10, 2006, 8:36 PM   #9
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There are others on the site with much more film background than me - I only shot film SLR for about 5 years.

In general what I have heard is that sharpness and color of DSLR has surpassed film. Here are some comparisons I'm stealing from one of JimC's posts comparing various megapixels to provia 100F and medium format

http://www.luminous-landscape.com/re..._vs_film.shtml

http://www.luminous-landscape.com/re.../d60/d60.shtml

I think the only edge film has over the current crop of non-full frame DSLRs is in dynamic range. Not sure how a full frame like the Canon 5d compares to film in dynamic range though.

I personally shoot with a Canon 20D. I bought the 20d because of the feature set for sports shooting - which I do a lot of. One of those features is high ISO performance. I've never used the D200, but I think the comments about less than stellar high ISO performance are only when you compare it to the leaders in high ISO performance:

Canon 20d/30d/350d and Nikon D50 - they all have excellent high ISO performance. From reading reviews it would seem the Nikon D200 is a better camera than the 30D in all regards except high ISO performance. So, you have to ask yourself, how often will you be shooting at ISO 800, 1600 or 3200.

As for post processing - I'm particular about noise so I run just about any photo ISO 400 or more through noise reduction but I try to apply it very conservatively. This is where DSLRs leave film in the dust - try getting rid of the grain from ISO 1600 film - no way it's going to look as good as a photo from one of the above cameras with the proper noise reduction applied (too much reduction makes a photo look bad though).

Here's a shot taken at ISO 1600 in poor indoor lighting with noise reduction applied:



Here's an ISO 800 shot:



Another ISO 800 shot





I'd say those turned out very usable

The key to keeping noise down is having a properly exposed picture in-camera. The noise manifests more in dark areas and really shows up when you need to lighten a photo in processing. So, if you can expose properly you won't introduce more noise by doing levels or curves work. From there you just have to use a good eye when determining what settings to use on the noise reduction software you use (I use Noiseware professional). As mentioned above if you use too much reduction you'll get an image that looks very plasticy.
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Old Aug 10, 2006, 11:12 PM   #10
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John,

Thanks for the comments. I have spoken to a few of the major camera retailers and a lot of people have tried to push me to the 30D (that's if I don't mention the 5D of course). Most of the comments againest the D200 had to do with backorders on batteries etc. One perosn who shoots professionaly and uses Canon, said I should get the D200 over the D30. I guess anothetr thing to consider is where I see my future because one I invest in the lenses, then it is better to stay put with either Canon or Nikon.

You are right regarding how much will I use the camera in low light situation. I don't think much except in doors and the D200 has a flash and it has thr ability to add a Speedlight flash.

I have two more questions. In shooting sports as you do, do I need to go to a higher ISO? Can't I just increase the lens speed?

Also, to take your quote: "I think the only edge film has over the current crop of non-full frame DSLRs is in dynamic range. Not sure how a full frame like the Canon 5d compares to film in dynamic range though."

Do you think that 5D compares better or worse in dynamic range than film?

Thanks- Ken



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