ND filters - DPChallenge Forums

Canon EF-S 15-85mm f/3.5-5.6 IS USM

02/04/2011 09:04:02 PM · #26

Personally I have 1,2 and 3 stop Hoya ND filters (their best line) that I stack in combination to get the desired result. I can also throw on my circular polarizer to get an addition 2 stops if needed. I have them in both 58mm and 72mm size which are perfect for the lenses I have right now. Not a huge fan of some step up rings so if my next lens is say a 77mm I will be looking more into getting the Lee filter system or equivalent. Well, it would either be the Lee or Cokin system (the pro version...not the lesser budget versions that aren't as good).

02/04/2011 09:08:05 PM · #27

But the more you stack the more you're goon to degrade your image quality because of the extra glass, no?

bspurgeon

Fujifilm x100

Canon EF 50mm f/1.4 USM

02/04/2011 09:25:11 PM · #28

Originally posted by gcoulson:

What's the name of the ND calculator app you use?

NDTimer

Canon EF 24-105mm f/4.0L IS

02/04/2011 09:54:48 PM · #29

A really basic question: if I have a 2-stop filter and stack it with a 4-stop filter do I end up with a total of 6-stops or 8-stops reduction? Ie do you add the stops or multiply?

DrAchoo

Panasonic Lumix DMC-LX5

02/04/2011 09:58:41 PM · #30

Originally posted by gcoulson:

A really basic question: if I have a 2-stop filter and stack it with a 4-stop filter do I end up with a total of 6-stops or 8-stops reduction? Ie do you add the stops or multiply?

They add, not multiply.

02/04/2011 10:02:57 PM · #31

Any recommendations for a polarizer filter and ND filter? Is sticking with Hoya or B&W a good choice?

bspurgeon

Fujifilm x100

Canon EF 50mm f/1.4 USM

02/04/2011 10:07:05 PM · #32

I use both, but mostly B+W, although most of my 77mm are Hoya primarily due to cost. The smaller filters are cheaper so I buy my personally preferred B+W. Seem more solid to me.

02/04/2011 10:10:55 PM · #33

Visually, what would be the difference between a 4-stop ND and a 2-stop ND + polarizer?

bspurgeon

Fujifilm x100

Canon EF 50mm f/1.4 USM

02/05/2011 12:07:00 AM · #34

I don't usually stack my polarizer due to the vignette I get from the rim, but the effect should be the same as if you just used the polarizer alone...just with longer shutter speed at the same f-stop and ISO. 4-stop ND will give the exposure without the effect of the polarizer, and without the potential vignette from the rim.

Pentax DA 16-45mm f/4.0 ED AL AF

02/05/2011 10:50:03 AM · #35

Originally posted by gcoulson:

But the more you stack the more you're goon to degrade your image quality because of the extra glass, no?

Yes. That's why I have 3-stop, 6-stop and 10-stop filters. I don't stack if I can avoid it. And yes, 10-stop is needed if you want exposures of 10 seconds or more in sunlight.

alohadave

Pentax K-5

02/05/2011 11:14:50 AM · #36

Originally posted by gcoulson:

Visually, what would be the difference between a 4-stop ND and a 2-stop ND + polarizer?

2 stops. It's the difference between 2 seconds and 8 seconds. Or 1/125 and 1/30. And etc.

Canon EF 24-105mm f/4.0L IS

02/05/2011 11:23:28 AM · #37

Originally posted by alohadave:

Originally posted by gcoulson:
Visually, what would be the difference between a 4-stop ND and a 2-stop ND + polarizer?

2 stops. It's the difference between 2 seconds and 8 seconds. Or 1/125 and 1/30. And etc.

That's the difference between a 2-stop and 4-stop ND filter. The polarizer's effect depends on how much of the light is polarized, and it may have different effects on different objects in a scene, but in general you can assume about 1 stop, maybe a little more. Therefore the 2-stop + polarizer will give about 3 stops, give or take. So if you have a 1-second exposure with no filter, add the 2-stop will give 4 seconds, and adding the polarizer on top of the 2-stop will give about 8 seconds.

DrAchoo

Panasonic Lumix DMC-LX5

02/05/2011 11:54:08 AM · #38

I dunno Fritz, I think a polarizer gives you 2 stops no matter what. It may take certain spots down more than 2 stops if it's removing a lot of light, but I think 2 stops is the minimum.

Pentax DA 16-45mm f/4.0 ED AL AF

02/05/2011 12:20:38 PM · #39

Originally posted by DrAchoo:

I dunno Fritz, I think a polarizer gives you 2 stops no matter what. It may take certain spots down more than 2 stops if it's removing a lot of light, but I think 2 stops is the minimum.

You know, I never have specifically tested it; now I have to do it! Stay tuned.

ETA:
Totally unscientific, but I de-focused my 24-70, pointed it out the window at a nice, uniform snowbank and adjusted exposure until the camera meter was centered. Then mounted the polarizer and metered the same spot. Finally, removed the polarizer and metered again. Results:
Inital, no polarizer: 0 EV
With polarizer: -1 2/3 EV, randomly bumping up to -1 1/3
Final, no polarizer: 0 EV

So for my polarizer, the effect for a non-polarizing surface seems to be in the range of -1 1/3 to -1 2/3 stops, so I'll call it -1.5 stops. Kinda between our guesses. I'm thinking that there is certainly some variability between polarizers, so YMMV.

