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ISO settings below 200

wrdpico

US
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wrdpico Silver Member Nikonian since 21st Jan 2009
Sun 22-Feb-09 03:06 AM

Some maintain that ISO settings of Lo .3, through Lo 1, clip highlights. Some say Lo reduces dynamic range. The User’s Manual states (pg. 107) when using Lo, "contrast is slightly lower than normal."

I don't understand Lo. Help!

wrdpico

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sthyde

Munich, DE
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#1. "RE: ISO settings below 200" | In response to Reply # 0

sthyde Registered since 08th Mar 2008
Sun 22-Feb-09 10:57 AM

What is it that you don't understand?

The D700 produces optimum dynamic range (9 stops) at ISO200. Dynamic range decreases as ISO increases until 6400 where it's only 5 stops. With regard to the LO ISO settings, Thom Hogan, in his D700 guide, states:

"The non-numbered ISO values are a warning to you that some aspect of image quality will be compromised. ... the LO ISO values can compromise highlights."

Thom goes on to say, "LO values work ok for low contrast scenes exposed normally, but are dangerous for high contrast scenes exposed normally, due to the possible loss of highlight information.

I'm not an expert, but it seems to me that the three aspects you mention are all related. In a high contrast setting, reduced dynamic range would result in something being clipped - highlights if you've exposed for the shadows or shadows if you've exposed for the highlights.

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dankeny

Roland, US
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#2. "RE: ISO settings below 200" | In response to Reply # 1

dankeny Gold Member Nikonian since 29th May 2006
Sun 22-Feb-09 01:01 PM

9 stops! In our dreams.

David

dankeny

Roland, US
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#3. "RE: ISO settings below 200" | In response to Reply # 0

dankeny Gold Member Nikonian since 29th May 2006
Sun 22-Feb-09 01:06 PM | edited Sun 22-Feb-09 01:11 PM by dankeny

I'm baffled by the Lo and Hi ISO as well. Me thinks, they approach the limits of the beast and things become less predictable, less precise. Lo-3 isn't called ISO 100 because it isn't, exactly. So, what's that mean to a hack like me? I have no idea. I just ETTR and do the best I can to get the subject somewhere in the picture.

David (Shum)

Edited to add: So, Michael, are you proficient with Gimp? Or do you cross over to the dark side to post process your wall hangings in PS.

sthyde

Munich, DE
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#4. "RE: ISO settings below 200" | In response to Reply # 2

sthyde Registered since 08th Mar 2008
Sun 22-Feb-09 01:57 PM

9 stops is what Thom Hogan states in his D700 guide (p. 296). DPReview claim they got 7.8 stops in JPGs and the following from RAW:

"The best result we could achieve was 11.6 EV which is almost 5 (!) stops more than the default JPG output. It's no surprise then that in our real world tests we managed to recover highlights that had been hopelessly blown out"

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sthyde

Munich, DE
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#5. "RE: ISO settings below 200" | In response to Reply # 3

sthyde Registered since 08th Mar 2008
Sun 22-Feb-09 02:05 PM

If they were to call LO3 ISO 100, you would expect it to provide better results than ISO 200. But it doesn't, (which they do tell you on page 107 of the manual) so they don't call it ISO 100.

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dankeny

Roland, US
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#6. "RE: ISO settings below 200" | In response to Reply # 4

dankeny Gold Member Nikonian since 29th May 2006
Sun 22-Feb-09 04:43 PM

Well, then, by Thom, 9 it is! Mine must be defective. Oh, wait, pilot error. Dern black box.

David

joeholmes

Brooklyn, US
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#7. "RE: ISO settings below 200" | In response to Reply # 5

joeholmes Registered since 26th Nov 2004
Sun 22-Feb-09 06:03 PM

I've compared ISO 100 and ISO 200 and there is actually visibly less luminance noise in the shadows at ISO 100. I haven't noticed more blown highlights at ISO 100, but didn't check for that.

These tests were with my D300. I assume I'd find something similar on the D700, though maybe not as dramatic.

wrdpico

US
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#8. "RE: ISO settings below 200" | In response to Reply # 3

wrdpico Silver Member Nikonian since 21st Jan 2009
Sun 22-Feb-09 07:14 PM

David,

I use CS3, ACR 4.5, Lightroom 2, and Corel Painter X. Adept, I'm not. Still, I've studied PS five years, starting with CS (PS 7), and I’m gradually becoming less ham handed. So far, I've learned how to open the programs, then wreck havoc. It's fun, and I'm growing into my style - it could be shabby chic, or simply shabby. Time will tell.

