longer focal lengths + filters

[ChrisGilbert]

I cadged a friends 70-200 f4 L to do some longer landscapes and found that when combined with a grad I couldn't get a sharp shot. Subsequent tests have shown that it is the Hi-Tech filter that is clearly aberrating the image. For you internal landscape shooters have you found this with other lenses ? Is it a generic issue with longer focal lengths or is this something specific to this generation of Canon lenses ... ? I can't honestly say it's something I've ever noticed before but then I've not used a 70-200 like this before either.

Your opinions are welcome ..

Chris

 

[Bristolian]

I had the same problem with a Hoya CPL filter on my 70-300 lens last year.

Putting the same filter on several other shorter focal length lenses gives great results - so it's not the filter. Having spoken to a number of other photographers it appears relatively common for filters to have an adverse effect on sharpness on longer lenses.

 

[ChrisGilbert]

Thanks for that Steve. It's worth knowing it's not the lens !

 

[HoppyUK]

Sharpness with longer lenses can be affected by anything less than the best filters, preferably glass (though they are far from immune to problems).

The longer the lens, the smaller section of the filter it actually 'looks' through, so any imperfections are greatly magnified. I've yet to try any resin filter (ie grad) that doesn't affect sharpness of 200mm-plus lenses at all, though Lee are pretty good.