Useable aperture settings... at DVinfo.net

Matthew Wauhkonen · April 23rd, 2005, 02:21 PM

I've read that the mini-35 can only use apertures of 2.8 and lower or else grain becomes extremely visible.

Is this the case with the micro 35 as well? I love shallow DOF, but if I can't close the aperture beyond f2.8, I don't think I can keep things in focus, especially with, say, a 200mm lens.

Though I've found 200mm f2.8 primes for cheap enough, so I'd probably buy the adapter anyhow.

It's Canon FD mount, by the way, right?

James Hurd · April 23rd, 2005, 04:04 PM

With the current GG, I haven't seen any grain with any aperture.

Hope this helps,

james
www.micro35.com

Brian Valente · April 24th, 2005, 05:54 PM

Matt - is there anywhere you can point me to on that mini35 info? I don't see any technical reason why aperture settings would affect grain.

I do know the gg is so fine and rotates at a speed that would make it invisible for every application I can think of.

Matthew Wauhkonen · April 24th, 2005, 07:11 PM

Q: How can I avoid having the grain of the projection glass showing up on the tape?

A: Don’t stop the taking lens down above 4 - 5.6. Regulate the light as much as possible with the relay lens only (XL1(s) version). Use neutral density filters when there is too much light.

From http://www.dvinfo.net/conf/showthread.php?t=16773 .

I've heard others who even advised f2.8 as the best max aperture setting.

Also, with rails and a really light SLR lens, how much does the set up weigh (including the dvx and rails..I want to use a steadicam.)

Brian Valente · April 24th, 2005, 09:36 PM

Hey thanks for sending that along - it's good info. Here's my interpretation of that FAQ answer (btw I could very well be wrong, so please someone help me out if you have info).

Parts of the answer seem to be specific to the XL1 version (for which the mini35 was designed, btw). I assume the best approach to all this is to keep the relay lens (which I assume to mean the camera lens) wide open, and stop the taking lens (assuming it's the 35mm lens) as appropriate. ND filters, etc. all still apply, as it would any other approach to lighting and getting a good contrast range.

Though with all these gg approaches, you lose to stops of light, so stopping down too much is less of a problem. What I take from this is defer to ND filters etc. to stop down when you need to instead of closing up the iris on the 35mm lens.

That's a good guideline.

B

April 26th, 2005, 09:17 AM

I read that too but it was in regards to the former mini35 which had a rotating and not and oscillating GG (which from my understanding resolved the problem) it was posted in an article about the mini35/xl1s used for a Seinfeld/superman commercial or short of some sort.

here's a link:
http://www.dvinfo.net/canon/articles/article84.php

Brian Valente · April 26th, 2005, 09:45 AM

I defer to James' earlier post. He has not seen grain on any aperture setting, and he's *the man*, so that's the more definitive answer.

Cody Dulock · April 26th, 2005, 06:15 PM

i didnt read your post completely but changing the fstop on your lens opposed to your video camera is way different... you have to keep that iris open on the lens so you can capture the image thats being projected onto the GG. i did a test today with my micro35 with a 400mm telephoto outside. it worked good, but you could tell it was kind of dark because the lowest aperture setting was f-6.5 on the lens. hope this helps.

Brian Valente · April 26th, 2005, 07:51 PM

Cody - You seem to be suggesting the opposite of what I said - that you should keep the (35mm) lens open as much as possible and stop with the (camera) lens. Am I understanding you correctly?

Dan Diaconu · April 27th, 2005, 01:10 PM

Just in case this might be of help:
-the shallow DOF is seen on the gg at wider apertures of SLR lens.(1.2 ,1.4 being the shallowest)
-to get a "proper" exposure for a given amount of light in a scene (shutter speed being set at 1/60 on the camcorder) you would need to open/close down the iris of your camcorder (or the relay lens if you use a mini35 for XL2) or use ND filters in front of SLR lens (if a matte box is available)
-you could keep the same aperture on SLR (1.4 or whatever else available) for the shallowest DOF and change the other two (shutter speed and iris) camcorder variables to get the desired look/proper exposure.
-for low light levels, 1/60 would be the most desirable choice and if wide open iris (on the camcorder) is not enough, some gain will do (to a certain extent)
Grain is visible at all apertures but more obvious in out of focus/less bright areas.
Aim your rig at a candle placed at 3ft and focus your SLR lens at infinity (better yet, set your SLR on 3-4 ft while aiming at street lights at night)
You will see the grain.(that being on a static GG) If the GG is moving, you will see a "motion blur" constant and even and not be able to spot individual grains anymore.
One other way to "overlook" the grain is when a scene is overexposed (too bright) ;brightness difference between the bright and the dark part of one grain does not show any more for it is beyond the chip's contrast range to show it. Don't take my word, try it yourself.

