I'd like to have an SLT-mirror that flips up during the shot

Started Oct 1, 2012 | Discussions
Luebke
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Re: Here are sample pictures with, and without an SLT mirror
In reply to Dirk W, Oct 3, 2012

Dirk W wrote:

It is too complex to explain to you, but it is very possible and has to do with the differences of light refraction in different materials (air, other material such as the SLT) and possible (constructive or destructive) interferences by reflection of part-waves from the sides of the mirror. No need to get too scientific here IMHO - you may keep ROFL.

Please get scientific. Since I earn my money with researching nonlinear ultrafast optics I am quite familiar with the basics of optics.

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Allan Olesen
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Re: Here are sample pictures with, and without an SLT mirror
In reply to Dirk W, Oct 3, 2012

Dirk W wrote:

It is too complex to explain to you, but it is very possible and has to do with the differences of light refraction in different materials (air, other material such as the SLT) and possible (constructive or destructive) interferences by reflection of part-waves from the sides of the mirror. No need to get too scientific here IMHO - you may keep ROFL.

Or... we could make it much simpler:

The DxO measurements you posted earlier in this thread show a 0.46 stop difference between the a57 (ISO 785) and NEX-5N (ISO 1079).

That is: The NEX-5N can make a photo with the same amount of noise using an amount of light which is 0.46 stops lower than the a57.

The mirror is known to steal approx. 0.5 stops of light.

In other words:

The full difference in the DxO measurements can be explained by the known light loss. So why should we go and invent theories of other fairytale sources for noise?

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Dirk W
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Re: Here are sample pictures with, and without an SLT mirror
In reply to theswede, Oct 3, 2012

I agree partly but the parallel shift and therefore the chromatic aberration depend much on the thickness of the tilted plane plate and the SLT is very thin, so that the aberrations could appear more like diffusion and cause noise. Also spherical aberrations are possible even on a tilted plane plate, which could explain the loss of detail in the samples of the A55. Then, as I said before, also the material has a substantial effect on the refraction: The SLT is plastic., i.e. has a different refraction index to glass and, consisting of long and "chaotic" hydrocarbon chains also leads to more molecular diffusion than glass with its crystal-similar structure, which could also explain loss of detail and more noise. Sorry if I don't use the correct English terminology, I am not a native English speaker.

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theswede
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Re: Here are sample pictures with, and without an SLT mirror
In reply to Dirk W, Oct 3, 2012

Dirk W wrote:

I agree partly

Really now.

but the parallel shift and therefore the chromatic aberration depend much on the thickness of the tilted plane plate

Parallell shift and chromatic aberration are completely separate phenomena with different effects. You have no idea what you're on about, that much is clear.

and the SLT is very thin, so that the aberrations could appear more like diffusion and cause noise.

Three separate phenomena which manifest in three completely different ways.

1. Chromatic aberration exhibits as a shift in color over distance in one or multiple dimensions, since that is what it is.

2. Diffusion manifests as mainly wavelength independent blur. CA will not cause this kind of blur blur. And finally:

3. Noise (as you have spoken of in this thread, which has nothing to do with the information definition of noise but is restricted to stochastic variation in luminance and chrominance) is the exact opposite of diffusion.

Thus, your causal chain is a vacuous mess. You really shouldn't be using words you don't understand in this manner.

Also spherical aberrations are possible even on a tilted plane plate

Given sufficient thickness and lack of homogenity, sure. Are you arguing the SLT mirror is thick enough for this to occur?

which could explain the loss of detail in the samples of the A55.

Oh my. It seems you are. You truly have no clue.

Then, as I said before, also the material has a substantial effect on the refraction:

And what effect does refraction have on the final image? Warning: this is a tricky question.

