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Old April 24th, 2004, 07:23 AM   #706
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Macro Solution

James,

I think the solution is simple. You need to get your hands on two 72mm +10 macros. Put those on first, then your 72-55 stepdown ring. That way the edges of the diopter would be covered by your stepdown and 55mm tube rig.

I just ordered two 72mm +10 macros off ebay for that specific reason. When they get here I'll let you know how it works.

John
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Old April 24th, 2004, 09:08 AM   #707
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One thing everybody might need to be mindful of is that when optical image erection into camcorder via prisms/mirrors is designed, things will change.

I haven't done it yet because I am too pre-occupied with more essential things right now.

Early experiments indicate that the current crop of close-up lenses, macros, etc., will shorten the camcorder to groundglass image path too much for a reflective erecting array to be inserted.

The longer path caused by the prisms/mirrors will require weaker lenses to be used. Co-incidentally, the deficits associated with strong lenses will be reduced though not avoided.
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Old April 24th, 2004, 12:34 PM   #708
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John -
I agree, the right 72mm Macros (could they be had) would likely resolve this issue. But you might want to go back and read up on the discussion about macros and why I went with the Hoya 55mm. You can start around here:
http://www.dvinfo.net/conf/showthrea...202#post144202

Then again, I haven't tested those eBay 10X 72mm macros. So they may work. Good luck and let us know!

In the light of a new day, I went back and tested various configurations (AGAIN!) of my adapter and found that with just a little more care taken on focusing I was able to reduce the smearing of the edges a little bit while staying close to the 36mm area of the GG.

The situation is (as Joel implied earlier), I'm so close to the macros that I'm unable to focus on the entire 24X36 image area. I can focus on the outer edge, but then the center area is slightly soft. For DVX100 users, the difference between the inner and outer focus point is around MF07 to MF04! So I decided to set the focus on MF05 @ Z57 which brought the outer portion of the image closer to focus while appearing to maintain focus in the center. It's not a fix but it's better. Along with letterboxing (which I almost always use for asthetic reasons), the image is somewhat more acceptable.
http://www.homepage.mac.com/dvx100/P...um5.html<br /> Note: This test (image) is not exact since I'm hand-holding the camera and also only approximating the distance between the macros and where the GG is ;)
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Old April 24th, 2004, 02:16 PM   #709
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Hi James, that looks a lot better. Thanks for posting the images. Those 72mm +10 diopters are the only ones I've seen anywhere, and there is no indication if they are achromats or not. It's worth a try though.

In the thread you posted a link to, Brett mentions that he heard Hoya came out with 58mm +10 diopters and was going to order a couple. Unfortunately, I haven't been able to find mention of those anywhere on the net.

So, is it safe to assume that this won't work with just one +10 diopter and the DVX100 (while still framing for 24x36mm)? I might have missed a post where someone verified that.

James, would you be able to verify that?

Bob, in my early designs, I considered a front face mirror and prism combo, but opted against it because of the associated light loss from the addition of those materials and the fact that this necessitated more zooming, which at a certain point, also made me lose 1.5 stops of light. Doing an LCD screen "erection" seemed like a better solution with regard to preventing light loss.

John, I hope those diopters give you good results, and if so, that they are available to the rest of us.

Good luck everyone.
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Old April 24th, 2004, 03:13 PM   #710
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I also didn't see anything in those auctions about those lenses being achromats. I'm really interested in seeing what kind of an image those macros will produce, can't wait to hear how they work John!

I posted something on the dvxuser messageboard and haven't gotten any responces yet so I figure I'll throw it up here and see if anyone has any thoughts that may help me out:

