SGpro doubts

[Barry_Green]

If anything I suspect the SG is decreasing the technically accurate DOF, and the Redrock even more so.

How could that be so? Lenses are intended to project their images onto a perfectly opaque surface, whether film or CCD or CMOS. If "apparent DOF" bcomes less due to more-transmissive ground glasses, the ideal film simulation should be achieved with the least-transmissive ground glass.

Look, I'm with Kholi in that there are some tradeoffs happening somewhere, and it'd be nice to know what they are. Doesn't make it "bad" but it means we want to know what's going on. For example, we know that the more-transmissive ground glasses appear to reduce the "apparent" DOF. That's a tradeoff we need to know about. And perhaps why the Brevis places such an emphasis on larger-than-cine frame sizes -- using the larger frame size gives shallower DOF, so perhaps the combination of more-transmissive GG + larger frame size gives a "net" effect of 35mm cine-style DOF.

Again, all fine and dandy, as long as we know how it works and can find out when it won't. For example, PL lenses aren't made to cover the 36x24 frame size, so if someone's using a Brevis with PL lenses they're going to *have* to zoom in to 24x18, and when they do so, that CF1L is going to deliver an apparent DOF that doesn't match what a cine camera does.

Some people care. Some don't. Some people are perfectly content to shoot on a PD150 in 60i, and "convert" to 24p in post; others of us find that unacceptable. Some are content to use a spatial-offset sensor, others demand only using "native pixel" sensors, others are happy with a Beyer pattern sensor. ALL of them have implications that WILL affect you. My mantra has always been: find out how it works, and learn what the tradeoffs are, and then you're prepared to make an intelligent decision on whether it'll work for you.

I might be worng about this but my understanding of DOF is that to some extent its arbitrary where you set the circle of confusion that determines when something is out of focus, and that depends on what the expected viewing conditions are.

Exactly. Circle of Confusion size is one of those things that people want to believe in as a matter of dogma, but it's lost most of its relevance because it is entirely dependent on viewing sizes. The larger your intended viewing screen size, the tighter your Circle of Confusion needs to be. Far from being "completely off-base" here, you're spot-on.

 

[Lenilenapi]

Barry,

Before I begin this tirade I want to make clear that I don't have any attachment to the Brevis in particular. i own a Brevis, an SGPro and a Letus, use them all and like them all and appreciate their different qualities. I seem to get roped into defending the Brevis over and over because some people keep slamming it on these boards due to mistaken understandings in my opinion. It just bugs me. I started talking to Dennis a year ago because I had problems with some of the design on then first adapter i bought. That led us into a few long conversations about how these screens act that were fascinating and surprising to me. I think both Dennis and others have sometimes described them in ways that seem like they "create more light", but that was just poor explanation.

1. You've misread the discussion about apparent DOF and gotten the observations about the Brevis vs say SGPro backwards. That explains why it seems illogical to you.

The Brevis CF1 as a more-transmissive GG exhibits GREATER DOF than the denser GG's like SG or especially the Redrock . Generally the more scattering of light in the GG (i.e less transmissive, denser screens) the less DOF as it seems that the there is more scattering in the circle of confusion. I hope that is clear.

2. The issue of greater or lesser scattering of light in the GG accounts for all of the phenomena we are arguing about in an entirely logical way to my mind. I believe it is why we tend to see no reaction to the wider f-stops on the more transmissive GG because we are looking at the image from a central point a distance removed form the film plane. Less light from the edges is scattered in our direction.


3. Yes - In film - Lenses are designed to focus on an opaque surface that does not itself scatter light at all. That is exactly the point. Exposure takes place on the film plane with no regard to how much light might be scattered by a GG toward an observer 3 inches further down the line.

Likewise DOF is a function of the optical qualities of the image produced on a film surface that does no additional scattering of light. That's why we can measure exposure and DOF objectively in film - because the film itself is not affected by the light scattering of a GG or the angle in which it is viewed by an observer ( in this case the observer is the video camera.)

4. However the adapter is a different case. The scattering qualities of the diffusion screen

- create an image in the first place

- affect its apparent DOF by scattering the circle of confusion

- affect the exposure as it is viewed by a video camera aprox 3" away.

5. The characteristics of the GG affect all 3 of these parameters in multiple ways.

If the GG is too transmissive you don't get an image at all, or it has too much of a hot spot, it vignettes, it probably doesn't handle highlights well etc. (This is what Kholi seems to accuse the Brevis CF series of doing.) As it gets denser it can begin to look better and better until it gets so dense that eventually the image deteriorates and diffuse too much.

