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L&M Bluefin / Z1 Macro Tests


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#1 Nick Hope

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Posted 23 August 2007 - 10:17 PM

I feel the need for another pseudo-scientific giant-test in the vein of my white balance test. So in advance of my month in Indonesia I'm planning a bit of a macro test with the Z1/Bluefin and the following 5 options:

1. 80 degree lens
2. 80 degree lens plus flip macro
3. Flat port
4. Flat port plus flip macro
5. Flat port plus Century Optics +3.5 achromatic diopter (which the UPS man just showed up with :( )

The reason I thought of this is because I really want to compare options 4 and 5.

My initial plan was simply to video a ruler in the local pool to see how much magnification I can get, then record the exposure settings and the distance from the port to the ruler. Will be 1080i50, gain zero, shutter 1/50 and fix the iris at around what the auto exposure gives me.

But any other suggestions or things you want me to test while I'm at it?

I was wondering about maybe printing and laminating a chequered pattern so we can have a look at the chromatic aberration. What sort of a pattern? Just black and white or colours too?

Then I thought I might include a 2nd ruler almost in line with the camera (90 degrees to the first one) so we can get a judge on depth of field as well.

Also I might fix the subject-to-port distance to say one foot and then compare the achieveable magnification from the 5 options.

Anything else?

#2 Drew

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Posted 25 August 2007 - 01:08 AM

Actually with the Z1 I'd keep the iris under f8. If you want to see the diffraction and drop in resolution, test f11 down to f1.6, you'll want to use ND filters all the time.
You'll see the CA once you shoot a res chart. If you use a ronchi diagram, you can see the birefringence fully zoomed in. This is the best test for the plastic filters.

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#3 CamDiver

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Posted 26 August 2007 - 09:03 PM

The above roughly translates as "Hey Nick, let us know how you get on".

Nick, interested to see how you like the Century Optics diopter.......if the first words outta yer gob ain't ......'kin 'ell ....... then you're doing something wrong!! haha

Best,
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#4 Nick Hope

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Posted 27 August 2007 - 02:26 AM

Just got back from the pool. Some very interesting results! I'll post some grabs later after capturing. Yep, the Century Optics diopter rocks.

#5 Brumpy

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Posted 27 August 2007 - 06:48 AM

looking forward to your results!
Thanxs for sharing this
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#6 Nick Hope

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Posted 27 August 2007 - 09:52 AM

I've been thinking of getting a Century Optics achromatic diopter for ages but since I got the Light & Motion Bluefin I've just been using the L&M flip macro diopter. I haven't been particularly happy with the sharpness of the results, and since Mark (Camdiver) had good experiences with Century diopters with his Z1 recently I thought I'd try one.

I believe Mark has been stacking the +2 and +3.5 diopters, but unlike the Gates, the Bluefin can only fit one of these diopters behind the flat port. So I chose the +3.5 version.

I printed out a checkered pattern of 2mm squares, laminated it, and taped it to a "brick" made of old VHS cassettes. I then videoed this at 1m depth in a swimming pool.

The first JPEG basically shows the maximum magnification I could achieve with my 5 different port/lens combinations. Each of the 5 rectangles represents the full captured image of the Z1.

So before losing focus it's possible to fill the screen with an object 2.6cm across using the flat port and Light & Motion flip macro diopter, or 2.8cm across using the flat port and Century Optics +3.5 achromatic diopter.

The other options are nowhere near that much magnification. The 80-degree port plus flip macro was next best but the rig is a long way from the subject. The flat port alone is not bad but the rig is extremely close to the subject.

The 2nd JPEG shows that the flat port and Light & Motion flip macro diopter gives significant chromatic aberration (the blue and red colouring next to the black squares) but that the Century Optics +3.5 achromatic diopter gives virtually none.

For me this explains why I've not been happy so far with my results using single-element diopters. That chromatic aberration basically means fuzzy images around the edges. I'm really glad I got the Century. But obviously it can't be flipped out of the way, so it's for dedicated macro dives only. Thanks Mark for blazing the trail. How about stacking 2 x +3.5 diopters next then?

