Architeuthis Posted February 16 Share Posted February 16 I am wondering whether there is information how WWL/WACP water contact optics affects aperture value: When using a teleconverter, because the focal length is changed by the TC and the absolute diameter of the aperture opening remains the same, the aperture number (focal length/aperture diameter) multiplies accordingly (e.g. 2x and 1.4x with appropriate TCs). Nauticam homepage says that WWL/WACP multiplies focal length by 0.36x. Does this mean it acts like a speed booster and apertures values of e.g. the Sony 28-60mm f/4-f/5.6 becomes f/2-f2.8 at the extreme ends? A photo taken with WWL/WACP at f/8 of the lens would be in fact taken at f/2.9?? Wolfgang Link to comment Share on other sites More sharing options...
Guest Posted February 16 Share Posted February 16 2 hours ago, Architeuthis said: I am wondering whether there is information how WWL/WACP water contact optics affects aperture value: When using a teleconverter, because the focal length is changed by the TC and the absolute diameter of the aperture opening remains the same, the aperture number (focal length/aperture diameter) multiplies accordingly (e.g. 2x and 1.4x with appropriate TCs). Nauticam homepage says that WWL/WACP multiplies focal length by 0.36x. Does this mean it acts like a speed booster and apertures values of e.g. the Sony 28-60mm f/4-f/5.6 becomes f/2-f2.8 at the extreme ends? A photo taken with WWL/WACP at f/8 of the lens would be in fact taken at f/2.9?? Wolfgang I have not really looked into this however I would think this is not the same of a focal reducer because the image is not straight. In fact the 0.36x is not an accurate figure it is simply a proxy for a diagonal field of view of a rectilinear lens If you were looking at a fisheye optic this factor would be a much smaller 20/28=0.71x Does this give half stop benefit? In terms of light? I do not think so Link to comment Share on other sites More sharing options...
ChipBPhoto Posted February 16 Share Posted February 16 (edited) 4 hours ago, Architeuthis said: e.g. the Sony 28-60mm f/4-f/5.6 becomes f/2-f2.8 at the extreme ends? A photo taken with WWL/WACP at f/8 of the lens would be in fact taken at f/2.9?? Hi Wolfgang, This is completely un-scientific, but here are some images for comparison. You can see FoV, DoF, and brightness differences between them. The camera body is in the same position for both images. Lens: Sony 28-60 at 28mm (manual, f/8, ISO 1250, 1/10) First image: Behind a WACP-C Second image: Lens only I'll let someone else do the actual math. 😀 Edited February 16 by ChipBPhoto Link to comment Share on other sites More sharing options...
Guest Posted February 16 Share Posted February 16 1 hour ago, ChipBPhoto said: Hi Wolfgang, This is completely un-scientific, but here are some images for comparison. You can see FoV, DoF, and brightness differences between them. The camera body is in the same position for both images. Lens: Sony 28-60 at 28mm (manual, f/8, ISO 1250, 1/10) First image: Behind a WACP-C Second image: Lens only I'll let someone else do the actual math. 😀 Water contact optics work differently in water hence the name most of those adapters are afocal Link to comment Share on other sites More sharing options...
Architeuthis Posted February 17 Author Share Posted February 17 (edited) 11 hours ago, ChipBPhoto said: Hi Wolfgang, This is completely un-scientific, but here are some images for comparison. You can see FoV, DoF, and brightness differences between them. The camera body is in the same position for both images. Lens: Sony 28-60 at 28mm (manual, f/8, ISO 1250, 1/10) First image: Behind a WACP-C Second image: Lens only I'll let someone else do the actual math. 😀 This is an interesting comparison. I believe the comparison could be valid if a WA (or better fisheye lens) with similar angle of view is taken and compared WACP-C (as Massimo says UW, but also over the water will give a hint (who of us is going to take the equipment UW, just to answer such a crazy question?😁)). Then one may be able to find out to which extend the aperture number is changed by the WACP/WWL... I think aperture value is altered for sure, as AOV and focal length change and this change is in favor of WACP/WWL, but certainly not by simply multiplying with the 0.36x factor that Nauticam gives (is this even a factor for focal length or maybe the change in size of an object at a given distance or something else?)... Wolfgang Edited February 17 by Architeuthis Link to comment Share on other sites More sharing options...
Guest Posted February 17 Share Posted February 17 31 minutes ago, Architeuthis said: This is an interesting comparison. I believe the comparison could be valid if a WA (or better fisheye lens) with similar angle of view is taken and compared WACP-C (as Massimo says UW, but also over the water will give a hint (who of us is going to take the equipment UW, just to answer such a crazy question?😁)). Then one may be able to find out to which extend the aperture number is changed by the WACP/WWL... I think aperture value is altered for sure, as AOV and focal length change and this change is in favor of WACP/WWL, but certainly not by simply multiplying with the 0.36x factor that Nauticam gives (is this even a factor for focal length or maybe the change in size of an object at a given distance or something else?)... Wolfgang The adapter is afocal so it has a focal lenght of infinity. I think is more where the focus point is place than an issue of depth of field. In fact most times I shoot video in manual and everything is in focus hence the whole point about CAF with those adapters is totally mooth Link to comment Share on other sites More sharing options...
Recommended Posts