Circles coming from adapter?

Cole

Cole

Well-known member
I am encountering a strange problem with my adapter. I recently sent in my Brevis Rev2 for an upgrade and took it out today for a test. Under certain circumstances I am noticing a pattern of circles that seems to start at the center and continue outward. I saw the effect using different lenses and did not see it without the adapter. This is not the same as having debris on the imaging element and seeing it rotate when the unit it on. These lines are there when it is on and off.

If you look at the attached picture you will see it just left of center and up a bit. Any ideas what is causing this would be greatly appreciated. I emailed Cinevate today but I thought I would check here to see if anyone else has seen this.

Cole

Adapter Circles.jpg
 
As I suppose this is a spinning adaptor, you may have friction between the ground glass and another part which left slices in the ground glass. You may have to replace the latter and check where the fiction point might be.
 
Well the first question obviously would be - under what "certain circumstances" . only thing that occurs to me is something like the so- called static grain pattern that appears when you stop down the 35mm lens . Is it when rotating or not and does rotation or f stop or lens change it at all. If you don't give any info its hard to evaluate.
 
This circles is not from a spinner. The brevis is a vibrating adapter and I believe this pops out either under very small apertures, say 8, 11, 16 upwards. Also at very high shutter speeds of 250 upwards, sometimes at 125 if your vibration is weak or the batteries low.

My experience is mostly from spinners having built 3, so don't take my opinion as fact on the brevis.
 
Wow, looks a lot like a thumb print. This strongly resembles the ground glass to an SLR to me.
Let us know what you find out.
 
Thanks for all of the replies. It was shot at 1080 24pa on an HVX200. This particular clip had a pentax telephoto lens (75mm-205mm) I don't recal the shutter speed but my guess would be 1/120 or 1/60. I tried again today without the flip so the problem is in the Brevis itself. I noticed today that I see it more when the brevis is off, if I am out of focus or if I bumped the camera. The shoot I was prepping for is over the next two weeks so I am shelving the adapter for now. When I here back from Cinevate and we figure it out I will post the findings.

I thought it was a finger print as well but it is perfectly round. It may have something to do with the speed it is vibrating. I need to pick up the proper Jelwers tool to adjust it. I am not knocking Cinevate because they are awesome, but I did not see this before I sent it in for the upgrade. I am sure this is user error, I am just trying to narrow down the possible casues so I can put it to use.

Thanks again.

Cole
 
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I recalled back in the day when making my adapters that telephoto leneses like my 80-200 tend to exhibit the GG pattern more than say a 50mm especially at small apertures. Yeah, do let us know how this turns out. And also asking like tie_sheperd, what was upgraded?
 
It does look like a thumb print. It could be on the GG or on one of the prisms.

Whoever did this, we can find out who it is. And there will be hell to pay. :)
 
yaounderespire said:
It does look like a thumb print. It could be on the GG or on one of the prisms.

Whoever did this, we can find out who it is. And there will be hell to pay. :)
Click to expand...

If it is a thumb print it is probably from an extra terestrial. It is a series of perfect circles. Screw it, run it through the database and see if we get a hit.

teddybear said:
And also asking like tie_sheperd, what was upgraded?
Click to expand...


They basicaly take the original Brevis Rev2 adapter and upgrade it to the current MP.2 model. Here is what it includes:

Motor turnover at lower speeds now possible.
- External, "on-the-fly" oscillation adjustment accessibility.
- Low battery system shutdown by microprocessor so charger will always work, and unit will never run flat if you forget to turn it off.
- Retrograde friendly to existing REV2 units.
- Improved, durable switch with rubber boot.
- Power LED flashes when battery is low.
- "Boost Start" system.
- Harness connectors for rapid field replacement of motor or internal cells.
- Better control of motor speed - by microprocessor.
- Internal electronic self-resetting fuse as extra protection from power surges.
- Firmware upgrade port for updates to code.
- Motor low speed cut-off to ensure that motor always oscillates.
- Up to 32 hours runtime now possible on a 25 minute charge due to microprocessor power management.
- Internal electronic self-resetting fuse as extra surge protection.

Right away I noticed a cleaner image, unfortunately it was coupled with the "Thumb Print". As I mentioned there is probably something I am doing wring, hence my post. But the project is standing still waiting for the adapter to produce a clean image so back to the stock lens for now. I need to shoot these exterior shots before the bulk of the leaves fall.
 
Cole, thats your groundglass showing. Its showing due to 2 things, your vibration is slow or your speed is too fast. Try removing the lens and turn it on, take a peek into your brevis through the lens mount, is it actually vibrating? if it is, turn up its vibration control(Im assuming the brevis has this). If both on the affirmative check your shutter speed. Shoot at 48 or 60.
 
teddybear said:
Cole, thats your groundglass showing. Its showing due to 2 things, your vibration is slow or your speed is too fast. Try removing the lens and turn it on, take a peek into your brevis through the lens mount, is it actually vibrating? if it is, turn up its vibration control(Im assuming the brevis has this). If both on the affirmative check your shutter speed. Shoot at 48 or 60.
Click to expand...

I heard back from Cinevate today and that is pretty much what they said. They say it is the imaging element and it could be the oscillation speed is too slow. Another is a combination of reason 1 and low light levels. I was outside in the sunlight so it doesn't get much brighter than that. I will try it out again on 1/48 and 1/60 in addition to adjusting the speed of oscillation.

I really want this up and running for these shoots so hopefully I will find time to get it adjusted properly. And I am very relieved that as far as I know an extra terrestrial did not have their thumbs on my unit.

Thanks for all of the help, I really appreciate it.

Cole
 
Cole, You still didn't provide all the information about how you were shooting, especially the most likely culprit - your f stop on the 35mm lens, and which Brevis screen you were using. You know I don't get why people post on here asking for help without posting all the details surrounding the problem. Its just a waste of your time.
OK - I see now you were outside. That makes it likely that you stopped down the 35mm lens. If you stopped much beyond 2.8 that could be your problem, though you should see grain as well. With some of the brevis screens I saw static grain wide open at 2.8 with my Nikon 80-200. Couldn't use the lens at all with that screen.
 
Lenilenapi - Thanks for the input. I was really trying to squeeze this adapter into my current production which was currently under way when the upgraded unit arrived. Once I discovered the problem, which wasn't there before the upgrade, I posted to see if anyone else had encountered this. I had no idea which direction it would go so I waited for some direction and to make sure it wasn't something obvious (which it may be- Oscillation Speed and/or shutter speed). I could have spent 5 paragraphs on details most of which could have been irrelevant and I truly had no idea where to begin. Once I saw it was going to take more time than I had the problem needed to be shelved and revisited once I am through the current writing/shooting schedule. By the way there were plenty of helpful suggestions that came from the info I provided.

All of my lenses showed the pattern at one time or another. The lenses are a Nikkor 50mm 1.4, Pentax 28mm 2.8, Pentax-A 50mm 2.0, and the one that captured the image I posted was a Pentax 75-205mm 3.5. The Pentax lenses are very old, like 20 + years I think. Not sure on the Nikkor, it came with the adapter. But all of them did show the circles, even the 1.4 stop. Once I get a little more caught up the adapter will come back out and I will apply some suggestions and report back.

I hear you about people posting problems without pertinent data but I really don't feel this was the case. Thanks again for your time, it is appreciated.

Cole
 
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