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02-28-2011, 12:29 PM   #16
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QuoteOriginally posted by nater Quote
There are a couple of sites that have some lens hood templates you can print, as well as the ability to create custom hoods based on your own specs, however it looks like you need to be a 'subscriber' to get access to that custom functionality:

Custom lens hoods

and for APS-C:

Customized digital lens hoods
Great sites, but it says: To help with bandwidth and hosting costs, an optional subscription fee can be paid. This allows you to create your own custom lens hoods to your own specifications.

I'm going to email them for info on cost & how to become a subscriber.

02-28-2011, 01:04 PM   #17
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QuoteOriginally posted by glee46 Quote
Great sites, but it says: To help with bandwidth and hosting costs, an optional subscription fee can be paid. This allows you to create your own custom lens hoods to your own specifications.

I'm going to email them for info on cost & how to become a subscriber.
What kind of template are you looking for? Are cylinders and cones sufficient?

If so, I'll post simple cone and cylinder templates soon.
02-28-2011, 01:27 PM   #18
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QuoteOriginally posted by glee46 Quote
Great sites, but it says: To help with bandwidth and hosting costs, an optional subscription fee can be paid. This allows you to create your own custom lens hoods to your own specifications.

I'm going to email them for info on cost & how to become a subscriber.
I got an email back from them..

For the most part they say their server is overloaded and the subscription is not available at this time. So, I'll try them again later, or find another site which might have this same offering.
02-28-2011, 01:45 PM   #19
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Making a hood from existing cone, box, or cylinder

Here's one way to make a lens hood if you've already got a cone, cylinder, or box of appropriate material.


02-28-2011, 02:58 PM   #20
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QuoteOriginally posted by glee46 Quote
... the subscription is not available at this time. . . . find another site which might have this same offering.
I suspect that with a little thought you'll discover you don't need the site.

Remember that the shape of the "tulip" is dependent on the proportional ratio of the sensor. Wrap a piece of paper around any APS-C format hood and you have the general shape.

Apply that outline to a tube of the appropriate length and diameter for the lens barrel and angle of view (which can be determined by trial and error) and you achieve class-2, DIY status. Make your own black flocking material for the interior and claim extra bragging rights.

You can scale the traced outline as necessary for different hood diameters by using a scanner or XEROX machine.

H2

[ Next month's project will be to strip and recover a Mamiya C22 TLR with exotic wood veneer! Yeah, the templates are already finished!]
02-28-2011, 03:05 PM   #21
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I figure that the optimum length of a conical style hood is the minimum focussing distance of the lens. Of course you could go longer if you knew you didn't want to use the hood with close subjects!
02-28-2011, 03:09 PM   #22
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I see no one has looked for the link with Hood-calc.xls.

Too bad

with a little programming you can make this define the tulip hoods also.

Note that cylindrical hoods are easier to make and attach than cones
03-01-2011, 08:29 AM   #23
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https://www.pentaxforums.com/forums/attachments/pentax-slr-lens-discussion/46...d-hoodcalc-zip

03-01-2011, 08:59 AM   #24
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thanks but it seems all the links are broken
03-01-2011, 09:16 AM   #25
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odd... I just downloaded the zip file 10 minutes ago.

maybe something in your browser is blocking the download?

if you still can't download it, pm me your email and I'll forward it to you.


hello from a fellow Torontonian.
03-01-2011, 12:29 PM   #26
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thanks but I don;'t need it, I just wanted to make sure others had it.

the general concept works well, but there are some thngs people need to consider when using it.

first, the diameter of the lens is NOT the filter attachment diameter but the actual diameter exposed of the front element of the lens, you will need to measure this.

second, the lens hood length needs to consider how far back the frong element is recessed into the lens itself. many lenses are set back 10-12 mm from the edge of the filter thread. Note this distance should be to the centerline of the first element, so a little guesswork is needed or just make the hood a few mm short to compensate. The easiest way to make hoods is to use black construction paper and either filters where glass has been removed, or stepping rings that you can wind the tube around.

As I pointed out earlier, if you do a little work in the formulas, you can generate a tulip hood, but you would then need to mark it out to cut. Tulip hoods would be best mounted on a polarizer with the glass removed so you could rotate it for correct orientation
03-01-2011, 12:53 PM   #27
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QuoteOriginally posted by Lowell Goudge Quote
....

first, the diameter of the lens is NOT the filter attachment diameter but the actual diameter exposed of the front element of the lens, you will need to measure this.

second, the lens hood length needs to consider how far back the frong element is recessed into the lens itself. many lenses are set back 10-12 mm from the edge of the filter thread. ....
The design I posted used the filter diameter because it guarantees no vignetting and allows one to use an empty filter ring to mount the hood.

Either way should be fine.

I guess I'm not clear in just what people are looking for in a "design template".

Are people seeking a fan shaped flat template to be cut and rolled into a conical hood? Just what is the goal?
03-01-2011, 12:58 PM   #28
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QuoteOriginally posted by newarts Quote
The design I posted used the filter diameter because it guarantees no vignetting and allows one to use an empty filter ring to mount the hood.

Either way should be fine.

I guess I'm not clear in just what people are looking for in a "design template".

Are people seeking a fan shaped flat template to be cut and rolled into a conical hood? Just what is the goal?
actually I don't see how your design gaurantees no vignetting because it does not consider the format of the sensor.

ASPC and Full frame (film) have different fields of view with the same lens., If you are not considering this, you are not getting the maximum design,.

As to what people are asking for, I think the title says it all, to me "optimum" hood design is a tulip hood, calculated specifically for the field of view on the sensor size used, for the exact lens being considered, therefore you need to consider the lens diameter and set back from the filter ring as part of the equation, as well as the format of the sensor (image)
03-01-2011, 01:59 PM   #29
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QuoteOriginally posted by Lowell Goudge Quote
actually I don't see how your design gaurantees no vignetting because it does not consider the format of the sensor.

ASPC and Full frame (film) have different fields of view with the same lens., If you are not considering this, you are not getting the maximum design,.

As to what people are asking for, I think the title says it all, to me "optimum" hood design is a tulip hood, calculated specifically for the field of view on the sensor size used, for the exact lens being considered, therefore you need to consider the lens diameter and set back from the filter ring as part of the equation, as well as the format of the sensor (image)
True about the different fields of view!

The design I posted isn't as small as possible, but as it will work without vignetting for a full frame sensor on a lens designed for a full frame sensor and on a lens designed for a crop frame (the angle between the entrance pupil and the filter ring is chosen by the lens designers to avoid vignetting - I just continued that angle.) Since it will work for a full frame it'll also work for a crop frame when a full frame lens is used on a crop frame camera.

I interpreted "optimum"as a kind of fuzzy request for least out-of-field-of-view light, in which case there is no optimum; such light will decrease continuously with hood depth.

Tulip design benefits escape me; maybe it is cool looking but I can't see that offers any special benefit other than using the minimum material for a given hood depth. What have I missed?

Dave
03-01-2011, 02:32 PM   #30
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QuoteOriginally posted by newarts Quote
True about the different fields of view!
Tulip design benefits escape me; maybe it is cool looking but I can't see that offers any special benefit other than using the minimum material for a given hood depth. What have I missed?
If you have a hood that is a cylinder of the same total length of the tulip then it will vignette. If you have a hood that is only the length to the cutouts of the tulip then you won't get as much light shielding. The tulip shape is "longest" where the angle of view is smallest and "shortest" where the angle of view is largest.
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