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herbko

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Posts posted by herbko

  1. Posted

    Steve,

     

    I tried to replicate your ISO 800, +4 exposure shot with lens cap on and got a very boring image. No features at all except a couple of slightly hot pixels. I think you need to send your camera in.

     

    Also, I've pushed up the dark parts of some of sunballs shots I've posted earlier by probably more than 2 stops using curves and didn't see anything near as bad as your dolphin tails.

  2. Posted

    Indeed it is and i'm happy especially for the Canon 1:6 people, We got our lens this morning and I noticed it would mount on the older A300 / Digital Rebel (pre EF-S camera), that should put a smile on theses owners, not only were they limited to full frame lenses but there was a serious lack of wide option in this area.

     

    The 300D / Digital Rebel has an EF-S mount. The more ancient 10D was the last 1.6x camera to have an EF mount.

  4. Posted

    My last visit was January 07. Indonesia stipulates two pages are required and added pages are not acceptable. The VOA takes up one page and the entry and exits stamps are put on the VOA. The only reason I can think the extra page is necessary is if someone makes numerous entries and exits on the same VOA (good for 30 days) then they need another page for the extra stamps.

     

    That's new. I was there in Aug 06 and my passport has added pages, and they stamped those pages. No problems. These are pages added by the state department and looks just like the other pages, not pieces of paper I duct taped to the back.

  8. Posted

    I don't know what's magical about 24X36. If 21x33 or whatever 1.1x works out to allows for better performance, I'm all for it.

     

    Up until now I've avoided buying DX lenses so presumably all of my lenses, with the exception of the 10.5, will work with this crop factor.

     

    The biggest impact will be wide angle lenses. You'll lose 10% coverage on the fisheye. 14mm will look like ~16mm and 16mm will look like ~18mm.

  11. Posted

    Most of the lenses we've been using were designed for film cameras. I don't see what the lens resolution and distortions have to do with the discussion on dynamic range and sunballs.

     

    Better dynamic range than what? Have you used a Canon 5D? As I mentioned earlier, I think the 5D images are limited by the 12-bit A/D. It would look better with more quantization levels at the dark end. Canon claims to have preserved that with the reduction in the size of the photosites. Of course this claim can't be verified until the cameras are out.

  12. Posted

    I think we've had a similar thread awhile back and found that some prefer heavy and some prefer neutral. I find my Aquatica 5D macro setup too heavy and plan to try adding flotation similar to James' setup.

     

    It's very simple to add weight and a pain to increase buoyancy. If you're in the process of buying parts for a system and are not sure what you prefer. I think it's best to try to make it as buoyant as possible.

  13. Posted

    So, this is how I see it (correct me if I am wrong): looking at the table above, say you expose the sun area correctly (exposure zone 1) and want to bring detail back to an area that was 4 stops underexposed. With the 12bit images you will have 256 levels available, with the 14bit image you will have 1024. The 14bit image will look better after post-processing, right?

     

    Nice chart. That's what I've been trying to say.

  14. Posted

    I don't have a lot of hard fast rules when shooting digital, but one of them is that I don't underexpose by 2 stops for the purpose of bringing it back up in post. Expanding thin (left) data just doesn't work. My preferences is to always compress thin data and stretch fat (right) data. Plus my suspicion is that 14-bit processing will accentuate the problems inherent in stretching thin data. It's going to let you really see how little data was applied for the lower levels.

     

    I agree with you that coupling greater than 12-bit processing with a sufficiently hi dynamic range sensor is the holy grail for these really high contrast shots, but in the case of sunbalss I don't see any benefit from 14-bit processing alone.

     

    14-bit A/D does no good if the sensor it's sampling does not have enough dynamic range. I thought that was clear from my last message. I think you developed your rule from using sensors with insufficient dynamic range.

  15. Posted

    I understand why we get what we get, but here is my thinking: why would 14-bit processing eliminate or mitigate blooming and the resulting visible fringing? Or why better defined and gradated color fringing (which probably won't be the reality anyway) is an improvement. As we know better defined errors or failures are one of the pitfalls of digital capture.

     

    I just notice that Canon has made no claim to the effect that the sensor has been enabled to bucket more charge. And that is what we are really looking for, at least those of us who do find sunballs/burst on current digital systems displeasing. I recognize that Herb, Paul and a few others disagreed with my earlier assertion that sunballs/bursts from current technology are bad (I may have said crap :) ).

