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Can we agree on Camera Equivalence for Comparisons?

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Scottelly said:
So what is all the B.S. about ISO 160 being the lowest ISO setting available for the m4/3 cameras. I mean there are cameras with 1" sensors that can do ISO 80.
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Perhaps you should read the date of the article plus notice that the reference was to 4/3 cameras, not micro-four-fours and not compacts.

"What we've got hyah is Failyah to Communicate": 'Cool Hand Luke' 1967.
 
So you compare a 40mm zoom against a fix focal lens optimzed for that camera?

Does this make any sense?
 
Thomas Mottl said:
So you compare a 40mm zoom against a [fixed] focal [length] lens [optimized] for that camera?
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I personally do no such thing - it was just an example for the purposes of illustration.

The way you put your rhetorical question is quite irritating, to be honest.
Thomas Mottl said:
Does this make any sense?
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This thread is besmirched with an error I made earlier and I had hoped that a Mod. might have deleted it.

Turns out that 35mm would have been more correct, so how about this one instead:

http://www.imaging-resource.com/lenses/sigma/35mm-f1.4-dg-hsm-a/review/

Please stop picking away, I feel bad enough as it is without you going on about 40mm.

--
"What we've got hyah is Failyah to Communicate": 'Cool Hand Luke' 1967.
 
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Hey Ted, don't feel so bad about a single error. It's no big deal to be fixed and keep pressing on with the discussion; the principles are the same whether we apply 1.316 or 1.11 crop factor. Imagine if every photograph posted that turned out to have a single technical flaw was withdrawn and the photographer 'felt bad'?
 
rf-design said:
TN Args said:
Scott, see my post to explain the ISO equivalence and other related equivalences. The author is trying to create identical images from two different-sized sensors, including noise.

What the author is trying to teach us, if I may use a better example and compare sdQ with sdQH, is that if we want to get an identical image from the two cameras, the crop factor of 26.6/23.5mm = 1.13 means that we need to adjust the sdQH as follows:
  • use a 35mm lens on the sdQ and a 40mm on the sdQH
  • use a f/4 aperture on the sdQ and a f/4.5 on the sdQH
  • use ISO 100 on the sdQ and ISO 125 (square law) on the sdQH
The two images will then contain the same scene edge-to-edge, same depth of field and blur, and same total noise, i.e. equivalent / identical-looking pictures as far as those parameters are concerned. (But the sdQH would still have more detail due to its additional pixels.)
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Thank you,

for clear state of the intention. I am also interested in the objective judgment based on a clear defintion of the intention.

In the past I made a calculation comparing APS-C and FF regarding noise in long exposure situations. The result is that there is no primary difference based on photon shot noise. So if the underlying sensor tech is near the shot noise limit FF give no advantage over APS-C in FoV limited situations.

https://www.dpreview.com/forums/post/41317004

A little bit different outcome exist if shot noise is not the only contributor to the sensor noise. If the leakage current start to dominate the final noise the bigger area of the FF lead to an disadvantage. I could not prove this because of not owning a FF with similar good sensors as the D7000.

https://www.dpreview.com/forums/thread/3807661

Regarding the leakage current it seems to me that the sweet technology point for low leakage current is already past. Newer sensors are getting shorter times where the shot noise equals the leakage current.

https://www.dpreview.com/forums/post/58893840

Coming back to the question of Equivalance with Focus Stacking.

I know that the technology for fast focus stacking, that should mean focus stacking within a single user taking but with multiple exposures, is not mature. For my practice of long exposure a made some experiments with stacking of long time exposures. So instead of using F5.6 at 16s I take two shots at F2.8 at 4s. The DoF is only half but by image stacking of two images I should get the same DoF.
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Don't you lose resolution because of this? I mean what lens resolves the same detail at f2.8 as it does at f5.6?
rf-design said:
Because the amount of light goes down with the square of apture but the DoF increases only linear focus stacking is different variable in the equivalence consideration.
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Thomas Mottl said:
All those endless comparisons between Sigma A and Sigma B or Brand X are leading to nothing.

In the good old days the print was the thing what matters, in my opinion this is also valid today.

Why compare a fixfocal lenght Camera like any DPxx against a interchangable lens camera?

The only result one can get is that the lens of one of those two cameras is better or equal as you just compare the lenses in my opinion.

Also Sigma has no 40mm fix focal lens so there is anyway nothing to compare!
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Really? I thought this thread was more about color differences, which are slightly affected by lenses, but often are affected much more by the processing done by the camera or raw development software, and possibly the sensor (though I don't think there has been so much difference from one sigma generation to the next, as there is today with the step from Merrill to Quattro). The 40mm difference is not such a big deal, if you ask me, but I do agree, if you think an SD1 Merrill should have been used instead of a DP2 Merrill. We use what we have available to us though.