Once a screen has achieved the qualities neccessary for creating an image that is photographically acceptable - i.e. No hot spot, a full range of grey scale, a pleasing image - then different screens can be designed for different qualities.
Some for greater transmission, some for prettier bokeh, some for more scattering of the circle of confusion (thus lower DOF), sharpness, eveness of the field, pretty diffusion qualities etc. Those are the differences between the looks of the adapters on the market.

Each maker has experimented with different materials to make what he thinks is the best trade off of qualities.

I believe in the CF1 series Dennis simply tried to make a screen with the greatest transmission that still had thorughly acceptable photographic qualities. Except for a few people like Kholi most users agree that the image form the CF1L & LE produce sharp quality images with no significant artifacts. He spent an enormous amount of time and money looking for these materials and designing them carefully - Throwing away ones that vignetted or artifacted. He is continually working on that.

That doesn't mean that the CF1 series has the most pleasing Bokeh, DOF or anything else, just that it has an acceptable quality photgraphic image with maximal transmission.

Exposure - After designing it he was probably as surprised as anyone to notice that wide f-stops didn't seem to be noticed by the adapter. There is no magic, voodoo or designing talent in this, it is part of the optics of a more transmissive screen. It probably has to do with less scattering of light from wider f-stops that we don't see from the position of the video camera. It ought to vignette , but it doesn't. That was Dennis achievement and he worked hard to pull it off. The designing talent is that he created a fast screen that made a good image. Other screens exhibit some of this exposure phenomena but none as much because the others aren't as transmissive.

Its no g-d d-mn big deal. Its just what happens. I cannot fathom why we are arguing about it.

7. Are there trade offs - Yes - of course - To my mind the CF1 series is kind of the most basic screen you can have. It is sharp, it doesn't flare like say the Pro35 or the Redrock do ( which can look like a Promist under some conditions) and as far as DOF goes, my guess is that it is the closest to film because it has the least additional scattering.

i've never compared DOF in an adapter to DOF in film and suspect that it would be hard to do technically, but my personal guess is that as the screens get denser progressively in the Letus the SG and the Redrock the DOF becomes lower than in film.

However the CF1 series is not neccessarily the most pleasing. To many eyes a more diffuse image that scatters light more tends to look more filmlike. No doubt the very nature of the GG surface plays a role in what is pleasing. So lots of people prefer the look of more diffuse screens.

They all have their pros and cons. None of them are actually like film or play by the same optical rules as film , or should be judged by exposure principles that apply to film.- they are just better "fakes" . The more "filmlike" adapters screens in fact are actually far more diffusive than film, they probably also have less DOF than film.

Yes the CF1 series has trade-offs but those trade offs don't mean it can't produce a photographically professional quality picture. It clearly does.

If you think the trade-offs on the CF1L are not pleasing or produce artifacting, point them out if you wish, but don't claim it can't look good because it makes no scientific sense to you.

8. Re: the 35mm screen size. Dennis didn't design around a 35mm SLR frame because of DOF issues or anything else. He simply figured as many of us do that if you are using 35mm SLR lenses you ought to be able to view the full size image those lenses were designed for.

This makes total sense. The Redrock also does this and the Letus will when they correct for HVX offset problems. To me this makes more optical sense than zooming in on the center of lens that was designed for a larger field of view and wasting the optical information. I know you are very concerned with emulating Academy framing (what about Super 35?, Vistavision, Cinemascope? they all look like movies to me) Regardless though - you can zoom in if you like.

To quote Barry Green:

"find out how it works, and learn what the tradeoffs are, and then you're prepared to make an intelligent decision on whether it'll work for you."

That is all we are trying to argue for here.

Lenny Levy

 

[Kholi]

Hey, you guys are the ones getting upset and flingin' around the term "troll". I specifically said, and keep sayin', that there's gotta be an obverse effect to it. I think it's a negative one just like you think not having SLR frame sizes is a negative one. The "problem" is that I'm not praisin' the oddity and callin' it an advantage. Til' we know what it is, I don't see it as an advantage. You might, but at least let people know that you have no idea what the obverse effects are because you and the rest of us really don't know. You're speculatin' as much as I am, but there's no proof on either side of the fence. You're quotin' Barry, but disallowin' me to seek that knowledge? Backwards kinda.

