The pine board camera build

[Tim Meisburger]

Use the 12". I assume the light bulb was relatively close to the lens, so the focal length will be somewhat less than that at portrait distance (which might be 6 or 8 feet. If it is a simple lens without a diaphragm (like a magnifying glass), you can calculate the speed of the lens using this formula: fl/d = f fl is focal length. If you focus on a person for a portrait and the distance from film (or ground glass) to lens is ten inches, that is the focal length for that subject. If the diameter of your lens is 2 inches, then 10/2 =5. This means the speed of your lens wide open at this focal length if f5, and if you have a light meter you can use this to calculate the correct exposure time (i.e. shutter speed, if your lens has a shutter).

[Pitchy]

Use the 12". I assume the light bulb was relatively close to the lens, so the focal length will be somewhat less than that at portrait distance (which might be 6 or 8 feet. If it is a simple lens without a diaphragm (like a magnifying glass), you can calculate the speed of the lens using this formula: fl/d = f fl is focal length. If you focus on a person for a portrait and the distance from film (or ground glass) to lens is ten inches, that is the focal length for that subject. If the diameter of your lens is 2 inches, then 10/2 =5. This means the speed of your lens wide open at this focal length if f5, and if you have a light meter you can use this to calculate the correct exposure time (i.e. shutter speed, if your lens has a shutter).

Thanks Tim, the light bulb was about four feet from the lens`s, the four inch magnifying glass gave the longest focal length at 11-12 inches.

No shutter just a cap and on the box camera outside it was about as fast as I could remove and install it with a stop of about 1/2 inch diameter ,that was using a 135mm lens.
I have a old light meter but outside the speeds are to fast to be of any help without a shutter.

Question, if you stop down a four inch lens to say two inch does that make the image circle on the glass smaller?

[winterclock]

no, it reduces the amount of light. Depending on where you place the stop it can make the image sharper or distort the image.

[Pitchy]

no, it reduces the amount of light. Depending on where you place the stop it can make the image sharper or distort the image.

Ok, thanks.
We`ll get out and see if we can get something to work in a bit after it warms up.

[Pitchy]

Bingo, the van is at 22 feet from the lens (4 in. magnifying) focal length 10 in. exposure 1 second.
paper size 5x7

Pretty happy , thanks for all the help, more to come.

[Louis Pacilla]

Bingo, the van is at 22 feet from the lens (4 in. magnifying) focal length 10 in. exposure 1 second.
paper size 5x7

Pretty happy , thanks for all the help, more to come.

Your getting it together Pitchy. You go my friend!

[Tin Can]

I agree, I think we have a natural, seeing these results this quick.

I think Pitchy is pretty handy as I spotted a large metal lathe in one of his posts.

Great progress.

Congratulations!

[HMG]

Definitely "up north".

[Tin Can]

Definitely "up north".

I really miss north woods.

Love moss, ferns, birch and pines.

And fish.

[Pitchy]

Thanks one and all, yep north central MN.
We just re made the tripod ,more sturdy and made a couple cardboard stops.
It was cloudy today and I can`t put that cover off and on any fast so I`ll need them.
What I really need is a bigger dark room, my small closet isn`t cutting it.

Also I forgot to mention, I used the contact method for making the picture from the negative.