Brian Valente · April 27th, 2005, 02:04 PM

Hey Dan - that's interesting food for thought. You seem to reenforce the approach of keeping the SLR lens as open as possible, and stopping down the camera - I stand corrected!

One thing I wasn't too clear on is why you are suggesting 1/60th shutter speed? I assume you mean for 30i. 1/48 would be a more appropriate shutter speed for 24p.

Also I'm not sure what you mean by "grain is visible at all apertures" - I don't know if you mean practically or theoretically. I've seen a lot of moving gg footage where you can't see the grain.

thanks again for the thougthful post

Dan Diaconu · April 27th, 2005, 03:59 PM

Quote:

Originally Posted by Brian Valente

One thing I wasn't too clear on is why you are suggesting 1/60th shutter speed? I assume you mean for 30i. 1/48 would be a more appropriate shutter speed for 24p.

yes.

Quote:

Originally Posted by Brian Valente

Also I'm not sure what you mean by "grain is visible at all apertures" - I don't know if you mean practically or theoretically. I've seen a lot of moving gg footage where you can't see the grain.

>>>>You will see the grain.(that being on a static GG)<<<<
If the GG is moving, you will see a "motion blur" constant and even and not be able to spot individual grains anymore.

April 23rd, 2005, 02:21 PM	#1
Matthew Wauhkonen Major Player Join Date: Apr 2005 Posts: 285	Useable aperture settings... I've read that the mini-35 can only use apertures of 2.8 and lower or else grain becomes extremely visible. Is this the case with the micro 35 as well? I love shallow DOF, but if I can't close the aperture beyond f2.8, I don't think I can keep things in focus, especially with, say, a 200mm lens. Though I've found 200mm f2.8 primes for cheap enough, so I'd probably buy the adapter anyhow. It's Canon FD mount, by the way, right?

April 24th, 2005, 05:54 PM	#3
Brian Valente Major Player Join Date: Jan 2005 Location: Hollywood, CA Posts: 293	Matt - is there anywhere you can point me to on that mini35 info? I don't see any technical reason why aperture settings would affect grain. I do know the gg is so fine and rotates at a speed that would make it invisible for every application I can think of. __________________ ========================== Brian Valente Redrock Microsystems

April 24th, 2005, 09:36 PM	#5
Brian Valente Major Player Join Date: Jan 2005 Location: Hollywood, CA Posts: 293	Hey thanks for sending that along - it's good info. Here's my interpretation of that FAQ answer (btw I could very well be wrong, so please someone help me out if you have info). Parts of the answer seem to be specific to the XL1 version (for which the mini35 was designed, btw). I assume the best approach to all this is to keep the relay lens (which I assume to mean the camera lens) wide open, and stop the taking lens (assuming it's the 35mm lens) as appropriate. ND filters, etc. all still apply, as it would any other approach to lighting and getting a good contrast range. Though with all these gg approaches, you lose to stops of light, so stopping down too much is less of a problem. What I take from this is defer to ND filters etc. to stop down when you need to instead of closing up the iris on the 35mm lens. That's a good guideline. B __________________ ========================== Brian Valente Redrock Microsystems

April 26th, 2005, 09:45 AM	#7
Brian Valente Major Player Join Date: Jan 2005 Location: Hollywood, CA Posts: 293	I defer to James' earlier post. He has not seen grain on any aperture setting, and he's the man, so that's the more definitive answer. __________________ ========================== Brian Valente Redrock Microsystems

