Zillions of adapter chart tests

Letus Ex it's 27.3mm -- Clarified. That's the number that I found, Tim Naylor found and I THINK B_G found when he first got the Letus. I don't have the post anymore, though.

Put the paper up Horizontally, Camera two feet away on a horizontal plane.

I do wonder what changes with each unit, however. The Adapter itself can't change FOV, only the Taking lens and the HVX lens? Or am I wrong about that?
 
Kholi said:
http://www.dvxuser.com/V6/showpost.php?p=1150979&postcount=44

For reference: an example of HVX + Letus EX + 50mm 1.4 Lens that... well... you be the judge.

I mean, I'm almost certain that If I did the same test I'd somehow end up with the same clean chart that Luis has. You'd probably be better at explaining why Luis' charts look a lot sharper on all fronts, I dunno myself.
Click to expand...

A few reasons why Luis' test are sharper.
He's more zoomed in for one (his chart's look flatter). E 2 E sharpness is more even zoomed in and his HVX is at a much higher stop. Also, Leni is testing the lowlight extremes (1.4 on the Nikon and pretty wide on the HVX as well).

What I find is that when I zoom in just inside vignetting, I get great rez on the highend but suffer more on the edges. When I zoom into cine FOV, the rez drops because of the magnification of the GG.

What I like about both tests is one gives me a good idea where to start to get it sharp across the frame and Leni's show's me the low end limitations.

Anyway, thanks for posting. I know what a sonafabitch it is to do these tests. In fact, whether you got eyes like a hawk or not, I strongly recommend shooting a chart right out of the box. It's the quickest way to know whether something is out of alignment or collimation.

Before I do a feature, my AC will spend a day shooting focus charts and color charts before we test on real meat with lights, etc. That way we can get rid of any gear that's less than before we get into the aesthetic testing.


Thank again.
 
Good point about alignment and testing out of the box for that.

I'm NOT discounting Lenny's tests at all. After learning about the strict LowLight testing it's also a different story.

And, I did say thanks for showin' us how to get better ALL AROUND sharpness instead of just center. I sure learned somethin!
 
Tim,

I think you totally got what I was trying to do as well as Luis. Interesting thoughts about the zoom in factors. No free lunch.

Its not easy to manufacture these optics.

BTW did you get my email about the SGPro Rev 3? I'm trying to find someone who can show me what it looks like when you unscrew the condensor tube to see if it will connect to a Brevis Flip like the Rev2 did.

Lenny
 
Lenilenapi said:
Tim,

I think you totally got what I was trying to do as well as Luis. Interesting thoughts about the zoom in factors. No free lunch.

Its not easy to manufacture these optics.

BTW did you get my email about the SGPro Rev 3? I'm trying to find someone who can show me what it looks like when you unscrew the condensor tube to see if it will connect to a Brevis Flip like the Rev2 did.

Lenny
Click to expand...

That was your email? I'll take a look later today.
 
The spacer goes between the achromat and the adapter. I doubt you could do this with the flip but possibly the flip negates the need to do this. Also an object of concern is the lens mount on your adapter and whether or not it is seated correctly. The original M42 mount for the Brevis made it near impossible to get good edge to edge but Dennis kindly sent me a newer mount that made a world of difference.


Marco

P.S. I once tried the Cinevate achromat & spacer ring in conjunction with the M2 and the image was very sharp.
 
Marco, How long is the spacer?

My Nikon mt is fine. Originally I returned my first to Dennis irritated about how it seated and the back focus hassles. He sent it back about 2 months later with the microcollimation system.

I don't think the flip would need it. I experimenetd with the spacers in various places on the flip with the SG and it didn't help as far as I could see. But then it ended up pretty good without anything.


Lenny
 
Lenny correct...no spacer is required or suggested with the flip. It's a huge pile of work to do this and a big pat on the back for posting. I'm going through the charts later tonight and will post a few comments.

We will be doing a lot of shooting in the next few weeks with our DSC labs rear-illuminated charts which you'll find very interesting. We've also figured out a small tool (mirrors based) that gets the camera perfectly aligned and centered to the chart surface. As you can attest Lenny, it's a bit*%$ to get right :-)

I just spent a full day in LA locked up in a room with two very respected optical engineers on the EX1 issue, as well as a few other projects we have in the fire. Very fascinating developments on the EX1 front ... but more on this later.
 
Boy a rear illuminated chart - now that sounds nice - better than my crappy bounced ceiling light.

Dennis, what about a spacer with the unflipped Brevis on an HVX? Thart's what Marco was suggesting?

- Lenny
 
Ah, yes the interaction of the field curvature of a given video cam lens, and an adapter is a hard thing to predict...case in point the rather atrocious behaviour of the EX1. Some users like Marco are using the spacer on the non-flipped achromat and finding it improves edge sharpness. From our rather large volume of data on the different cams, I'm pretty sure this is not consistent across all HVX's but worth a try if you've got an off axis imager block.

It's important to note that an achromat cannot solve issues like the EX1 has. Yes you can get the camera into less zoom, where the problem is less, but zoom into academy frame and the problem is magically back. That said, I believe that we have a $50 fix for this issue :-)
 
You must log in or register to reply here.
Back
Top