GO-35 Pro adapter test #1

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Daniel Wee

Active member
I finally got my hands on the GO-35 Pro adapter and am in the process of familiarizing myself with it for a shoot but also testing it's performance. This is the first part of my test, basically to see how the general feel of the adapter performance is like.

There is nothing to complain about the construction of the adapter itself. It is well made and seems to be sufficiently rugged. It came clean with no visible dust specks inside the system so that's good news too. The achromat comes as a separate unit so you have to screw the adapter and the achromat together before using. This is trivially simple and will only take a minute to figure out (or less).

Light loss is a bit more severe than I had expected but I will test this more thoroughly under controlled conditions in the second part of my testing. Sharpness is noticeably lower than without the adapter. Bokeh is good and there is no noticeable fringing or chromatic aberration. Grain has not become a problem yet in my testing. My biggest complaint at this time is the light loss but we'll deal with that later.

This footage is a bit jerky as I was not using an external LCD or the flip hack. Basically I was trying to look at the LCD upside down and as a result fumbled a bit with the panning. I also did not have rails on but simply supported the extension with my hand. With rails, LCD, and the adapter, the whole thing can be very heavy and cumbersome, and not really suitable at all for handheld operation.

Here's the clip - give it some time to load. It's about 25MB and will not auto-play so you need to click on the play button once you've loaded enough of the stream to get it started. It was shot at 25p using the recommended settings:-

Detail +7
VDetail +7
Detail coring +7
Chroma level +7
Master ped -5
Cinegamma D
Cine matrix
Skin DTL ON

This was the given settings in the instruction sheet. The focus settings I used was MF30 and Z79 but the instructions said MF20 and Z73. I'll have to test that to see if I can get better performance with the recommended settings. It does say though, that the settings may be different between the DVX100a and the 100b version. I am using the DVX102b which is the same as the 100b.

The idea width for viewing this clip is around 640. You can size the window accordingly but if you get too large you will see pixelation. So 640 is the best horizontal resolution for viewing this clip (shot in SQUEEZE mode for 16:9 aspect ratio).

http://blog.tsebi.com/video/GO35Test1.swf

Feel free to ask any questions you have or if you want specific tests done.


Daniel Wee
 
GO-35 adapter test #2

GO-35 adapter test #2

Okay, I've added another video that shows the light loss, which in my opinion is pretty severe. This was shot with a 100W diffused 5600k light about 4 feet from the subject. You can see how a perfectly bright scene gets transformed into something almost too dark to use.

The camera was set to F2.0 using the same settings as above. I noticed that there was some solarization, probably due to the fact that the chroma setting was maxed at +7. The lense was a 50mm F1.4 wide open. No color correction was made in post.

http://blog.tsebi.com/video/GO35Test2.swf

I intend to do more test under different circumstances but at this point, the light loss is worse than I had hoped. It's okay outdoors in broad daylight but indoors, I'm thinking that you'll be needing something 300W and above to make it decent. It would seem that shooting with 6dB gain makes things a bit better. This in turn means more graininess but it's actually quite hard to shoot without the gain boost as you can hardly see clearly enough to focus unless you have those hot and bright lights on the scene, which affects the subjects in question.

From what I'm seeing so far, I'll probably use the adapter only in broad daylight and when the situation really calls for it, and in those situations I'll need lots of lighting. I'm wondering now if the lower loss adapters like the Brevis fares any better in this regard.

Daniel Wee

Additional note on zoom setting

When I'm shooting 4:3 aspect ratio, Z79 is the smallest zoom without any vignetting at all. From 71 to 79 you get increasing amount of vignette and 74 is probably usable if you don't mind just a little bit of vignetting. However, if you are shooting 16:9 aspect ratio, you can actually go even wider and Z63 for example, may work. This results in a wider field of view as well as even less possibility of seeing any grain (which to this point I've seen none).
 
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Daniel, with a 50mm f1.4 fully open, the Brevis (using the standard diffuser) will cause your camera to increase exposure .5 to .7 stops over shooting without the adapter. In other words, you'd characterize total system loss (50mm f1.4 + adapter) at .5 to .7 stops.
 