Occasionally, my stuff sells. I once had a magazine cover (Popular Doorstops). The operant word is occasional. Like any intermittent reinforcement schedule, episodic sales are very addictive. Good grief, I’m hooked!

wrdpico

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dankeny

Roland, US
1555 posts

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#9. "RE: ISO settings below 200" | In response to Reply # 8

dankeny Gold Member Nikonian since 29th May 2006
Sun 22-Feb-09 10:01 PM

As I'm sure you already know, pretty much anything bad you do to the capture short of blowing all three channels can be saved (to some extent) in ACR. So if the situation demands, live on the edge, shoot at Lo3. ETTR and get aggressive in ACR. All things being equal, I assume Nikon's advice is sound, so I avoid Lo when I can.

Call mom once a week, don't run with scissors, drink responsibly and avoid lo when I can. That's a lot for this cowboy to remember.

David

wrdpico

US
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#10. "RE: ISO settings below 200" | In response to Reply # 0

wrdpico Silver Member Nikonian since 21st Jan 2009
Mon 23-Feb-09 07:01 PM

In post nine, David suggests I should take Nikon’s word for Lo being something to frequently avoid. He’s probably right. Yet, I really want to grasp what Lo is. So beware, it’s onward through a speculative fog!

If Thom Hogan is correct (he usually is), and high contrast light clips highlight data (but low contrast light works okay) - then Lo may be cooking the histogram. Lo may be pushing the histogram to the right, with useful implications for RAW images. Moderate over exposure (shooting to the right) improves RAW image quality.

I generally expose a RAW image so that its data falls toward the right side of a camera’s JPEG histogram. I over expose to evenly spread the data. Highlight data outnumbers shadow data by a substantial margin. In images containing five stops of dynamic range, the brightest stop contains space for over half the data. By moving an exposure to the right, I make room for more shadow data. I can then recover most, if not all of the apparently clipped highlights in ACR 4.5, or Lightroom 2.

If Lo forces one to shoot high contrast JPEGs, to the right, that’s bad news. When JPEG highlights become clipped, they are not recoverable. Yet, if Lo forces the shooting of high contrast RAWs to the right, a more benign process will occur in post. That’s good news.

One other precaution comes to mind in this scenario. If Lo mode cooks to the right, and one’s habit is to shoot RAW, to the right, take care not to duplicate over exposure.

I’ll shoot a test sequence of Lo mode shots to see how the histograms respond. One method might be to shoot four RAW+JPEGs in Lo 0.3, 0.7, 1, and ISO 200 - first in low contrast light, then repeat the foursome in high contrast light. By bringing these shots into ACR 4.5, and exploring histograms, I’ll see how the sensor is recording light.

If I find anything interesting, by eye, or by graph, I’ll post it. Better methods to assess the Lo effect are likely. A Nikonian has probably already devised these methods. If you’re that Nikonian, please share your findings with the rest of us.

Post seven, by Joe is interesting. He is getting good-looking noise results out of his D300 in Lo 1 (ISO 100). If D300, and D700 Lo algorithms are similar - then Lo on the D700 could be useful in tripod work. One might squeeze acceptable table tops out of this low-light beauty. I’ll do almost anything to forestall paying $8,000 for a D3x.

I’m positing events, and asking if anyone has any thoughts. My suppositions are just that - guesses. Nikon’s Lo exposure mode probably works in a different way from what I’ve fancied. If that’s the case, please help me understand. Three baffling sentences on page 107 (from a fearsomely large owner’s manual), and (thanks to Steve in post one), two brief quotes from Thom Hogan are not enough!

wrdpico

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dankeny

Roland, US
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#11. "RE: ISO settings below 200" | In response to Reply # 10

dankeny Gold Member Nikonian since 29th May 2006
Mon 23-Feb-09 09:28 PM

Remember that the on-board histogram is a histogram of the jpeg processed image even when you shoot raw. It applies the special sauce from the camera settings. Example: Vivid setting skews the on-board histoogram, but does not touch the raw image. In addition, I believe it to be conservative with regard to highlight clipping (as is the blinky).