So when someone puts it through the paces to find out what's goin on-- that you and others just might not see-- that's when we'll know the trade and be able to judge. Yeah, I do think that it's pretty much decreasing the ability to control highlights. Even Dennis (quote him) says that he wouldn't go without a Mattebox y Filters at this point. Although if the Redrock or another Mattebox were out right now I wouldn't go without them anyway, everyday, for every thing.

On about Frame Sizes: Whatever floats. But the one thing I've noticed is that anything outside of 36x24 is overtly shallow and strange looking. The only term I can think of is that it doesn't look "Film-like" in a professional sense. Probably just trained to see it, but the FOV just doesn't look proper. And only gets better as you zoom in on these things. Edit here -- I was one of those people that didn't care about the Academy, VistaVision formats. The more I keep watching movies, the more I keep "seeing" what's different. The stuff just isn't as shallow as what I see here.

If there's anything that all of these adapters are about to gain it's the ability to zoom in to a "traditional"-- something some of you may or may not care about-- frame size to be able to use PL lenses and such properly. That's thanks to the flip modules.

The Letus already has it locked down, although X/Y offset peripherals are coming (as stated in another thread) for those that want the SLR frame size.

I still can't fathom why, though, because utilizing any full frame size on any lens increases the chances of edge softness. The further you dig into the good part of the glass, the better off your image is going to be. Or, is that theory just not realistic?

 

[cordvision]

On about Frame Sizes: Whatever floats. But the one thing I've noticed is that anything outside of 36x24 is overtly shallow and strange looking. The only term I can think of is that it doesn't look "Film-like" in a professional sense. Probably just trained to see it, but the FOV just doesn't look proper. And only gets better as you zoom in on these things. Edit here -- I was one of those people that didn't care about the Academy, VistaVision formats. The more I keep watching movies, the more I keep "seeing" what's different. The stuff just isn't as shallow as what I see here.

You cannot distinguish if a Academy or VistaVision "sized" GG was used without knowing the focal lengh/aperture it was shot on. The FOV can look the very same and you can match the DOF too by using a higher fstop when shooting VistaVision vs Academy.

 

[setarcos]

1. But the one thing I've noticed is that anything outside of 36x24 is overtly shallow and strange looking.

2.I still can't fathom why, though, because utilizing any full frame size on any lens increases the chances of edge softness.

1.Not all SLR lenses cover the 24/36mm equally. Some hardly do, others have room to spare.
The 1.4/35 Nikon does a perfect job on the 24/36 frame with sharp fall-off outside the frame while 1.2/55 covers a much larger frame (35/50???) and only at the widest aperture.:undecided
Some cameras are 16/9 while others are 3/4 (SLR frame is 2/3!). Lens and GG should provide enough to choose when you zoom in to fill the frame.

2. Each video camera needs an optimum distance to focus on the GG.
The larger ones (DVX, PD, HVX, etc) will need a longer distance than the smaller ones due to their own lenses.
Test YOUR camera by focusing on a business card (marked inside with 24/36 frame) and take note of the shortest distance (and zoom) where you can get a sharp image from corner to corner (adjust light levels to get to wide open aperture)
Get closer and zoom out and observ focus. Make notes of focus/zoom settings.
This should solve the distance where the adapter should mount to obtain a corner-corner sharp image.
I hope my2c helps.:thumbsup:
Best,
Dan

 

[Lenilenapi]

1. Soft cornering on wide lenses is a good argument for being able to zoom in on the GG and we all appreciate the ability that the flips have created for us. However it just means you need an even wider lens to get a wide image so you are back to the same problem at greater expense. Those are trade off issues. I doubt you can make a good optical argument for the superiority of only using the center of the glass on a GG, but that's beyond my expertise.

2. Re highlight rendering - Most of these adapters have trouble with highlights to some extent, the question is how bad is it and what is acceptable to you. Highlight rendering is a significant part of what makes the image pleasing. The Redrock flares highlights as does the Pro35. I've seen strobing highlights on some. The Letus has its own problems with highlights (look for them Kholi they are there). I have seen unacceptable highlight rendering in one of the older Brevis CF2's. I don't recall loving how the Brevis CF1L handled highlights but it was not unnacceptable to me. The SGPro seemed like it did a pretty good job overall - but they all have potential problems. These are anecdotal observations by me . I don't want to make firm statements because I don't have frame grabs and haven't studied them under lots of circumstances carefully and don't want to get into any more arguments.
Regardless of those problems all of these adapters put out good pictures most of the time. If there was a big gotcha on the Brevis it was have stood out by now.

