# 5D3: ISO 160, 320, 640 etc cleanest ISOs?



## xthebillx (Apr 16, 2012)

Hello!

I know that with the 5D2, ISOs 1/3 stop below the native ISOs are cleaner due to a digital "pull", primarily with video (but I've read that it pertains to RAW as well). Conversely, ISOs 1/3 stop above the native ISOs (125, 250, 500 etc) are noisier because they are achieved by a digital "push" over ISO 100, 200, 400, 800 etc.

Does anyone know if the the same is true with the 5D3?


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## Daniel Flather (Apr 16, 2012)

iso 64/125/250/500/1000 are native stops, or am I incorrect?


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## Viggo (Apr 16, 2012)

I thought that varied from model to model?

My 1d4 was cleaner at 160, 320, 640 etc, but the 5d2 looked better at 100, 200, 400....


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## TrumpetPower! (Apr 16, 2012)

I've never seen a real-world difference. Sure, you can shoot the inside of your lens cap and run some sort of meaningless statistical calculation and come up with a number that says there's a difference, but I've yet to see a print where you could tell the difference in a third of a stop of ISO.

If you're really shooting something where a third of a stop of ISO noise will actually make a difference, I'd strongly suggest doing some real-world tests in the actual shooting conditions where you'd be deciding which to use, and basing your decision on your own evaluation of the results you get.

Me? I pick whole number ISO settings because it makes the math easier for me.

Cheers,

b&


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## JR (Apr 17, 2012)

I cant see much difference from my own shots. Though i will admit my eyes may not be well trained for this! Getting old!


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## LetTheRightLensIn (Apr 17, 2012)

xthebillx said:


> Hello!
> 
> I know that with the 5D2, ISOs 1/3 stop below the native ISOs are cleaner due to a digital "pull", primarily with video (but I've read that it pertains to RAW as well). Conversely, ISOs 1/3 stop above the native ISOs (125, 250, 500 etc) are noisier because they are achieved by a digital "push" over ISO 100, 200, 400, 800 etc.
> 
> Does anyone know if the the same is true with the 5D3?



For stills RAWs the 160,320,640 are the same as 200,400,800, they are the exact same thing only the camera meter over-exposes the 1/3 below the main ISO 1/3 stop.

For video or jpg with baked in processing perhaps they could be better since jpg and video are said to chop off some high-end DR anyway so maybe you lose nothing?


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## LetTheRightLensIn (Apr 17, 2012)

Daniel Flather said:


> iso 64/125/250/500/1000 are native stops, or am I incorrect?



No, in fact they have less dynamic range than 1/3 stop below and 1/3 AND 2/3 stops above.


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## Jettatore (Apr 17, 2012)

Tests like OP is searching for (which are only useful if done in real world conditions) vary greatly if you are testing the low light performance of a higher ISO, or if you are testing that same ISO in adequate light and using it specifically to buy yourself a faster shutter speed/smaller aperture, etc..

My suggestion for testing is just shoot as you normally would with what ever you are testing, try to get good pictures, and if time allows, take the same picture multiple times with a wide variety of settings. EXIF data will tell you which is which when you get them back to your computer, and other than that, just try to keep extra variables like camera shake and focus, etc., consistent so that your tests are more useful. After you do this quite a bit, you will know how to best use the camera + lens you are testing and get the best out of it and that is really a big key to getting great pictures before the editing stage begins. 

Everyone, myself admittedly included, worries so much about non-real world details and it's a mind killer. Just use what you got/buy what you can afford/you know you can profit from, and learn to test/use that to it's best, then go rent/try any new equipment and test the hell out of it before you buy it. If the upgrade is worth it to your art or is clearly a worthy investment, then you don't have to worry so much. I say this as a persevarate endlessly about which lens I'm going to sell and which one I'm going to buy next or if I'm selling a lens at all or buying a lens at all, if I need another camera body...... Decisions, decisions.


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## spinworkxroy (Apr 17, 2012)

I used to shoot at ISO160/320/640 etc because tests have shown those are cleaner than ISO100/200/400
However, that was on a Crop camera.
I believe the 5D3 is so castly superior at low ISO that up to maybe ISO800, you won't notice any difference whichever ISO you use. I do believe that even an ISO 400 is the same as ISO100 on a 5D3.
maybe at higher ISOs it will matter but if you're giong to shoot at that high ISO, most likely you're more concerned about shutter speed instead of ISO values. But yes, whole numbers are so much easier to remember so i'm using that now instead
http://a2bart.com/tech/allcamdknz.htm
Check out that "test" if you really want to see "noise" in detail…as i mentioned..ISO100-800 looks identical on the 5d3


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## naterz (Apr 17, 2012)

Here is a very unscientific test I just did in my Kitchen as I was very interested in this as well. It runs out when shooting RAW, staying in multiples of 160 definitely pays off. I purposely underexposed the shot, shot it in RAW, and then pushed it 5 stops in LR to bring out the noise. These are 100% crops with ISO 320 showing considerably less noise than ISO 250.