David

wrdpico

US
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#12. "RE: ISO settings below 200" | In response to Reply # 11

wrdpico Silver Member Nikonian since 21st Jan 2009
Tue 24-Feb-09 09:30 PM

Yes, and that's why I'm pressing this issue. Thom's comments may apply to the in camera histogram (JPEG), and not the "real" (RAW) file. If so, we can probably apply Lo to a RAW file, then get more shadow detail in post. This may be what Joe’s comment suggests. ACR 4.5+, or Lightroom 2 could then recover highlights that Lo moves to the right. We might milk more apparent DR out of all Nikons with a Lo setting.

Again, that's if my assumption about Lo cooking to the right is correct. It may use other means to do its alchemy. A one stop ND filter may be all that Nikon gave us. If so, I'll go quietly to my room.

wrdpico

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bclaff

Vancouver (WA USA not BC Canad, US
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#13. "RE: ISO settings below 200" | In response to Reply # 0

bclaff Awarded for multiple contributions for the Resources Registered since 25th Oct 2004
Wed 25-Feb-09 12:45 AM

Michael,

There is a great deal on misinformation and speculation on this subject.
Here is the story, based on knowledge about how sensors work, and real objective measurements on raw camera data.

For exposure purposes the Lo settings act exactly as you would expect.
So, for example, on your D700 Lo 1.0 is exposed as ISO 100.

For the numbered ISO values, ISO 200 to ISO 6400 on your D700, the sensor gain is directly proportional to the ISO.
Gain is the raw levels per electrons (ADU/e).

The highest dynamic range is always at the lowest ISO; period.
Because below the lowest numbered ISO, ISO 200 on the D700, gain still decreases, but not proportionally.
(Although admittedly only the D300 does it drop significantly.)
The lowest gain always produces the highest dynamic range.

The poorly worded Nikon warning arises from the fact that because gain is not proportional to ISO in the Lo range; there is an increased likelihood of highlight clipping.
People read into Nikon's statement that dynamic range is reduced, but it is not reduced, only shifted.

So, if you watch your exposure, and especially if you Expose To The Right (ETTR) then there is no reason not to use Lo ISO values.
(Again, the only current Nikon DSLR where this makes a real difference is the D300.)

Note in this discussion when I say "dynamic range" is better, I'm also saying that there is less apparent noise in the shadows.
There statements are inseparable.

Consult the Photographic Dynamic Range Chart at my site to see measured dynamic range data for most Nikon models at all whole ISO values.
(These numbers are comparable to the DxOMark dynamic range.)


Bill

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dankeny

Roland, US
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#14. "RE: ISO settings below 200" | In response to Reply # 13

dankeny Gold Member Nikonian since 29th May 2006
Wed 25-Feb-09 01:04 AM

Michael and others,

Of those who give advice and information on the subject of the physics of photography and especially Nikon DSLRs, there are precious few I take without a large grain (often an entire mouthful) of salt. Bill is the exception. Check his site. Read his posts.

David

robsb

San Jose, US
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#15. "RE: ISO settings below 200" | In response to Reply # 13

robsb Platinum Member Fellow Ribbon awarded for his expertise in CNX2 and his always amicable and continuous efforts to help members Laureate Ribbon awarded for winning in the Best of Nikonians 2013 images Photo Contest Donor Ribbon awarded for his enthusiastic and repeated support to the Fundraising Campaign 2014 Donor Ribbon awarded for his generous support to the Fundraising Campaign 2015 Nikonian since 23rd Aug 2006
Wed 25-Feb-09 02:37 AM | edited Wed 25-Feb-09 02:38 AM by robsb

So Bill you are saying that you are in basic disagreement with Thom Hogan who says the dynamic ranges for 100 and 200 on the D700 are the same? I think from my reading of Thom's book he agrees that the lower bias does shift the highlights, but he is saying except for low contrast scenes that causes you to blow out the highlights at 100. So how much better do you think the dynamic range on a D700 is? Your example seems to imply similar to the D300, is that your intent?

Bob Baldassano
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"Nikonians membership - My most important photographic investment, after the
camera"

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Old age is a special gift that very few receive. Be thankful if you get it.

bclaff

Vancouver (WA USA not BC Canad, US
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#16. "RE: ISO settings below 200" | In response to Reply # 15

bclaff Awarded for multiple contributions for the Resources Registered since 25th Oct 2004
Wed 25-Feb-09 03:15 AM

Bob,

you are saying that you are in basic disagreement with Thom Hogan who says the dynamic ranges for 100 and 200 on the D700 are the same?

