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herbko

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Posts posted by herbko

  1. Posted

    I was there this August. The accommodations are excellent, large bungalows, comfortable beds, working ac and internet connection in the room. The food is exceptional, the best I've had at a dive resort. The only issue for non-diver and children is that it's very isolated. The only other thing to do is hang out at the beach and read.

  4. Posted

    Hi David,

     

    Looks like you're off to a good start. THe sunballs look a little over exposed to me. Are you shooting raw? If so, you can probably get the sunballs to look better with a little WB and exposure adjustments. In general, the secret to a good sunball is to shot at low enough exposure to not over expose the sun and use curves to bring the rest of the image (which may end up underexposed as a consequence) back to the correct exposure.

     

    The raw file from ISO 50 is the same as ISO 100 for the same exposure. Setting ISO 50 from 100 only changes the metering and the JPEG conversion.

  5. Posted

    10 Mbps :)

     

    Well...I guess only 8Mbps today...maybe a heavy load on the servers :blink:

     

    52642.png

     

    That's impressive!. I have Comcast cable and they claim up to 6M, but the fastest I've ever seen it is just short of 5M. This afternoon it's down to 2M ;) Too many on this line watching Youtube.

  6. Posted

    #1 When Contax made the first digital camera with a 36mm X 24mm sensor they abandon there film lens mount and enlarged the mount to sensor size very much the way Olympus has done, thus starting from the ground up to improve on current film lens mounts. This pissed off many owners of existing contax lenses. At the same time they released the N1 a 35 mm film camera with the same mount and a set of Zeiss lenses which are some the the better lenses ever made. Both the film and digital cameras also allowed the contax 645 lenses to be used on the bodies. Giving the 36 X 24 mm sensor a crop factor of about X 1.7 compared to 645. Had this camera become the gold standard perhaps we could have stopped talking about crop factors and understood that if a lens is designed for the sensor size it is being used with there is no crop factor.

     

    The evidence that I've seen are

     

    1) There are existing Leica and other lenses that do work quite well on Canon FF.

    2) Nikon have a even smaller mount and there weren't that many complaints about WA lens vignetting from people shooting the Kodak FF.

     

    I have not designed a lens myself and really don't know any more about it than that.

     

    #2 And I'll try to make this easy for you. The Olympus 50 mm macro has an angle of view of 24 degrees and the Canon 100 mm macro has an angle of view of 24 degrees when used on a 36 X 24 mm sensor or film.

     

    The Canon 100 mm has a depth of field from 0.99 to 1.02 feet at 1 foot and f-16 for a total depth of field of 0.03 feet ( on the 35 mm sensor).

     

    The Canon 50 mm on a 35 mm sensor and the Olympus 50 mm both have a depth of field of 0.96 to 1.06 feet at 1 foot and f-16 for a DOF of 0.06. Thats is twice the DOF not the same DOF as the 100 mm lens.

     

    This in fact applies to all lenses that are 50 mm regardless of format size.

     

    Please read what I wrote more carefully. This case does not contradict what I wrote as you seem to think it does. If you are shooting the same subject at the same distance you need half the focal length on the Olympus, so, ignoring the 4/3 vs 3/2 for the moment, 100mm on the FF and 50mm on the Olympus gives the same photo of the same subject at the same distance. If you use the same aperture the Olympus will have greater depth of Field. You need to open up the Olympus 2 stops to get the same DOF. This is essentially what I wrote. Actually for macro the correction is slightly different. That's why I didn't use a macro example.

     

     

    Your example using the 20 mm is wrong. At 10 mm Olympus 4/3 lens would have the same angle of view as a 20 mm used on a 35 mm sized sensor but twice the DOF not the same amount and a 20 mm on a 6 X 7 body would have twice the AOV but the same DOF as your 20mm.

     

    Again. Please read carefully. You have to open the Olympus 2 stops to get the same DOF.

     

    Last of all if you point an Olympus camera and a 35 mm sensor camera at the same light source, with lenses of the same AOV and both are set for ISO 100 at say F-8 the resulting exposures will be the same.

