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01-20-2015, 08:13 AM - 1 Like   #1
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0.25x reducer design possible?

In 2015, there are several focal reducers for different mirrorless systems, but none for the Q. Apparently difference between FF or APS-C size and Q is very big.
I am not an optical designer but I am curious if there can be such strong focal reducer made. I typed in Kodak 1994 0.5x focal reducer patent (for DSLRs) and tried to modify it. (The Kodak reducer has very strong negative elements in the front to win some space because it needs to have large backfocus, and in practice barely usable). Here's what I've got. It compresses APS-C image circle by four times, and f-stop becomes f/2.5 from f/10.
Maybe someone finds this amusing.

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01-20-2015, 09:04 AM   #2
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See thread on speed booster
01-20-2015, 10:13 AM   #3
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QuoteOriginally posted by SteveNunez Quote
See thread on speed booster
= TL; DR

Nice work, OP.
01-20-2015, 12:12 PM   #4
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Looks .... large.

01-20-2015, 12:21 PM   #5
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If you can believe the ray tracing, it means the image is separated into spectral lines or points. It has to be a specialist lens if that's the case, not a reducer. Either that, or someone in marketing was let loose on it.
01-20-2015, 02:20 PM   #6
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QuoteOriginally posted by RobA_Oz Quote
If you can believe the ray tracing, it means the image is separated into spectral lines or points. It has to be a specialist lens if that's the case, not a reducer. Either that, or someone in marketing was let loose on it.
You sure? Looks OK to me... It's not the most elegant presentation, and I'm not exactly sure if the image would be flipped correctly, but other than that...
01-20-2015, 02:26 PM   #7
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QuoteOriginally posted by Giklab Quote
You sure? Looks OK to me... It's not the most elegant presentation, and I'm not exactly sure if the image would be flipped correctly, but other than that...
Well, each object point is shown as radiating separate colours, each of which terminates at an image point that is the same for each individual colour, and not corresponding to the individual object point. To me, that says "extreme colour separation"…

…unless, of course, what I take to be the object plane is just the rear element of the objective lens, in which case it's a moot point.
01-20-2015, 02:48 PM   #8
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I don't believe the colors of the lines necessarily correspond to hues, but rather to the point source of individual rays of light intended to discretely depict the amount of refraction involved at a very few points in the optical components.

Keep in mind that every point of light impinges upon every point in all the lens surfaces and must be "reconciled" to its corresponding point at the focal plane. Three colored lines here are no comparison of the complexity. Dealing with the difference in refraction of each color's wavelength at each point in the lens is as tough as herding cats when it's time to reassemble the image at the sensor plane.

In a prior physics class lab you may have played with a prism to demonstrate refraction (made a 'rainbow). Perhaps you even tried to undo the effect with a second prism. Not a chance, eh? The complexity of precisely re-combining ray paths through many "prisms" in a lens is mind boggling to me.



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