Vincent, Nikon has focus screen type D that is completely clear of any markings.

That's what I use as GG.

It is sold for about $30 at B&H (http://bhphotovideo.com)

Glass GG is probably a no-go as it is times heavier than the plastic D-screen in its tiny plastic frame... thus the glass will require much more powerful vibrations and they certainly will transmit to the camera's lens as well...

Stay put for the photos of my tests later today, hopefully.

>> PS- I think we have to call it something with your name
>> on it- Vibro35 sounds like the stuff people try to sell me
>> on Spam mail.

Hmmm, we dont want any obscene names for such a beautiful thing as mini35 adapter...

how'bout this: if you guys do like my results, then you can call the adapter alex35.

If you rather don't like the results, then it's vibro35 :)

Deal?

Ok- it's a deal Alex

I'm ordering the screen you recommend

Thnks--Vincent

So how is it working out?

I've been alternately incapacitated (operation)/insanely busy lately, so sorry for no progress yet.

I'm dying to continue working on it, should be able to do so later this week!

Yikes... I like your humor !!!!

Take care , I'll stay tuned for when you have time to play again!
-Les

I hadn't followed this thread for a long time, but things are now sounding very interesting. I look forward to more info on the "Alex35".

P.S. I gather these tools flip the image backwards and upside-down and that this will be corrected in post. We were just thinking if there was interest we could put the image flip as part of the HDLink capture app. This would take no CPU time and save a bunch of post processing steps.

I can't speak for anyone else, but the rotating in post is such a simple operation that I almost view it as a non-issue. However, I'm sure it wouldn't hurt to have it as a bullet-item on your product, which would also allow you to appeal more generically to the seemingly growing number of home-made adapter-builders. Despite the ease of the rotate, I have stumbled across a not-so-small number of people who don't seem to see how to do it easily. Your inline rotation during capture would appeal to those folks for sure. Doesn't seem like it would be a bit hit to your dev team either...

It is true that users who making such devices are probably not all that concerned with workarounds in post. :) Still if someone had to do a lot of work with a flipped image, I guarantee your current workflow would be painful compared with it being handled automatically. ;)

P.S. I just looking for the excuse to do it. This is very cool.

Don't get me wrong - I was trying to make the point (eventually) that you should do it! In fact, I'd probably use it if it meant one less step in post. I'm biased because in my particular case, I run *everything* through post, so its a given in my process that I'll have a certain amount of simple 'cleanup' tasks (de-interlacing, rotating) prior to any post-effects work or grading. I think an inline solution would be great - so there's your excuse!

David, Jonathon: thanks for your interest in this adapter.

I'm on the path to use piezo elements as an oscillator for the ground glass (rough idea). I don't like micromotors too much, because their vibration is uncontrollable.

In my version of the adapter, camera is mounted *upside-down* in front of the adapter, thus capturing the *correct* image on tape/outputting it on the production monitor.

Therefore no problem with flipping in post - it simply is not necessary in my case.

Also, this way you can combine any number of segments on tape shot with and without the mini35 adapter. They all will have "normal" image orientation, because without adapter, the cam is obviously not mounted upside down.

David, you sure can introduce the flip-switch in your capturing software, but then you're assuming that the whole tape is shot one way or another - say, with mini35 adapter - which may not always be the case in practice.

Microcrystalline focus screens?
 

I'm getting hints that NO vibration might be necessary with Minolta focus screens made with microcrystalline technology.

Supposedly their grain is so small, camera can't resolve it. Thus no need for oscillating the ground glass.

Does anyone know which of Minolta focus screens made with microcrystalline technology is CLEAR (unmarked) and how to buy it?

Hi Alex,

Re- Minolta screens.
I ordered a Nikon unmarked GG and meanwhile got my hands on a Minolta screen - type PM 90/70.
I don't know if it is crystelline technology but it is remarkably grainless with virtually no hot spot.

Problem is I can't get one without markings. This one I got is the clearest I could find but has a faint circle in centre. Good images though.