     

    Once again. Please read carefully. I wrote same amount of light captured not exposure: 1/4 the exposure on 4x the area (again ignoring the 4/3 vs 3/2). This is important because for a given silicon sensor technology the image quality captured ( signal-to-noise at a given resolution ) essentially just depends on the total captured light.

     

    Having double the depth of field for any given AOV with the Olympus lenses seems to me a good thing for underwater photography especially when you consider the number of low light situation that are presented underwater.

     

    The catch is that resolution on the Olympus will be diffraction limited at 2 stops wider aperture. For a given resolution the FF can achieve any DOF that the Olympus can just at 2 stop higher aperture. Actually the larger sensor is better than that at macro shots.

     

     

    I know that you can crank up the ISO on your camera to compensate but at a loss of image quality.

     

    Phil Rudin

     

    A loss in image quality compared to what is achievable for FF not what is achievable compared to the Olympus. Fundamentally, the limit is the light captured: 4x the area 4x the light for a given exposure. Have a look at the noise test charts on dpreview. You have to move the Olympus noise graphs over two stops to the right to match the Canon 5D, and it's not even matching the resolution.

     

    I'll try once again to make it as simple as I can. Assuming I have a Canon lens that is as good as the Olympus counterpart that is 1/2 the focal length and set to 2 stops wider aperture, I can mount that on the 5D and shoot at ISO 400 and get the same field of view and DOF and exposure and capture the same amount of light per photosite if the two sensors has same number of photosites.

  7. Posted

    We will see if the other manufacturers will provide WA lenses that get around the problems (significant vignetting, corner shading) in the future, especially on FF bodies.

     

    Helge ;-)=)

     

    There's really not much evidence that the problem is the lens mount. There are examples of excellent results from lenses made by Leica and others mounted on Canon FF cameras. One thing that seems to missed by many in comparing lens performance between different size formats is that you need to scale the F-stop by the length of the sensor in the comparison. For example, to get the same field of view, the same depth of field, and the amount of light to fall on the sensor, of a 20mm lens at F/8 on a FF, you need a 10mm lens at F/4 for the Olympus 4/3 size sensors.

  8. Posted

    What appeals to me is the concept of starting from scratch. No legacy features, parts etc. that get into the way of a for-digital-optimized design. The smaller sensor is a trade-off for weight and size.

    There are limits to the system for sure but there are also limits that apply to Canon and the others. It only depends if your application requires to push the limits. I know pros (people really making their living by taking pictures) working with Canon and Olympus as well (selecting the appropriate tool for a job) or even with Olympus alone.

     

     

    What do you have in mind as legacy features and parts that get into the way? I really can't think of anything that Canon has carried over from the film EOS system that's preventing their DSLR from being better than it currently is. The digital sensor has shown up some problems in some of their wide angle lenses and the smaller acceptance angle of the senor probably has made the vignetting worst in some places. These aren't problems that are cause by features carried over. The system does not prevent Canon from producing better WA lenses than some of their current ones, they just have not done so. There are numerous reports of excellent results from lenses from Leica and others mounted on Canon FF cameras.

  9. Posted

    I cam across the following in a Canon EOS publication, which might be useful to note down:

     

    Canon Close-up lenses

     

    500 = 2 dioptres, 450 = 2.2 dioptres, 250 = 4 dioptres, 240 = 4.2 dioptres

     

    The D designation indicates a two element construction (thicker/heavier)

     

    thes are/were available in 52mm/58mm/72mm/77mm filter mounts

    .

     

    I have a 500D which is very good with only marginally soft corners at times (above water that is!) which is what I would expect with a close-up lens.

     

     

    There's no need to take notes. The naming convention is very sensible. The product number is the focus range in centimeters: 500D = 1/2 meter = +2 , 250D = 1/4 meter = +4 ....

