Frustrating 4x5 Negative fogging

[douglas_stow]

<p>I posted this fogging business not long ago. I just developed 6 TXP320 4x5 sheets, 2ea. with each of my 3 lenses (75mm, 150mm, 210mm) and they all came out with varigated fogging in the sky area. It always seems to occur in the sky or extreme highlight area of the negs. I used fresh film, fresh chems., controlled temps, and all other proceedures that haven't had problems in the past. I use a rack for the film and constantly dip the negs in D-76 for 7 1/2 minutes, stop 30 secs, and powdered fix for 9 mins. Recently I developed several negs that I put in the camera and removed the slide but did not release the shutter, they developed prefectly. I also shot three instant films with each lens and each of them are spot perfect. I'm about ready to give up 4x5, used to be sweet. </p>

[richardsperry]

Take one of your negatives into a darkroom.

 

Cut some RC paper the same size as the negative.

 

Put it in your holders.

 

Put the holders out in the sun for a while, both sides.

 

Then develop the paper.

[douglas_stow]

<p>What difference would that be from doing the same thing with film?</p>

[geoff_r1]

<p>Nothing, but paper is cheaper and faster to process than film. All you need to find is black blobs. </p>

[thirteenthumbs]

<p>If you want to check your shutters for accuracy open the PDF in<br>

<a href="../large-format-photography-forum/0044cW">http://www.photo.net/large-format-photography-forum/0044cW</a> . The phototransistor is no longer available but a low cost infrared led is that will work is.<br>

<a href="http://www.radioshack.com/product/index.jsp?productId=2049724">http://www.radioshack.com/product/index.jsp?productId=2049724</a> or similar at several online electronic component retailers.<br>

Change the 4000 ohm resistor to 100 ohms or eliminate completely. Remove the battery and capacitor if your computer microphone plug provides 1 volt or so to the jack. <br>

<a href="http://www.radioshack.com/product/index.jsp?productId=2062452">http://www.radioshack.com/product/index.jsp?productId=2062452</a> mono microphone plug.</p>

<p>Mount the photo transistor on in a piece of foam core or small box. Connect as in the schematic using #22 speaker wire long enough to make testing easy.<br>

Download and install an audio editing program if you do not have one such as <a href="http://audacity.sourceforge.net/">http://audacity.sourceforge.net/</a> .</p>

<p>A #25 red filter over the transistor or shutter being tested with a bright light source is required to register in Audacity. A red laser pointer works well.<br>

<a href="http://www.ebay.com/itm/NEW-5mW-Ultra-Powerful-Red-Laser-Pen-Pointer-Beam-Light-/150599450466?pt=LH_DefaultDomain_0&hash=item23106d3f62">http://www.ebay.com/itm/NEW-5mW-Ultra-Powerful-Red-Laser-Pen-Pointer-Beam-Light-/150599450466?pt=LH_DefaultDomain_0&hash=item23106d3f62</a></p>

<p>My procedure:<br>

Plug the photo transistor into the front panel mic jack.<br>

Open the shutter to be tested on T.<br>

Set the aperture to minimum.<br>

Set the shutter over the phototransistor with the transistor centered in the aperture opening.<br>

Set the aperture to maximum.<br>

Close the shutter, set it to the speed to be tested, and cock the shutter.<br>

Open Audacity, press Pause then Record. Select Waveform db from the recording box drop down menu.<br>

Press pause to start the recording.<br>

Position the laser over the center of the shutter and turn it on then trip the shutter.<br>

Recock and repeat 2 or 3 more times<br>

Stop recording.<br>

Using the time expand, shift, and index tools check each time.</p>

<p><a href="http://www.flutotscamerarepair.com/Shutterspeed.htm">http://www.flutotscamerarepair.com/Shutterspeed.htm</a><br>

<a href="http://www.photographyuncapped.com/articles/photography/iso-shutter-speeds-f-stops/">http://www.photographyuncapped.com/articles/photography/iso-shutter-speeds-f-stops/</a></p>

<p>Does this happen in the studio with strobes or hot lights?</p>

[john_shriver]

<p>When you loaded and unloaded film from the camera without tripping the shutter, did you take the camera out in the sun? If you didn't, you haven't ruled out bellows leaks, or leaks in the spring back.<br>

You may want to slightly fog a sheet of film and process it. Maybe take out one sheet in darkroom, put a sock over an electronic flash at 1/64 power, and pop the flash. You won't see uneven processing unless there's enough exposure of the film to cause it to develop.</p>

[douglas_stow]

<p>Thanks for all of you folks responses, this is a tough one. After putting two sheets of fim in the bellows area and setting the camera out in an f/16 light outside for 5mins., they developed totally clear, I am taking the stinking thing to an expert repair shop.</p>