No, I agree that for the D700 the dynamic range for ISO 100 (Lo 1.0) and ISO 200 are essentially the same.
(Not true for the D300 and D90.)
There are people who claim dynamic range is lower for Lo settings; that is flatly wrong.

he agrees that the lower bias does shift the highlights

Yes.

So how much better do you think the dynamic range on a D700 is?

I don't understand the question. Better than what?

low contrast scenes that causes you to blow out the highlights at 100

I would not use the term "low contrast" but it is also true that you are more likely to need negative exposure compensation to avoid highlight clipping with ISO 100 as opposed to ISO 200, but for anyone who pays attention to their exposure it is no problem whatsoever.

Your example seems to imply similar to the D300, is that your intent?

If I understand your question, the D300 and D90 are less prone than the other models to needing negative exposure compensation to avoid clipping at Lo ISOs values.
That's because the Lo gain values are closer to linear.

See my chart as quoted in this similar thread in another forum: D90 ISO Question
The closer to linear the Lo values on this chart are, the less likely there will be highlight clipping due to the shift.

Regards,
Bill

Visit me at Photons To Photos

robsb

San Jose, US
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#17. "RE: ISO settings below 200" | In response to Reply # 16

robsb Platinum Member Fellow Ribbon awarded for his expertise in CNX2 and his always amicable and continuous efforts to help members Laureate Ribbon awarded for winning in the Best of Nikonians 2013 images Photo Contest Donor Ribbon awarded for his enthusiastic and repeated support to the Fundraising Campaign 2014 Donor Ribbon awarded for his generous support to the Fundraising Campaign 2015 Nikonian since 23rd Aug 2006
Wed 25-Feb-09 05:54 AM | edited Wed 25-Feb-09 05:56 AM by robsb

Bill obviously I misunderstood you. I thought you were saying ISO 100 dynamic range on the D700 was better than ISO 200 and I was asking how much better, but I see you agree with Thom. In the words of Gilda Radner "Never Mind"

Bob Baldassano
My Nikonians Gallery

"Nikonians membership - My most important photographic investment, after the
camera"

Retirement is a gift of time - Don't waste it!
Old age is a special gift that very few receive. Be thankful if you get it.

wrdpico

US
157 posts

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#18. "RE: ISO settings below 200" | In response to Reply # 13

wrdpico Silver Member Nikonian since 21st Jan 2009
Fri 27-Feb-09 11:26 AM

In post ten, I asked if any Nikonian had researched Lo, and if so, to please share the results. It looks like we’ve hit the mother-lode. Bill Claff is doing first-rate stuff. It’s being presented in a parallel universe - the D90 forum, under “D90 ISO Question.”

Two of Bill’s quotes help clear some smoke. First, “The lower the ISO setting, the lower the noise, the higher the dynamic range; always. Below the lowest numbered ISO, the raw data is shifted toward the right; so there is an increased possibility of clipping highlights.” Second, “Lo is NOT ‘bit shifted’ (as in Hi) it is done with lower bit non-linear amplification.” Bingo - thanks Bill, there is life under ISO 200.

A graph in this D90 thread (thanks to Brian, post 26) shows that Lo doesn’t increase measured DR in the D700. Yet, the graph records DR improvement in the D300, and D90 (Joe, this seems to validate your visual). Still, the graph shows that Lo does not harm DR in the D700. The RAW file may even take on an apparent (if not real) betterment of dynamic range. The increased shadow data seems key.

It looks like Lo drags the shutter a bit, and turns down sensor volume. If volume changes are “fuzzy” (not equal steps), then we might experiment with “fuzzy” shutter speeds. In manual mode, slight shutter adjustments should improve Lo dynamic range. Sweet spots could be isolated for each Lo settings.

Nikon’s unclearness about Lo is puzzling. It’s as if they’ve given us a tool, and have conspired against our applying it. I guess innovative camera use might sidetrack some D3x sales. It would surely increase resistance to NAS, and help sustain enjoyment of our cameras. Then we could tarry, no longer slaves to the product cycle. We would lurk in ambush, patiently waiting for the inevitable - a lower priced model with a D3x chip. Hmm, who’ll be pouncing on whom?

David, you’ve been mentioning ETTR. I finally got your shorthand, “expose to the right.” Thanks for your comment about Bill’s veracity. I'm new to the site, and am learning the players. Bill is a PLAYER!

wrdpico

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G