Building a DIY Lens

[David Mitchell]

Just added a simple card aperture to the front of the lens, this is the 6 dioptre (166mm) lens with a 20mm hole (or there abouts) so this is at around f8.



Here is the 14 dioptre (71mm) lens stopped down:

 

[Pete Askew]

That looks to have made quite a difference.

If nothing else, this whole exercise will help illustrate why good, fast optics are so bloody expensive!

 

[David Mitchell]

That looks to have made quite a difference.

If nothing else, this whole exercise will help illustrate why good, fast optics are so bloody expensive!

Indeed, fast optics are cheap, good fast optics aren't due to the number of elements to correct all of the imperfections caused by using the lens the light just went through lol.

I think I am going to go and buy a set of 88mm close up filters though, I think that a stopped down 85mm optic will outperform a 50mm optic wide open.

The 6 dioptre lens works with the bellows extended to the normal position, with the 14 dioptre lens the bellows are basically all the way home lol

 

[Pete Askew]

Don't forget that you can drop the lens board on the Speed Graphic (and most folding technical cameras) to accommodate very wide angle lenses when the bellows are closed. Press the closing catches but push the board downwards.

Nikon D3 + AF-S Nikkor 24-70mm f1:2.8 G ED. ISO 400, 1/200s at f1:3.2. PP in LR5 and Nik ColorFX Pro 4.

 

[David Mitchell]

Thanks Pete, I forgot about the bed drop, I remember that the camera can take a 90mm lens but completely forgot about the fact that it does have a bed drop.

I have just drawn up some basic plans for the actual camera as well

 

[Pete Askew]

Plans eh! I started with a sheet of A4 paper to guide the size of the negative, checked the focal length and then picked up a craft knife! The basic camera took about 6-7 hours to make and I have added bits and improvements as I've thought of them. Probably the total build time including the latest 'upgrades' is about 24 hours. The plastic is very quick to work with (and I bought two more sheets yesterday!).

When I get back to the UK I might start a new project for a 16x12" but in wood (the plastic would be too weak I think). I need to tidy the workshop up first though!

 

[David Mitchell]

Plans eh! I started with a sheet of A4 paper to guide the size of the negative, checked the focal length and then picked up a craft knife! The basic camera took about 6-7 hours to make and I have added bits and improvements as I've thought of them. Probably the total build time including the latest 'upgrades' is about 24 hours. The plastic is very quick to work with (and I bought two more sheets yesterday!).

When I get back to the UK I might start a new project for a 16x12" but in wood (the plastic would be too weak I think). I need to tidy the workshop up first though!

Just started the LF build thread with my intial plan

 

[David Mitchell]

Just been into a local hardware store, saw that there are 50mm compression coupler fittings, these might be useful for mounting a lens at each end and then cutting a slot in the centre to drop in waterhouse stops

I also saw a standard 110mm pipe connector....you can get 110mm diameter lenses cheaply ....aero lens lol

 

[David Mitchell]

Just ordered some larger close up filters which should give me 2 lens combos:

166mm f2 = 55mm equivilent for a 5x4 camera
71mm f0.85 = 23mm equivilent for a 5x4 camera

I also have most of the parts in place for:

150mm f1.4 = 50mm equivilent for a 5x4 camera

This could also possibly make the below lens (or event wider) however I probably won't make this as I want a longer lens for portraits:

100mm f0.9 = 33mm equivilent for a 5x4 camera

I will post photos up on the build once the parts arrive I am going to be working on the waterhouse stops soon

 

[David Mitchell]

The barrel for one the lenses will be on its way now and should arrive soon, due to the barrel length I have on order the lens will be a 135mm f1.2 which will be interesting to shoot

 

[David Mitchell]

I might also have to make my own shutter as well looking at the shutter speeds I will probably need for these lenses, I might however look at adding ND filters on the front to stop down the lens but not change the aperture.