There's a few questions I wanted to ask you guys about the achromat diopters. _I'm shooting on a 100A and most likely won't need two 10x pieces. _If I used two 10x anyway would that hurt me in any way? _The reason I would just get two 10x instead of experimenting is at least I know I can work multiple lens type usage in there somehow and I don't have the time or money to try all different power levels. _But if I did take the easy way out would I have to just zoom in more and possibly deny myself of the ability to attain a lower f-stop? I've already started principle photography on a sketch comedy show I'm shooting and the sooner I can be running accurate tests the better!
_
I understand in full the purpose of the condensor, but am not completely sure what I should be looking for to use as one. _This would be a piece along the lines of a fresnel right? _If Brett or anyone out there can bear with my newbie-style questions I'd be all too thankful _
_
Since I was first thinking about Building the Agus my brain is still bent on thinking about a spinning ground glass, or at least one in some form of movement. This static adapter is much less bulky and easier to start out with, especially for the DVX, but can't there be some way we can incorporate the moving ground glass into this "barrell" style design
_
This was rolling around me head lastnight, so please try to follow my fragmented logic
_
Let's say we had a threaded filter that has the ability of its glass element to spin in its housing for adjustments to be made in its orientation. _I'm not sure if these really exist, but for some reason I feel like I've seen them before. _That would mean if it was used as the ground glass, there would be a way for it to spin already. _The motor would obviously have to spin the ground glass filter from the outside, and that is something a little tricky to figure out. _Maybe using the basic principle of a follow focus mount to spin the glass? _I'm sure I'm simplifying it, but mount a geared ring around the ground glass filter and place another gear to work with that one at 90 degrees and thats the one you can hook the motor to. _So the motor will spin the gears and in turn spin the ground glass. _Can someone shoot me down cause I know I have to me missing something and I bet its impossible!
_
And if this was even able to be employed, would we experience the "grain vortex" that I've read about with the older P+S mini35 models? _ Just a thought that maybe can get some of these great minds on this messageboard brewing some new innovations! _
_
Maybe we could get real fancy and figure out a way to make the glass oscillate so that vortex isn't an issue _
_
Hope to hear all your comments and opinions soon!
_
Nick
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Old April 24th, 2004, 03:36 PM   #711
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I thought of this a while back playing with a polarizer filter in my hand...it would be something like an extended middle section with a ball bearing assembly so it could be spun. I wasn't even thinking of gears, but more of a direct drive type where the motor would have a rubber wheel attached and this would spin the glass. I guess you could have a belt drive too, which would also probably be easier than gears.

I never really pushed this idea since I heard people talking of a...oh now I forget...how...ME! It was an effect of spinning the GG in a circle --the grain would create some weird effect where the image would appear as a...a...AHHH! sorry. The grain wouldn't be moving over the image area in the same way -- the grain at end of the gg would be always spinning and moving quicker than the grain near the centre.

someone PLEASE help me out with what i am trying to say...ugh sorry!

Rob
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Old April 24th, 2004, 03:52 PM   #712
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Joel -
I can assure you the DVX100 won't work with just one 10X. Brett Erskine estimated that you'll need at the minimum +17 (again for the DVX100). I just went ahead and got (2) 10x Hoyas because I thought the extra power would help and that's what Brett was planning to use.

Oh, and if memory serves me I think if you read a little further from the mention of the 58mm macros, he recants. As far as I know the Hoya 10X only come in 55mm.
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Old April 24th, 2004, 03:57 PM   #713
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Nick, maybe you could try the Century Optics 72mm +3.5 diopter in conjunction with a Hoya 55mm +10. Though, bear in mind that the Century Optics lens costs $325 at B&H. I don't have the ability to test it myself, but +13.5 might be a good number.

Focussing at a very short distance (such as the distance dictated by a +20 diopter i.e. 5cm), as James has seen, causes some edge blurring if the diameters of the diopters you are relying on are significantly smaller than 72mm. In addition, focussing on anything with the DVX at 5cm ( in this case the GG), causes a fair amount of barrel distortion. The barrel distortion is unrelated to
the diopters you might have on the camera at the time. That's something inherent to the DVX100's own lenses when focussing so close.

Something like +13.5 diopter combination would put your focussing distance to 7.4cm (regardless of whether you have a DVX100 or DVX100A or even a Sony XYZ) and should improve the barrel distortion a bit, since the focussing distance is now a bit longer. But the main fact that one of the diopters has a 72mm diamter might give you less edge blurring.

Although, James's newest zoom/focus tests look to be pretty good on their own.

If you have the ability to test a Century Optics +3.5 72mm diopter and a Hoya without purchasing them, then you might want to do that and please tell us what you find).

Good luck on your show.
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Old April 24th, 2004, 04:23 PM   #714
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72mm +10

James

Yeah, I actually read that original post about the hoya +10s. The second webaddress does confirm that those hoyas are 2 element macros. But the first address where you purchased it doesn't... and as a matter of fact, it goes out of the way to separate them from the 2 element macros they're selling. And since I wasn't absolutely sure who was telling me what, and didn't want to spend $120 to experiment with two macros (especially since I knew they would at best give me the problem you're seeing), I went with the 72mms on ebay. They may not be good enough, I have no idea, but they're cheap enough for me to experiment with. Here's to hoping they work... for everyone's sake.

