Silvarum

Silvarum

Lives in Russian Federation Russian Federation
Joined on Jul 2, 2011

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Total: 118, showing: 1 – 20
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On FAA proposes regulations for commercial drone usage article (110 comments in total)
In reply to:

FRANCISCO ARAGAO: The potential for disaster is enormous.

@AlexisH: And the point of regulations is not to completely eliminate risk, but to reduce it to acceptable level. There still will be disasters, but not as often if not regulated.

Direct link | Posted on Feb 22, 2015 at 09:20 UTC
On FAA proposes regulations for commercial drone usage article (110 comments in total)
In reply to:

FRANCISCO ARAGAO: The potential for disaster is enormous.

Sure, airplanes and automobiles are also dangerous. But you do not often see airplanes flying over people heads, do you? Or automobiles driving though parks full of people?
That is because they are regulated by laws and rules.
Besides, drones are very loud and annoying.

Direct link | Posted on Feb 21, 2015 at 15:48 UTC
In reply to:

Raist3d: So sad to see Russia doing this. I hope the rest of the world can serve as a living example of why this is ridiculous.

I live in Russia. I care about gay couples about as much as straight ones - not at all. It is not my business and not my life, they can do whatever they want as long as it doesn't interfere with others. Same true for all. "The right to swing my fist ends where the other man’s nose begins."

@D1N0: About US political system: there would be so much less trouble in the world if US would simply care just a little bit less for things like gay rights in OTHER countries. US very easily imposes its own way of life to others, but doesn't want to take any responsibility for it.

@Raist3d: and you should probably read less news ;)

Direct link | Posted on Feb 17, 2015 at 18:19 UTC
In reply to:

Jonathan Lee: would it be full frame mirrorless and take k mount? i would hold on buying the other brand's FF mirrorless.

And waste 40mm of space inside? Much better choice would be some-other mount mirrorless body with K-mount adapter.

Direct link | Posted on Feb 6, 2015 at 04:53 UTC
In reply to:

LBJ2: "which offers a fast maximum aperture of F2.8 throughout its zoom range"

Applying the crop factor, is this new lens really an equivalent f2.8 "throughout its zoom range" or is it really equivalent to 24-83mm f4.2 ?

I see it that way - when you press shutter button, what your camera does - is simply collecting light. And in the end, all that matters is how much light you've collected. And that is defined by shutter speed and aperture diameter (focal-length divided by f-stop) and maybe sensor efficiency too.

Direct link | Posted on Jan 11, 2015 at 12:24 UTC
In reply to:

LBJ2: "which offers a fast maximum aperture of F2.8 throughout its zoom range"

Applying the crop factor, is this new lens really an equivalent f2.8 "throughout its zoom range" or is it really equivalent to 24-83mm f4.2 ?

Well, maybe we a bit off on semantics then. I understand light gathering capabilities as "how much light in total goes through this particular lens". Not how much it projects per unit area. I simply don't see how "per area unit" fits in "gathering" - you either gather it or not, doesn't matter how you will project it afterwards.
In the first case, f2.8 is not f2.8 across different formats. In the second case, I agree, f2.8 is f2.8, but then you still have to consider different sensor (gathering) areas as separate argument.

Direct link | Posted on Jan 11, 2015 at 12:15 UTC
In reply to:

LBJ2: "which offers a fast maximum aperture of F2.8 throughout its zoom range"

Applying the crop factor, is this new lens really an equivalent f2.8 "throughout its zoom range" or is it really equivalent to 24-83mm f4.2 ?

Exactly - to gain exposure! If as you say we assume DOF is not considered here, then why bother with f-stop at all? Just use higher ISO setting to gain exposure. Only you would use larger aperture rather than ISO to gain exposure because with larger aperture you will gain more light and have less noise, and that was my point.

Original question was about light gathering capabilities, which is not exposure, because lenses for bigger format will gather more light at same f-stop.

Direct link | Posted on Jan 11, 2015 at 11:06 UTC
In reply to:

LBJ2: "which offers a fast maximum aperture of F2.8 throughout its zoom range"

Applying the crop factor, is this new lens really an equivalent f2.8 "throughout its zoom range" or is it really equivalent to 24-83mm f4.2 ?

But you can easily have same brightness by changing ISO setting. And have two photos that are equally lit. Why bother with f-stop at all?

Direct link | Posted on Jan 11, 2015 at 10:46 UTC
In reply to:

LBJ2: "which offers a fast maximum aperture of F2.8 throughout its zoom range"

Applying the crop factor, is this new lens really an equivalent f2.8 "throughout its zoom range" or is it really equivalent to 24-83mm f4.2 ?

Ok, why do you want to compare same exposure?