Circle might disappear if I blur GG

Flipping the camera to orientate everything is definately the way to go for on set monitors. editing etc.- much less hassle eventually.

Of course here in Oz, we don't have to do that because everything is upside down anyways

regards

Vincent

This is my first post. I am working on a static 35mm adapter for my GR HD1 and I was wondering if anyone has had any experience with making a Bossreen type GG? It was referred to in an earlier post and described as not having any visible grain. It is simply two pieces of optical glass sandwiched together with paraffin.

These threads and all of your posts are an amazing resource.

I hope I can help contribute to the process.

Alternate Thread
 

You may have already found this, but http://www.dvinfo.net/conf/showthrea...threadid=23827 contains some discussion on making your own bossscreen. I believe that they found it was too difficult to get an even surface without bubbles, etc. and gave up. (perhaps you'll have better luck?)

Heh, by the way, Alex - I tried using my camera upside down with my latest adapter and discovered that, although the image gets flipped (recorded correctly to tape), all of your on-camera viewing mechanisms get flipped too (eyepiece, LCD). This effectively flips those guys TWICE so they're still rotated. You still need a separate monitor which is not upside down to view the 'correct' recorded image. Which you already said you're using. Just passing along the findings of my feeble brain -- I had somehow not done all the flips right and thought the upside-down camera might make the existing camera completly usable, even without additional monitors, but that's not the case. Still good to not have to flip in post.

Still looking for a non-external monitor way of viewing a 'correct' image, as when moving quickly, its hard to drag a ton of extra equipment around with you. (Recently shot at the top of a 2,000 foot granite rock... glad I didn't lug an external monitor!).

Jonathon: I always use external monitor, so on-cam eyepiece/LCD do not concern me usually...

Roger: Bosscreen - I bought the piece and ditched it. There's no grain per se, but instead there's smooth "lunar surface"-like imperfections, plus very bright little bubbles. All this is not visible (almost) with the naked eye, but for our application it renders Bosscreen unusable...

Anyone knows Minoltas? What Minolta focus screens have no grain/no markings? Rumor has it that some Minolta GGs do not even need to be oscillated as their grain is super-fine already. But which ones?

Thanks for the info on Bosscreen. I won’t waste time with it.

I did read on another thread that you can flip the flip out LCD image on most cameras with either a small magnet or inserting a pin.

Does that work with the JVC HD cameras?

BEST NEWS SINCE SLICED BREAD: GRAINLESS GG DISCOVERED!!!
 

Finally!

Forget aluminum oxide and UV filter glass.

Forget agus35, vibro35 and alex35.

Welcome to the Minolta Focus Screens - when used as ground glass (GG) in STATIC mini35 adapter (originally aldu35), they do NOT produce any visible grain... even with HD resolution!

To recap... my experiments proved that neither homemade GG from UV filter, nor Bosscreen, nor Nikon focus screen is suitable as mini35 adapter's GG for HDV cam - because of the grain.

My idea (not really mine) then was to vibrate the GG so the grain would blur to the camera, while image is still sharp (as image is not moving). Problems with vibration is:
- Well, vibration. It's hard to effectively isolate vibration to the GG only, while...
- Maintaining GG strictly parallel to the cam's lens and to the back of SLR lens;
- Batteries, switch needed - inconvenience relative to power-less static version.

Interestingly, someone has been e-mailing me incognito, inciting me to try Minolta focus screens as GG. However that incognito person did not say which focus screens should be used.

Through quite a bit of research (my posts to different mini35-related boards on this forum were fruitless) it looked like Minolta Screen G for Maxxum cams is what I'm looking for.

Yes and no.

Yes because is produces NO visible grain!

No... because it does have, albeit faint, markings in the center.

So all we need now is the final push: to find Minolta focus screen that uses the same technology as type G for Maxxum (millions of conus lenses) but WITHOUT the markings.

Just clear matte Minolta focus screen.

Anyone?

