Subtronic Strobes

[DreiFish]

On 7/23/2024 at 3:04 AM, Architeuthis said:

 

These are all very interesting comparisons. I would say that the intensity in the center is similar between HF-1 with 5500 K diffuser and Ikelite DS230 w/o diffuser. The carpet is, however, much darker with HF-1, compared to Ikelite. I interpret this the way that light distribution is clearly more even with the Ikelite w/o diffuser compared to HF-1 with diffuser...

 

=> This sounds pretty bad as even light distribution is something highly desired by everybody...

One must say, however, that normally for WA one uses two flashes and the objects in the center are normally lit by the periphery of the flash beams. The centers of the flash beam lit at most the corners of the scenery and these may be the problematic regions where light drops off in real life conditions (so more intensity there may be well a benefit). In the center the two flash beams add up and give good brightness.

I cannot remember that ever I had a problem with WA and two flashes, where the center was not bright enough due to uneven light distribution of the flash beam (YS-D2s and Z330s; all linear flash tubes) - unless the object in the center was close and I did not pull the flashes close enough together...

 

Maybe the more uneven light distribution becomes a problem when WA with a single strobe, but few people do this...

 

 

Wolfgang

 

 This is a great observation I didn't initially catch in reviewing my shots, Wolfgang -- you're right, center illumination (which is what I was measuring) may be the same between the circular flash tube strobes and the straight flash tube strobes with a diffuser, but the circular flash tubes throw more light towards the edges of the shot like on the carpet. I have a look through the comparison images I took again and now I do see a clear difference in light coverage between the circular flash tube strobes and the Backscatter HF-1/Sea & Sea YS-D3 and the Marelux Apollo 3 with their diffusers... 

 

Basically, the diffusers aren't necessarily spreading the beam wider, they're just dimming down the center and thus making the overall illumination more even. But importantly, they're not really increasing the amount of light that falls towards the edges of the image. This is visible when you look at no diffuser vs. flat diffuser, but it's even more evident with the dome diffusers. In each case, edge illumination remains basically the same -- it's just the center that is attenuated, leading to overall more 'even' light intensity across the frame. 

 

 

Makes me rethink my earlier conclusions about diffusers and straight flash tube strobes. If you care about edge illumination, it seems that what you really should be focusing on is how well the strobe performs without diffusers or light modifying accessories, as they don't (can't?) actually improve the brightness of the edges, they can only dim down the center hotspot. 

[atus]

On 7/23/2024 at 9:54 AM, Alex_Mustard said:

 

Here are some reasons:

https://wetpixel.com/forums/index.php?/topic/14391-subtronic-nightmare-continues/

https://wetpixel.com/forums/index.php?/topic/55535-subtronic-support-did-it-again-be-aware/

https://wetpixel.com/forums/index.php?/topic/63755-troubles-with-subtronic-underwater-flashes/

https://wetpixel.com/forums/index.php?/topic/50432-subtronic-issues/

https://wetpixel.com/forums/index.php?/topic/44156-subtronic-customer-service/

https://wetpixel.com/forums/index.php?/topic/23076-subtronic/

 

You need to be a member of the other place to read.

I didn't know anything about this, but in my experience the service has change a lot for better. i had issues with one of my 160 pro fusion unit during a trip to Tulamben, the green led light was blinking while diving and the flash didn't fire anymore, so I sent it to Subtronic when I arrived home, in 30 days I had my strobe back again at home and working fine, they said it was an overheating issue and had to replace something inside. I paid 200 euros shipping incluided. I was all winter long using it while diving in Ibiza, then I went back to Indonesia, and the second day ( I'm not the luckiest guy) the same flashgun start failing again with the same issue, so I sent a very angry email to Subtronic, I had an answer in less than 12 hours, asking me to do something with the dials which didn't work, they said Sorry and I sant them back to Germany when I arrived home in Spain. In less than 2 weeks I had my strobe again at home, thay said than the first issue was caused by this other piece but they didn't detected it at the first time. They charge almost nothing for this repair  and I paid the shipping again. Now I am diving with it for more than 6 months, in the cold winter mediterranean waters and the last time was today with water in 25 ºC. No issues, they are working flawlesly. In october I'm going in a trip to the Red Sea. I hope I will not have issues again. But almost the service they give me was fine.

[ChrisH]

6 hours ago, DreiFish said:

 This is a great observation I didn't initially catch in reviewing my shots, Wolfgang -- you're right, center illumination (which is what I was measuring) may be the same between the circular flash tube strobes and the straight flash tube strobes with a diffuser, but the circular flash tubes throw more light towards the edges of the shot like on the carpet. I have a look through the comparison images I took again and now I do see a clear difference in light coverage between the circular flash tube strobes and the Backscatter HF-1/Sea & Sea YS-D3 and the Marelux Apollo 3 with their diffusers... 

 

Basically, the diffusers aren't necessarily spreading the beam wider, they're just dimming down the center and thus making the overall illumination more even. But importantly, they're not really increasing the amount of light that falls towards the edges of the image. This is visible when you look at no diffuser vs. flat diffuser, but it's even more evident with the dome diffusers. In each case, edge illumination remains basically the same -- it's just the center that is attenuated, leading to overall more 'even' light intensity across the frame. 

 

Makes me rethink my earlier conclusions about diffusers and straight flash tube strobes. If you care about edge illumination, it seems that what you really should be focusing on is how well the strobe performs without diffusers or light modifying accessories, as they don't (can't?) actually improve the brightness of the edges, they can only dim down the center hotspot. 

 

Yes, exactly! The better the strobe the more the diffusor is an option rather than a necessity! If the strobe has really good quality of light, you might find yourself using the diffusors only for special applications like CFWA and leaving them on land most of the time.

Actually I don't even own diffusors for my Seacams and used them on the Retras only to get warmer color temperature.

 

In your test shots, I think you can clearly see the Ikelite just lighting up the whole scene overall quite nice and even and other strobes having a much harder "fall off" towards the edges (floor, plant and the picture on the wall). Based on this test shots, the Ikelite would be my preferred one.

 

EDIT: sorry for OT!

Edited July 24 by ChrisH