File :-(, x, )
Anonymous
hey /p/
I'm looking to open a blog to follow my camera construction project, where do I make it? Blogspot or LJ? Other choices? Pic related.
>> Anonymous
blogspot
>> Anonymous
Why don't you just try them? They are not going to charge you any money.
>> Anonymous
>>191580
Or I'll just do both as some friends suggested. Thanks for the replies. I'll post one day once the project is more advanced or successful.
>> Anonymous
care to give more details?

you say your constructing a camera?
>> Anonymous
pinhole?
>> Anonymous
>>191589
Yes sir, down to grinding the lenses by hand, building my own shutter, aperture system, lens barrel (Im refusing to buy premade pvc tubes even), reflex focusing system etc. A royal pain in the ass in other words.
>> Anonymous
>>191591
Nope, definitely not pinhole.
>> Anonymous
blogspot
>> Anonymous
>>191567
i remember you..
any pics since the "curing of lenses" ?
>> Anonymous
     File :-(, x)
>>191601
Hey, yep, I do. I finally figured out how to cure the lenses correctly, but I have yet to perfect my pouring technique. I sometimes get these weird bubbles in the inside of the lens, forming a sort of ripple in the refracted image. It might not be as damaging as it seems though.

If you remember, I was trying to make the lens go up to F1.1. I attempted to make an aperture ring for F1.1, but... the fucking lens would have been around 10cm in diameter, even if it was a 13-blade aperture (13 for the sake of it) because of the materials I'm using.

I did try it though, and and failed. I was too tight on tolerances, and broke several blades while trying to make the assembly. Pretty ballbreaking, so I decided to step it down a little. It's going to be an F1.4 lens with 8 blades because it's simply easier to make. I'll try the F1.1 or higher on another occasion, but not this time.

Also, I was delayed by personal reasons, but I'm back on track.

Picture of the original lens and the first clean copy.

Camera-Specific Properties:Equipment MakeSONYCamera ModelDSC-P200Maximum Lens Aperturef/2.8Image-Specific Properties:Image OrientationTop, Left-HandHorizontal Resolution72 dpiVertical Resolution72 dpiImage Created2008:04:17 18:08:45RenderingNormalExposure ModeManualWhite BalanceManualScene Capture TypeStandardContrastSoftSaturationHighSharpnessHardExposure Time1/160 secF-Numberf/2.8Exposure ProgramManualISO Speed Rating200Exposure Bias0 EVMetering ModeCenter Weighted AverageLight SourceTungstenFlashNo Flash, CompulsoryFocal Length7.90 mmColor Space InformationsRGBImage Width3072Image Height2048
>> Anonymous
>>191607
legos huh?
>> Anonymous
give up now.
>> Anonymous
>>191607
are you looking at trying to reduce fringing etc?
also.. how are you going to build all the parts like lens barrel, focus ring, viewfinder, etc ?? i suspect it will only be a basic viewfinder (if at all) as opposed to a rangefinder or SLR..
>> Anonymous
>>191608
Only for holding uncured lenses by the rim. When theyre uncured, it's easy to damage the lens by simply touching the surface. You can print your fingerprints all over them. Lego's good enough for the task, and not a great loss if it gets all sticky : P

>>191609
I considered it, but no. I'm going all the way. Suck my dick.

>>191610
>are you looking at trying to reduce fringing etc?
I'd like to, but seeing how I only have one type of plastic (at the moment) at my disposal, I might not be able to get an equivalent of a different type of glass. I'll try it though. Still though, I knew it would be fringing galore the moment I made this thick lens, so no surprises there. From the looks of it, I'll have to make it a triple element lens, so might be a chance to slip in a second type of plastic there.

>also.. how are you going to build all the parts like lens barrel, focus ring, viewfinder, etc ??
I'm studying industrial design, so I was taught how to use various materials for making prototypes, many of which are also used by figure sculptors and model artists. In other words, stuff like body filler, styrene and laminated plastic of different calibers.
>i suspect it will only be a basic viewfinder (if at all) as opposed to a rangefinder or SLR..
I'm planning to make this an SLR, actually, but only with a waist-level viewfinder (or top-down viewed, since it's going to be a little small, being for 35mm).

