Brevis soft focus issue, help!

C

ClayM

Member
I recently got my Brevis back from Cinevate after a rebuild and I'm experiencing a really weird issue. I'm getting soft edges on every lens I have (28, 35, 50, 85, 105 Nikons). I'm setting the back focus, and getting focus in the center, but the edges are soft even without a lens on. It's a HVX Cf1le setup, with 72 zoom, 9 mf without a spacer, and 76 zoom, 11 mf with a spacer. Neither with our without a spacer is correcting the problem.

I've been trying to get ahold of Dennis for about a week via the telephone with no luck. From a company that prides themselves on customer service, this has been more than a little frustrating. The adapter is ruining my wides on a short film I'm working on because there is no way to take attention away from the edges. Any help would be awesome.

Here is the GG back focus bare.

GGbig.jpg




Here is the back focus with a 50mm 1.4 Nikon stopped down to about f16

50mm.jpg
 
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Try adjusting the HVX focus until it's somwhere in the center of everything. So that the edges are in focus as well.
 
I don't think thats the problem.... I'm not able to get it all in crisp focus at once. It's all on the same focus plane so you would think it should be crisp all the way across.
 
have you tried it or are you just discounting the advice? =P

Try it. The HVX lens isn't made for such an application. We've all discovered and learned from Lenny (Lenilapi (spelling?)) That a compromise focus on the ground glass actually produces more pleasing images overall than simply center-focusing the screen.
 
Check your lens mount. If your mount isn't sitting perfectly straight I would bet this is your problem. Also make sure the Brevis is straight vertically and horizontally with the HVX.


Marco
 
screenies06.jpg



(Image property of PUFFIN FILMS: User BEAT TAKESHI)

This is a wide from the Brevis as well. Same issue that you seem to be describing. The quality of the wide also plays a part but let us know how you get along with the compromise focus.
 
Kholi said:
have you tried it or are you just discounting the advice? =P

Try it. The HVX lens isn't made for such an application. We've all discovered and learned from Lenny (Lenilapi (spelling?)) That a compromise focus on the ground glass actually produces more pleasing images overall than simply center-focusing the screen.
Click to expand...

I'll try it, but I feel like it's more complicated than that.
 
If it is then that sucks! Let's hope you can get rid of it with some focus adjustment that way you can get back to shooting your short.
 
marco0782 said:
Check your lens mount. If your mount isn't sitting perfectly straight I would bet this is your problem. Also make sure the Brevis is straight vertically and horizontally with the HVX.


Marco
Click to expand...

The lens mount not being perfectly straight wouldn't affect the GG bare being soft would it? The Brevis is centered perfectly.

Kholi said:
screenies06.jpg



(Image property of PUFFIN FILMS: User BEAT TAKESHI)

This is a wide from the Brevis as well. Same issue that you seem to be describing. The quality of the wide also plays a part but let us know how you get along with the compromise focus.
Click to expand...


This is the look I'm getting, however I'm getting it across the board with all lenses. I know that this can happen with say a 28mm lens, but it shouldn't be occurring with my 1.4 50mm up to my 105mm.
 
That's very true. Especially if you're getting it with a 105mm!!!

Dennis traverses the boards, hopefully he'll see it here in public and help you out.
 
Did you have edge to edge issues before sending your Brevis for repairs? Where are you putting the spacer? It needs to go between the achromat and the adapter.


Marco
 
Kholi is right. You can check my tests at :

http://www.leonardlevy.net/Adapter_stills_master_Final.htm


I suggest to everyone who owns an adapter that they download a chart and start looking at sharpness issues in a controlled way. Instead of looking at the GG wouldn't you rather know exactly what the real image is doing?

I think a disservice was done to all when the manufacturers told us to focus on the ground glass since that encourages focusing in the center only.
Perfectly flat focus is extremely difficult to achieve optically and while some adapters can do it, there is often nothing at all lost by finding a mid point between corners and center.

Marco has suggestions about using a spacer that might help though i've never tried it.

Lenny Levy
 
To add to Lenny's thoughts:

It's also safe to change focus for different shots. If you need much more center sharpness, then go back to center focus. It helps.

If you need all around edge to edge, then do the compromise focus.

Lenny's owed a lot of credit for bringing this to light! Although others may have suggested it, he's the only one to put the info out there in a hard fashion to show people.
 
I just know that I used to encounter the same soft edges with my Brevis until I started using the spacer between the achromat and adapter.


Marco
 
Thanks Kholi

NOTE: Sometime's I may seem brash and combative. I'm really not and I have nothing against you; promise.
Click to expand...

Actually, Who are you kidding - you are brash and combative - but it is greatly tempered by your willingness to back off and admit when you're wrong. An important and valuable sign of character.


Marco I hope to try that out when I get a chance.


Lenny
 
marco0782 said:
Did you have edge to edge issues before sending your Brevis for repairs? Where are you putting the spacer? It needs to go between the achromat and the adapter.


Marco
Click to expand...


No issues before it was sent back, but it was being used on a dvx with a cf1. The spacer is placed between the achromat and the adapter.

Lenilenapi said:
Kholi is right. You can check my tests at :

http://www.leonardlevy.net/Adapter_stills_master_Final.htm


I suggest to everyone who owns an adapter that they download a chart and start looking at sharpness issues in a controlled way. Instead of looking at the GG wouldn't you rather know exactly what the real image is doing?

I think a disservice was done to all when the manufacturers told us to focus on the ground glass since that encourages focusing in the center only.
Perfectly flat focus is extremely difficult to achieve optically and while some adapters can do it, there is often nothing at all lost by finding a mid point between corners and center.

Marco has suggestions about using a spacer that might help though i've never tried it.

Lenny Levy
Click to expand...


Why don't manufacturers state this? I've talked to Hubert at Cinevate like 15 times in the last week explaining my problem and he has never even mentioned this. I'll setup the test tommorow and see if this doesn't solve the issue to some degree.

To make everything clear.... you're setting up the chart and the adapter, and then zooming in 10% past the edges, and instead of stopping down to see the GG, your actually just basing it off the image clarity? Or are you stopping it down to see the GG like in my second picture, and just focusing more evenly on the grain?

Thanks for all of your help guys, ... keep it coming.
 
Kholi said:
To add to Lenny's thoughts:

It's also safe to change focus for different shots. If you need much more center sharpness, then go back to center focus. It helps.

If you need all around edge to edge, then do the compromise focus.
Click to expand...


This sounds like a complete pain in the ass to do since the HVX requires gaff tape just to lock in the Zoom and Focus. Are you just shifting between the predetermined zoom and focus numbers and then relocking it in?
 
I just don't touch the focus ring anymore. Become conscious of it. I no longer lock down my ring, though.
 
Kholi said:
I just don't touch the focus ring anymore. Become conscious of it. I no longer lock down my ring, though.
Click to expand...


Sounds pretty ballsy to do it that way. I'm working on a 15 day shoot, sometimes shooting for 10 hours at a time while switching from sticks, to a jib, to a dolly and back again (switching base plates)... so just being conscious of it wouldn't be enough i don't think. I'll play around with it though.
 
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