If you can't find a focus screen without the center markings, is it possible the the post-process the markings away? How faint are they?

maybe type C?
 

Alex, look at al minolta's at bhphoto

http://www.bhphotovideo.com/bnh/cont...minolta+screen


i think the one we are searching, without marks, is the type C. what do you think?

ciao

Hi Alex, etc,

as previously posted Minolta screens are great- but couldn't find one without markings- sounds like this Type "C" is the answer. However there is hint of grain

Here is another twist.

I actually like some grain in GG- but because it is the same in every frame looks wrong.

In film of course one has grain but it is different pattern in every frame- so distincly a "film look".

What about moving the GG screen slightly, and slowly so that although the grain is not blurred, it is different in every captured frame??

Vincent

Seems like the screen type C is *not* made with the same microlens technology taht produces grainless image? Judging by price, microlens-made type G is also 50% more expensive than C.

David: the markings are faint on the image that was displayed online when I bought the screen, to the point that I thought it was a clear screen. In reality they are engraved into the flat surface (the G screen is acually a fresnel, so it does have a curvy side that faces the cam in my mini35 adapter). I was hoping that the marks are painted and thus I could remove them - but this does not seem to be the case.

Any thoughts on the BeattieScreens? They purport to be way brighter and from their descriptions look like a fresnelized GG like you describe of the Minolta. They definitely have clear (in about 1000 different shapes - mounted in frames, etc.)

Beattie Link
 

Alex,

I was actual suggesting a software filter to remove any distortions the markings produce in the output stream. This would greatly depends on who damaging the markings have on the final image.

David, I would not rely on software for that... If we are panning, then the software may have enough info to remove the "obstructing" markings; but what if the image is static?

BTW, I did understand your question correctly, then jumped through the thought as above and posted my reply accordingly. Sorry, too many things going on, I'll try to be more coherent next time :)

This is turning into a great conversation!

heath

I found a microlens focus screen without any markings here:

http://www.intenscreen.com/products_...mat_contax.htm

I ordered it from B&H for $79.95 here:

http://www.bhphotovideo.com/bnh/cont....x=4&image.y=5

I will let you know if it works when it comes in. It is a special order item which means no return and it will take two weeks to get here.

Roger

Focus Screen
 

How about finding a grainless focus screen for a medium format camera (with marking or without) ? It may be big enough that breaking off only a portion of it without the marking would work well. What do you think?

Right now, for testing purposes I'm just using a piece of plastic diffusion cut to the size of a 35mm frame and stuck flushly against my condenser. Could a similar piece of a focus screen work? If the screen was big enough.

John

John,

I was trying to go that way, but Minolta support could *not* tell me which of their larger focus screens are made with microlens technology. left a message with Minolta engineers but wouldn't hold my breath for them returning the call...

Alex,

This is very interesting. How is this project coming along? Have you heard from Minolta? Would not Nikon or Canon have similar screens? I'm surprised that here are a lot of Canon people on this site. Maybe someone could help.

Mike

Mike and all,

Minolta does not seem to have any acute matte aspherical microlens screens *without* markings and/or grid.

I asked them to produce a custom focus screen for me without markings for $$$, but their Japanese guys are not interested.

According to Minolta engineers, said focus screens are made in 100,000s at once for years in advance.

Originally these screens did NOT have markings. However they were etched later on all of them.

And no, minolta did not keep any of the original unmarked focus screens that could be traced...

One more bummer: there's a very small, faint circle right in the middle of the focus screen. It seems to be INSIDE the plastic, having nothing to do with markings per se.

So even when markings are not there, the circle will still show.

I do not know whether the circle is part of the focus screen design or a fresnel artifact or what.

All in all, best shot seems to have this focus screen custom-made (in which case I'd prefer it as a circle 49mm in diameter so it'd fit inside the 52mm filter ring) by some optical company that possesses the microlens technology.

Any leads?

