How sharp can you get a pinhole image?

[m1tch]

Hi all,

I will be getting into large format photography at some point next year but I am gradually purchasing the parts over time to spread the costs, anyway I have some 5x4 double slides coming in the post for the camera (I don't have yet) and I thought in the interim I might look into pinhole photography. I see that there is a nice guide for an 8x10 pinhole on this forum which looks like you just simply strap the film holder to a recess in the back with some rubber bands lol so I might look at making one of those as it seems pretty simple to make considering its a box with an opening at one end

Anyway, I was just wondering about how sharp you can get a pinhole image, I know that with normal lenses there is a 'sweet spot' with regards to image sharpness and resolution, I am not after anything tack sharp as I don't really want the image to be clinical as it is with some digital images, but not massively blurred.

Is anyone able to post up a pinhole image from a 5x4 camera and let me know what the calculated F stop is for the 'lens'? It would be cool to compare and see what the different effects on the image a small change to the F stop might bring.

[pdeeh]

low res scan of a contact
f/176

[rbeech]

There is an optimal pinhole diameter for any given format and focal length. Use this caclulator: http://www.mrpinhole.com/calcpinh.php

The difficult part is creating the pinhole itself.

[RalphLambrecht]

Keep in mind that there are two optimal pinhole diameters,one for resolution and one for sharpness. i suggest optimizing for contrstnd sharpnessas that gets the most apparend sharpness, which the eye appreciates more than resolution. a high-resolution mage canstill look'unsharp'. a low-resolutionbut high-contrast image, on the other hand, looks sharper.

[m1tch]

Thanks for the comments, I might just go with a pre-made laser cut sort, or indeed use a pin/needle of a certain size, for a sheet of 5x4 the optimal specs are apparently:

Focal length = 6.4"
Pinhole diameter = 0.54mm giving F302
Angle of view would be 53 degrees

I'm going to get some materials together and have a look at some designs, I need to get development equipment together as well so I have a bit of time before I will be taking any shots with it!

Playing around with some numbers I have found this to be perhaps something to aim for:

5.5" focal
0.5mm pinhole
f279
60 degree FOV
3 second exposure on a sunny day with ISO 100 film

Looks like if I aim for a pinhole at around 0.5mm and a focal length of around 5.5-6" it should be good for a 5x4.

[RalphLambrecht]

just start playing withit.pinholes are so much fun and surprisingly good at imaging.

[m1tch]

just start playing withit.pinholes are so much fun and surprisingly good at imaging.

I will have a go, my 5x4 double dark slides have arrived so I just need to build a camera now lol

[MartinP]

Foamboard works a treat for the cam body, much easier and quicker than plywood etc. though also weaker.

[ic-racer]

If I wanted a sharp pinhole image I'd shoot on 8x10" film and reduce it to 4x5" when printing, that would double the resolution. Though, I'm not sure why I would want to do that, because if I wanted a sharp image I'd just use a lens.

[DWThomas]

Here's a 4x5 negative scan:



A 0.305 mm pinhole @ 63 mm from the film plane, a relatively wide angle of view.
Arista ULTRA 100 exposed 8 sec with the f/210 pinhole.

The camera was a relatively fancy project using plywood.