Filters and Vignetting

[Dustin]

Apologies if this post should be moved to the lenses thread...

I have used a Genustech Eclipse Fader 72mm Variable ND for the better part of 5 years. When I originally acquired it, I was using a Nikon d5300 and a tamron 17-50 2.8 lens with a 72mm thread. Having moved over to a Sony a6500 three years ago and a Sony 35mm 1.8, I figured I’d just buy a step up ring and I’d be good. I quickly realized that while the Sony 35mm vignettes on it’s own, this combined with the 72mm filter provided for uneven polarization of the sky and vignetting for a not so filmic look. 

Recently upon browsing YouTube I came across a video where a fellow “filmmaker” was saying he uses an 82mm filter to help with the vignetting. Is there any merit to this? He also showed off a slick looking magnetic regular nd filter that obviously didn’t have any of the issues I’m getting with my variable ND. Any thoughts on affordable $100 ish regular nds? Is my Genustech Variable ND just behind the times or is the Sony Lens just going to make all nd’s vignette but perhaps a better Nd might help with even polarization of bright skies? Also my Genustech seems to always result in weird colors. Which is a shame because I remember it being fairly expensive back in the day but hey no hard feelings.

Thoughts/Advice is welcome as I realize this is a bit of a rant. I should add my current lens kit includes a 28mm, 50mm and 100mm Nikon E series primes I borrow when not shooting film. Idk maybe I should just sell the Sony 35mm and get the Sigma 18-35 everyone seems to have? Lol

[tupp]

More info would help, and it is not clear whether or not you are seeing additional vignetting on the Sony lens with the step-up/down ring and the filter.

 

 

15 hours ago, Dustin said:

I quickly realized that while the Sony 35mm vignettes on it’s own, this combined with the 72mm filter provided for uneven polarization of the sky and vignetting

If you are seeing more vignetting than before, do you have any other filters mounted to the Sony lens?

 

 

15 hours ago, Dustin said:

Recently upon browsing YouTube I came across a video where a fellow “filmmaker” was saying he uses an 82mm filter to help with the vignetting.

Does your Sony lens have a 55mm filter size?  If so, an 82mm step-up/down ring would probably not reduce vignetting compared to a 72mm ring.

 

 

15 hours ago, Dustin said:

perhaps a better Nd might help with even polarization of bright skies?

A regular ND just reduces overall intensity of light -- it doesn't have any special interaction with polarized light.

 

The unevenness in the sky could be a product of the cross polarization of your variable ND, or the sky could just be uneven.  By the way, polarizing filters only affect a portion of the sky.

 

You're not using a separate polarizing filter with your variable ND, are you?

[Dustin]

6 hours ago, tupp said:

More info would help, and it is not clear whether or not you are seeing additional vignetting on the Sony lens with the step-up/down ring and the filter.

 

 

If you are seeing more vignetting than before, do you have any other filters mounted to the Sony lens?

 

 

Does your Sony lens have a 55mm filter size?  If so, an 82mm step-up/down ring would probably not reduce vignetting compared to a 72mm ring.

 

 

A regular ND just reduces overall intensity of light -- it doesn't have any special interaction with polarized light.

 

The unevenness in the sky could be a product of the cross polarization of your variable ND, or the sky could just be uneven.  By the way, polarizing filters only affect a portion of the sky.

 

You're not using a separate polarizing filter with your variable ND, are you?

All helpful suggestions thank you!

1) Filter size is a 49mm and it’s definitely the cheaper apsc lens not the newer FE.

2) There are no additional filters mounted to the lens. Was literally just using the step up ring and filter. 

3) Understand with regards to the diff in polarizers and vari-nd’s. I think some of the problem is the Sony screen is so hard for me to see what’s actually going on in great detail. There are min/max markings on my filter but they don’t really line up.

 

Some additional thoughts...would I be better served by getting a newer variable Nd filter? I’m def not dropping cash on a peter McKinnon vari nd. I also wonder about picking up some magnetic step up rings instead of the screw on type I have. I tried my new step up ring for my 12mm Samyang f2.0 lens the other day and I think just due to how small it was, I had to use contact cleaner just to get the thing off the variable nd filter! (Btw I’m probably going to sell this lens, have not had favorable results)

[Trek of Joy]

It may just be your filter, I think there are better vari-ND's compared to the Genustech. I have the 2-5 stop McKinnon and its really nice, no vignetting or uneven color with the 16-35 on FF at 16mm. I have a couple budget vari-ND and its much better. I think I'm going to buy the other one as well, they're expensive but I use them every day so for me its a good investment instead of dealing with wonky color shifts. Buy the 82mm and just use step down rings on all your lenses with generic $3 lens caps off ebay or cheap neoprene covers. YMMV. 

Chris

[Dustin]

1 hour ago, Trek of Joy said:

It may just be your filter, I think there are better vari-ND's compared to the Genustech. I have the 2-5 stop McKinnon and its really nice, no vignetting or uneven color with the 16-35 on FF at 16mm. I have a couple budget vari-ND and its much better. I think I'm going to buy the other one as well, they're expensive but I use them every day so for me its a good investment instead of dealing with wonky color shifts. Buy the 82mm and just use step down rings on all your lenses with generic $3 lens caps off ebay or cheap neoprene covers. YMMV. 

Chris

Thanks! Yup might pick up a new Nd filter. Don’t want to drop the cash for the Peter McKinnon filter but it seems to be the best engineered variable ND. After watching Gerald Undone’s variable nd test, I might try the k&f filter or honestly may look at regular nd filters.

[Trek of Joy]

1 hour ago, Dustin said:

Thanks! Yup might pick up a new Nd filter. Don’t want to drop the cash for the Peter McKinnon filter but it seems to be the best engineered variable ND. After watching Gerald Undone’s variable nd test, I might try the k&f filter or honestly may look at regular nd filters.

If you do the magnetic filter holders you can avoid the hassles of screwing filters in over and over. The only reason I didn't go that route is because in the end it would cost as much as the more expensive vari-ND and then I'd have to carry more filters instead of just moving the vari with my thumb as I'm shooting. The K&F looked good in that test too. Cheers

Chris

[Dustin]

@Trek of Joy so which nd’s would I need help if I just went the regular route? An 8 and 16? Also if I get the k&f I’m not sure which version I need, the 2-5 or 3-whatever stop. 

[Trek of Joy]

I have the Polar Pro 2-5 stop and cheaper one that's about 4-9 stops that's getting replaced by the other Polar Pro, I use them both, but I'm out in the sun a lot. If I were buying individual, I'd probably do something like a 3 & 6 and stack them if needed, but then you're also adjusting ISO or aperture to get proper exposure with nothing between if one is too strong or weak, I've done it both ways, I prefer the vari because its much more efficient with the way I work. But I shoot run-and-gun outdoors so I have no control over lighting, the vari-ND for me is a vital tool. YMMV.

Chris

[Dustin]

@Trek of Joy quick question..which one of these is more useful for video?

 

K&F ND8-ND2000

K&F ND2-32

 

 

[Dustin]

4 hours ago, Dustin said:

@Trek of Joy quick question..which one of these is more useful for video?

 

K&F ND8-ND2000

K&F ND2-32

 

 

Edit.

Pulled the trigger on the ND2-32 model. Will see how it goes!