phil_dickinson

I use d40's and metz's (with sca390).

TTL flash exposure works great on my 503cx and 553elx. Although I need to set the ISO dial 3 stops fast when using a

digital back.

Lol.

Though..... If Satya is up for a 50c, I just heard they're down to £5995, that's got to be nudging $US9,000?

If it keeps heading in that direction, I might have to trade in my h25. :D Nah, I'm enjoying it too much.

Hi Daniel, the h25 has the same aspect

ratio as the 50c.

Focus errors are hidden by having

fewer pixels.

I doubt someone considering a

Hasselnuts is a proffesional, but

probably is someone that could afford

an H25. Nor are they likely to consider

a 50c.

I like to be helpful when responding to

people.

There are cheap digital backs around (although cheap is a relative term).

I bought my Phase One H25 for about $900.

Yes it's tethered, but my 13 inch MacBook Pro in a satchel is no burden. Just leave Capture One running with the lid closed. You can see

the images apear on a wifi connected iPhone running Capture Pilot within a few seconds and tap to zoom to 100%.

It's only 22MP, but that's so much easier to get in to perfect focus than 50MP.

Finally, it's 1.1 crop factor (compared to 645) is much bigger than the 50C's smaller sensor and 1.3 crop.

<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>

Aerial image....

I found an interesting stub in Wikipedia. Does anyone have a link to more information?

http://en.wikipedia.org/wiki/Aerial_image

Hi Q, I'm having difficulty working out how it would work without a screen. My mind just can't cope with that idea.

Yeah taking a pic of my viewfinder does show dust etc, but with the focussing screen mounted in the back, and sealed

from dust, it should be ok. Or at least as ok as a sensor would be. Possibly easier to clean.

I'm using an SWC focussing back for the project. I've taken out its ground glass screen and put in an Acute Matte screen

minus it's glass backing. I had to dismantle it from the frame. An interesting excercise. It's only held in place with a bit of

tape at the moment. The SWC back gives me a base for mounting the electronics and tiny camera too. I have an old

70mm back that might be interesting, at some point, as an enclosure.

<p>Lets discuss how good or bad an image could be using the concept of a small sensor taking a photo of an acute matte screen.<br /> I just did a test by taking a photo of my viewfinder, using my little Fujifilm pocket camera. The image is about 2.5 MP, unfortunately I shot it at ISO 6400, so its not as good as it could be, its showing a lot of noise, but don't you think it shows some promise?.....</p>

<p>https://farm6.staticflickr.com/5558/13863405744_f17a94ff09_o.jpg</p>

<p> </p>

An interesting branch in the discussion.

Do we have a 56mm square sensor yet?

This thing, if I ever finish it, will capture a relatively low resolution digital image of the full 56mm x 56mm image.

It will operate like a digital back.

It won't compete with a digital back, nor will it compete with film. It will be something different. You may need an

imagination to think of a role for such a device. Luckily I do have an imagination.

My early tests suggest that it will deliver an image that is recognizably from a medium format camera, with some

degradation due to the Freznel lens possibly, but less than I had expected.

I see it as a valid capture device.

It does not compare to the aforementioned art form that used a point and shoot camera to capture an image from a

viewfinder.

As I keep saying, this device will operate like a digital back, it will require the operator to judge the light and select an

aperture and a shutter speed and to set it on a lovely Zeiss lens, just like a real Hasselblad, and to focus just like a real

Hasselblad, and to compose as though they were a real photographer. Wow. Pressing the shutter release will be

required to capture the image, winding the crank will also be required.

It can be swapped for another back, a feature of these fine cameras. It doesn't have to stay attached. It's just another

type of back, like cut film, or polaroid, or 70mm etc etc

Potential resolution.....

In Wildi's "The Hasselblad Manual" fouth edition, pp 113-114, the only useful reference source I have for this, he

describes the Acute Matte screen as ....

"The focussing screen consists of seven and a half million microlenses on one surface and a fine Fresnel (22 line/mm)

pattern in the other."

It is far from just a ground glass screen.

So if the microlenses is the limit to our resolution we should be able to achieve 2738 x 2738. Given that sensors tend to

be 4:3, we would need a sensor of about 10MP to take advantage of it.

The question remains how visible the Fresnel will be, or how distracting.

But seriously..... This is a bit of fun. If I can come up with a very cheap digital back that would give me web quality, whilst

retaing a full 56x56 frame and all the characteristics of same such as DOF etc. then I'll be ecstatic.

It's the raspberry pi camera. But with a c mount lens.

The sensor is an Omnivision 5647.

http://www.ovt.com/products/sensor.php?id=66

Once the project is finished it should act just like a conventional digital back, with exposure determined by the blad's lens

settings for aperture and speed, and using the real shutter.

Yeah it works very much like the hasselnuts toy back, but instead of using an iPhone I've used some dedicated

electronics, and mine will be triggered by the flash sync like every other digital back.

Using the acute matte screen where the film would normally go has worked out pretty well, I tried some conventional

screens but they just show grain. I really don't mind the crosshairs, it reminds me of the old Apollo photos.

I'm running some tests to see what sort of ISO equivalence I will have, it will be quite low, possibly around 25.

I plan to upgrade the sensor, I think I can go as high as about 8mp and still get ok quality with the 42165 screen.

This has been under development for a little while, I don't move quickly. Lol.

Btw, it already has a touch sensitive screen and support for wifi to automatically upload images.

<p>I had a go at making my own digital back. It captures a full frame 56mm x 56mm.<br>

See comments on the pics for more info....</p>

<p>https://www.flickr.com/photos/94282195@N04/sets/72157643730022314/</p>

The 500el/m circuit is the same, except it doesn't have the diode to prevent charging. This diode would be necessary to

prevent an earlier charger being used, and potentially doing damage.

The 500el/m circuit also has pin 4 the same.

It must have a use! Lol.

External exposure is between pins 1 and 3.

External power is between pins 1 and 5.

What is the purpose of pin 4? It seems to connect to the positive side of the motor.

Any ideas?<div></div>