Hi Daniel, are you using the AF lenses or the manual lenses? Reason is that i'm trying to get 50mm 1.4 MF but only could find AF lenses in Singapore.
Thanks, much appreciated

Derrick Ng
 
Thanks for the write-ups and sample footage, Daniel.

I'm a bit surprised by the results of your footage, but I have been exchanging notes with a few other shooters, some of whom have received more than one diffuser to test. What I'd shipped to you represented the best all around performer where grain is concerned. Ive learned now that it also suffers about a half stop to a full stop more light loss than the diffusers that shipped with the beta units. What you're seeing is about 2.5 stops of loss.

The relationship between grain, proper bokeh and total light loss is a tricky one -- especially for a static solution -- and they're factors I'm trying to find the best balance among. I'm going to be assembling new diffusers in the coming two weeks to test out, and will ship you a replacement to see if you'd be more satisfied using a different solution. Ideally I'd like to get the loss closer to 2 stops or just under, but anything less will make the grain too evident.

However, I'd stress for anyone intending to shoot with an adapter (any adapter), you should realise you will need to adopt dramatically different shooting methods than what you've come to expect from video. Anytime you want to shoot with an SLR lens stopped to f/2.8 or up on interiors, you're going to need to bring in a good amount of light to get proper exposure.

In the video world, 100W of diffused light might seem like enough, 300W might seem like overkill, but in the world of film they are actually quite little. To shoot with an adapter, you're going to need to shoot as if you're shooting more like film than video. From bringing in 500W and up to light a scene, to learning how to pull focus and hit marks, it's a very different game -- but the results can be amazing.
 
Hi zizou,

I'm using the Nikkor 50mm F1.4 AFD so it's not the MF version but you can always use it manually. It's not that much different. If you really want to you can try getting the 50mm F1.8 AFD. It's a lot cheaper.

Hi Jim,

Thanks and I look forward to the replacement diffuser. The grain is indeed so low that I don't even know where to start talking about it since I can't see any. However, the light loss is way beyond what I was hoping for - 1.5-stops max. If you can get it to 1.5-stops it would be great. At this rate, I'm not sure that going from 2.5-stops to 2-stops is going to be much help judging from how dark the scene already is. I've seen some footage using the Canon EE-A screen which is showing some 1-stop or less of light loss. I believe it's in one of the homemade adapter threads where there is footage showing the with/without adapter shots. That was fantastic, and I can see how that would make a very good solution.

(http://www.dvxuser.com/V6/showthread.php?t=45972&page=122 post #1218 has the comparison shots)

I was prepared to use more lighting but the thought of having to lug 1k lamps around is really going to limit the usability of the adapters. There are lots of situations where that is just not going to be feasible, say inside a moving car. I think if we're looking at 1.5-stops we can get by, barely. At 2-stops and above, the options are narrowed severely.

One of the shoots I had planned with this adapter was an interview shot with sunlight from the window and some fillers. Right now I'm not sure if this is going to work and the thing is, the shoot is scheduled for today. We'll have to see if this works out or I'll have to re-do the shoot without the adapter.

Daniel Wee
 
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Jim makes a good point. Although there are technologies out there that significantly reduce light loss, there is one truth that remains. Diffusion levels are inexorably tied to both light loss, softness and grain, regardless if it's a static, or moving solution. There is a balance there that will vary significantly depending on shoot conditions.
 
I setup tests with a new diffuser last night and shot some stuff with 3 mixed lights around the room -- an overhead 40w equivalent compact flourescent, a 60w lamp about 6 ft away, and 75w clamp light with no diffusion about 4 ft away. The room I was shooting in is in the center of railroad style house, with no windows.

At f/2.0 and 1/60th on my GL1, with the 50mm lens set to f/2.0 I could get a decent enough exposure without gain. Since the GL1 only goes to 1/60th, I think it's a comparitively poor guage (versus any relatively modern cam, like the DVX), but it gives you an idea of the ballpark we're talking. I would say that anyone looking to shoot interiors with the Go35Pro should expect to need a minimum of the following to shoot comfortably: 250W collective (depending on their distance relative to the subject and their diffusion), shutter speed at 1/30th, SLR lens capable of a minimum f/2.0-2.8.

