Resolution of camera vs. using 35mm adapter

Forrest Schultz

Forrest Schultz

Active member
Now i hope that what i am about to type makes sense. if you dont understand what i am meaning, youll have to read it over a couple times.

We all know that with the new (semi-new) hd cameras: hd100 , hvx200 ect. that by using a 35mm there is going to be SOME loss in resolution due to the Ground glass. (factors include grit size, material, ect.) Point is, the camera without any adapter has a set resolution, and by adding the adapter, you lose some resolution, whether its a little or alot, thats not important, fact is, youll never gain resolution by adding a gg in the picture.

what i am wondering is, since once you add your adapter, you are now at the mercy of it in terms of resoultion... for my next point, I am going to use a analogy of resolution so instead of saying 1080 lines of resolution, ill just say 100% resolution. so 1080 = 100%, just for the sake of simplicity. Ok here we go:

so Camera A has a resolution of 100%

Camera B has a resolution of 80 %

now, adding a 35mm adapter on Camera A now brings its resolution to 75%. , given that 75% is all the ground glass is capable of. so we lost 25% of the resolution cuz lets say our gg isnt too good.

NOW! adding the same adapter to camera B, since the adapter has only a resolution 75%, also brings Camera B down to 75%.

Therefore, both cameras, even though one is 20 percent better than the other in resolution before the adapters are added, are now made equal because each has an adapter in place. THEN, Does this mean that one camera has an adavantage over the other? I say not.

even if Camara C has an original resolution of 120%, your adapter still is only going to give you a 75% resoultion.

Lets say Camera D has a pixel area of 3000x1687 pixels. and it has a 200% resolution. very big and nice picture. but then focus it onto your 75% adapter. Now all you get is a really big picture pixel-wise. but its resolution still only picks up 75%

do you get it now?

my point is this. If one camera is superior to the other, but lets say they are both above the adapters ability. are now made equal by using the same adapter. this can be a good thing. because it shows that you dont have to have the sharpest camera in the world because your only going to get as sharp as your ground glass. Am i right? i mean, i tested this myself, i have a cheap sony handycam i used for my 35mm adapter, and then i tested a network camera that is really sharp and has a resolution of 1440 x 800 at 24 fps, and by using the same gg, the picture lost alot of its sharpness, because i am limited by the gg sharpness, no matter how big i want my picture size to get.

If i am wrong, please let me know, and explain. OPINIONS arent important, facts are for this thread. so i hope no one gets hurt or anything.
 
is the grit size reffering to the size on the GG that the light "packet" hits, and then diffuses onto...similar to the way an ice cube tray collects water in compartments...only on a tiny tiny scale?

if this is the case - then the 9-24 micron sized pixel-cell of the CCD will become the weakest link (assuming you have a GG grit smaller than 9-24 microns)

right?
 
Well im pretty sure thats wrong, because if the glass reduces the resolution on one camera, it has to on any camera.... so infact, camera a's resolution would be reduced down to 50% resolution. the more glass you add to a camera, the lower the resolution is going to be, the actual camera's resolution doesnt change that.... the lens reduces the resolution no matter what the camera's is. Idk its hard to explain, but i've found this out the hard way between the dvx100 and a vx2000 when i used the same century optics fisheye lens on both of them....
 
Robert, you are correct too. I like the ice-cube tray anology, thats how i see it too. Anyways, but there is no adapter that allows the camera resolution to stay the same. there is always some drop in resolution, not matter how small. Ive never seen the resolution stay exactly the same as the stock camera. So what i can say is that if one 35mm adapter has a set resoultion, then it doesn matter what camera you put it on (resolution wise) as long as the camera has a stock resolution higher than that of your 35mm adapter.
 
There's more to it than that though. The codec also enters into the picture (literally!) HDV or other long-GOP codecs do not like spinning-ground-glass adapters, the texture of the ground glass plays havoc with their ability to encode, so the images get really soft, really fast.

I think in general you do have a point, I mean, in any system the better the lens you're using, the better the end image will be. And putting the same ground glass in any imaging chain is going to affect that imaging chain equally. The question is whether the ground glass's resolving capability is above the CCD's resolving capability.
 
There's also the issue of image size on the diffuser/focal plane. Some adapters use a 35mm SLR full frame (36x24mm), others a smaller working area.
 
maybe if i am wrong, but the camera is still recording in HD

you are only shooting the image on the GG and are in fact not losing resolution in terms of CCD but is at mercy of how well the GG shows the the image

so instead of thinking the camera lose resolution, can we think of it as which groundglass gives the most sharp image for a HD CCD

phally
 
Barry, you nailed it. yes

bklyndv , also nailed it, cuz the more you zoom in, the more you are enlarging the grain, and showing the limits of the gg

phally, definitly, i should have said it that way before. Your totally right, the camera never loses resolution, but your stuck with the resolving power your ground glass gives you. And as Barry said, spinning adapters make your image soft fast.
 