Some Leads
 

Reflexite Display Optics
1300 Mt. Read Blvd.
Rochester, NY 14606 USA
585-647-1140, fax 585-254-4940
http://www.display-optics.com/pdf/focusing_screens.PDF

Also, Olympus seems to use microlens focusing screens too - maybe someone can track down a clear one?

http://focuscamera.com/prods/964590614.asp

HI Guys

By the look of it they will do custom orders, over at the Static thread they are looking into it. I think it canbe made fine enough for HD (which might fit in with the Static thread order):

http://www.dvinfo.net/conf/showthrea...&pagenumber=21

(if it comes out with the wrong page, times the page nuimber by 2 or 4, I'm using 50 or 100 posts per page)

They also found a very fine Nikon type D, unmarked matte screen:

http://www.dvinfo.net/conf/showthrea...&pagenumber=23

Wayne.

Unfortunately the grains on the Nikon type D are too large for HD use unless vibrated.

Attn Roger Collier
 

Roger, what about the GG you ordered - did it work? No markings? Please advise...

Microlens focus screen from B&H
 

Alex,

The microlens focus screen came in and it has no markings whatsoever. I am having a little trouble getting my GR-HD1 to focus on it. I have a +10 macro between it and the camera. It looks like I will need to add one more +10. I’ll have to order one.

I did make an interesting discovery though. Try this. Just screw a +4 or +10 filter on the front of your camera. For close-ups you get instant short depth of field. The depth of field shortens with the increase in magnification of each filter. It is a pretty dramatic effect. If you try to zoom in all you will get is a blur.

I will post a clip when I get another +10 macro.

My earlier post:

I found a microlens focus screen without any markings here:

http://www.intenscreen.com/products...rmat_contax.htm

I ordered it from B&H for $79.95 here:

http://www.bhphotovideo.com/bnh/con...4&image.y=5

Roger, many thanks for the fast reply.

I'll order the microlens GG from B&H today.

> I did make an interesting discovery though. Try this.
> Just screw a +4 or +10 filter on the front of your camera.
> For close-ups you get instant short depth of field.

Actually, even without the macro-lens, if you just move to the telephoto end of your HD10 lens, the depth of field becomes rather shallow.

However, I have a huge problem with that as folows:
1. Servomotor that controls HD10's Focus is exceptionally bad and does NOT allow hitting any repeatable marks.
2. This method forces me to use an unknown lens angle.

So if I wanted to have a shallow DOF in the scene where I use say 50mm lens and focus racking, it seems that the only way to go is a mini35 adapter as it resolves both problems ## 1 and 2 as above.


> I am having a little trouble getting my GR-HD1 to focus on it.
> I have a +10 macro between it and the camera. It looks like I
> will need to add one more +10. I’ll have to order one.

What size is your GG then? With +10 macro on my HD10, I can focus all the way into the GG that is about 1/2 size of a 35mm film (not that I need it to be that small, of course).

intenscreen
 

Roger and co -

I looked into an Intenscreen custom order over on the static thread, but got stuck when they asked me for a focal length spec for the screen (didn't know how to factor in all the glass), and then I got sidetracked on an Optosigma gg.
For all I know the screen focal length might not even be an issue, but I didn't have one to specify or a screen to test. In any event Roger, the increased magnification, though probably needed, may not fully solve the problem.

These lists sure have their effect; as far as I can tell, Hoya +10 filters are out of stock across the country - everywhere I've called has them backordered. Thefilterconnection.com said the distributor THK is waiting on the next container ship. Meantime, you might want to stack a few smaller macro's to check if you can actually achieve focus on the screen. I'm very interested and would love to move forward with a custom order if it works out and we can enough people in - please let us know what happens.

and... what are your thoughts on mounting it? Does cutting it to fit a round fiter ring seem possible?
thanks -

- Damion

Guys,

Has anyone tried a white rubber balloon tightened? I remember we tried that once to adapt lenses to a small miniDV camera and it worked like a charm. It was a really temporary fit but it could work, I doubt there is grain...