Direct link | Posted on Jan 11, 2015 at 10:40 UTC
In reply to:

LBJ2: "which offers a fast maximum aperture of F2.8 throughout its zoom range"

Applying the crop factor, is this new lens really an equivalent f2.8 "throughout its zoom range" or is it really equivalent to 24-83mm f4.2 ?

Total Light = Exposure x Sensor Area. You cannot ignore sensor area if it is different. Same f-stop will produce different result on different formats.
If total amount of light was irrelevant, then f/2 on my tiny mobile phone camera would have been same as f/2 on full frame. It is not. Full frame gets more light -> more signal -> less need for signal gain -> less noise and more DR.
Brightness however is irrelevant, as digital sensors have only one real sensitivity value and most cameras today use "isoless" ADC (except maybe for Canon), which means that noise produced by them will be the more or less the same regardless of ISO setting. You will get similar results by increasing exposure in post-processing. You can check it yourself by taking two pictures at for example f/4, 1/500, ISO100 and f/4, 1/500, ISO800, and then increase exposure in post by +3 for ISO100 shot.

Direct link | Posted on Jan 11, 2015 at 10:30 UTC
In reply to:

LBJ2: "which offers a fast maximum aperture of F2.8 throughout its zoom range"

Applying the crop factor, is this new lens really an equivalent f2.8 "throughout its zoom range" or is it really equivalent to 24-83mm f4.2 ?

But it's like comparing engines for cars and trucks. 1hp of power is 1hp on both of them, but doubtful, that 600hp truck can go as fast as 600hp car.
If you want equivalent shot or looking for equivalent lens on other camera format, then you need 3 things to be the same: DOF, angle-of-view and shutter speed. Aperture size defined by DOF and angle of view for specific format. Brightness of shot is irrelevant as it can be changed either afterwards in post processing or via ISO on camera, does not really matter.
You say, by using same focal length, angle of view will be different, therefore you cannot treat same focal length lenses for different formats as the same. I say, by using same f-stop on different formats, DOF (and total amount of light) will be different, and therefore, you cannot treat same f-stop lenses for different formats as the same. It will be unfair.
Either use same both focal length and f-stop (and then crop larger format) or none at all.

Direct link | Posted on Jan 11, 2015 at 10:02 UTC
In reply to:

LBJ2: "which offers a fast maximum aperture of F2.8 throughout its zoom range"

Applying the crop factor, is this new lens really an equivalent f2.8 "throughout its zoom range" or is it really equivalent to 24-83mm f4.2 ?

Sure it is. 16-55mm is still 16-55mm also, not 24-83mm.

Direct link | Posted on Jan 11, 2015 at 07:55 UTC
In reply to:

LBJ2: "which offers a fast maximum aperture of F2.8 throughout its zoom range"

Applying the crop factor, is this new lens really an equivalent f2.8 "throughout its zoom range" or is it really equivalent to 24-83mm f4.2 ?

Michael_13:
But learning is such a great thing! Theory can help to choose right system for those rare applications where sensor size can make difference.
Any person can take pictures without any knowledge of optics and physics (most consumers probably do). Sometimes even monkeys can do that ;-)

HowaboutRAW:
But why do you reduce noise? Reducing noise simply to reduce noise is not very rational thing to do. Let there be some noise if it looks good enough and not disturbing.

Direct link | Posted on Jan 9, 2015 at 21:02 UTC
In reply to:

LBJ2: "which offers a fast maximum aperture of F2.8 throughout its zoom range"

Applying the crop factor, is this new lens really an equivalent f2.8 "throughout its zoom range" or is it really equivalent to 24-83mm f4.2 ?

Michael_13, I disagree. It does help with buying decisions as it shows that bigger sensors will not necessarily be a better choice as they only offer you more flexibility on open end and slightly better low light performance. As for optical performance - yes, bigger sensors have less demand for lens quality. For sensor efficiency - smaller sensors usually have advantage here.
For your last post - that is true. I am just saying, that whole cult about bigger sensors and full frame is irrelevant.

Direct link | Posted on Jan 9, 2015 at 10:52 UTC
In reply to:

LBJ2: "which offers a fast maximum aperture of F2.8 throughout its zoom range"

Applying the crop factor, is this new lens really an equivalent f2.8 "throughout its zoom range" or is it really equivalent to 24-83mm f4.2 ?

My point was, that they are getting same exposure, but not same amount of light and therefore it would affect noise levels in the end.
We are not increasing ISO on FF to match noise on APS-C. We are increasing ISO to match same level of signal gain, so we can fairly compare both results.
If you want fully equivalent picture (that is DOF, AOF and shutter speed) then you will get same amount of light regardless of camera format you use.
f2.8 does not equal f2.8 across different formats. Just like focal length will give you different angle of view, aperture size will give you different amount of light.