Got a load more stuff including the same at different exposures and depth-of-field comparisons. Plus I'm taking it on a proper dive tomorrow. Will upload more in due course...

Attached Images

  • max_magnification_comparison.jpg
  • Century_vs_LM_flip_chromatic_aberration.jpg


#7 wagsy

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Posted 27 August 2007 - 05:34 PM

We are impressed with your work Nick...well done.

I suppose one has to weigh up each methods good and bad points.
With the century Optics achromatic in.... will be the day something big an amazing happens around you. :rolleyes:

But they certainly are the way to go by the looks for best macro.
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#8 CamDiver

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Posted 27 August 2007 - 05:55 PM

Thanks Mark for blazing the trail. How about stacking 2 x +3.5 diopters next then?

Great stuff Nick,
Way to go mate. Hey I'd love to stack a couple of 3.5's but I have only the one. That may also be up for grabs soon as I'm discussing a complete gear sell off to pave the way for RED.

Cheers,
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#9 Nick Hope

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Posted 28 August 2007 - 03:05 AM

With the century Optics achromatic in.... will be the day something big an amazing happens around you. :rolleyes:

Would be neat to machine off the threads and modify a flip arm to take the Century. Not sure it would clear right out of the way of the lens in the Bluefin though.

Hopefully if the housing manufacturers are reading this they might consider a flip achromatic diopter for the likes of forthcoming XDCAM EX housings??? One can dream...

#10 Nick Hope

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Posted 29 August 2007 - 07:16 AM

Ok, real life... Here are some 50% size grabs of a bearded scorpionfish from Racha Yai using the flat port and Century +3.5 diopter.

Light & Motion halogen lights (probably at their brightest), Gain 0dB, shutter 1/50, iris... er.... whatever the auto said then locked down and reduced by a notch or 2.

Lessons learned:

- Very small depth of field at high magnification
- Really need to rig up some sort of tripod next

Attached Images

  • scorpionfish_wide_small.jpg
  • scorpionfish_medium_small.jpg
  • scorpionfish_tight_small.jpg


#11 Nick Hope

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Posted 29 August 2007 - 09:16 AM

Here's some depth of field comparisons from the pool, all at maximum magnification achievable with the lens used.

Very short DOF with the Century at full zoom. The flip macro diopter gave a similar depth of field as the Century.

Attached Images

  • Century_DOF_comparison.jpg
  • Flat_Port_DOF_comparison.jpg
  • 80_degree_DOF_comparison.jpg


#12 shawnh

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Posted 29 August 2007 - 10:17 AM

Nick,
this is some great stuff. also confirms things i have experienced as well. when i shoot macro it is dedicated. as such sticking a century optics in for a dive is no problem...giant squid be damned :rolleyes:
What did that century cost you?
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#13 Nick Hope

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Posted 29 August 2007 - 10:20 AM

This one shows how crappy the image gets when the iris gets really small (F11). A similar result happened with the other lens combinations.

As the Z1 manual says, "If you close the iris extensively when recording a bright subject, diffraction may occur, resulting in a fuzzy focus. (This is a common phenomenon with video cameras.) The ND filter suppresses this phenonemon and gives better recording results".

What's also interesting is that auto exposure was giving a darker result at the small iris, even though there was plenty of scope for the camera to slow down the shutter.

Attached Images

  • Century_iris_comparison.jpg


#14 Nick Hope

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Posted 29 August 2007 - 10:34 AM

Nick,
this is some great stuff. also confirms things i have experienced as well. when i shoot macro it is dedicated. as such sticking a century optics in for a dive is no problem...giant squid be damned :rolleyes:
What did that century cost you?
shawn

Well, the wide scorpionfish shot shows that you're not totally limited to minute stuff when the diopter is on. Definitely no giant squid though. I'll have it fitted for most night dives in Indonesia and a selection of daytime ones.

Shawn, the lens was $339.95 from Adorama (plus shipping). B&H have it at $319.95 but wouldn't accept a UK credit card and ship to Thailand. Adoraman wouldn't match their price but it sure arrived quick.

#15 CamDiver

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Posted 29 August 2007 - 02:36 PM

Great stuff there Nick.

Cheers,
Mark.

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