Do 35mm-Adapters change the possible dynamic range?

H

hannibalekta

Member
Hi,

after some years of reading in the forums and after having bought a 35mm-Adapter and so on, I realized, that, what really makes film look like film technically spoken - is the dynamic range. I really enjoy the film look of a 16mm-Camera (even if theres no DOF/good lighting/good choice of setting or costumes ... whatever).

So my question: does a 35mm-adapter in front of my HV20 increase the dynamic range of the image captured? I mean: if I'd capture a 35mm film projection from a big screen, the image would keep the dynamic range, captured by the film cam (in theory), would'nt it?

Okay ... this all sounds a bit complicated but maybe you understood what i meant (sorry for my English).

Hannes
 
Yes, adding a 35mm adapter can affect your dynamic range. It will NOT improve it, however.

Think about it... your camera already has a zoom lens with lots of glass between your subject and your sensor. By installing a matte focusing screen, a prism to flip the image, and an additional lens with lots of glass in it, you have tons of factors that can soften sharpness (focus errors, improperly adjusted backfocus) and degrade color (flare/ghosting) if not set up properly, and also a guaranteed loss of at least a stop and a half loss of light or more.

Adding an adapter like a Letus, Brevis, RedrockMicro, SGBlade, TwoNiel, etc will allow you to get shallow depth of focus, and that's it. If set up properly, adapters won't hamper your image quality. Any improvement to your color will come from color grading in post.
 
Despite all that JasonAllen says about the image being degraded (true) he isn't really addressing the question of dynamic range which refers strictly to range of useful exposure. I'm embarrassed to say i haven't checked though. I wouldn't be surprised if it did increase it a bit as it overall appears to soften the contrast.
On the other hand:

"f I'd capture a 35mm film projection from a big screen, the image would keep the dynamic range, captured by the film cam (in theory), would'nt it?"

The answer here is a resounding no. You will get a very marked increase in contrast if you try re- photographing a projected image. This partly because the the center of the mage tends to overexpose and the sides get darker, but any copy of a film loses dynamic range when copied.

Lenny Levy
 
Indeed, using an adapter softens the contrast as the ground glass is lit from the front lens and the light affects the whole glass, not only specific pixel like when projecting image to the sensor, and i find the image pleasing because of that.
 
Tomas Riuka said:
Indeed, using an adapter softens the contrast as the ground glass is lit from the front lens and the light affects the whole glass, not only specific pixel like when projecting image to the sensor, and i find the image pleasing because of that.
Click to expand...

That's what I thought as well but I just wasn't shure .... or it was never proven to me.

Thanks for your answers!
 
It is incredibly hard to quantify the dynamic range issue but we've shown for one thing that light loss through an adapter is not linear. Lenny will remember that epic (many, many pages) discussion that ended when we hooked up our adapter system live to an XH-A1 and demonstrated on a waveform monitor.

From our recent test shots of the XF305 on the Brevis 35 with CFXL, we're seeing about 7 IRE of difference on the top end (analyzing frames in the NLE scopes). I'd be comfortable in saying that you're sneaking an extra 1/4 to 1/3 stop in range. Check the post a few threads down from the XF305 and Brevis. Take the adapter off and the bright part of Chris's face looks to go up about 5 IRE on the scope when we attempt to duplicate the shot with the adatper off, and exposure at the low end matched.

Cheers,
 
I'll try to check it out next time I use the adapter but I'd be pretty surprised if you don't gain a little bit. In principle it's like using low con filter or an ultra-con - it should preserve some shadow detail that otherwise would get too dark - or as Dennis suggests preserve highlight detail depending on how you expose. My guess is Dennis is right in seeing an extra aprox 10IRE in range. It will vary with the screen on your specific adapter as well.
 
We had the same experience using an adaptor with an HVX and found that with the adaptor, the camera seemed to gain about a 1/2 stop of latitude.
 
Very interesting ... I always had the feeling that with the adapter, the image looked flatter but I'd never thought of 1/2 stop! :) Thanks for your comments.
 
I don't know that a DOF adaptor changes the amount of dynamic range that a camera can record, but I do know that the transition from highlight to blown out is much more pleasing with a 200+Extreme combo than the 200 alone.


Jason
 
I agree with others here on a couple of things. I do know that the adapters soften the contrast taking away from that stark harsh video contrast, thus giving you a perceived dynamic range but not a true one. You can get close with tiffen filters. I've also noticed that the older adapters that had more vignetting gave off a certain look that was pleasing, almost acting as a flag in a way, giving the video more depth.
 
reem12 said:
I agree with others here on a couple of things. I do know that the adapters soften the contrast taking away from that stark harsh video contrast, thus giving you a perceived dynamic range but not a true one. You can get close with tiffen filters. I've also noticed that the older adapters that had more vignetting gave off a certain look that was pleasing, almost acting as a flag in a way, giving the video more depth.
Click to expand...

agreed; any filter, (and in one sense a 35mm adapter is a filter in that it diffuses inbound light) cannot POSSIBLY change the inherent dynamic range of a given sensor. the frosted/ground glass can diffuse light, and thereby decrease contrast, but cannot stretch it beyond what the sensor is capable of recording, period.

perceptibly i can understand the argument, but on a physics level, the sensor is ONLY capable of a set dynamic range. the frosted/ground glass spreads light through diffusion, decreasing contrast, but that is all that you get out of it; no magic dynamic range stretch.
 
Zissou,
Without testing I cannot say for sure, but i think what you are saying though true is irrelevant. You can't change the sensor, but diffusion can increase the dynamic range before the sensor gets the image. This is certainly the entire concept behind the Tiffen Ultra Contrast filter as well as the concept behind pre-flashing matte box systems that used to be used in film.

Lenny Levy
 
It is true, that dynamic range won't get wider, but imho it is 'squeezed' more pleasantly onto the ground glass, which is easier for the camera to handle, than harsh direct light.
 
Zissou said:
agreed; any filter, (and in one sense a 35mm adapter is a filter in that it diffuses inbound light) cannot POSSIBLY change the inherent dynamic range of a given sensor. the frosted/ground glass can diffuse light, and thereby decrease contrast, but cannot stretch it beyond what the sensor is capable of recording, period.
Click to expand...

Of course the sensor dynamic range won't change. Just as you said, the contrast of the scene will be reduced, so it might fit better within the camera dynamic range. Diffusion filters and pre-flashing result in similar contrast compression. The image is flatter.
It has some advantages - less of your highlights gets clipped and you can later increase the contrast in post. This, however, requires stretching the midtones so some artifacts might show up (your bitdepth is limited...). One of the reasons why 10 bits is better than 8 for grading.
 
You're right. A 35mm-adapter finally behaves like a filter and no filter can change the dynamic range a sensor is capable to record. Even the word "change" ist wrong because the world we film already has the FULL dynamic range ... there is nothing to change IN FRONT OF the sensor cause the reality already has enough dynamic range ;)

Best regards
Hannes
 
IMO the 35mm adapter is dead. Just buy yourself a Canon T2i, a zoom H4n audiorecorder and a DSLR kit and you are ready to do more than you could with the 35mm adapter. The resolution specs and low light performance, will be much better with the T2i. The manupulation of the DoF is slightly better with the adapter i.e. under the same conditions you can have a little more blurred background with the adapter.
 
You must log in or register to reply here.
Back
Top