[raider]

Hi

My FA80-320 does not come with lens hood. Is there any third party product I can use?

Thanks

[raider]

Sorry. I should check ebay before posting this. Found 1 rubber collapsible hood.

[Lowell Goudge]

There is a spreadsheet available to design your own lens hoods.

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Please excuse the language of the page but look for hoodcalc.zip and at the right end of the line is the download site to click on.

This will design circular hoods which you can make.

Note it will ask for your sensor size, because the hood size is sensor dependant for vignetting.

Also note that the hood inner diameter is relitively simple, it is how big around you want to make the hood.

Lens front diameter should be the actual diameter of the front element (not the filter diameter)

you can make a hood by simply putting a tube around the filter, and this program calculates the length of the tube.

Note for lens focal length,
- because this program independantly considers the sensor size, you enter real focal length in mm not the 35mm equivelent
- for a zoom, you must enter the minimum focal length otherwise, you will get vignetting at minimum focal length.

It is possible to also make petal hoods, but that requires modifying the sheet somewhat.

[raider]

Thanks for the link!

It is a korean site I see. I have downloaded the file and will have a go at it.

My FA80-320 is really in need of a lens hood as it is so easy to knock the front of the lens, if not being careful enuf.

[raider]

Okay. I loaded the spreadsheet and put in the film format height and width as 23.5mm and 15.7mm respectively. This refer to the sensor size of my k100D's CCD right?

Then I put in the focal length of the lens as 320mm. Diameter of lens hood is 58mm.

The spreadsheet say I don't need any lens hood! Even if I change the focal length to 80mm, 100mm, etc.. I still get the same results. What am I doing wrong?

[Lowell Goudge]

Okay. I loaded the spreadsheet and put in the film format height and width as 23.5mm and 15.7mm respectively. This refer to the sensor size of my k100D's CCD right?

yes, but it might be better to use 24 x 16 because accuracy will be everything, and if you are too close you will get vignetting.

Then I put in the focal length of the lens as 320mm. Diameter of lens hood is 58mm.

no,

first, for a zoom you put the minimum focal length not the maximum, because if you put the maximum it will restrict the field of view at minimum focal lengths

Second, you need to put the real diameter of the exposed portion of the front element. For example my FA 28-105 uses a 58mm filter but the actual diameter of the exposed front element is 48mm, you would use this smaller diameter as the lens diameter.

The spreadsheet say I don't need any lens hood! Even if I change the focal length to 80mm, 100mm, etc.. I still get the same results. What am I doing wrong?

Actually if you enter the same diameter for the lens and filter the spread sheet really states no hood is possible as it will restrict field of view.

That is why you need to look at your lens and use the actual exposed element diameter, for the lens diameter, and not the filter.

If you use the filter diameter, then you would need to make the hood much larger than the filter diameter because it is all about the filed of view and geometry