April 26th, 2005, 07:51 PM	#9
Brian Valente Major Player Join Date: Jan 2005 Location: Hollywood, CA Posts: 293	Cody - You seem to be suggesting the opposite of what I said - that you should keep the (35mm) lens open as much as possible and stop with the (camera) lens. Am I understanding you correctly? __________________ ========================== Brian Valente Redrock Microsystems

April 23rd, 2005, 04:04 PM	#2
James Hurd Micro35 Join Date: Jul 2004 Location: Texas Posts: 221	With the current GG, I haven't seen any grain with any aperture. Hope this helps, james www.micro35.com

April 24th, 2005, 07:11 PM	#4
Matthew Wauhkonen Major Player Join Date: Apr 2005 Posts: 285	Q: How can I avoid having the grain of the projection glass showing up on the tape? A: Don’t stop the taking lens down above 4 - 5.6. Regulate the light as much as possible with the relay lens only (XL1(s) version). Use neutral density filters when there is too much light. From http://www.dvinfo.net/conf/showthread.php?t=16773 . I've heard others who even advised f2.8 as the best max aperture setting. Also, with rails and a really light SLR lens, how much does the set up weigh (including the dvx and rails..I want to use a steadicam.)

April 26th, 2005, 09:17 AM	#6
Guest Posts: n/a	I read that too but it was in regards to the former mini35 which had a rotating and not and oscillating GG (which from my understanding resolved the problem) it was posted in an article about the mini35/xl1s used for a Seinfeld/superman commercial or short of some sort. here's a link: http://www.dvinfo.net/canon/articles/article84.php

April 26th, 2005, 06:15 PM	#8
Cody Dulock Major Player Join Date: Sep 2004 Location: arlington, texas Posts: 420	i didnt read your post completely but changing the fstop on your lens opposed to your video camera is way different... you have to keep that iris open on the lens so you can capture the image thats being projected onto the GG. i did a test today with my micro35 with a 400mm telephoto outside. it worked good, but you could tell it was kind of dark because the lowest aperture setting was f-6.5 on the lens. hope this helps.

April 27th, 2005, 01:10 PM	#10
Dan Diaconu Major Player Join Date: Dec 2004 Location: Vancouver, Canada Posts: 804	Just in case this might be of help: -the shallow DOF is seen on the gg at wider apertures of SLR lens.(1.2 ,1.4 being the shallowest) -to get a "proper" exposure for a given amount of light in a scene (shutter speed being set at 1/60 on the camcorder) you would need to open/close down the iris of your camcorder (or the relay lens if you use a mini35 for XL2) or use ND filters in front of SLR lens (if a matte box is available) -you could keep the same aperture on SLR (1.4 or whatever else available) for the shallowest DOF and change the other two (shutter speed and iris) camcorder variables to get the desired look/proper exposure. -for low light levels, 1/60 would be the most desirable choice and if wide open iris (on the camcorder) is not enough, some gain will do (to a certain extent) Grain is visible at all apertures but more obvious in out of focus/less bright areas. Aim your rig at a candle placed at 3ft and focus your SLR lens at infinity (better yet, set your SLR on 3-4 ft while aiming at street lights at night) You will see the grain.(that being on a static GG) If the GG is moving, you will see a "motion blur" constant and even and not be able to spot individual grains anymore. One other way to "overlook" the grain is when a scene is overexposed (too bright) ;brightness difference between the bright and the dark part of one grain does not show any more for it is beyond the chip's contrast range to show it. Don't take my word, try it yourself.

April 27th, 2005, 02:04 PM	#11
Brian Valente Major Player Join Date: Jan 2005 Location: Hollywood, CA Posts: 293	Hey Dan - that's interesting food for thought. You seem to reenforce the approach of keeping the SLR lens as open as possible, and stopping down the camera - I stand corrected! One thing I wasn't too clear on is why you are suggesting 1/60th shutter speed? I assume you mean for 30i. 1/48 would be a more appropriate shutter speed for 24p. Also I'm not sure what you mean by "grain is visible at all apertures" - I don't know if you mean practically or theoretically. I've seen a lot of moving gg footage where you can't see the grain. thanks again for the thougthful post __________________ ========================== Brian Valente Redrock Microsystems