Jump to content

Algwyn

Member
  • Content Count

    71
  • Joined

  • Last visited

  • Days Won

    2

Algwyn last won the day on October 24 2019

Algwyn had the most liked content!

Community Reputation

8 Neutral

About Algwyn

  • Rank
    Lionfish

Profile Information

  • Gender
    Male
  • Location
    Paris

Additional Info

  • Show Country Flag:
    France
  • Camera Model & Brand
    Nikon D7500
  • Camera Housing
    Easydive Leo 3
  • Strobe/Lighting Model & Brand
    Subal SN800, Sea&Sea YS-D2, Retra Strobe

Recent Profile Visitors

1411 profile views
  1. @Pavel Kolpakov aren't some of the issues reduced when using on-board flash in "Commander" mode, like on Nikon cameras?
  2. Let's see... It'll probably depend on the success of the D780 ... and we may get a D7800 instead of a D7600!
  3. You may be mistaken on that point. While the D500 has indeed been rumored as not being replaced, this is not the case of the whole APSC DSLR. The D7500 may still be replaced, hopefully in the D780 fashion.
  4. I am afraid that using laboratory test poorly reflects the actual performance of the cameras in real life situation, even less in underwater situations. Imaging Resource warns that these low light AF are only relevant in stationary situations. Indeed, if you are shooting a reef in wide angle, the performance of the autofocus will not be an issue. In the other post, examples were given of situations where camera autofocus is challenged: black water diving: this is perhaps the most challenging. My experience of black water diving is that there is constant movement and very low light. macrophotography: here the issue is not that the subject is moving quickly, but that the depth of field is so shallow that the slightest move (current, etc.) will have a huge impact on the focus juvenile fish portraits: those little devils typically keep moving very fast. Another challenge for autofocus Performance in these real life situations cannot be measured in stationary laboratory tests. In term of difficulty of focusing, I am not sure that shooting a bird in flight is more difficult that focusing on a pigmy seahorse in a wavy sea ... Autofocus is an extremely complex topic, and different test protocols may get very different results. For example a French photo magazine (Chasseur d'Image, excellent publication, really independent minded and thorough test methodology) is using a moving target at 50 km/h and measure the ability of the camera to make shots as the target move from 50 m to 0m. Most modern cameras are able to focus accurately, at 5 to 9 i/s depending on their speed. But as the target gets near, some AF start to fail, as the nearer the target, the greater AF adjustment is needed between two shots. How relevant for our UW photography? Not much probably (more relevant for car racing maybe), but it shows the difficulty to test such complex features as AF. It also shows that thanks to progress, most good modern camera perform well in normal situations. However in UW photography, we are often far from "normal" situations. Therefore I would not draw any conclusions from these tests for UW photography. You are right to highlight the need to know the camera features, and how to select the right parameters depending on shooting conditions. It probably matters much more than the difference of performance between otherwise very good cameras.
  5. I believe that you are missing the point made by @oneyellowtang. There are other sensitivity measures than the main sensor sensitivity. Low light sensitivity of the Autofocus system is one of them. He was referring to the ability of the camera to focus in low light situations, and more generally of the autofocus performance of the various systems. Also, you cannot draw conclusions based on the performance of the camera sensor only. You cannot shoot a picture without a lens. What we need to take into account is the system: camera body + range of lenses available. That's the whole point, the system (camera body + lens) deliver more light to sensor, which results in better image. For a picture where depth of field is not significant, this matters.
  6. The article is interesting, and the theory described interesting. Overall, it is a good idea to debunk "myths". However, I think that some of the conclusions do not reflect actual photography usage, and should therefore be nuanced. If we take the first "myth", you draw conclusions from the theory based on the assumption that the photographer works at constant depth of field. In that situation, indeed there is no difference in signal to noise ratio between large and small sensors. When working at constant aperture, there is a significant difference, as illustrated in the Clarkvision article that you quoted: These two pictures are taken with the same parameters: ISO 400, f/4.5, 1 second exposure. In this situation, the larger sensor gives significantly better results. Depending on the situation, the photographer may have different objectives related to the depth of field (DoP). In some situations, the key will be whether one can shoot at the hyperfocal distance. In others, the objectives will be to minimize or maximize the DoP. Given these other parameters, the smaller sensors may be at disadvantage depending on the objectives of the photographer. So I believe that beyond the theory, your guide should take more into account the type of usage and photography. Your point related to the final output medium is also very relevant. To push the comparison a bit further, for most online media, the small camera sensors found on smartphones are totally sufficient. My own conclusion was that APS-C provides an excellent compromise between the various parameters. But I understand that others may have different needs and objectives and would weight the strengths and weaknesses differently.