By the way, I just want to commend you on such a fantastic design. When I first saw it I had a mixed reaction of "YES!!", and "Man why didn't I think of that!" I can't stand the look of PVC or tape anywhere in the design. I know that's sounds base, but what can I say? I'm trying to come up with a really clean, fully metal, version of what you've made, but with an adjustable tube. I'm experimenting with filter rings of varing sizes that slide over the the top of the 55mm section snugly... I'm gonna use little plumbing O-rings to furthur seal off light, and a screw (similar to the one used with the DVX's plastic mattebox) to lock it in place. Any thoughts? Ideas? Wish me luck.
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Old April 24th, 2004, 04:53 PM   #715
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Thanks for the response, James. Based on my own estimates as well, I figured a +10 probably would not be sufficient, but would be pretty close. I just wanted to make sure. I don't want to start a big debate here about Brett's estimates, but I'm not as convinced that you will need a +17. Brett, I believe, also wanted to be able to focus down to a 16x22 target, which is not my intension. I think a +13.5 should be sufficient for framing 36mm across, but it should be tested, and in fact, I would have thought a +10 would have been just a few mm shy of being able to frame 36mm across. I'm using some visualizaton software to do the calculations, but they still aren't real world.
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Old April 24th, 2004, 05:15 PM   #716
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John-
Well according to B&H they are 2 element: http://www.bhphotovideo.com/bnh/cont...u=94233&is=REG

Here's the actual link that convinced me to buy them in the 1st place (although the samples don't show them stacked): http://www.lensmateonline.com/A80macrocomp.html

Concerning the design, I really went for the simpliest way to make the adapter. I wasn't too concerned with versatility and compatibility with different types of lens as much as I just wanted to make one that worked with the lens I had ;)

Joel-
Allow me to clarify. I misquoted Brett. This is actually what he said: "... +16 diopter(s) or stronger is whats needed if you plan on using cine lenses. Still lenses work with +13 maybe +12". Sorry about the misquote - just trying to pass along information :)
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Old April 24th, 2004, 05:28 PM   #717
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Oh hey, James, don't worry about the misquote. Thanks very much for clearing it up. That does seem to line up with my own calculations.

I wonder if you've noticed any barrel distortion with the +20? I suppose as you start to shoot a larger variety of subjects, such as poles or wall edges, etc, that might start becoming apparent. However, probably the best test would be to shoot some grid paper with your macros, much as you have shot the newspapers.

Great effort everyone!
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Old April 24th, 2004, 06:30 PM   #718
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Here are the numbers I've come up with for the DVX100:

36X24mm = Just over +10 power diopter (+13.5 will be enough)

24X16mm = aprox +17 power diopter or stronger



Here are the numbers I've come up with for the DVX100A:

36x24mm = I've HEARD you dont need any diopter at all due to it better minimum focus specs

24X16mm = If the above statement is true then logic tells us a +7 or stronger diopter should work


I've based my numbers on real world test with the diopters.

If you plan to use a anamorphic field lens for your GG then then your target numbers are going to be even smaller which means a stronger diopter.

Unless Hoya JUST came out with a new version of 72mm diopter in the last few months your ebay diopter is going to be a single element.

55mm is a big as anyone they make them when it comes achromats.

58mm dont exist. It was a misprint on a web site.

EVEN the 55mm Hoyas are two element achromats, they have the slightest amount of chroma abberation. Its much less than anything else out there of the same power and it becomes slightly more noticeable when you stack two. Using larger ones would be better but they dont seem to exist.

When focusing extremely close to a flat object like the GG when using two diopters you'll notice that the center is in focus while the outside of the image is not. This is due to the minor distance between the two points and the lens. Increasing the distance between the GG and the first diopter is the simplest way to fix this problem.

Glad you guys are still keeping this project alive. It just goes to show you that their are plenty videographers out there that truely understand and appreciate the subtle characteristics of a film image. Unfortunately I've been too busy lately to do much work on it but last time I screwed around with it I was working on incorporating a synced 180 degree rotating shutter with the GG. This achieves smoother, more natural film motion blur that even some of the most expensive HD 24p cameras lack and defeats the problem with apparent grain in the GG at the same. Anamorphic GG, tilt shift movements the possibilities seem endless. The goal: a adapter that allows small, light weight, inexpensive cameras such as the DVX100 to step up and produce the images that dont compromise our creativity and do it at a price where ownership makes sense in this progessively fast moving digital market.

-Brett Erskine
www.CinematographerReels.com
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Old April 24th, 2004, 06:39 PM   #719
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<<<-- Originally posted by Brett Erskine : The goal: a adapter that allows small, light weight, inexpensive cameras such as the DVX100 to step up and produce the images that dont compromise our creativity and do it at a price where ownership makes sense in this progessively fast moving digital market. -->>>

Here, here, Brett. Thanks for all the info. But, wouldn't an anamorphic pcx increase your target area? You aren't planning to squeeze the image in width, but actually stretch it in height. Unless, you're doing it the other way around for some reason.

Joel
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Old April 24th, 2004, 09:30 PM   #720
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Hmmm..... how could a second shutter on the GG (in addition to the existing shutter on the camera) help? The motion blur is going to be determined by only one thing - the time the shutter is open for the CCD on your camera. I must be missing something... I saw the word 'synced' but doesn't that just eliminate the need for the second shutter (making it exactly the same as the first shutter)? Help me to understand this...
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