Message edited by author 2011-02-05 12:31:22.

alohadave

Pentax K-5

02/05/2011 12:54:50 PM · #40

Originally posted by kirbic:

Originally posted by alohadave:

Originally posted by gcoulson:
Visually, what would be the difference between a 4-stop ND and a 2-stop ND + polarizer?

2 stops. It's the difference between 2 seconds and 8 seconds. Or 1/125 and 1/30. And etc.

That's the difference between a 2-stop and 4-stop ND filter. The polarizer's effect depends on how much of the light is polarized, and it may have different effects on different objects in a scene, but in general you can assume about 1 stop, maybe a little more. Therefore the 2-stop + polarizer will give about 3 stops, give or take. So if you have a 1-second exposure with no filter, add the 2-stop will give 4 seconds, and adding the polarizer on top of the 2-stop will give about 8 seconds.

Oops, sorry, missed the polarizer part of that. A polarizer varies from 1-2 stops depending on how much it is turned, and what you are pointing it at. It doesn't apply equally to all subjects.

02/05/2011 05:15:32 PM · #41

This is a really nooby question, but is there a way I can get a shutter speed longer than 30 seconds on my d80? I have read up on specifications of the 5d mark ii that its longest shutter speed is 30 seconds but people seem to have done it longer than this?

02/05/2011 05:19:18 PM · #42

Originally posted by adamelliott111:

Not a silly question at all. Many DSLRs have the 30 second limitation, however they also pretty much all have what is referred to as "Bulb" mode, where the shutter will remain open as long as the shutter button is depressed. Also, they pretty much all are compatible with some sort of external release or timer that enables releasing and holding open the shutter without actually keeping your finger on the button. Some of the timers have advanced functions like shooting at set intervals.

02/05/2011 05:29:53 PM · #43

double post

Message edited by author 2011-02-05 17:33:46.

02/05/2011 05:29:54 PM · #44

Originally posted by kirbic:

Thanks for the help, I was also wondering how you would guess what kind of shutter speed to look at in bulb mode if you didn't want to under/over expose?

03/02/2011 12:15:53 PM · #45

This is the most relevant thread I could find, when using bulb for things such as star trails, how do you not under/over expose??

Thanks in advance

Nikon AF-S NIKKOR 24-70mm f/2.8G ED

03/02/2011 12:47:00 PM · #46

Originally posted by adamelliott111:

This is the most relevant thread I could find, when using bulb for things such as star trails, how do you not under/over expose??

Thanks in advance

Star trails are actually a special case. Since the stars move, the things that affect the brightness of the individual trails are:
1.) Aperture
2.) focal length
3.) ISO
Notice that shutter speed is not listed! What affects the amount of light that hits individual pixels is how long the image of the star remains on the pixel(s). That does not depend on the shutter speed.
Shutter speed, ISO and aperture will also affect the brightness of the sky background. This will limit the maximum exposure time that's feasible. For star trail images, apertures of f/4 or f/5.6 usually work well, with low or moderate ISO. With these settings, the longest feasible exposure might be as short as 10 minutes or as long as an hour or so, depending on the darkness of the area you are in. Even in the darkest areas, the sky is not completely black, and you will have a limit on exposure.
For shooting moonlit scenes, it may be possible to get a valid exposure reading using the camera's meter, if you have a very fast lens set wide open and use high ISO; this may bring the reading within the 30-second limit. You can then calculate what's required for lower ISO and smaller aperture. Personally, I start with 30 seconds, look at the histogram and tweak from there. Most of the time I don't want a "proper" exposure at night anyhow. I'm most often looking to retain the mood by underexposing.

Citadel

Nikon D7500

03/02/2011 01:00:39 PM · #47

More related to the original post, I just happened to come across this:

//www.photorepublik.com/articles/20110202/all-one-cameron-mc-fader-nd-filter

You can adjust the ND effect from 1 to 8 stops. I know Singh-ray has something similar but its stupidly expensive. This one looks to be bit more reasonably priced.

Message edited by author 2011-03-02 13:01:51.

Sony 24-70mm F4 Vario-Tessar T* FE OSS

03/02/2011 01:49:14 PM · #48

Originally posted by kirbic:

Thanks a lot for the advice, will hope to try it soon. Sounds like it takes practice.

Message edited by author 2011-03-02 13:49:21.

Bear_Music

Samsung Galaxy S24 Ultra

03/02/2011 01:59:08 PM · #49

Originally posted by Citadel:

This appears to be two polarizing layers co-axially mounted. That got me to thinking, I had an "AHA!" moment: I have a 77-67mm stepdown ring, and I have 67mm and 77mm polarizers, so this means I'm all set right?

NOT.

I think because mine are circular polarizers, the effect doesn't happen. I'm assuming the referenced variable ND Filter uses linear polarizers, which can cancel each other out? Anyone know?

R.