  7. Do you then put these cubes in the checked luggage? For carry-on luggage, these cubes add too much weight ...
  8. Have you tried with multi-core fiber optic? From your ealier pictures, it seems that you are using mono-core fiber, which are typically more brittle than multi-core fibers, and therefore break very easily.
  9. It was taken at f8.0 1/125 ISO 100, with a ⌀160 mm dome and a Nikon D7500, a single Retra (original) strobe. It's a good lens for travel. On a diving cruise, you almost never do twice the same site, and in some locations (Indonesia, Philippines, ...) most diving sites are very diverse, with reef, pelagic, fish portrait, macro ... For these type of dive, a versatile lens is very useful.
  10. That's well understood. My point was about how the "Smart SL" user setting in the Retra could enable to shoot in both manual flash and TTL, without having to change camera settings underwater. This would be very convenient as turning a knob on the Retra Flash to switch from TTL to U1 or U2 is much easier than changing flash mode on camera. Many thanks that would be useful for Nikon users like me.
  11. Thanks for this explanation, it's very clear. So it seems that to get Smart SL to work reliably on Nikon, Retra would have to correct their algorithm to use timing instead of number of preflashes, unless there is another way to manage this with the Retras.
  12. Have you considered shooting in ambient light? Codes of conduct for responsible diving with large pelagic recommend to minimise use of flash or strong artificial light (some even prohibit flash). Also, the size of these pelagic make it very difficult to light them properly with strobes or lights. Unless you are very close (<3m) to these pelagic (again against responsible diving rules), few strobes or lights will manage to provide good lighting of these subjects. For good ambient light pictures, shoot in raw and correct color in post-processing in Lightroom/Camera Raw. To facilitate post-processing, use a small white balance card, take shots of the card regularly as you change depth. A magic filter may be useful to get better reds at depth > 10m. A WB card and filter will be much lighter to dive with than big strobes/lights (and much more affordable).
  13. Smart SL is intended for cameras where it is not possible to disable the TTL pre-flash, which prevent the flash to operate in Manual. It may therefore be used to operate the flash in manual mode, while the camera is shooting in TTL with pre-flash. However, this has to be tested, Oskar mentioned that some TTL converters change the number of pre-flash used, which prevents this feature to work. When this feature works, it enables to switch the flash mode between manual and TTL without changing the camera settings.
  14. From the Retra Manual: So I guess this would be useful with cameras where there is no manual flash mode, or where you cannot switch between manual and TTL underwater. This enables switching between TTL and manual from the Retra flash without changing camera flash mode. It may be faster under water to do so.
  15. Actually, not the exposure latitude test: this test take pictures at the camera smallest ISO, and compare how decreased exposure when the picture is shot can be compensated in post processing. This is what I believe is more relevant to reflect how well a camera will behave when processing significant WB correction. Overall, smaller sensor means "Low light ISO". There is large variance within each category, due to the quality of the camera, and progress of technology (overall each camera generation improves on the previous). The top MFT camera (Lumix G9) is at the level of the top APS-C (D7500), but overall there is a significant difference. The gap is wider with FF: sensors cannot defy physics. I agree with you that in most cases, it is the photographer which will make the difference, not the camera. Not least because the good photographer will know the limits and weaknesses of his camera. Also, for most "normal" shooting conditions, current cameras (MFT, APS-C, FF) will get great shots, with limited difference in quality from a practical point of view. But in challenging conditions, the camera will enable a better image "quality". This in itself is relative: "grain" is not always a defect, but can be used with an artistic intent.
×
×
  • Create New...