When it comes down to it, the resolution issue ranks right up there with both chromatic abbreviation and vignetting. I would love to see manufacturers use a standardized resolution test of some sorts.
 
this is a never ending battle guys


YES having a better gritt GG will give a sharper image, and yes youll lose less light, but watch how the bokeh changes significantly, going from an out of focus look to a diffused look.

everytime you go for sharper image, you loose less light but your depth of field suffers.

those that loose the most light have the niceest bokeh in my opinion and have the biggest grain, so you loose sharpness.
 
PaPa, thats exactly what ive noticed with my testing. More light transmission equals fine grit, butter better diffusion equals bigger grit. I can never tell where the compromise should be placed, between bokeh and light loss. As you said, some adapters that lose the most light have the most film-like bokeh.
 
thats why just go for something that you like

The biggest problem is everyones looking for hte best adapter, when in reality, they are either the same, or give one of these qualities more than the other.

so what you should really be looking for is which LOOK do you like? More light, but clearer bokeh, or more light loss and filmier bokeh?
 
.. ultimately its really a non issue.

it doesnt matter if the image resolution is limited by the adaptor no matter what the camera. the only reason this would really matter is if there was only a limiting adaptor(s) in existance, and one was to base there camera choice off using the only adaptor(s) available. however, better adaptors do in fact exist, and it would be silly to base the choice of your camera off of a limiting accessory. so to conclude that one does not need to have a higher resolving camera because they are going to shed its resolution with a limiting adaptor anyway is sensible from a low/no budget standpoint where only limiting adaptors are able to be aquired and one must be used, but from a production quality standpoint it is somewhat akward.

since ultimately (setting aside color fidelity and other image qualities brought about by lesne and codec ect.) the original question is in regards to final image resolution and clarity, and its limitations in production, ...we must look at what the limiting factors really are, and attempt to remove them. let us compare the original DV cam to the higher res network cam. out of the box the network cam has a substantially higer resolving power than the dv cam. it is not until we place the limiting adaptor on that the playing fields are leveled. so we recognize the adaptor as the limitation. with little rumination we can surmize that if we want to maintain a better image quality than a DV camera using the adaptor, we must simply use a better adaptor on the higher res network camera. therefore if we are to question the ultimate quality in resolution of a production we must look at the most sensible workflows and then draw our conclusions from there. if there is budget and workflow for a higher level camera, there is likely budget for a higher level adaptor to go with it. i would hope that one would think it silly to use a ferrari F1 in a race with volkswagon beetle rims and tires on it stating that there was simply no budget for the right outfit for the car. likewise , it would be silly to bring a VW beetle with the same wheels to a race when the fully outfitted ferrari is available to you. so in the search for the best resolution we can safely take the best resolving camera as a good choice. and as mentioned by previous posters it is when we start looking at accessories such as an 35mm adaptor that we need to make an equally wise choice, and choose a higher resolving adaptor. becuase, to place it in perspective the question at hand is the equivilent to "why drive a ferrari with VW beetle rims and tires when a VW beetle with the same tires will have the same amount of traction?" in reality we would have to question who on earth in a quest for traction would put VW rims and tires on their ferrari to begin with, and why on earth would they drive a VW when the ferrari has so much more to offer than traction anyway.

anyhow, just an opinion.
 
The fact that the Brevis has swappable diffusers, and a second diffuser in testing, is exactly the response to the issues being raised here. I am of the belief that the "silver bullet" GG does not exist. We are looking more at an exact film match at all f/stops in terms of bokeh and diffusion. At f2.8 - f4 and above, we have that, with .5 stops light gain, and sharpness beyond the needs of HD, in the current setup.

For those that need a film match at f1.2 to f4, don't mind more light loss, and don't care about using a lens outside its sweet spot, we have the second swap-in diffuser in development. This footage is an example of that prototype's output. It will likely show a 0 to -.5 stop adapter loss, and show grain at higher f/stops...but for that, the current diffuser will be dropped in.

Ultimately we are trying to capture the characteristics of an image, normally terminated in an emulsion, through rear projection. To do this accurately, through the entire f stop range, with no haze, proper diffusion, smooth grain, accurate bokeh, and minimized light loss etc. is one heck of a job for one diffuser to do through the entire range.
 
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That's right.
I will be busy for a while so don't get upset if I don't respond to questions. The above album shows the difference between HVX200 stock lens vs. image converter.
I did the "split screen" clip and I (or the new public relation dept) will post it.
The nearest I could get to a film look and yes, Dennis is right, there is no magic bullet, just different flavors.
 
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