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Messages - K-amps

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1291
About 6 years ago, the air conditioning on the roof of the building I was working in had a problem with a bearing. It produced a very high pitch noise that I could hear and gave me a headache but nobody else in the office could (I was the youngest...)

Dare I ask what your thoughts are on 96kHz audio? I've got a few SACDs and the appropriate equipment to deliver 192/96 to the amp and out of the speakers...

Exactly! I suspect that if a 5DX were to have a foveon style sensor with colours arranaged vertically rather than in a horizontal 2x2, we'd find companies doing the Sigma thing and calling a camera with 15MP a 45MP camera.

Dilbert: We live in a world where the youth of today embrace the MP3... so 96kHz was pretty much dead on arrival. The beauty of SACD was not only the 96/192kHz sampling, but the ditching of discrete paralell bits and going for a stream of data. It was just a different way of processing data, not merely an upsampled engine that CD used. I too have a few SACD's lying around, they are not bad,  the pricing killed it as well.

Going back to the topic: Looking at apple/ google, buying off companies seems to be the best way to get Patents... however I suspect the fact that the Fovean did not dazzle people like they expected it to may have something to do with it...

1292
One of the problems with very tiny photosites is the narrow angle of view of each photosite.  Those toward the outer edges have a real issue trying to get light due to the angle of the light rays.   

Does that in any way translate to more vignetting at the corners on the 7D?

1293
If the maximum resolving power of the current L-series lenses is around 45MP for full-frame 35mm cameras then when the MP count exceeds 90MP is when we have too many MP. Why 90? Because at that point we've got enough resolution to properly sample the light and give clear definition to the 45MP worth of detail.

Kind of like how the music on CDs is sampled at 44khz, whereas the human can't hear much over 22k. The higher sampling gives better definition to what can be heard.

I may not be an expert in Digital photography, but I have spent half a lifetime as an Audiophile. If they had designed a "decent" Brick Filter at 22kHz, we would be fine. The issue was not frequency limitations, rather phase shifts caused by the brick filtering at 44.1kHz. Moving out the frequency bandwidth, merely softened the phase shift. PS: Most of us can't hear above 16kHz (maybe we could 20 years ago)   :-\ but in trying to stick to the topic, why not 135mp (each photosite does RGB ) or even 180mp for in Camera 4 to 1 binning?  :)

1295
Lenses / Re: 70-200f2.8 mk.II vs 70-300L sharpness test
« on: December 03, 2011, 09:14:34 PM »
Thanks for the tests!  I will reiterate that using autofocus is not the best way to test lens sharpness, since you're not testing just the lens, but how well the lens is matched to the camera's AF.  Also, an angled ruler is a challenging target for the AF system. So, while I appreciate the efforts, and acknowledge this test has meaning for your camera+lenses, I don't believe the results can be generalized to these lenses as a group, due to the confound of using AF (with no ability to calibrate it).

I understand about generalizing the tests for all lenses.

However, grant me this... if I saw the numbers sharper at the higher or lower end of the scale (lets say 13" or 11" etc, then it would indicated forward or back focus, this is not the case, the lens is correctly focusing at 12"
 
The older 70-200 (1st pic) has a slight back focus, however it is still withing the dof and captures 12" at good sharpness.  The second is centered at 12" meaning it is optimally focussed.

Given that the slanted ruler, an inaccurate focus would be visible either up or below (instead of 12"), thus I still believe, this test is valid for this set of 3 lenses.

The proof is that maximal sharpness is visible between 11.5" to 12" for all lenses.

1296
Lenses / Re: 70-200f2.8 mk.II vs 70-300L sharpness test
« on: December 03, 2011, 05:40:12 PM »
The camera did not move from the tripod, I switched lenses while the camera was latched on to the tripod. I know it did not move. While I can understand what you are referring to, I would like to think that the focal lengths are referenced to the sensor, again which did not change in distance to the ruler.

If you check the exif information in each jpeg, it shows 200mm for each shot (if you care to download the attachments).

1297
Lenses / 70-200f2.8 mk.II vs 70-300L sharpness test
« on: December 03, 2011, 05:07:54 PM »
Did some tests as a result of a discussion on another thread. Comparing the sharpness of the 2 great lenses with the following test conditions: Subject shot = a Ruler placed 45 degrees on the wall and focused on the 12" mark.