I could do try 2 options:

Variable shutter speeds + no ND filters
Fixed shutter speed + ND filters

I am thinking about creating either a leaf, packard, rotary or guillotine shutter (will probably spring load the guillotine if I use that).

I could try something simple such as a fixed shutter speed shutter by simply having a spring loaded/rubber band powered shutter:

Lens cap on (or dark slide)
Pull a board in a runner with a set sized slot across against a spring/band
Lens cap off
Let go of the board with the slit in it to go past the now open lens
Lens cap on (or dark slide)

Basically firing a board with a slot cut in it across the lens so that its tight tight, slot passes past and then light tight again.

I could have a set of slotted boards with different shutter speeds depending on the slot gap, or I could used a fixed board and simply put an ND filter on the lens.

 

[David Mitchell]

Hmm just thought of a shutter design, its simple and i've never seen it done before so it might be a first lol

I am going to look into building a double iris shutter using springs and 2 sets of iris one in front of the other, the first is sprung so that the iris is held closed, the other the iris is held open. To use it you would simple put tension on each in the opposite way to put them under spring tension, remove the lens cap and let go. If the spring tension is different on the front and rear then one would close sooner than the other with one of them being closed in the 'rest' position.

I will try and draw a diagram of the idea later.

 

[Pete Askew]

Interesting idea. That'll be a challenge to calibrate!

Direct sun, f/32 is 1.5s for Ilford MGIV RC (ie ISO 6). I just checked.

 

[David Mitchell]

Interesting idea. That'll be a challenge to calibrate!

Direct sun, f/32 is 1.5s for Ilford MGIV RC (ie ISO 6). I just checked.

I will have a think about it, might just end up with a rubber band powered slider, just trying to work out how to make it compact otherwise the slider needs to be 3 times the diameter of the lens.

 

[David Mitchell]

Ok, so here is my initial idea with regards to the shutter, I might just go with a powered guillotine or a rotary but here is the idea I have:

There would be 2 states the shutter will be in, at rest and tensioned, the first 2 image are the front and rear irises at rest and the last 2 are under tension (as can be see by my badly drawn springs/bands).



Basically the delay between the closures of them will give the exposure much like the slots in the curtain shutters etc.

One iris is closed at rest and the other open at rest, I guess what I could do is have the shutter release like a pin I could pull out at different speeds. The gap between the shutters going back to rest will depend on when they are released so I could have some sort of pin which I can pull out, pull out half way one fires, pull out all the way the other fires.

If I pull the pin out quickly then both fire close to each other, pull the pin out slowly then the gap is longer - pulling the pin quickly would allow me to have a much faster shutter speed than if I tried to do it manually due to the spring tension.

Here is a badly made gif showing the 2 states open and closed

 

[David Mitchell]

Ok, this next image may not seem much but its quite important to me, here is an in camera cyanotype negative using the speed graphic and the 7 dioptre filter lens, its quite dark out now, long exposure (something like 20 minutes) and the cyanotype was created a while back so not that fresh.

It might not seem much but this is a test shot against that test window again, its not very clear due to the paper and lack of UV at this time, but you can kinda of make out the window edges and the apartments across the way (the brickwork is a different colour:



Here is what it would look like when looking through the ground glass (image flipped correct way up)

 

[Pete Askew]

Interesting. Can you scan and invert the tones?

 

[David Mitchell]

I have inverted it and turned it black and white, I need to recoat some paper again with some fresh cyanotype as this was just a basic bit that wasn't coated the best and the paper finish doesn't help lol but there is definatly an image on there, be it not sharp or decernable, its also shot wide open, might try it again tomorrow when its brighter, its 144mm @ f2.8.

I have only ever seen anyone make an incamera cyanotype with a 35mm camera, but they had something like a 6 hour exposure lol.

 

[Pete Askew]

Have you already left to right transposed this?

 

[David Mitchell]

Have you already left to right transposed this?

I think I did flip it, I will recoat some paper tomorrow and retry with some fresh.