@HowaboutRAW: It does not reduce noise, but isn't it the point to have aesthetically pleasing picture?
Read noise tends to be about the same regardless of pixel size. High res cameras would produce more detail for NR algorithms to work with. But, you are right, low res sensors have less read noise. For video low res sensors definitely have advantage.

Direct link | Posted on Jan 9, 2015 at 10:13 UTC
On Opinion: The myth of the upgrade path article (1406 comments in total)

"If you want the best image quality but don't want to spend the money or carry the bulk of..." Then I've got bad news for you! :)
And it should be "spend the money" AND "carry the bulk". Unless you have assistant who carries all stuff for you and makes cold beverages.
Anyway, history shows that smaller format eventually win the day with simple good enough quality.

Direct link | Posted on Jan 8, 2015 at 21:08 UTC as 314th comment | 1 reply
On Opinion: The myth of the upgrade path article (1406 comments in total)
In reply to:

nerd2: The hard fact is the FF system is usually the CHEAPEST to get some FOV/shutter speed combination, with the additional bonus of highest DR and resolution. D610 plus 50mm 1.8 is 2 stop faster than APS-C plus 35mm 1.4, and 3 stop faster than m43 with 25mm 1.4. And they cost about the same!

@cinemascope
I'm sorry, but nerd2 is right. Perspective distortion really depends only on camera-to-subject distance. Don't believe? Shoot scene with tele lens and with wide lens. Crop wide shot and compare two pictures.

Direct link | Posted on Jan 8, 2015 at 19:48 UTC
In reply to:

LBJ2: "which offers a fast maximum aperture of F2.8 throughout its zoom range"

Applying the crop factor, is this new lens really an equivalent f2.8 "throughout its zoom range" or is it really equivalent to 24-83mm f4.2 ?

ISO settings just map signal gain number to same standard. I think it is mapped so exposure of 0.1 lux*seconds will be converted to 18% grey (118 sRGB for 8-bit file, or L=50 for lab) for ISO 100.

@HowaboutRAW: well, that is why going FF will probably be the best thing if APS-C is not enough :)
Grain per square cm will be the same. It will just look bigger, because you will magnify it more for smaller film for the final image.
And amount of pixels have little impact on noise. You can always downsample to get less noise. Of course, because not all pixel area is used to capture light, you will loose some useful sensor area with higher amount of pixels.

Direct link | Posted on Jan 8, 2015 at 14:04 UTC
In reply to:

LBJ2: "which offers a fast maximum aperture of F2.8 throughout its zoom range"

Applying the crop factor, is this new lens really an equivalent f2.8 "throughout its zoom range" or is it really equivalent to 24-83mm f4.2 ?

Consider it like this:
You have 35mm f2.8 for APS-C and 50mm f2.8 for FF. You shoot both at f2.8, ISO 100, same shutter speed lets say 1/50. You will get same exposure and similar angle of view (not DOF though). Total amount captured of light is proportional to area of the aperture. For APS-C it will be 122mm², for FF - 250mm². Therefore FF will get more light through that lens. Because it gets more light, it will have more signal to work with and to achieve ISO100-like behavior it does not need to amplify it during Analog-to-Digital conversion process as much.
If you set FF camera to ISO 200 and lens for f4, then it will be exactly same exposure as APS-C with ISO 100 and f2.8 lens. You will have same DOF, angle of view and exposure. Exactly the same picture. This way aperture area for FF will be 122mm² (same as for APS-C) and because you set it to ISO 200, actual gain will be about the same as for APS-C.

Direct link | Posted on Jan 8, 2015 at 13:55 UTC
In reply to:

LBJ2: "which offers a fast maximum aperture of F2.8 throughout its zoom range"

Applying the crop factor, is this new lens really an equivalent f2.8 "throughout its zoom range" or is it really equivalent to 24-83mm f4.2 ?

Naveed, total light is all that matters in terms of noise.
1. For digital sensors ISO is just a number to represent lightness of image like if you'd took the picture with same ISO on film. Actual signal gain different for each sensor (even between same sized) and calibrated by manufacturer. ISO 100 of FF and APS-C is totally different signal gain. Because APS-C does not gather as much light as FF, it needs to amplify the signal more to achieve ISO 100 like behavior, which means that it will amplify noise too. If you set ISO in way, that signal gain will be the same, then, surprise, you will get more or less same amount of noise.
2. If you put lens with FF coverage on APS-C camera, then APS-C camera will not gather all light produced by that lens. But if you use device like Metabones SpeedBooster, then it will concentrate all light on APS-C area and you will get different exposure time.

Direct link | Posted on Jan 8, 2015 at 12:49 UTC
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