It's going to be a major bitch.
>> Anonymous
>>191616
sounds pretty fucking awesome, can't wait to see some pics taken by it..
building the shutter and aperture sounds like its gonna be a bitch.
what focal length are you going to make the lens??
Also, will your next camera project (if this one is successful) be a camera with changeable lens?
>> Anonymous
     File :-(, x)
Here's another picture of the first properly cured lens and a second lens I made through a different method. The second one is a planoconcave, but it isn't good enough yet. It's too thick, I'll try making it thinner to make its curve a bit stronger. (that's pretty much how a lot of this is going, by approximations, at least in the optics department. Please remember I dont have an optics or physics major, only a lot of interest in this kind of stuff)

Camera-Specific Properties:Equipment MakeSONYCamera ModelDSC-P200Maximum Lens Aperturef/2.8Image-Specific Properties:Image OrientationTop, Left-HandHorizontal Resolution72 dpiVertical Resolution72 dpiImage Created2008:04:21 23:07:53Exposure Time1/40 secF-Numberf/2.8Exposure ProgramManualISO Speed Rating400Exposure Bias0 EVMetering ModeCenter Weighted AverageLight SourceDaylightFlashNo Flash, CompulsoryFocal Length7.90 mmColor Space InformationsRGBImage Width1280Image Height960RenderingNormalExposure ModeManualWhite BalanceManualScene Capture TypeStandardContrastSoftSaturationNormalSharpnessHard
>> Anonymous
>>191618
>building the shutter and aperture sounds like its gonna be a bitch.
You bet, I'm worried specially about the shutter though (since I already got the aperture business kinda figured out). I can already make a functional focal plane shutter with a single speed. I need to figure out how to assemble it in a way that I can change its speed. I even investigated how leaf shutters work, but even looking at many disassembled compur shutters and stuff, I couldnt make any sense of it. There's not enough clear information about this stuff online. Considered a rotary shutter like the ones used in the Pen cameras, but I dont think it would work as well on a full frame, not without making it much bigger.

>what focal length are you going to make the lens??
This lense's focal length is approximately 55mm, but I'm going to add elements behind it to increase the backfocus distance to give me some space to work. Im not entirely sure how this affects the actual field of view. Anybody know this?

>Also, will your next camera project (if this one is successful) be a camera with changeable lens?
If this one's successful, I -will- be able to change the lens for another one! After this, though, if it works, I'll probably try to build a medium format rangefinder.
>> Anonymous
Interesting. How do you make the lenses?
>> Anonymous
>>191623
Massive pain in the ass. I sand a block of soft material into the shape of the lens, make a negative mold with it, then fill the mold with thermosetting resin.
>> Anonymous
>>191625
Also, -many- hours of grinding/sanding follow. Over 12 for that finish.
>> Anonymous
     File :-(, x)
And one last image, the last update for now.

The failed blades for the 13-blade assembly for an f1.1 aperture. Keyboard keys in the image for scale.

All of this stuff will be on the project blog later on, when I post it farther ahead in the project. Well, I'm gonna go now, going to draw the plans for the interchangeable film backs.

Camera-Specific Properties:Equipment MakeSONYCamera ModelDSC-P200Maximum Lens Aperturef/2.8Image-Specific Properties:Image OrientationTop, Left-HandHorizontal Resolution72 dpiVertical Resolution72 dpiImage Created2008:04:22 20:48:00RenderingNormalExposure ModeManualWhite BalanceAutoScene Capture TypeStandardContrastSoftSaturationNormalSharpnessHardExposure Time1/125 secF-Numberf/3.2Exposure ProgramManualISO Speed Rating400Exposure Bias0 EVMetering ModeCenter Weighted AverageLight SourceUnknownFlashNo Flash, CompulsoryFocal Length9.20 mmColor Space InformationsRGBImage Width1280Image Height960
>> Anonymous
>>191627
sweet,
let us know of the blog link
>> Anonymous
>>191630
Yup, will do
>> Liska !!LIVFOETqL8j
This is pretty cool. Interested to see what you come up with.
>> Anonymous
>>191619
i do physics,