3. One more word I thought about the Brevis GG's last night. From my conversations with Dennis I infer that he designs these things, he doesn't just find a material that he likes. That's why he's constantly tinkering and coming up with a GG to fix say wide angle or telephoto vignetting issues. I don't know what he's doing - it's proprietary - and maybe he's just doing a good PR job, and blowing smoke up my butt. But if he is tinkering with the optical qualities of the GG then that could explain how he has managed to get a decent image out of a less transmissive GG that ought to be vignetting , and that also suggests why maybe the wider f-stops don't affect it as much. That's my 2 cents and its just an idea. Letus may be doing something like this too. The spinners cannot do this.
Whether the resultant image is good or bad to your taste feel free to comment on here. If you find a stunning flaw- post about it.

But I keep posting about this because I find it disturbing to keep slamming the guy for doing something you don't understand. (Maybe its a reaction to the way he markets). Nevertheless, I think he should be getting props for exploring this area and coming out with ever new products whether you like them or not.

Lenny Levy

 

[TimurCivan]

That's different, you can zoom in and focus to a person's pupil, for example, then zoom out and you know you're still in focus. But I had a rude awakening one time when I was using the viewfinder's GG to focus to a very close object and it appeared sharp in the GG but I was under the minimum focus of the lens and the footage turned out soft. This was on a high end Super 8 camera and it would probably be a non-issue on an Arri/Panavision ground glass. The point I was trying to make though is that the ground glass is only representative of the way the film is going to catch light and it can be off from the truth.


Marco

THis is why you use a tape measure and lens markings. Im not doing these things for my health or to seem cool. These conventions are in place for a reason. You should also get a collimeter, and back focus your lenses, this way you know the lens markings are correct, and then have your GG adjusted till its accurate too.

Tim is right, the GG should be accurate, but on a feature i 1sted for 3 months ago, rented an ARRI BL4 that was "slightly off on the Tape measure" but sharp in the GG. the GG was true. However the BL4 was truly and royally F***ed. Ruined 3 days of footage. When stuff doesnt line up, theres something off......

 

[Kholi]

You cannot distinguish if a Academy or VistaVision "sized" GG was used without knowing the focal lengh/aperture it was shot on. The FOV can look the very same and you can match the DOF too by using a higher fstop when shooting VistaVision vs Academy.

Show me. You need to stop down a lens VERY FAR to emulate the same DOF and that's not a possibility for everyone no matter which adapter you use. Anything wider on my camera looks strange to me. That's what I'm saying. When's the last time anyone actually used VistaVision? Not on DVxuser, I'm talkin' about an actual Film/movie.

1.Not all SLR lenses cover the 24/36mm equally. Some hardly do, others have room to spare.
The 1.4/35 Nikon does a perfect job on the 24/36 frame with sharp fall-off outside the frame while 1.2/55 covers a much larger frame (35/50???) and only at the widest aperture.:undecided
Some cameras are 16/9 while others are 3/4 (SLR frame is 2/3!). Lens and GG should provide enough to choose when you zoom in to fill the frame.

2. Each video camera needs an optimum distance to focus on the GG.
The larger ones (DVX, PD, HVX, etc) will need a longer distance than the smaller ones due to their own lenses.
Test YOUR camera by focusing on a business card (marked inside with 24/36 frame) and take note of the shortest distance (and zoom) where you can get a sharp image from corner to corner (adjust light levels to get to wide open aperture)
Get closer and zoom out and observ focus. Make notes of focus/zoom settings.
This should solve the distance where the adapter should mount to obtain a corner-corner sharp image.
I hope my2c helps.:thumbsup:
Best,
Dan

That's even more reason to stay zoomed in further?

1. Soft cornering on wide lenses is a good argument for being able to zoom in on the GG and we all appreciate the ability that the flips have created for us. However it just means you need an even wider lens to get a wide image so you are back to the same problem at greater expense. Those are trade off issues. I doubt you can make a good optical argument for the superiority of only using the center of the glass on a GG, but that's beyond my expertise.

2. Re highlight rendering - Most of these adapters have trouble with highlights to some extent, the question is how bad is it and what is acceptable to you. Highlight rendering is a significant part of what makes the image pleasing. The Redrock flares highlights as does the Pro35. I've seen strobing highlights on some. The Letus has its own problems with highlights (look for them Kholi they are there). I have seen unacceptable highlight rendering in one of the older Brevis CF2's. I don't recall loving how the Brevis CF1L handled highlights but it was not unnacceptable to me. The SGPro seemed like it did a pretty good job overall - but they all have potential problems. These are anecdotal observations by me . I don't want to make firm statements because I don't have frame grabs and haven't studied them under lots of circumstances carefully and don't want to get into any more arguments.
Regardless of those problems all of these adapters put out good pictures most of the time. If there was a big gotcha on the Brevis it was have stood out by now.