The SLT is plastic., i.e. has a different refraction index to glass

So are many lense elements. According to your "hypothesis" (it makes a bad taste in my mouth to call your gibberish that) that would mean modern lenses will cause, how was it now, chromatic aberration leading to diffusion leading to noise.

and, consisting of long and "chaotic" hydrocarbon chains

Using words from cutting edge physics does not help your case, especially when air itself is a lot more "chaotic" than any solid material ever has any hope to be, and thus will affect the light a lot more from that perspective.

also leads to more molecular diffusion than glass

You realize that "molecular diffusion" is just a fancy name for "opacity", right? What you have just described is a weak ND filter. Which, incidentally, everything which lets light through is. Plastic, glass, air, lenses, SLT mirrors, pentaprisms, you name it.

You're arguing that an ND filter directly adds noise to an image capturing device. Not through light loss, but through some hitherto unknown mechanism of physics which involves chromatic aberration becoming diffusion becoming noise.

Madness.

with its crystal-similar structure, which could also explain loss of detail and more noise.

No, it could not explain anything like that.

Sorry if I don't use the correct English terminology, I am not a native English speaker.

You sure seem to be a native speaker of gibberish.

Jesper

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Dirk W
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Re: Here are sample pictures with, and without an SLT mirror
In reply to theswede, Oct 3, 2012

Its not worth any more effort.

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Dirk W
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Re: Here are sample pictures with, and without an SLT mirror
In reply to Allan Olesen, Oct 3, 2012

I don't think you can calculate it that way because the ISO difference is not a linear function.

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TrojMacReady
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Re: Here are sample pictures with, and without an SLT mirror
In reply to Dirk W, Oct 3, 2012

Dirk W wrote:

I don't think you can calculate it that way because the ISO difference is not a linear function.

You can calculate it that way because the measurements show a pretty fixed difference across the ISO range. And the SNR curves of recent Exmor sensors are rather linear on the log scale.

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Allan Olesen
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Re: Here are sample pictures with, and without an SLT mirror
In reply to Dirk W, Oct 3, 2012

Dirk W wrote:

I don't think you can calculate it that way because the ISO difference is not a linear function.

The ISO scale is linear. You need twice as much light to make the same photo at ISO 100 as you do at ISO 200. And 4 times as much at ISO 50.

So the ratio between two ISO values can be found by simple division. Then, if you want to convert that ratio into stops, you have to use logarithms.

Difference in stops: ln(ISO[1]/ISO[2]) / ln(2)

Simple math for anyone who understands it. Those who do not understand it just say "I don't think you can calculate it that way."

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theswede
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Re: Here are sample pictures with, and without an SLT mirror
In reply to Dirk W, Oct 4, 2012

Dirk W wrote:

Its not worth any more effort.

I've known that for a long time, but I don't want newbies who come here to be impressed by your use of words you don't understand.

You've demonstrated you have no idea what you're on about, and you can't explain by what hitherto unknown mechanism an ND filter will introduce noise unrelated to the light loss.

Jesper

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Fujifilm FinePix X100 Konica Minolta Maxxum 5D Sony SLT-A37 Sony 50mm F1.4 +2 more
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Dirk W
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Re: Here are sample pictures with, and without an SLT mirror
In reply to theswede, Oct 4, 2012

LOL! YOU have proven being the one who does not understand a thing. Fact is that in a comparison of cameras with the same sensor on dpreview lab (eg. also D7000 and A57), ALWAYS the ones with the SLT have more noise AT THE SAME HIGH ISO than the ones without. Your lame argument attempts about white balance etc. could maybe have an effect SOMETIMES, but not in ALL samples, that's why your arguing is so ridiculous. The optical reason for the noise addition by the SLT may not be clear, and optical reasoning obviously too advanced for you, but it is there and the result are clearly visible for everybody (without your eye problems or mind blockage).

 Dirk W's gear list:Dirk W's gear list
Olympus Stylus XZ-10 Sony Alpha NEX-5N Sony Alpha NEX-6 Sony Alpha NEX-3N A3000 +18 more
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