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## Viggo (Apr 17, 2012)

Oh, well, I might be accused for this and that, but I see the difference in all shadows. Seems the mk3 is the same as the 1d4, 320-640-1250, looks better...


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## wockawocka (Apr 17, 2012)

Theroetically the basinc stop multipliers should be the cleanest. 

100, 200, 400, 80, 1600 and so on.

Anything else, 320, 640 aren't supposed to be as they boosted by software. (i.e. 200 is pushed to 320)

This is different from hardware amplification which goes from 100-200. I never have expanded ISO available.


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## Viggo (Apr 17, 2012)

wockawocka said:


> Theroetically the basinc stop multipliers should be the cleanest.
> 
> 100, 200, 400, 80, 1600 and so on.
> 
> ...




can't 320 be an underexposed 400?


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## pz-photography (Apr 17, 2012)

Exactly, ISO 320 IS an underexposed ISO 400, thats the reason why it seems "clearer". 
If you want more info check this out  http://shootintheshot.joshsilfen.com/2010/05/13/canon-hd-dslr-native-iso/


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## naterz (Apr 17, 2012)

Whether it's native or not, the multiples of 160 definitely look better in videos and stills. So that's what I'm going to stick with.


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## AprilForever (Apr 17, 2012)

Someone once started this discussion about the 7D. It grew to like 15 pages, and the smites were handed out like candy. 

Ahhh, the past golden days o' smiting! Well, I am sure that the conclusions reached here will be similar, and I will in no case really care, because I can't see a difference, and neither can anyone else who is acting rationally!


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## Orion (Apr 17, 2012)

This is kind of a spammy post, but . . .

have you guys even seen ISO 2000!? It is amazing! I don't really care about multiples with this camera 

I have also noticed that if you guys want the BST images with the mkIII indoors, use a flash and you will be amzed at the sharpness and detail. That is the best way to use this camera indoors. Without flash and high ISO your images will appear not as clear and sharp. but with that little flash it is simply amazing like nothing I have ever seen almost. In a dark hall, use 3-4 strobes mounted on small light duty stands placed around the room and fire away anywhere you want using almost any ISO you want without fear. For small living rooms etc, use 2 stobes at eirthter end of the room and enjoy! The ISO will be SOO much better . . .! And while this subject of multiples is a valid one for greater understanding of your camera's inner workings, I think that it goes by way of the dodo once you switch to mkIII and flash fill. . . . .. mmmmmmmmm


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## nitsujwalker (Apr 17, 2012)

Important thing to remember about the 160, 320 etc

"Because ISO 320 is actually ISO 400 pulled 1/3 of a stop, that means that the highlights are going to clip at exactly the same point as they would at ISO 400. The 1/3 stop pull is just making that point 1/3 stop darker than pure white. The entire image at ISO 320 is 1/3 stop darker (and may be less noisy) than the image at ISO 400, so the blacks lose detail 1/3 stop sooner, but you don't get that 1/3 stop back at the highlight end of the range -- it's still gone. Therefore, at ISO 320 you're losing a net 1/3 stop from the total usable dynamic range that you would have if you were shooting at ISO 400."

http://shootintheshot.joshsilfen.com/2010/05/13/canon-hd-dslr-native-iso/

but they do have less noise..


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## LetTheRightLensIn (Apr 17, 2012)

wockawocka said:


> Theroetically the basinc stop multipliers should be the cleanest.
> 
> 100, 200, 400, 80, 1600 and so on.
> 
> ...



Actually 160 and 320 are NOT pushed from the stop below but the stop 1/3 above over-exposed by 1/3 stop and then with the RAW levels reset in cam so you gain 1/3 stop in the shadows and lose 1/3 stop highlights, you'd get the exact same thing though by using ISO200 and ISO400 and using EC +1/3 ;D.

The ones like 125 are bad though since they are just ISO100 pulled up 1/3 stop after being under-exposed 1/3 stop, they actually end up with a little bit less dynamic range than ISO100 or 160 or 200.


