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Achromat Status?

Discussion of Beta Testing.

Achromat Status?

New postby DJ Lewis on Wed May 03, 2006 10:20 am

Hey Dennis, what's the word?
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New postby Dennis Wood on Sun May 07, 2006 12:26 am

Missed this, we should see them in three weeks, the initial model for approval..hopefully next week.
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New postby Rafael Lopes on Tue May 09, 2006 4:23 am

Crespo used a +10 (!) and he still didn't manage to avoid filming the interior of the adapter. Do you think the achromat will solve this issue? All 72mm achromats I've seen are like 300$!! The fact that you managed to come up with a solution under 100$ is amazing. I can't wait to see the results.
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New postby Dennis Wood on Tue May 09, 2006 9:11 am

It's really hard to say if the current achromat will allow sufficient zoom in for slower lenses all by itself. The issue is that an achromat that is overkill for an HVX, may not be powerfull enough for a DVX with a slow 35mm lens. The solution is to either use two, a combination of singlet and achromat lenses, or move the achromat back from the adapter to increase magnification factor. Once I test the "approval" version of the achromat, I will make the decision to stick with it's strength, or up the ante to +10. Stacking macros provides a rough idea, but not conclusive as the camera is moved back from the GG at the same time that mag factor is increased.

This isn't a Brevis specific issue..it applies to all adapters.
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New postby Rafael Lopes on Tue May 09, 2006 11:09 am

I have Moises Crespos' exact same 72mm achromat. I really hope it works with the brevis and the FX1. Apart from the vigneting, the footage looks really nice and filmic.
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New postby DJ Lewis on Tue May 09, 2006 2:54 pm

Dennis Wood wrote:Direct attach with 82 to 58 step down set.


So you do need an achromat for the HVX? How strong do you figure?

Also, do you know a source for 72 or 82mm spacer tubes? I can find 58mm's, but maybe you can have 72/82mm's made cheaply?
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New postby Andy Gordon on Tue May 09, 2006 6:47 pm

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New postby DJ Lewis on Tue May 09, 2006 7:09 pm

those may work, but they don't say how long they are.... but these do.

http://www.camerafilters.com/pages/spacerrings.aspx

Are the ones from your 2filter.com 1 inch, 1.5 inch? or just an empty filter?
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New postby Andy Gordon on Tue May 09, 2006 7:12 pm

They're 5mm long. Maybe not what you want.
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New postby Dennis Wood on Tue May 09, 2006 10:18 pm

The HVX needs about a +4 to properly frame 16:9, and nothing in 4:3 modes. So the "standard" achromat will give the HVX plenty of extra room for zoom-in if required. The MPIC technically requires a macro on the HVX, but Steev Dinkins is zooming the footage in post to accomodate.

That's a good link Andy. Originally I had planned to make the rear ring adjustable for depth, but later came to the conclusion that very few cams would benefit from this feature. The spacer rings are the best solution..if in fact the FX1 will require them. At this point, based on my research, I don't believe it will, however the wildcard here is the FX1's consistency of focus across the frame. If any spacing is required, I believe it will be minor. Certainly, using a 55mm achromat in front of a 72 or 82mm lens is not ideal, and I'm pretty convinced is the reason for the edge softness experienced by M2 users with the larger lens cams.
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New postby Rafael Lopes on Wed May 10, 2006 12:41 am

I'll be filling the FX1 gap soon enough. I'm hoping a +10 achromat will do the trick.
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New postby Francois Poitras on Wed May 10, 2006 7:33 am

Rafael, if you ever need a deeper spacer ring :

http://cgi.ebay.ca/72mm-Spacer-Ring-Bra ... dZViewItem

It’s 72mm, 1.5 inch deep.
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New postby Rafael Lopes on Wed May 10, 2006 11:17 am

Thanks for the tip, François...although I REALLY hope the achromat will do it by it self.
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New postby DJ Lewis on Wed May 10, 2006 12:22 pm

I will do some testing on fx1 in the next day or so; I'll let you know what I find out Raf
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New postby Rafael Lopes on Wed May 10, 2006 5:06 pm

DJ Lewis wrote:I will do some testing on fx1 in the next day or so; I'll let you know what I find out Raf


Great to hear, DJ. Do you have an achromat? Spacer tube? Some footage would be cool to see more less what can I expect.

cheers
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New postby DJ Lewis on Wed May 10, 2006 6:07 pm

I have +7 stack, and stepdown which will work as a spacer ring. I will also take some other uv filters to ad space, but Dennis is confident that it will fine without it. I'll let you know tomorrow.
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New postby Rafael Lopes on Thu May 11, 2006 3:05 pm

How is it going, DJ? Any progress with the FX1? Dennis, please answer my email, broham.
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New postby DJ Lewis on Thu May 11, 2006 8:44 pm

Rafael Lopes wrote:How is it going, DJ? Any progress with the FX1? Dennis, please answer my email, broham.


I never got the go ahead call today, so I will just show up tomorrow with the brevis and commandeer the fx1. :)

sorry for the delays....
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New postby Moises Crespo on Fri May 12, 2006 11:33 pm

DJ any footage yet?
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M2 moving to 72mm achromats

New postby Dennis Wood on Mon May 15, 2006 7:28 am

Redrock has "seen the light" and is making a 72mm achromat "HD" available. The edge to edge softness issue was specifically why I decided to go to a larger achromat...I was surprised to find out that the M2 was using a 55mm achromat up to now. Why they didn't figure that out a long time ago is a bit of a mystery as DVX users have been complaining of the edge to edge softness issue for quite some time.

In any case, my prototype is still not here, but I've requested another update on delivery....stay tuned.
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