1/f = (n-1)(1/R1 - 1/R2)

where f is the focal length, n is the refractive index of your lens material and R1 and R2 are the radii of the ends, it's an approximation, but should be good enough for your project. i'm assuming you are using spherical sides.
>> Anonymous
>>192473

Step aside this physicist knows the lens makers equation! Genius.
>> Anonymous
>>192473
I'm glad to see that you completed grade 10 science.
>> Anonymous
>>192473
"It's an approximation, but should be good enough for your project."
-Nikon
>> Anonymous
>>192473
They're spherical yes, but all of the lenses I've made so far are planar on one side. I dont know how the formula would work considering this condition. Also, I saw this formula on wikipedia, but didn't apply it for this same reason.
>> Anonymous
Nevermind, I googled it already. Support appreciated though, thanks. :)
>> Anonymous
In case you don't know, there are hobbysist who grind glass mirrors for home-made Newtonian telescopes. They buy kits with Corning glass blanks and grinding and polishing grits. If you're polishing plastic for 12 hours, you might as well consider using glass instead. I have seen loooooong tutorials on this, but don't have the notes now.
>> Anonymous
>>192884
Hi! Yeah, I've read about some people who've done that before.

>They buy kits with Corning glass blanks
The problem with that is that I don't quite have a way to get those over here. Shipping to where I live is a bit of a problem. :[

The good thing about plastics is that once the 12-hour grind is done, I can repeatedly make water clear copies of the lens without having to grind it .
>> Anonymous
>>192890
Where do you live?
>> Anonymous
>>192484
>>192586
well excuse me for offering information. if he wanted to know more he could ask
>> Anonymous
>>192891
>Where do you live?
Sorry, but I'll say it later on. For now I'd like to avoid arguments on that matter. It's no big deal, but.. just not yet. Not til' later along the project.

>>192894
It's well appreciated, and I do have a doubt you could possibly help me out with. I'm having trouble finding information on this, but in a lens array, which lens dictates the final focal length of the system?

Say we have 3 lenses. The first one, to make things simple is a 50mm. Due to the combination of this lens system however, the real image forms at 50mm -behind- the last lens, whose focal distance is -not- 50mm. What's the real focal length, or which one defines this? Is it the first one?

Another example. Comparing a 35mm single element lens and a two element pair, consisting of a convex lens on the front and a 25mm lens behind it, giving the same angle of view. say it forms an image of the same size at the same distance behind the last lens... is it a 35mm lens in both cases or is it different?
>> Anonymous
>>192900
I would use matrices to calculate the combined effect, you can read up about it on wikipedia here : http://en.wikipedia.org/wiki/Ray_transfer_matrix_analysis
(aproximate your lenses as thin lenses)

if you have not done calculations with matrices, i can do it for you if you draw me a diagram of the system, i dont quite get it from your discription. but you'll have to wait until tomorrow.
Its not too hard, just make sure you calculate them in the order it happens.
>> Anonymous
>>192914
I see, I'll read into this. Also, how thin is a thin lens, or when does a lens become classified as a thick one?
>> Anonymous
>>192944
>if you have not done calculations with matrices, i can do it for you if you draw me a diagram of the system, i dont quite get it from your discription. but you'll have to wait until tomorrow.
Its not too hard, just make sure you calculate them in the order it happens.

Ah, unfortunately the examples I listed were just random samples I got from a brief explanation of how a retrofocus lens works. I don't know the actual system.
>> Anonymous
>>192946
you can use the same method to deduce where to put your lenes if you know how much space you have.
>> Anonymous
If you use Blogspot you can also import the entries into Wordpress.

Makes it easier to compare and decide which you prefer. Or you can use both.
>> Anonymous
op is a genius. good luck with your project and hoping to see the link soon.