Attached are 3 shots; 2 of the 70-200mk.ii (I have 2 copies, the old one is a refurb unit and the new one is a new unit bought from adorama) and the last 1 of the 70-300L

1) ISO = 100
2) F5.6 (favors the 70-200 slightly since it is natively larger aperture)
3) 5D mounted on tripod
4) camera jpeg used: zero PP done except 100% crop .
5) Spot AF at the 12" Mark. Did not MF since I seldom use MF with these 2 lenses; Spot AF relevant for my use.
6) Used various focal lengths but the attachments are for all 3 at 200mm
7) Ruler was vertically placed with top = higher numbers on scale. After cropped I turned the crops 90 degrees clockwise for better viewing.

Conclusion:

1) The 2 copies of the 70-200mk.II are very similar in sharpness and focal length
2) The 70-300L set at 200mm shows a smaller frame compared to the 70-200's not sure which one is accurate the 200's or the 300.
3) The 300 seems slightly sharper than both (though it is a toss) and has a greater DoF at f5.6 than the 200's.

Hope this helps people who are considering both:


1298
Canon General / Re: 15% Off at Canon Refurbished Store
« on: December 02, 2011, 04:37:57 PM »
15% would be an even better bargain if Canon would not slap sales tax on the final invoice value... BH/ Adormama etc are cheaper cause they don't put sales tax on top when shipping to Indiana.

1299
Lenses / Re: 70-200 f/2.8LisII with x1.4TC VS 70-300 f/4-5.6L
« on: December 02, 2011, 04:35:10 PM »
Not bad...pretty usable. I'd rather have this then miss a shot.

1300
Landscape / Re: Some new works.
« on: December 02, 2011, 03:24:37 PM »
Love the effect ! #1 and 3 are very well done.

I like the aspect ratio as well.... take it fomr a guy who has been printing 8x10 for the last 2 weeks and having to crop his hard work...  :P

What filters / PP have you used to get this effect?

1301
United States / Re: Prime lenses you currently own or on your wishlist.
« on: December 02, 2011, 02:33:39 PM »
I currently have (FF):
35mm f2 (indors)
50mm f1.4 (outdors and portrait)

Wish I had 80mm f1.2  and a macro prime (no matter the focal distance)

If funds are an issue... get the non-L 100f2.8 Macro. It is as sharp as the L, I still miss mine. A good MINT copy can be had on ebay for about $460, which is a bargain, when you consider, it takes nice portraits too.

1302
Lenses / Re: 70-200 f/2.8LisII with x1.4TC VS 70-300 f/4-5.6L
« on: December 02, 2011, 02:31:29 PM »
mostly the 70-300 goes on the 5DII and the 70-200II goes on the 7D/1D4 due to the use that I make of the different bodies.

In your case, they would have similar lengths and would be substitutes to each other; Interestingly, I was thinking the other way around  :):  70-200 on the FF for portraits and indoor shots and the 70-300 on the Crop for more reach, I don't need redundancy as much, I want range.

Agreed - that's why I use the 100-400mm on my 7D and the 70-200mm on my 5DII, for the most part.

I am sure you must have tried the 2x on the 100-400 on a 7D... Thats close to 1300mm equivalent !! Was the footage usable?

1303
Lenses / Re: 70-200 f/2.8LisII with x1.4TC VS 70-300 f/4-5.6L
« on: December 02, 2011, 01:16:53 PM »
I believe that the 70-300L is better at the 70-100 range than the 70-200II - however it may be better colour contrast . However this is personal preference based on A3 prints rather than some scientific test.

That said both lens are top draw - I am happy to have both  - mostly the 70-300 goes on the 5DII and the 70-200II goes on the 7D/1D4 due to the use that I make of the different bodies.

In your case, they would have similar lengths and would be substitutes to each other; Interestingly, I was thinking the other way around  :):  70-200 on the FF for portraits and indoor shots and the 70-300 on the Crop for more reach, I don't need redundancy as much, I want range.

1304
Lenses / Re: 70-200 f/2.8LisII with x1.4TC VS 70-300 f/4-5.6L
« on: December 02, 2011, 12:30:29 PM »

The usual testing procedure is to manually focus (10x live view) or better yet, focus bracket (and take the sharpest image) to compare sharpness across lenses.

Liveview? You are rubbing it in again  :P

1305
United States / Re: Prime lenses you currently own or on your wishlist.
« on: December 02, 2011, 11:37:57 AM »
50mm f1.8 mk.II
180mm f3.5L

Wish list: 135mmL f2

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