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## LetTheRightLensIn (Apr 17, 2012)

Viggo said:


> wockawocka said:
> 
> 
> > Theroetically the basinc stop multipliers should be the cleanest.
> ...



you mean 320 is an OVERexposed 400 and yes, that is exactly what it is


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## LetTheRightLensIn (Apr 17, 2012)

nitsujwalker said:


> Important thing to remember about the 160, 320 etc
> 
> "Because ISO 320 is actually ISO 400 pulled 1/3 of a stop, that means that the highlights are going to clip at exactly the same point as they would at ISO 400. The 1/3 stop pull is just making that point 1/3 stop darker than pure white. The entire image at ISO 320 is 1/3 stop darker (and may be less noisy) than the image at ISO 400, so the blacks lose detail 1/3 stop sooner, but you don't get that 1/3 stop back at the highlight end of the range -- it's still gone. Therefore, at ISO 320 you're losing a net 1/3 stop from the total usable dynamic range that you would have if you were shooting at ISO 400."
> 
> ...



That is wrong, with ISO320 you gain 1/3 stop in the darkest shadows and lose 1/3 in highlights and get 1/3 better SNR across the board since it gets exposed to light for 1/3 stop longer than ISO400. ISO320 and 400 have the exact same dynamic range and they are equivalent, if you use EC +1/3 ISO400 it is the same as using ISO320 and if you use ISO320 EC -1/3 it is the same as using ISO400 (the file contents are stored a touch differently in what range of numbers they use, but the true end result is the same). That is for RAW.

For jpg and video it might be different since they chop off some of the DR that RAW has and depending upon what tone curve and how they chop things it's possible ISO320 and 400 might not be the same and that using EC +/-1/3 might not be able to make them the same. I never looked into it too much myself. Some claim the 160,320, etc. are better for jpg/video since they claim the top 1/3 of highlights that ISO160/320 chop off get chopped at ISO200 and 400 so you don't lose that relatively speaking but you do gain 1/3 in shadows, which may seem even larger since you might rise above the worst of banding, and SNR, not sure if that is true, but some have said that. For RAW shooting that is definitely not the case though.


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## THX723 (Apr 18, 2012)

Referring to Mr. Claff's Photographic Dynamic Range chart:
http://home.comcast.net/~NikonD70/Charts/PDR.htm#EOS%201D%20Mark%20IV
_(note: select EOS 5D Mk III)_

The analysis methodology appears sound imho, however regardless of the _absolute accuracy_, it is the _delta_ that is of interest here and with that, it clearly supports the multiples of 160 theory (at least for the 5D Mk3).

Put another way in terms of read noise:
http://home.comcast.net/~NikonD70/Charts/RN_ADU.htm

again clearly shows iso160, 320, 640, etc. having the least noise.


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## jrista (Apr 18, 2012)

All Canon cameras *most definitely* have NATIVE ISO 100, 200, 400, 800, etc. stops. The reason noise is cleaner on the -1/3rd stop ISO settings is because Canon uses a Base/Push/Pull approach to ISO. As an example, ISO 320 is actually ISO 400 with a -1/3rd stop "pull" that underexposes the ISO 400 shot by one third of a stop, then "recovers" the underexposure with a bit of extra analog gain. That "pushes down" noise at ISO 320, which is why it looks cleaner...but, its at the cost of an additional third-stop of dynamic range.

You can find a complete analysis of Canon's method of achieving the various ISO settings at the following link:

http://photography-on-the.net/forum/showthread.php?t=1081982

Core ISO levels up to ISO 1600 (which, in the case of the 5D III, might now be ISO 12800) are a base ISO setting (initial amplification) with a push or pull of 1/3rd stop of analog gain. Beyond the maximum core ISO setting, things tend to get a bit nastier, and you might have initial amplification, analog gain, digital gain, and metadata settings that tell the RAW processor to boost even more in post. 

Personally, one of the things I was really hoping Canon would improve on with the 5D III and 1D X was their approach to ISO. Its annoying to alternatively lose a third stop of DR for "non-native" ISO settings. It would be much nicer to simply have electronic amplification right off the pixel directly to the appropriate ISO. Thats what Sony Exmor sensors do, and they seem to do a pretty good job of it until higher ISO settings. In the grand scheme of things, though, it doesn't really matter a wit to IQ...having shot Canon cameras for a number of years now, lower-ISO noise is largely indistinguishable across settings when you properly expose. It may only manifest as a minor problem if you need multiple low-light shots from a sequence that involved differing lower-ISO settings to be very consistent...in which case you might notice slight differences in noise characteristics between frames. On an individual shot basis were no consistency is necessary, the only real drawback is that 1/3rd stop DR loss for non-native (100, 200, 400, etc.) settings.