Incidentally, I'm not up on the minimum lux ratings of the GL1 versus the DVX, but I can only imagine the DVX has a huge advantage in this area.

Today I did similar tests with a diffused portable 500W halogen worklight -- the kind you'd get from Home Depot for about $35.00 -- and despite the GL1's limitations, the image looks great. You could stop down to f/2.8 with this kind of light, no problem. The light was about 6 ft away, with some velum clipped over the bulb cage, and in no way uncomfortable to work under.

I know one of the Go35Pro/DVX-100 shooters from this board is bringing the adapter on a shoot soon with a 1k and two 250's. Once the footage is up, I'll post it.
 
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In case anyone was curious as to what I meant by "decent enough", this is a short full res clip showing the Go35Pro on a GL1 with 175W of light collectively. The relevant stats of the shot: GL1 at 1/60th shutter, f/2.0, no gain; Nikkor 50mm f/1.4 lens at f/2.0. Minor bump to gain in post, with a very shallow s-curve for CC.

I can't stress to anyone looking to use an adapter on their shoot just how important a decent field monitor is. I shot this clip looking over at a live feed from the cam into a 14" Sony PVM and playing with it there has been revealing, to hazard a bad pun.

What I've found is that the diffuser for the Go35Pro actually benefits from using a smaller than 36x24mm imaging area because the tradeoff is a near imperceptable increase in grain for a dramatic increase in perceived detail.

edit: and yes, I need a haircut and a shave badly :D
 
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Daniel Wee said:
I've seen some footage using the Canon EE-A screen which is showing some 1-stop or less of light loss. I believe it's in one of the homemade adapter threads where there is footage showing the with/without adapter shots. That was fantastic, and I can see how that would make a very good solution.
Click to expand...
Hi Daniel,

The comparison footage was mine. Glad you liked it and found it helpful in determining light loss. I think the Canon Ee-A focusing screen is a good solution.

For those who have not seen the above referenced thread, here are the direct links to the footage. The tests were shot with my homemade adapter with the Canon Ee-A screen. There was no color correction or gain added. This is straight from the camera. The focusing isn't as tight as I wanted, but I think that was due to it being dark and trying to use the LCD panel on squeeze.

Please right-click and Save As...

Comparisons with and without the Canon Ee-A adapter.

Interior Night Florescent Light (51 sec., 4.10mb, WMV)

Exterior Night Parking Lot (17 sec., 1.60mb, WMV )

Exterior Night Bokeh (1 min. 9 sec., 20.9mb, WMV )

With the Canon Ee-A adapter only.

Exterior Day Tree Firetruck (27 sec., 12.2mb, WMV)


StormFactory
 
15-minute documentary using the GO-35Pro

15-minute documentary using the GO-35Pro

I've finished shooting a project using the GO-35Pro. Note that this is my first real project using any 35mm adapter so it may be a bit on the rough side. It was also shot in about 3-days. I'd say about 60-70% of the shots were made using the adapter and it should be pretty obvious which are the ones. You can see it here:-

http://blog.tsebi.com/index.php?option=com_content&task=view&id=16&Itemid=9

You need to click on the "play" button to get it started after you see the download bar move a bit.

Daniel Wee
 
Wow, the adapter footage looks great. Interesting video as well.

Are you using a DVX with all this?
 
There's some rich shots there. Thanks for posting! Is that shot with him kneeling over the water with the stick made with the adapter? The bokeh in the ice melting shot has me happy.

Your diffuser was sent off today. Should increase light significantly, hopefully enough to make you pleased with the purchase.
 
Yes, that shot was done with a 50mm F1.4 on the adapter.

Looking forward to the new diffuser. Thanks.

Daniel Wee
 
I just had a spot open up for the discounted adapters that are to ship on the 6th. The adapter is already made, just waiting to ship.

Email me if you're interested: info@go-35.com
 
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