What is so wrong about comparing? I like comparing. Obviously a lot of other poeple do too . . . not just Sigma fans. Have you seen the Stido Scene Comparison Tool here on DPreview?

 
Comparing is good, as long one not compare apples with oranges, it leads to nothing.

I buy cameras to take pictures and I do not look back when I made the purchase. This is the tool I have and I have to work with it. Also I know when buying a Sigma camera no matter what iteration, I will be limited in many ways. I accept this before the purchase.

I do not buy cameras to compare it endless thereafter.

And comparing a dpx with an interchangable lens camera leads to nothing cause the dpx will always lose as soon as it come to the changing lenses thing. Two total different devices.
 
TN Args said:
Hey Ted, don't feel so bad about a single error. It's no big deal to be fixed and keep pressing on with the discussion; the principles are the same whether we apply 1.316 or 1.11 crop factor.
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Thanks, Arg, I appreciate your advice.

I was actually being a bit dramatic in my response to the 40mm fixation, bad Ted, bad ;-)
 
Thomas Mottl said:
Comparing is good, as long one not compare apples with oranges, it leads to nothing.

I buy cameras to take pictures and I do not look back when I made the purchase. This is the tool I have and I have to work with it. Also I know when buying a Sigma camera no matter what iteration, I will be limited in many ways. I accept this before the purchase.

I do not buy cameras to compare it endless thereafter.

And comparing a dpx with an interchangable lens camera leads to nothing cause the dpx will always lose as soon as it come to the changing lenses thing. Two total different devices.
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They each have their advantages, and I think it would be a mistake not to compare them. If you have both, then you will know what situation each camera is best for, if you do compare them, but you will not know if you don't compare. I think comparing is a great way to learn about the little nuances of various camera and lenses, and I like to compare my own equipment and I like to see comparisons of other equipment . . . even equipment that I have little interest in purchasing (though that does have its limits . . . i.e. cell phone cameras and point-and-shoot cameras with small sensors - I have no interest in the noise characteristics of different cameras with sensors smaller than 1").

EDIT:

Actually . . . that's a lie. I have a camera (waterproof Olympus) that has a 1/2.3" sensor, and I am interested in the noise characteristics of that camera, its competitors (which seem to be quite lacking at the moment), and anything radically new or different that I might come across. I do use that camera to shoot photos like this:




I shot this with my Olympus



--
Scott Barton Kennelly
http://www.bigprintphotos.com
 

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I think the camera equivalence is really useful to understand the lens options for various mirrorless cameras.

For example, Olympus recently introduced a new lens 25mm f1.2 for micro four thirds (e.g. https://www.dpreview.com/samples/4774502912/pinnacle-prime-olympus-ed-25mm-f1-2-pro-samples-gallery ). At first you probably think f1.2 is really crazy - but camera equivalence reveals that it all makes perfect sense!

All the following will result in identical images with regard to motion blur, DOF, and noise:
  • micro four thirds (crop factor 2), ISO 100, 25mm, f1.2
  • APS-C (crop factor 1.5), ISO 178, 33mm, f1.6
  • APS-H (crop factor 1.3), ISO 237, 39mm, f1.8
  • FF (crop factor 1), ISO 400, ISO 400, 50mm, f2.4
  • GFX (crop factor .79), ISO 640, 63mm, f3.0
Interestingly, all of these equivalent setups are possible in actual hardware!

For example, the normal kit lens for the Fuji GFX medium format camera is the 63mm f2.8, so using the Olympus lens at ISO 100 is equivalent to shooting the GFX at ISO 640! Which shows the 3 stop advantage of the medium format camera vs. the m4/3, but also shows you can reqally do very decent images with a m4/3 body today!

It also explains why the SIgma 30mm f1.4 is indeed a good choice for a kit lens for the SD quattro (or similary the Fuji 35mm f/1.4 for fuji X series).

Similary, if I like my DP2 classic with f2.8 and 24mm lens but wish for a compact camera with a bit better iso (say up to 1600 ISO), what are my options? Camera equivalence will suggest the following:
  • APS-C: 27mm, f3.2, ISO 2055
  • Micro 4/3: 20mm, f2.4, ISO 1156
So e.g. a Fuji XE1/2 with the Fuji 27mm lens will do perfectly! or a Panasonic M43 body with the 20mm lens.
 
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