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## LetTheRightLensIn (Apr 18, 2012)

jrista said:


> All Canon cameras *most definitely* have NATIVE ISO 100, 200, 400, 800, etc. stops. The reason noise is cleaner on the -1/3rd stop ISO settings is because Canon uses a Base/Push/Pull approach to ISO. As an example, ISO 320 is actually ISO 400 with a -1/3rd stop "pull" that underexposes the ISO 400 shot by one third of a stop, then "recovers" the underexposure with a bit of extra analog gain. That "pushes down" noise at ISO 320, which is why it looks cleaner...but, its at the cost of an additional third-stop of dynamic range.
> 
> You can find a complete analysis of Canon's method of achieving the various ISO settings at the following link:
> 
> ...



160 is not 200 underexposed 1/3 stop and then given an analog boost, that doesn't even make sense.

And the 160,320, etc. ones do NOT lose any DR compared to 200,400, etc.

Again all they are are the 1/3 ISO above ISO (200,400, etc.) exposed 1/3 longer than the metering indicates and then digitally brought back down. So you get the expected 1/3 stop better SNR than 200 because it was exposed for 1/3 stop longer (NOT underexposed 1/3 stop, it gets over-exposed 1/3 stop) and you get 1/3 stop better shadows and the 1/3 stop clipped highlights.


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## LetTheRightLensIn (Apr 18, 2012)

THX723 said:


> Referring to Mr. Claff's Photographic Dynamic Range chart:
> http://home.comcast.net/~NikonD70/Charts/PDR.htm#EOS%201D%20Mark%20IV
> _(note: select EOS 5D Mk III)_
> 
> ...



Weird, he gets some 1/3 down ISOs with higher DR, since everyone else has gotten 160/200, 320/400 to have the same DR for the 5D2. I wonder if he estimated or measure them.

See for instance (note that is a straight engineering DR chart, it doesn't take into account banding visual look; also it doesn't take into account how ISOs are rated camera vs camera):


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## jrista (Apr 18, 2012)

LetTheRightLensIn said:


> jrista said:
> 
> 
> > All Canon cameras *most definitely* have NATIVE ISO 100, 200, 400, 800, etc. stops. The reason noise is cleaner on the -1/3rd stop ISO settings is because Canon uses a Base/Push/Pull approach to ISO. As an example, ISO 320 is actually ISO 400 with a -1/3rd stop "pull" that underexposes the ISO 400 shot by one third of a stop, then "recovers" the underexposure with a bit of extra analog gain. That "pushes down" noise at ISO 320, which is why it looks cleaner...but, its at the cost of an additional third-stop of dynamic range.
> ...



Sorry, the extra analog gain is only applied to settings above 1600 (or possibly higher with the 5D III). It is a _digital_ correction, not an analog correction (apologies for the miss), that would either underexpose (as in the case of ISO 160, down from 200) or overexpose (as in the case of ISO 250, up from 200). BOTH third-stop cases, 160 and 250, DO indeed lose a third stop of dynamic range. Whether you actually clip highlights and gain shadow SNR would entirely depend on the photographer...generally speaking, any half-witted photographer can use the in-camera histogram to avoid an overexposure, which would mitigate any SNR gain on the shadow end. Thus...loss in DR, not a gain in shadow performance.

Actually, one of the DR comparison charts that pitted the D800 against the 5D III clearly indicated the slight drop in DR in the 1/3rd stop ISO settings between ISO 100 and 400 on the 5D III. I'll see if I can find the link you posted, I forget what thread it was to. I am not exactly sure how that particular chart is derived, it seemed to be offset from DXO numbers by a few stops, but it definitely demonstrated the loss in DR on Canon cameras at non-native low-ISO settings.


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## LetTheRightLensIn (Apr 18, 2012)

jrista said:


> LetTheRightLensIn said:
> 
> 
> > jrista said:
> ...



What you say doesn't match what countless people other than what the one Nikon guy linked to above discovered.

Nobody else has found the 160,320 to lose 1/3 third stop of DR compared to 200,400, etc.

Measure black frame read noise at ISO160 and 200 and then measure saturation point, in the end, you end up with the same DR, the only difference is the metering system is biased in favor of shadows if you use ISO160 and biased in favor of saving highlights if you use ISO200.


