Jump to content


Tom_Kline

Member Since 07 Nov 2004
Offline Last Active Yesterday, 10:58 PM
*****

Posts I've Made

In Topic: 11-24mm Super Wide ?

28 June 2019 - 11:27 AM

A candidate: https://www.usa.cano...1-24mm-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.


In Topic: Blackwater photo tips?

19 June 2019 - 10:31 AM

I found a narrow-beam focus light was much easier to use than a wide angle one. For some reason a wide beam was almost vertigo inducing. I don't know if all BW dives are like this, but my experience is from Anilao and being in the water reminded me of a snow storm.  The narrow beam, with its limited field of view, was much easier comprehend. 

  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.


In Topic: Strobes

18 June 2019 - 02:28 PM

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!!


In Topic: Strobes

18 June 2019 - 02:01 PM

He is talking about the two retra pro/prime whose construction except power is identical he is not comparing different brands


Sent from my iPhone using Tapatalk

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.


In Topic: Strobes

18 June 2019 - 12:49 PM

I am not sure what you are saying, but my curiosity was whether the shape or pattern of the light output would change underwater.  It is really an academic question, I suppose.   I am not sure it could realistically be tested.  I was not really talking about the power of the flash.

 

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.