Topic: Peter's Pinhole project

[Peter84]

So like promised my pinhole project.
Large format has always appealed to me, The bigger the better right....  and after reading Francois's article about his contraption 17

http://www.filmwasters.com/forum/index.php?topic=7035.msg89597#msg89597 it started to itch.

I thought I can do that or sort of that...  I found a couple of 4x5 negative holders on a local auctionsite and I decided to make a camera based on a Noon pinohole, myself .....     http://www.ebay.co.uk/itm/261570239347

So I designed a box which can hold a 4x5 filmholder, 70mm focal length and it should have a 0,3mm pinhole, which gives F233...
I started with some beech plywood, I learned this from francois's project, this stuff doesnt splinter as much so after a while I had the box ready. I painted the insides matt black and I milled out a bit, so the negative holder fits in snug. I Ordered a HSS drill sets at conrad's which has a 0,3mm drill, used an underside of a tomato puree tin to drill it in. I Also  painted this matt black and glued that in to the wooden box.
Glued the back on it, bought a box of Ilford FP4 4x5, while I was in Berlin at Calumet and tried it on when I got back home.... so the first shot  wasn't all that I would like it to have been, when scanning I had to put the clarity full out to get a visible image and there was quite a light leak, so I decided to tape of the whole film holder with masking tape and sticking to the recriprocity failure times list listed some where else on this forum for ILFORD FP4, so with an eight minute exposure I got the last attached image, still a light leak, maybe through the dark slide, but considering that for something that I made myself and actually got an image, that is reasonable,  I feel proud!!?! 

Maybe some of you got tipps for avoiding the light leaks at the darkslide? Let me know. I had some great fun making this and I'll keep perfectioning this till it gives half  decent images. 

[Bryan]

Looks great Paul!  If it's the dark slide that's a problem with the film holder.  I would think it's where the film holder seals against the wood of the camera.  Maybe attach some felt to make a better seal.  I'm not sure how your pinhole is mounted but light could be getting around the that hole in the front of the camera if it's not a perfect seal.  If you're doing a long exposure it could be a very small leak that would be hard to detect with the naked eye.

[ManuelL]

Hi Peter, it is hard to see from the photos. Do you have a velvet (or other soft material) rim on the surface where you put the holder? This usually closes with the holder tightly to prevent light coming in. My other recommendation would be to use some rubber bands to push the holder tightly against the camera.

[Francois]

Light can sneak in quite easily. That's why I used a very deep light trap. Also, the small ridge on the back will prevent it from sitting flat. That's why I made a small groove on the camera's back.

[gsgary]

Birch faced plywood is better

[Francois]

When I look at the picture of the camera, there seems to be an awful big gap on top of the film holder...

[gsgary]

Did you mastic all the joints inside before painting ?

[Peter84]

Thanks for all your tips, The large gap I fill up with a piece of foam and on the second shot I taped of the entire filmholder.... but I loaded up the filmholders, put them in and taped the whole thing of again with masking tape, also found a black fabric bag which I'm gonna put around the filmholder/camera. See if it makes a difference... I keep trying and I'll keep you posted (if only the weather got a little better  )

[Francois]

I can probably trade you bad weather for a sea of orange construction cones...

When building my 4x5, I quickly discovered that the important thing is the fit of the holder.
One thing you could do that would help is add strips of wood inside to make the back fit more snugly and use the back panel with some hinging mechanism to finish sealing-up the thing. It would also hold the back in place.

You can use some foam insulation strip as a spring to push the holder against the box. That's one of the things I was thinking about until I got the idea of the rat trap.

[Peter84]

So a couple of weeks passed since the last post. I invested in black electrical tape to tape of the entire holder and made another shot, same result.... That made me think maybe it's something different. I still had a couple of soft black fabric bags lying around from blind wine tasting.... (they go around the bottle...  ) After I loaded up the filmholders I placed them in the bag, kept it there till shooting, made the shots, put it back in the bag, developed it and the result is below.... No leaks at the borders. So could it be down to my own way of handling the 4X5 holders? I must admid I just tosted them in the car and left them there for a day till I found some thing I wanted to make a shot of. That sorted now getting the exposures right