View Full Version : Lens Shades - How do you choose the right one?

16-Jun-2005, 15:27
This thought came to me when I was standing next to my 8x10 2D today. I have my 270mm apo rd artar using my 35mm Nikon system 52mm Nikon filters. Since I have several Nikon metal lenshoods The flash ignited in my brain as to what would be the best way to determine the proper size shade?

Normally I SWAG it and compare the focal length to my Nikon lenses, wide normal long? How do you choose? Is there a quick tip to select?

Funny idea today. Paul

Eric Biggerstaff
16-Jun-2005, 15:44
I use one of the heavy rubber hoods by Hoya ( I think that is who makes them). One hood will cover wide angle to telephoto as it will collapse to the size you need. I use just one to fit my largest lens then use step rings if needed. They cost about $20 bucks and save a lot of room.

ronald moravec
16-Jun-2005, 15:46
Compendiums are best, but a pain. Just extend til you see it in the corners, then pull back.

I switched to a field camera, so I purchesed some generic rubber ones designed for med and small format. They work ok.

Next step will be a three sided shade that lays on the front standard and extends over the lens and also balances by extending over the bellows. It remains to be seen how to fasten this down.
Perhaps a rubber band around the bottom.

Eric Biggerstaff
16-Jun-2005, 15:49
By the way, the Hoya multi hood is available through www.2filter.com and at is most expensive is $17.00. I have purchased from this company with no problems. The hood is listed on their product catalog page at the bottom.

16-Jun-2005, 16:07
Eric, I too use a bunch of step rings! That is how I am using my 52mm filters across several lenses. I have one 67mm metal hood that is made specific for wide angle. 6 - 52mm metal nikons and some huge series viii metal monsters. Not one rubber lenshood in the lot I found out!

16-Jun-2005, 16:10
Ron, I use a compendium on my Cambo view system for its real multi use funtionality. I can really see where one might be a pain in the field?

Ernest Purdum
16-Jun-2005, 16:27
If the corners of your groundglass are clipped, looking through them as you take a prospective lensshade on and off is the best way.

Alan Davenport
16-Jun-2005, 18:40
I have a couple of the screw-on rubber hoods, which seem to work OK with 150mm or longer lenses. But the truth is, I seldom use those; I figure I have a great lens shade in my hand the moment I pull the darkslide from a holder.

16-Jun-2005, 18:41
Ernest, if the corners are gone (I think all my cameras have clipped corners) "What exactly am I looking for?"

I'm a bit puzzled here, Paul

16-Jun-2005, 18:51
Allan I have that same one! My Stilson hat works too but the wax melts in the summer Florida heat!!!

Jerry Fusselman
16-Jun-2005, 23:02
How to check the corners for vignetting: Close down your lens to the taking aperture. How much of the circle (or oval or smashed pentagonish shape depending on several factors) is obscured by the hood when looking in the corners cut out from the ground glass? The ideal is if about 1/10 or 1/6 of the circle of the taking aperture viewed in the extreme corner is obscured by the hood. This will cause very slight vignetting in the corner, but it would be noticable rarely, if ever. The advantage of a hood that clips a little bit of the light at the corners is that you get maximum flare protection at the expense of a nonnoticable decrease in light in the extreme corners.

18-Jun-2005, 11:44
Jerry, I'm trying but I am afraid my eyes are having a bit of a strain seeing anything! Perhaps I'll try a faster lens than the Artar which is f9.5 I'll try my 210 Fujinon W it is f5.6 maybe I'll have better luck?

There must be some "Rule of thumb" to go with this problem besides seeing corners clipped after processing. Of course that is pretty darn certain then!!! Thanks everyone, Paul

Jerry Fusselman
18-Jun-2005, 14:05
Paul, sorry, no, there is no processing of film involved with following my directions. Lens speed does not matter at all either. I will try to explain it better.

You know how when you look at a lens from the front (with light coming through) and vary the f/stop, you see a round or pentagonish shape changing size? Well, the same thing happens from behind. You can vary the f/stop and watch how the aperture changes shape. If you look from behind with your eye centered on the lens axis, it looks quite circular, but if you look from an open corner of the ground glass as you vary the aperture, it often has more of an oblong shape---especially with wide-angle lenses. Indeed, you can estimate the off-axis light loss from a wide angle lens by how much your circular aperture has been smashed into a more oblong shape. The ratio of areas between the oblong shape you see and a hypothetical circle circumscribing it is an upper bound to the ratio of light that will reach the film. (The other factor is the distance the light must travel.)

Anyway, when you add a lens hood, it can make the aperture appear smaller: It is obvious when you add the hood while looking from behind. How much light is lost in the corner because of the hood is measurable by seeing the area of the aperture that is lost while looking from behind. If the entire aperture image while viewing from the corner behind is obscured by the hood, then the corner will indeed be black. But if you can see some of the apeture, the corner will not be totally black.

I have talked as if the only way you can tell is by repeatedly installing and uninstalling the hood, but there is an easier way. You can learn how after 5 minute's practice; you should be able to tell, say, that at f/22 the current hood blocks 10% of the light and at f/32 it blocks 0% of the light in the corner. (When you vary the aperture, the part that the hood blocks does not move, so it is easy to estimate that part.) If 10% of the aperture is blocked, then 90% reaches the film, which is great.

10% obscured in the corner translates to 1/6-of-a-stop light loss in the corner; 16% obscured translates to 1/4-of-a-stop light loss. In situations where flare is a real possibility, I would adjust my hood or shade (and aperture) to this kind of light loss in the corners.

I have a short pdf written by a 6x6 manufacturer that describes this process better; if anyone would like it, please drop me an email.

Jerry Fusselman
18-Jun-2005, 21:42
The pdf I mentioned is available from http://www.vanwalree.com/optics/lenshood.html It was once downloadable from www.hasselblad.com

I also recommend reading the lenshood article at vanwalree.com. His figure 5 shows what you would see in a case where you can tell that the lens hood causes a 40% reduction in the light reaching the corner.

19-Jun-2005, 07:26
Hello Jerry,
I went to the webpage and that is the best article I have seen regarding our topic. This morning I am going to line up my lens shades and keep trying until I get this down to root memory!

Thanks Jerry I think I will have a very good understanding after today! Back to reading now. . .Paul

Jerry Fusselman
19-Jun-2005, 07:55

You are welcome. Your expression "keep trying until I get this down to root memory" really made me laugh, for that's what I did when I read that article.

19-Jun-2005, 09:45
Hello Jerry,
I really recommend the pdf file to all because it also helps me with the use of my compendium shade on my view cameras. After reading the article and reviewing the diagrams on the end it help me to finally see what you have been explaining. So with success I think I'll go shoot some film today. . . Thanks to everyone. . .Paul