Home made digital back

[phil_dickinson]

<p>Thanks Bill, that is fascinating.... I'd love to hear more. <br>

When you say "near the image plane" for the field lens, could that be behind the image plane?<br>

I'm also curious what you mean by "somewhat degraded".</p>

[Bill C]

<p>Hi, there's definitely some leeway as to where you place the field lens, in either direction. By being slightly off the image plane, any defects in the field lens won't be so obvious.</p>

<p>Degradation of the image depends a lot on what you use for a field lens. If you're doing it on the cheap, it'll probably be a single element. Consequently you'll get some field curvature - instead of staying reasonably flat, the "plane of focus" will bulge slightly in the center. The added element will also give some extra reflection - unless you design carefully and get a high-quality anti-reflection coating, you'll get a noticeable (?) amount of extra flare. I think these will be the main issues. If you look more closely, you'll probably see some chromatic aberration, where the red, green, and blue spread out a tiny bit.</p>

<p>I can't say how badly these will affect you, but a longer fl on the digital camera will minimize things other than flare. Do you know what lenses you hope to be using at this point?</p>

[djthomas]

<p>Phil--</p>

<p>This is very cool. I just happened to stumble onto this discussion and find it fascinating. To me, the better part of a project like this is to actually make this thing work. It's not like the expectation is that you are making the equivalent digital back of a medium format camera from one of the camera manufacturers. Reminds me of creating a pinhole camera--people look at them and the subsequent images and comment that it doesn't look like a picture from a 'real' camera. Love it. Not to pry, but if you don't mind sharing, what sort of investment do you have in this back (excluding camera and lenses). It would be nice to see a video on something like this--building and shooting. I know very little about this kind of stuff, but was also wondering how you are storing the images--do you have to use traditional digital media cards, or (if speed isn't an issue) can you pretty much write to anything--like directly to a laptop/PC--or even a flash drive?</p>

[joseph_wisniewski]

<blockquote>

<p>An interesting branch in the discussion.<br>

Do we have a 56mm square sensor yet?</p>

</blockquote>

<p>Not since the Dicomed about 15 years ago. That proved that no one wanted to pay $70,000 for one.</p>

[javier_ossa]

<p>Hi to all,<br>

I had been looking also to make my digital back, found a medium format sensor but it cost around 10K to 11K Euros, plus developing and making the rest of the circuits i guess that will be around an other 3 to 5K more, the approach with the Raspberry Pi is good bur as part of the big solution, also must consider to use FPGA programs circuits to get the image out of the image sensor, and some more FPGA and DSP chips to give format to the image, i think that economically it would be great idea to go on when finding a lower price image sensor.<br>

Does any one knows where to buy image sensor CCD or CMOS for full frame or medium format that wold be much, far much more cheaper?<br>

Any way with the raspberry Pi can be done all the TFT panel control, saving the image, interfacing the push buttons and the logic to take the picture.<br>

But the Image sensor driver, image format and communications protocols has to be implemented in other circuits.</p>