  10. Posted

    I recommend getting the 100mm and an 1.4x teleconverter. That'll give you the flexibility of having a 100mm and a 140mm lens. For underwater use, where there's little opportunity to shoot a 150mm lens anywhere close to wide open, there's not a huge advantage to having the extra stop of the Sigma 150mm. At F/8 or smaller, where you'll use it almost all the time, I don't think you'll see much difference in the image quality. The Canon 100mm is great at autofocus and does very well even with an 1.4x.

     

    Even if cost is not a consideration, I'd take the extra 1.4x magnification of the 100mm 1.4x combination over the 150mm and it's extra stop.

  12. Posted

    This is the lens that's on my 5D most of the time. It's a great walk-around lens for a FF. It'll probably make a good fish lens. I've been meaning to try it. It's not supported by Aquatica, but I played around trying to make it work with my old Sigma 105 focus ring. I think it'll zoom with a little duct tape engineering.

  14. Posted

    Were you able to preserve any texture in the white stripe on the clownfish? The jpg looks blown, but the raw may not be. Those are tough exposures.

     

    Chris,

     

    You're right. There's more detail in the white stripes. I had to bring the saturation way down to see it.

     

    IMG_1475a.jpg

  15. Posted

    Were you able to preserve any texture in the white stripe on the clownfish? The jpg looks blown, but the raw may not be. Those are tough exposures.

     

    Good question. I'm think it's very likely that there still room for lower exposure in the raw conversion on that that shot. I try hard to not clip any of the channels in the image, but may not have notice clipping that since it's a small area. I'll have another look later

  16. Posted

    Thanks. This was my first overseas trip with this setup.

     

    The EXIF is embedded in all the photos. Look there for the camera settings. In all the WA shots at least one of the two strobes was on full power, usually both. White balance and saturation adjustments in the raw converter makes a big difference. Some of the sunball shots were done in C1, the rest were done in Canon's DPP.

  19. Posted

    Herb

     

    Your photos really rocked. You seem to be into the macro cirtters too.....

     

    One of the things I envy about still shooters is you don't need to keep yourself as still as us videographers do....

     

    Those shrimp on the sea fans/whip coral, there is just no way I could get a whip coral to stay perfectly still in a current.......

     

    On another subject, rumor has it that the people at Wakatobi are realy militant about not touching anything underwater.....to do macro of animals, for me that is just not possible, I must come to rest on my knees of I can find a sandy area to stablize myself to minimize movment....

     

    What is your take on their alleged policy?

     

    Thanks. I have no experience with video and don't know how hard it would have been to shoot those shrimps on whip coral. Wakatobi is mostly walls and those whips were coming out of a wall and there was nothing to hang on to. Also, this is my first trip with this camera and I found that the macro setup is too heavy to shoot one handed, something I plan to fix before the next trip. I took almost all my shots without a hand on anything, and didn't really put their policy to the test much.

  21. Posted

    Oh! UWphotoNewbie, Lord of Wetpixel, please excuse us worms for discussing stupid things! :):D

    There may be one of your sheep out there who cares about it!! :)

     

    Let's try to get along. :)

     

    UWphotoNewbie has a point that the subject "what 1:1 really means" has been rehashed lots and lots of times on these forums, and so too has the subject of "whether having a smaller higher pixel density sensor is a net win". Perhaps he would like one of these sensors

     

    http://www.dpreview.com/news/0611/06110801sharp12mpccd.asp

     

    in place of his current one. Think of the tiny subjects that can resolve. :D

  22. Posted

    For the sensor size in your camera, a 105mm would only be good for very smaller subjects. If you fit anything bigger than 3 to 4 inches in that frame you'll be too far away to get a really good shot. A 50mm is more versatile, you can use it on a wider range of subjects. Add a teleconverter to it when you want to shoot something very small.

  25. Posted

    Matt's right. Higher magnification helps. A larger sensor also helps. Here's one of my first shots after I got the 5D. Just testing the new toy. Shot with the 100mm macro at F/2.8 and ISO 1600.

     

    flower0091.jpg

     

    I really like the looks of shallow DOF shots. I'll have to try more of it underwater the next chance I get.

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