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## Janco (Apr 18, 2012)

I literally don't get NOTHING of this discussion, simply because maybe I have a misunderstanding how different ISO's in digital cameras are achieved. I always thought ISO settings in digital are only made by different multiplication factors of the amount of sensor information (signal+noise) readout, so for example ISO200 would be achieved simply by boosting/amplifying the number of photons that hit any example pixel by the factor 2 (double) in comparison to the value it would have for ISO100 and ISO320 would be amplified 3.2x the value it would have at ISO100. With this theory there would not be a reason to take the picture at ISO400 but underexpose it by a third or pulling pushing something? OR is this because of FULL stops at aperture and speed? I guess I answered the question already, but I'm not sure if all is that simple. Or hmm, I guess it is?
Please enlighten me! Thanks....


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## Jettatore (Apr 18, 2012)

I would say in general this simply doesn't matter for real world use. I actually like the discussion that is going on above, but it really doesn't matter for an end user who's goal is to take nice clean images. The best way to reduce noise in an image before editing is to expose the image properly and not try to use the camera as a nightvision scope. Properly exposed shots that are adequately lit, using higher ISO's to buy smaller aperature and faster shutter speeds do not suffer the same noise issues that improperly exposed shots making up for dramatically bad lighting conditions do.

Example: ISO 1600, f/8.0, 1/250 (using higher ISO to stop action and incread DOF) :: ISO 1600, f/2.8, 1/25 + a steady hand (using high ISO to see in the dark)

When I shoot in severe low light, I try to capture exactly what my eyes can see in that situation and work my compositions around that philosophy. A small touch of RAW noise removal and post editing yields phenomenal results with this type of approach. The nice thing on top of all this is that as the cameras keep getting better and better, you actually can use the camera's as if they were night vision goggles and get away with it if you're clever.


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## esi32 (Apr 18, 2012)

Janco said:


> I literally don't get NOTHING of this discussion, simply because maybe I have a misunderstanding how different ISO's in digital cameras are achieved. I always thought ISO settings in digital are only made by different multiplication factors of the amount of sensor information (signal+noise) readout, so for example ISO200 would be achieved simply by boosting/amplifying the number of photons that hit any example pixel by the factor 2 (double) in comparison to the value it would have for ISO100 and ISO320 would be amplified 3.2x the value it would have at ISO100. With this theory there would not be a reason to take the picture at ISO400 but underexpose it by a third or pulling pushing something? OR is this because of FULL stops at aperture and speed? I guess I answered the question already, but I'm not sure if all is that simple. Or hmm, I guess it is?
> Please enlighten me! Thanks....



Broad strokes: Photons hit's photo site, some get converted into an electron. The electrons accumulate during the exposure and create a vary small voltage. That voltage is amplified by one or more variable gain amps then fed into the Analog-digital converter (ADC). The number that comes out of the ADC goes to the RAW file.

Now fun part is when you get to doing the amplification. There are several ways to go about doing it, the following 3 have actually been used to my knowledge in cameras.
1) a single amp that has 1/3rd stop steps (AFAIK Nikon does this)
2) a single amp that has 1 stop steps and push and pull via software and adjusting the meter (AFAIK Canon's non EOS-1 bodies do this)
3) 2-stages of amps that handle full and fractional stops in stages (AFAIK, Canon's EOS-1 bodies, at least I know for sure the Mk3s do it this way). 

For case 1, lower ISOs are always better (less noise more DR) than higher ones.

For case 2, the +1/3rd stop ISOs are worse for noise and DR than the base ISOs. The +2/3rd stop ISOs are better for noise but not DR than the base ISO, and at low ISOs often better for noise than the +1 ISO. Once you hit unity gain it doesn't matter, things just go down hill anyway and you want to use the lowest ISO you can.

For case 3, below unity gain, IME all +1/3 ISOs are worse than the base ISO, and +2/3rds ISOs are worse than the base and base +1 stop ISOs. Once you hit unity gain ISOs get progressively worse as you'd expect.

Expanded ISOs (L, H1, H2) are merely mathematical manipulations of the highest (or lowest) real ISO setting the camera can do. IMO, these are the "when having a picture is more important than having a good picture" settings, at least H1 and H2.

Unity gain, is the point where 1 collected photon == 1 RAW value step.


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## Janco (Apr 18, 2012)

Thank you esi32! I could imagine you're either some kind of camera engineer or maybe a teacher with excellent camera knowledge (assuming you're right with your post ;D )


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## psolberg (Apr 18, 2012)

the noise at low ISOs is very disturbing on the 5DmkIII
http://diglloyd.com/ (subscription required, I can't post links but you can read his "reader comments")


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