10-Stop Neutral Density Filters: 4x4 Resin or 77mm Screw-on ?

What's the best format of Neutral Density filters to use? 4x4 square resin filters like Lee/Hitech or a standard 77mm screw-on ND filter like those made by B+W?

I'll be ordering a Lee holder once they come back in stock, so initial setup costs aren't a concern. Currently, I'm leaning towards the 4x4 resin option, but am interesting in learning more about the potential of stray light entering in around where the filters and holder meet (and if this makes any difference at all during long exposures (2-10 minutes)).

I've heard pros & cons for both setups:
4x4 resin ND filters:
-Pro: Easy to use (simply lift up the filter to compose/focus)
-Con: For long exposures, I've read that stray light can sneak in along the sides???

Screw-in ND filters:
-Pro: No light leakage for long-exposures
-Con: Kind of a pain to work with as you've got to constantly screw on & off the filter as you set up each shot.

I'm just researching this myself, so to list another con of the flat filters: You can't use a lens hood, so flare can be an issue. I have heard of "hoods" that you can put on the front of a flat filter system, but that seems to adds a level of difficulty because now you have another thing to put on and take off. And purchase.

Another con: The flat filter system means more stuff to pack. And their more difficult to pack.

Another pro for the flat system: They're easier to stack, with no issues with vignetting. So if you have a 10-stop and a 4-stop it's easier, and better for the picture, to get 14 stops by stacking. Vignetting can occur when doing this with screw-in filters.

I've decided on the screw-in, mainly because I like to travel light.

Lee has several hoods for their system that you can use in conjunction with the holder or attach directly to a lens via an adapter ring. I use a WA hood that has two regular filter slots and a built-in retaining ring for a 105mm CPL (I use a B+W Kaeseman), so I do not even need to use the holder. Also, many choose to hand-hold these filters, as I sometimes do, which makes these filters even easier to use.

The "flat" filters are actually easier to pack. I use the Lee filter wallet, which holds 10 4x6" filters and takes up less space than would 10 screw-in, round filters.

Vignetting is definitely an issue when using the "flat" filters, because the holder slots have thickness. The filters don't cause vignetting, the holder does.

And, of course, the primary reason for the existence of 4x6" filters is for the GND filters. As has been discussed here many times: round, screw-in GND filters are next to worthless because the transition line of the filter is always dead center of the frame, which is where you must always place the horizon.

Scottes wrote in post #8468261
I'm just researching this myself, so to list another con of the flat filters: You can't use a lens hood, so flare can be an issue. I have heard of "hoods" that you can put on the front of a flat filter system, but that seems to adds a level of difficulty because now you have another thing to put on and take off. And purchase.

Another con: The flat filter system means more stuff to pack. And their more difficult to pack.

Another pro for the flat system: They're easier to stack, with no issues with vignetting. So if you have a 10-stop and a 4-stop it's easier, and better for the picture, to get 14 stops by stacking. Vignetting can occur when doing this with screw-in filters.

I've decided on the screw-in, mainly because I like to travel light.

Why on earth would you want a 14 stop filter?

If your exposure without filter was 1/125 @ f8 @ 100 ISO, a 10 stop filter would give you 8 secs @ f8 and a 14 stop would give you 2 mins @ f8

If you use a square filter system, you have to somehow ensure that there is no light leakage between the filter and holder as due to the excessive change in exposure from the filter's use any leakage will affect the contrast and quality of the result.

The other advantage to the flats is that you'll be wanting graduated NDs somewhere along the line, and screw-in is not a viable option for those, so you'll need the slotted holder anyhow.

EdBray wrote in post #8468382
Why on earth would you want a 14 stop filter?

If your exposure without filter was 1/125 @ f8 @ 100 ISO, a 10 stop filter would give you 8 secs @ f8 and a 14 stop would give you 2 mins @ f8

Making people disappear in a cityscape, for one.

Jon wrote in post #8468386
The other advantage to the flats is that you'll be wanting graduated NDs somewhere along the line, and screw-in is not a viable option for those, so you'll need the slotted holder anyhow.

Making people disappear in a cityscape, for one.

You can do that with a 10 stop. Just lower the ISO and/or close down the aperture!

If you use a square filter system, you have to somehow ensure that there is no light leakage between the filter and holder as due to the excessive change in exposure from the filter's use any leakage will affect the contrast and quality of the result. How do you light seal the filters in the holder when stacked?

EdBray wrote in post #8468395
You can do that with a 10 stop. Just lower the ISO and/or close down the aperture!

Sometimes you don't want to, sometimes you can't. I can't go lower than ISO 100, and I don't want to get diffraction problems by going to f/22.

Obviously, YOU have other ideas. So do them, or not. Whatever.

EdBray wrote in post #8468403
How do you light seal the filters in the holder when stacked?

Gaffer tape.

NYPhotog wrote in post #8468358
The "flat" filters are actually easier to pack. I use the Lee filter wallet, which holds 10 4x6" filters and takes up less space than would 10 screw-in, round filters.

I can't see how this is possible, since the flat filters have so much more area. A 77mm filter has 2000 square millimeters of area. A 4x6" has almost 16,000 square millimeters of area. It seems that 10 4x6s will take up a lot more room.

Not trying to argue, just trying to understand since I'm not experienced with the flat filter system. And the holder has to take up a decent amount of room, too.

If you've got a 4x6, you're talking a grad. And there's no way I'm going to let the filter decide my composition for me, like a screw-in grad would force me to do.

Solid NDs are 4x4. And remember, those square filters are only 2 mm thick. How thick is your 77 mm screw-in? And do you stack them without a case, just end caps, or do you keep them in a case? If the latter, you need to allow for the size of the container. If the former, the convenience or not of unscrewing the needed filter from the stack vs. sliding one out of a case.

i just ordered an 8 stop flat, i'll let u know how that goes

Lazuka wrote in post #8469519
i just ordered an 8 stop flat, i'll let u know how that goes

Which filter?

One thing to consider - you'll probably be focusing manually, or at least without the filter since AF likely won't work with a 10stop ND, and the VF will be pretty dim if it's on the lens. That means there's a good chance that you focus without the filter, and then slap on the filter when you're ready to take the shot. A slip-in filter might be less annoying than having to screw in a round filter when it comes time to take the shot.

NYPhotog wrote in post #8469727
Which filter?

cokin, cause i'm cheap