3. One more word I thought about the Brevis GG's last night. From my conversations with Dennis I infer that he designs these things, he doesn't just find a material that he likes. That's why he's constantly tinkering and coming up with a GG to fix say wide angle or telephoto vignetting issues. I don't know what he's doing - it's proprietary - and maybe he's just doing a good PR job, and blowing smoke up my butt. But if he is tinkering with the optical qualities of the GG then that could explain how he has managed to get a decent image out of a less transmissive GG that ought to be vignetting , and that also suggests why maybe the wider f-stops don't affect it as much. That's my 2 cents and its just an idea. Letus may be doing something like this too. The spinners cannot do this.
Whether the resultant image is good or bad to your taste feel free to comment on here. If you find a stunning flaw- post about it.

But I keep posting about this because I find it disturbing to keep slamming the guy for doing something you don't understand. (Maybe its a reaction to the way he markets). Nevertheless, I think he should be getting props for exploring this area and coming out with ever new products whether you like them or not.

Lenny Levy

1. You can't go wider with Pro Glass, why go wider with SLR? Move the camera back if you need to go hyper wide for whatever reason. Or, use a 17mm lens?

2. I haven't seen anything displeasing about the Letus, but I'm sure someone could which goes to show you: We all see something different. I'm not about to tell you that you're crazy, I'll just ask you to post it and show it. JUST like I asked Tim Naylor to post his findings with edge softness. If I see something wrong with an image, I post about it or show an example and STILL get reamed because you think I'm "slamming" something. I'm just callin' what I see.

3. Why do you think that a Spinning Ground Glass adapter can't do that? I can say that perhaps they won't do that at this price point. But, rest assured that the same light loss, edge to edge, and overall sharpness can be applied to the spinning method... remember I said that. Now, you say I can post about a "stunning flaw", but when I post about the super soft right side of the frame you call me crazy when I can point out a host of people that see it.

Ought not to decide for me who I should be givin' "props" to. It's my choice to want to know how and why. If I didn't want to know these things I'd just buy whatever, whichever at whenever time. I wouldn't chance to build my own computer or deconstruct my HVX200. If you're fine with what it is and choose to use it, keep doin' so. Nobody's stopping you, nobody's going to dislike you for it. But, I'm not slamming anyone or anything in these discussions. I've simply pointed out an image flaw I've seen with the Brevis and what I think about the GG and this whole "light efficiency" debacle.

 

[jenningsp]

These are anecdotal observations by me . I don't want to make firm statements because I don't have frame grabs and haven't studied them under lots of circumstances carefully and don't want to get into any more arguments.

this overly careful way of writing is becoming too common in the adapter forum. can't we just accept that the SGpro is the best adapter and everyone else who bought a different one is stupid and i am great for being able to see that even though you mightn't be able to see it right now as soon as someone points it out you'll be able to see it so now that i have pointed it out you all realize that your lives are worth nothing but never the less the brevis looks like crap the letus looks like crap the m2 looks like crap the sgpro is great you all suck?

in 3-5 business days when my paypal money from selling my old adapter clears, i will be the proud owner of an order form saying my SGpro will be dispatched in 4 weeks

i am infallible!!!!!!!!

 

[Lenilenapi]

Amen jenningsp!

Timur, Have you used a collimator on your adapter GG. I've been planning to get by a camera shop and try it. Now I will rush down there. That's great news.

My local repairman told me it wouldn't work and won't let me try his. It P'sdme off and I'm not returning to that character, but another shop said sure come on down.

Lenny

 

[rawfa]

Oh, brother...I did not expect the this thread to go this way when I started it.
Alls I know is that pretty soon daddy's gonna have a brand new sgpro to play with.

 

[TimurCivan]

Amen jenningsp!

Timur, Have you used a collimator on your adapter GG. I've been planning to get by a camera shop and try it. Now I will rush down there. That's great news.

My local repairman told me it wouldn't work and won't let me try his. It P'sdme off and I'm not returning to that character, but another shop said sure come on down.

Lenny

Im notsure it will work.

But the Sgpro can be fine tuned for back focus while attached to the camera, and running, with lens on. you set the lens to infinity, hook it up to a HD monitor, and adust till the image is RAZOR, at infinity. then your numerical values on your lenses are correct.

