Which filter to use??

[RyanEustace]

I plan on buying a 400mm f5.6 lens but im struggling on which filter is best to put in front , if at all any filter.

Which filter do you use as an all purpose one ( by that i mean to protect the glass , e.t.c...) , or do you just not bother ??

[Roy C]

You will get mixed responses on this one but I would not use one at all on a telephoto. I have a quite good quality filter (hoya pro digital) that fits both my 17-40 and the 400/5.6 that I used to have. On the 17-40 I could not notice much difference in IQ with the filter attached but the same filter on the 400/5.6 showed a definite deterioration in IQ.

[Rob Chace]

I personally would not bother, just make sure you use the lens hood to protect the front element.
Rob

[RyanEustace]

What about polarizers , and nd graduation?

[RAH]

What about polarizers , and nd graduation?
I think people thought you meant filters that you might permanently mount on the front as protection (like a UV filter), which is the subject of more debate than just about anything I can think of (except the war in Afghanistan ;) )

As far as the 2 you mentioned, the polarizer is of course useful for removing glare from non-metallic surfaces, and making the sky bluer. It doesn't seem all that useful to me for a long telephoto lens like a 400mm, but it might be worthwhile having for certain occasions.

The regular (non-graduated) ND filter is useful for cutting the light, which you might want to do if you were say photographing a brook and you wanted to give the water that silky look (via a slow shutter speed). The polarizer can also be used for this.

The Graduated ND filter, which is dark at the top and gradually gets lighter as you go down, is very useful for landscapes where the sky is bright and the land is darker. They sell MANY varieties of these graduated filters. The best way to go is with the rectangluar sliding filters, especially the Cokin sytem. If you have a lot of money, you can get Lee system or Singh-Ray filters.

However, again for a 400mm lens, these ND filters, especially the graduated type, would seem to be of limited usefulness.

[alan_rymer]

I plan on buying a 400mm f5.6 lens but im struggling on which filter is best to put in front , if at all any filter.

Which filter do you use as an all purpose one ( by that i mean to protect the glass , e.t.c...) , or do you just not bother ??
Hoya skylight!

[Duke Leto]

dont forget that a polariser and ND's reduce light, 2 stops nominally for a polariser and varying for ND's. with a 400/5.6 it would become a 400/8 with a polariser on.
they do do clear lens protection filters, but get a good quality one if you buy one as its been mentioned this subject has a long history of debate and benefits.
All my smaller lenses have filters on, normally hoya pro or kenko pro uv filters, the main reason is if a lens cap pops off in the camera bag and the primary objective lens is rubbing against the interior, again not a problem unless grit etc has found its way inside you bag. I'd rather chuck away a filter than send the lens away for a new main objective lens.
I have personally never knowingly suffered from a reduction in quality by the addition of a filter unless it was designed to do so. Saying that if I take certain shots, I'll remove filters to ensure no issues with contamination, such as sunrises, sunsets where a mark my cause some kind of flare.

[Roy C]

2 stops nominally for a polariser and varying for ND's. with a 400/5.6 it would become a 400/8 with a polariser on.
.
Two stop loss on a f 5.6 lens would mean f11 wouldn't it.

[Duke Leto]

Thanks Roy my mistake it is indeed f11

f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32, f/45, f/64, f/90, f/128