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Everything posted by Tom_Kline

  1. Stephen Frink did some extensive testing of the 17-40 Canon lens as well as other lenses a few years ago. See results here: https://www.seacamusa.com/uncategorized/lens-testing-underwater-use/ and https://www.seacamusa.com/lenses-ports-domes/canon-16-35mm-ii-lens-test/ The super dome he used has counterparts in most underwater housing systems - the glass part may be made by one company. Note that both the 35-40 and 16-35 lenses that were tested have been replaced by much better lenses. As well, the relatively new Sea and Sea Internal Correction Lens is a game changer for this using type of lens (there are several threads on Wetpixel about this lens). Also on Wetpixel - there are a lot of threads on the 17-40 going way back as this was popular lens because of its cost.
  2. I bought a Seacam Pro VF from Ian Marsh from this ad: This was an excellent transaction. Great communication. The VF arrived very promptly and well packed. I would buy from Ian again. Thank you Ian! Tom
  3. I am seeing it OK in subsequent posts. The arrows (left and right) are below the level of the reply box. Maybe need to scroll down a wee bit more?
  4. Correct. If the subject is centered and has just water as a background one can use a larger aperture. Out of focus blue is not so noticeable.
  5. This is due to the curvature of the virtual image generated by a dome port. Basically you are trying to focus on the inside surface of a large bowl. Stopping a lens down increases depth of field increasing the chance of getting the sides of the bowl in focus.
  6. Nice shot, working for me too! Hint for newbies - click on a person's avatar to see this.
  7. The 25cm is minimum focus distance and not working distance. Measured from the image plane. Need to subtract the length of the lens plus the back focus aka registration distance from 25cm to get to working distance which will be very close.
  8. https://wetpixel.com/forums/index.php?/discover New link for recent topics works for me!
  9. I guess we need to actually use WP to find the issues. Did find signature editing a second ago!
  10. Maybe that is why signatures are missing, just now noticed by me after making a post on another thread. PS. Signature suddenly appeared! Did NOT see signature editing in my profile a minute ago.
  11. This is a lens for some mirrorless cameras and maybe even some dSLRs in live view, e.g., Nikon Z6 which compensates for darkness in the VF rather nicely. The video shows the lens elements moving inside a fixed length barrel and confirms a bellows extension effect by change in exposure (See Chris' post above). Looks sharp but one must NOT stop sown very much at 2:1!! A manual focusing ring might cost as much as half the cost of the lens so needs to be considered.
  12. Table at the end is OK but not clear if the listed Seacam strobes are the more recent ones with a D in the name or the older ones without (as listed). Scott's table would be more clear if it included beginning and ending years for each model. Good having older ones listed as well for reference.
  13. The "topics" box (lower right) contains just a few and does not seem to be bookmarkable. Not a satisfactory replacement in my book.
  14. I am not seeing a reply to thread so started this new one (green button obvious). Also I cannot find a recent topics button. Using Firefox on a Mac. Tom PS I just now did see a reply to topic (green button) on a thread started by Interceptor but still am not seeing one in this topic or Adam's in the announcement forum. Hence I am using edit.
  15. A candidate: https://www.usa.canon.com/internet/portal/us/home/products/details/lenses/ef/ultra-wide (weitwinkel)-zoom/ef-11-24mm-f-4l-usm My understanding is that this lens is used by vid makers to deal with the crop factors of DSLRs when used for vids.
  16. Good point! I use a 5 degree Inon light for looking around and a moderate wide angle light for focusing (AF on a DSLR). The 5 degree light also works well for daytime dives for looking in crevices, under overhangs etc.
  17. I have the S&S 250 as well as the older Z220s. I also have the Seacam strobes (250D, 150D, and 60D) and have used just one of these strobes to successfully light up fisheye shots to the corners which is not possible with the others. Used diffusers for all shots. So I concur with post 25. IMHO it is end results that count, not wall test shots!!
  18. From post 16: "With regard to the image above showing the dispersion pattern, I am wondering if the pattern in air is similar to what one would get under water? In particular should one expect a non-diffused Z330 to have such a pronounced cross shape in actual use?" The question was under water vs in air. Retra vs. Retra (the new ones) is more obvious. If both were used at full power the more powerful one would cover a bit more as you suggest but could be overexposed in the center. Should be the same if exposure was equalized.
  19. It will and is a variable due to the dome shape of the port used on the strobe. Like with the dome port of a housing the interaction with water results in a lens different from when it is used in air. Recall the difference in infinity focus position with dome optics. Some strobe domes are truer domes than others. Looks like there is a trend with new strobes more dome like, especially the Inons. I think the effect is not academic.
  20. One is continuous (like a regular light bulb) whereas the other one flashes.
  21. Alex M was able to make it work here: http://wetpixel.com/articles/field-review-retra-lsd-prime-snoot Do you have an older Z240 with a bulb rather than an LED? see this: http://wetpixel.com/forums/index.php?showtopic=51586 See what Oskar says in post 10: http://wetpixel.com/forums/index.php?showtopic=62595 An idea: swap your 2 Z240s so the one on the camera is now the slave. Maybe the other one lines up better????
  22. Sounds like you passed the mirror test, part 1. Repeat with snoot. Repeat again after each adjustment. I gather the LSDs have been problematic with Inons - there may be something on this somewhere on Wetpixel. There is a diffuser in the LSD that should help but having the aiming light in the center of the flash tube (may be the case with the 330) is better.
  23. Sounds like it should be working. First thing I would do is the mirror test. See my example. Remove the snoot first. You may have to do this with a spot next to you where you can place the slaved strobe. The idea is to make sure both strobes are going off and synch with the shutter. I took this last month in Hawaii.
  24. Make sure your main strobe is not using pre-flashes!! You might be seeing the slave responding to these. If the snooted strobe is not a slave you need a more complete description of your setup to figure this out.
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