     

     

    It's often necessary to underexpose to keep from blowing out a sunball. The rest of the pic can be brought back up to a proper exposure at post processing. A low noise sensor gives you the good signal-to-noise necessary to push the underexposed water and subject a couple of stops and still not be noisy. The limit in the 5D in this process is not the noise of the sensor but quantization of the dark parts when brighten 2+ stops. Going from a 12-bit to a 14-bit A/D will make this quantization/banding problem much better.

     

    In summary, it takes a high dynamic range sensor (large charge bucket and low noise) and fine quantization levels(more bits).

  16. Posted

    Here's my guess at what the high contrast mode does:

     

    1. meter exposure at ISO 200 setting

    2. process the sensor output at ISO 100

    3. apply a tone curve to bring the mid tones and shadows back up to ISO 200

     

    This has the net effect of reducing blown highlights at the expense of more noise and banding at the mid tones and shadows. Since the sensor has very low noise to start and now has a 14-bit A/D, the higher noise probably will not be noticed. The two extra bits will give smooth tones to the under exposed and pushed up parts. This essentially the technique for getting a good sunball.

     

    The dynamic range of the sensor is (maximum signal captured before clipping)/(noise level). The new 14-bit A/D does not change that. It just divides the signal into more levels and let you brighten the underexposed regions more and still have smooth tones.

  17. Posted

    are these features really worth more than double the cost of a D200?

     

    I for one see $4K as rather pricey...

     

    I think this is targeted towards the PJ's, especially the ones covering sports. Those making a living with a camera can work out the dollars and sense of the $4k price for their own business. For those who's got this expensive hobby, it cost less than a D2Xs.

  19. Posted

    It's on dpreview:

     

    http://www.dpreview.com/news/0702/07022208...os1dmarkiii.asp

     

    Some of the early speculations about this being full frame is wrong. It's 1.3x cropped.

     

    It looks like they up the speed and resolution by ~ 20%. They also put in 14-bit image processing, the one feature that I was looking for. Hope that'll be in all their future high end cameras including the 5D replacement, when they get around to it.

     

    Oh Yea, and live view!

  21. Posted

    As an excuse for allowing noisier sensors? :lol: Just downsize and noise is interpolated out...

     

    Not quite. Noise in the shadow is dominated by the output amp. Taking one large pixel and split it in two and recombine the outputs afterwards will increase noise by about ~1.4x compared to the original.

     

    Looks like Canon is giving you a choice. There's no reason at all to get the new 1Ds if you prefer 12M pixel over 22M pixel.

  22. Posted

    My 1DSs already stress many lenses - I can see flaws in even L lenses - so I'm not certain why 22MPixels is seen as an advantage...

     

    That may be true; however, there are lenses that can resolve better than that in their sweet spots. So the small increase in resolution from ~17M to 22M may be an improvement for some. At 22M pixels it's still not as dense as the D2x sensor which would be 28M pixels if it's expanded to FF.

     

    I agree about the bit depth. The FF sensors really can use a 14bit to 16bit A/D converter.

     

    If these leaks are true, I suspect the new 1D will be far more popular than the new 1Ds.

  25. Posted

    Hi Fred,

     

    I was not disputing your conclusions about loss of resolution with magnification, and your example is probably technically correct. The reason that moving the lens twice the distance from image plane halves the resolution is that the aperture is moved twice as far away. The lens is stopped downed two stops, and the diffraction fringes are twice as big. If you open that up 2 stops you'll get back the resolution but your depth of field will be much worst. You're right that my example of focusing at 10m is not that good either.

     

     

    This is why I am interested in the new macro lens Zeiss will soon be offering in the Nikon mount. IF there really is a significant difference in resolution, as Zeiss claims, I believe it will show up more clearly at higher magnifications. And this is also a type of photography where the fact that the Zeiss lens doesn't have auto-focus will make the least difference.

     

    Fred

     

    Please let us know your findings. From what I learned about optics in the classroom, at small enough aperture, ~ F/22 for film and sensors like the ones in the Canon 5D and 1DsII, you'll be diffraction limited and better glass won't help much. I really like to see a careful test of this.

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