[SpottyMatic]

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I have a couple of 200mm lenses that I would like to equip with a suitable hood and without buying three or four different length hoods to see which cause vignette problems, is there a simple calculation to determine the longest hood that can be fitted without vignetting...?

Both lenses are 200mm F3.5 and both have 62mm filter threads.

Thanks for any advice

[foxhead]

The calculation would involve simple trigonometry using the diagonal field of view angle which is usually published. The hard part would be finding the length to the focal point of the lenses and the diameter and length of the hoods. I don't think that data is normally published.

[1r0nh31d3]

Or if your if your a liberal arts major and can barely do any math, like myself, then the process involves some rolled up cardboard and trial and error with some test shots.

[Blue]

You could look at some of the longer Tak hoods or aftermarket metal hoods, or rubber hoods about 65 to 75mm in length.

[les3547]

I second the rubber collapsable lens hood suggestion. I bought my first one a year ago for the DA 55-300 zoom. At first I kept switching back and forth between the rubber hood and the stock plastic hood that came with the lens because of feeling like I might be doing a disservice to the lens somehow by using a cheap rubber hood. But after a few months of that silliness I found out a lot of positive things about using a rubber hood.

Many rubber hoods, such as most of these found on Ebay, extend into three different lengths, so you can choose what works for your lens (though for very wide lenses look for a hood designed for that). They are lighter than any plastic or metal hood, and after collapsed are more compact.

Some additional benefits I've discovered is that they serve as a cushion for the lens, and the rubber around the lens helps secure the lenses in lens compartments in a camera bag. Also, if you make sure the rubber hood has threads that accept a filter in the front, you can use step up/down adapters to get by with one set of polarizing and ND filters, as I detailed here.

My lenses with rubber lens hoods:

[thethirdcoast]

I third the rubber hood suggestion. I've had good luck with the ones I've picked up from 2filter.com.

[SpottyMatic]

Thanks for all the suggestions - I guess the rolled-up cardboard tube is the easiest way forward...I'll have a look at the rubber type too.

[Lowell Goudge]

do a search on the forum for a file called HoodCalc. I uploaded it (in a zip file), as I had found it on the web and it is used for doing the exact calculation you want.

a couple of things to note when using the program.

front element diameter is the actual exposed front element, which is considerably less than the filter diameter.

When calculating hood length, this is from the centerline of the front element, if you use the filter ring, then this will result in a hood longer than desired and vause slight vignetting.

[SpottyMatic]

Thanks Lowell - I'll have a look for it.