 

[Tim Naylor]

That's different, you can zoom in and focus to a person's pupil, for example, then zoom out and you know you're still in focus. But I had a rude awakening one time when I was using the viewfinder's GG to focus to a very close object and it appeared sharp in the GG but I was under the minimum focus of the lens and the footage turned out soft. This was on a high end Super 8 camera and it would probably be a non-issue on an Arri/Panavision ground glass. The point I was trying to make though is that the ground glass is only representative of the way the film is going to catch light and it can be off from the truth.


Marco

I grant you that the eyepiece on a film camera has nothing to do with exposure but in terms of framing and focus it has to be dead one. Your super 8 camera needs to go the shop, the moment it's markings and eye focus don't agree. How do you know which is off?

Viewfinder optics have to be accurate focus wise or we could never do tape/eye tests to check the accuracy of our lens markings or eye focus on set (which contrary to what you may think, is done quite often). If the tape measure and the viewfinder don't agree - it's the lens or the viewfinder. Eithercase, the rental house/owner has to fix it. Anyone who accepts such a discrepancy is an amateur at best or knows little about what to expect from film cameras.

 

[Tim Naylor]

Uhm, Hien Le explained it. None of you have anything to say about it. I'd like to add that the Le brothers DO have engineering backgrounds.

It's not that it's too good to be true, it's just like you BOTH said: there's a trade-off.

Find the trade-off, make people aware of it, then you have your end of story.

And don't act like I'm the only one that asked the question, there are two other's that openly want to know what the trade-off is and how it works.

Just like "no one" could see the super smear on the sides of the image. But there's plenty of people seein' it now. Although really? If you can't see it, then it doesn't matter what you use.

I went to the link and it didn't quite explain how there's no response in the lower stops of a Brevis (1.4-4.0). That's all I'm looking for.

 

[Tim Naylor]

Tim if you read through that long thread there were a couple of good possible explanations offered. if I can find mine I'll email you , but i don't want to redo the whoile thing again.

One person who posted there observed that if you have a 35mm SLR look through the viewfinder as you close down an f1.4 lens and you may see that the first few f-stops don't seem to show the expected full stop of light change each. Gradually the difference per stop becomes more noticeable. I believe this is the same phenomena, but it may vary depending on the GG of your still camera. If you exposed film in that camera you would get an absolutely predictable full stop though.

Lenny

What would the threads be under. I'm tempted to pick up a Brevis because of its low light capabilities but I just have to know what makes it do what it does.

 

[Lenilenapi]

Tim,

"It probably has to do with less scattering of light from wider f-stops that we don't see from the position of the video camera. It ought to vignette , but it doesn't."

That's my best shot and it makes enough sense to me but I'm not an optical engineer. The light from the wider part of the iris when wide open doesn't scatter toward the viewer who is in the center looking at the lens from a few inches away. This is different from what happens to film exposed at the film plane. My only guess is that Dennis has done something with the design of the optics or the GG itself to mitigate the vignetting that you would expect in that scenario, but that's the best I can do. It works - that's really all know, but it may not be as pretty as the SG you have been using for along time. If you need the speed especially with a zoom though...

The fact that you can see something very similar just looking at the GG in a 35mm camera tells me its related. Make sure you hold the button that allows you to actually see the light change in the viewfinder BTW.

I haven't seen the DOF response Dennis mentions and that might puncture my own theory, but it works so I'm not freaked out by it.

I'm sorry this hijacked an SG thread BTW, just felt the need to respond to slams on the unit, especially when Barry misread the statements about DOF.

Timur, I'll let you know what my luck is with a collimater.

Lenny

 

[marco0782]

But the Sgpro can be fine tuned for back focus while attached to the camera, and running, with lens on. you set the lens to infinity, hook it up to a HD monitor, and adust till the image is RAZOR, at infinity. then your numerical values on your lenses are correct.

Adjust what exactly?

 

[Lenilenapi]

On the SG Rev2 there are four screws on the case that adjust the screens position at each corner. It works.

 

[marco0782]

Interesting, I thought they were there to open up the adapter. I'll take a look at that tonight, thanks Lenny.


Marco

 

[Lenilenapi]

There's two sets of screws. I seem to recall these were more inside.

Be careful - Wayne said be sure you turn them the same amount one by one until all 4 are done before testing. If you get off in the balance you'll throw the whole screen off angle and its hard to get back. Try just a quarter or a half turn each at first. And stay alert its very easy to forget what your doing. Can also email wayne for advice.

Lenny