Luminous Landscape Forum
Equipment & Techniques => Medium Format / Film / Digital Backs – and Large Sensor Photography => Topic started by: henrikfoto on June 11, 2012, 03:10:38 pm
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I need to get some ND-filters and wonder what type is the best?
And what is the most useful "strenght"?
Are these filters affecting the sharpness of the picture or in other ways degrading the picture?
Henrik
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Adding more glass elements and space in between the light / lens / sensor is always going to degrade the image quality to some extent. However the extent of it is largely dependent on the filters used. Everyone is going to have a different opinion on this matter, however what I personally use are B+W filters (made by Schneider) they make great threaded filters, with extra wide / thin mounts which let you use them with wide angle lenses with ease (I use these on all my lenses though, since I figure they will have even less of an impact). If the filters are too thick they can introduce vignetting which is extreme with wide angle lenses sometimes.
B+W makes filters their threaded filters, but they also make 4x4 glass filters which will fit into holders like those from LEE, which let you use not only full natural density filters, but also grad ND's and more with even more precise control if thats your thing. There are lots of strengths, but the common ones are 0.3 / 0.6 / 0.9 / 1.8 which are 1 stop / 2 stop / 3 stop / 6 stops and can be used in combination to get even more extreme effects. Having a set helps you when you are in a situation so you are not limited.
I use B+W because they are the best in my opinion, however there are other companies which make excellent filters.
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The effect of filters on image quality is a perennial problem question, the answer is neatly given by lens rentals who show the effect of 50 UV filters, yes I know 50 but the effect of one is hard to show convincingly. Then they show "good" v "poor" quality filters. It is well worth a read. Of course unlike UV if you need an ND effect you have no choice, but buy carefully is the take home.
http://www.lensrentals.com/blog/2011/06/good-times-with-bad-filters
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I recommend Lee ND filters and their filter holder. Many highly regarded photographers have been using these hand made filters for years and they are designed for use on MF. They make both "hard" and "soft" ND grads, amongst others. Not cheap, but good.
http://www.leefilters.com/ (http://www.leefilters.com/)
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The effect of filters on image quality is a perennial problem question, the answer is neatly given by lens rentals who show the effect of 50 UV filters, yes I know 50 but the effect of one is hard to show convincingly. Then they show "good" v "poor" quality filters. It is well worth a read. Of course unlike UV if you need an ND effect you have no choice, but buy carefully is the take home.
http://www.lensrentals.com/blog/2011/06/good-times-with-bad-filters
Hm.. amazing what people waste their time on.
This is a useless test.
Henrik
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Hm.. amazing what people waste their time on.
This is a useless test.
Henrik
Kind of goes to an extreme, I suppose. But you'd be surprised how many still try to take the shortcut when it comes to optical quality. Sometimes you really have to hit someone over the head with an example like this to get the message to sink in. No one I know, of course, but...... ::)
Steve Hendrix
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Aloha,
Lee holder is fine, but check out hitech for filters, really nice quality a lot less money
for grads I would get; three soft, three hard and a reverse, you can use the filters in many creative ways, not just to balance out the exposure, get the rectangular sizes as they are much more useful they are lots of fun!
lee does have the "big stopper" which is really nice...
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Useful strength's of ND filters depends on what you want to do with them. If you just need to drop the shutter speed a few stops, maybe 2 or 3 stops would work. If you after doing long exposures of water when the sun is still out, then you may need 6-10 stops.
If you only need a few stops, Lee, Hightech, Singhray are high quality. Some photographers (i'm one) also use split ND filters frequently, lots of threads about those with discussion about pros and cons of still using these or doing it in post (or as I do, a combination of both). Cokin filters are pretty inexpensive, but yes will affect the quality.
Sing Ray and B+W both make a high quality variable ND filter, I"ve used both. They are double polarizers, and can go from 2.5 stops up to 6 or 7. They work pretty well, although I think they affect water reflections ... they are polarizers.
If you want to do some serious ND, I would recommend you look closely at Tiffen's ND filters, originally designed for the video/film industries to solve the issue if IR pollution when using a large amount of ND. These will offer cleaner color once you get to 6 or more stops. I have a 6 stop and a 4 stop, and have used them combined to get to 10 stops several times. They are pricey but I think they give cleaner files.
http://www.tiffen.com/artadams.html
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As Wayne mentioned, it is important to decide what you want to use ND filters for specifically as they are available in varying strengths ranging from 1 stop through to 10+ stops. If you want to shoot fast glass wide open in the middle of the day then you may only need 1-4 stops.
I use the LEE system NDs & graduated NDs for my general filters ranging from 1 stop though to the Big Stopper 10 stop filter. These are pretty decent at filtering IR which becomes a significant problem as you extend exposure due to the IR sensitivity of the sensor (without IR filtering you'll get magenta colour shift).
I'm also actually a big fan of the Tiffen IRND filters for my DSLR lenses. I regularly shoot extended exposures in daylight that require up to 13 stops and for that amount of time the IR filtration is important and the Tiffen IRND work extremely well. I will stack the IRND 1.8 & 2.1 filters and use a step up ring between them so that one filter is 77mm and the outside filter is 82mm - this helps avoid any vignetting when shooting wide. In reality if you stack filters, only one needs to be IR filtered but I find it easier to buy only the Tiffen IRND's for my screw on filters.
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These are pretty decent at filtering IR which becomes a significant problem as you extend exposure due to the IR sensitivity of the sensor (without IR filtering you'll get magenta colour shift).
It isn't really the IR sensitivity of the cameras which is the problem here - with the built-in IR blocking filter over the sensor, that sensitivity is tiny in comparison to its visible light sensitivity.
The problem really is that the ND filter is not strictly "N" (neutral): most ND filters are not uniform attenuators over the whole spectrum of light that reaches the sensor. Blame the ND filter, not the sensor. The term "neutral density" can be used by anyone - it's not regulated and can mean anything really. Neutral over what range of wavelengths?
What you get with these Tiffen IRND filters and the like is a filter where the "N" extends over a sufficiently larger range of wavelength to avoid a colour cast with just about all sensors.
Ray