Cheap densitometer.

[rootberry]

The title kinda says it all. I'm looking for the absolute cheapest densitometer that will work with BW negatives with pyro stain developers. I've been frustrated with my results since I started shooting again, and would really like to start learning about sensitometry. What models should I be looking for at what price? Thanks guys =)

 

[Eric Rose]

Check out the book on Beyond the Zone System. Phil Davis has a whole thing on using your spotmeter as a densitometer. He even includes the planes for a jig you can build.

 

[Anupam Basu]

I use a photodiode positioned within a 35mm film canister. The meter readings can be translated to densities if you use a calibrated step-wedge from Stouffer. Whole setup runs about $20.

-Anupam

 

[Steve Duprey]

Anupam,

Now that would be something to see! Any chance of sharing pix and schematics?

Vest regards,

-Steve

 

[donbga]

The title kinda says it all. I'm looking for the absolute cheapest densitometer that will work with BW negatives with pyro stain developers. I've been frustrated with my results since I started shooting again, and would really like to start learning about sensitometry. What models should I be looking for at what price? Thanks guys =)

VueScan Pro scanning software can be used with many different film scanners. The Pro version has a densitometer function. The limitation is the dyanmic range of the scanner so you would be limited to film densities probably no greater than 2.2 or so using a desktop type scanner.

Frankly if you want a densitometer I wouldn't waste my time trying to build one. Used Xrite 810 densitometers can be purchased relatively inexpensively on eBay.

Of course if your are interested in building electonic gizmos then go for it!

 

[Anupam Basu]

Now that would be something to see! Any chance of sharing pix and schematics?

I don't have a digital camera so pics will take a couple of days, but the principle behind it is really simple and it is accurate. I drilled a small hole in the back of one of the black kodak 35mm film canisters. The sensor of the diode is just beneath this hole - the legs stick out from under the canister. Tape everything down with electrician's black tape and you're set.

The idea is to have a small dark chamber where the only light hitting the diode comes through that hole. I put the thing under a steady source of light like a desk lamp. Now as the intensity of the light is changed, the resistance in the arms of diode changes as well and can be measured with a multimeter. So as you hold a sheet of film over the hole the light decreases and the resistance increases.

Now to go from here to actual film densities is the trick. I used to calculate them using log and it can be done but its tricky mainly because the response curve of the cheap diodes isn't linear particularly for higher densities and so your reading would be a bit off (about 10-20% in the diodes I have tested). A much more reliable and in fact totally foolproof way of doing it is using a calibrated step wedge from stouffer. The step wedge comes with density readings for the various steps and so let's say that you have a piece of film that is registering a reading of 10.2 on the multimeter. Now all you need to do is figure out which step in the wedge generates a reading of 10.2 or as close to it as possible. Read off the corresponding density from the chart they supply you and that is your density - guaranteed with no error.

Is it worth your time to build? Well, it was worth mine. It takes a few minutes, is negligible in size and is dead accurate because I don't have to worry about the accuracy of a second hand densitometer off eBay. As long as Stouffer has theirs set up correctly my reading will be accurate. Because I am just comparing density values to the wedge by converting it into multimeter readings there isn't much that can go wrong.

Hope this helps.

Anupam

 

[GeorgesGiralt]

Hi !
If you print your negs, you may find the RH-Designs Analyser Pro the better piece of equipment to put into your darkroom.
And, icing on the cake, it doubles as a densitometer also....
Just my 2¢

 

[dancqu]

Is it worth your time to build? Anupam

Well I would wonder. I've calibrated my EM-10 against
a Stouffer step wedge; the wedge in the enlarger and
the head's position exactly noted. Replace the wedge
with a negative and take your readings.

The EM-10 is in effect a very small spot enlarging spot
meter. I set my wedge for 8x10 and so can read very
detailed areas of the negative.

The EM-10 is non-linear. For better accuracy I've
calibrated for 3 f stops. BTW, under $30. Dan

 

[Nick Zentena]

My colour densiometer was something like $60 a few years back. MacBeth 504. I doubt similar vintages are any more expensive today.

 

[paul ron]

I have an Epson 3170 scaner that has a feature in it's scaning software that will allow you to use it as a densitometer. I haven't used it but now that I see someone trying a film can n photodiode, I just may do some experimenting now.

 

[rootberry]

The macbeth 504 will read BW negatives? or just stained negatives?

 

[jstraw]

Here is my understanding:

Color densitometers will read color negs and transparencies and black and white negatives, whether stained or not stained. Black and white densitometers will not accurately read stained negatives. Densitometers that can read UV but not color can read black and whit negs whether stained or not.

Have I got it right?

 

[rootberry]

I don't know, this is all rather confusing to me. I would imagine that a color dens. would have be able to read BW fine, on a visual or white light channel I guess?

 

[Nick Zentena]

Mine is status A and M. Which I think means it'll do any kind of film. But different models exist.

 

[bill schwab]

I got a Macbeth TD 904 in perfect working order off ebay for $9.00. It will only do transmission, but there are many that will do both. With print shops getting rid of their old gear, they are quite readily available. Don't forget to try Craig's List too. I have gotten some great deals on darkroom equipment there as well.

Good luck,

Bill

 

[rootberry]

I have actually found a few on ebay for 9.99$.. I think I will pick up that Macbeth 504, for that price I'd be silly not to. Of course, it's being sold as is so it might show up here not working, worth the chance for sure though.

 

[Helen B]

I got a Macbeth TD 904 in perfect working order off ebay for $9.00. It will only do reflection, but there are many that will do both. ...

Don't you mean transmission only?

For Macbeth:

TD = transmission only
RD = reflection only
TR = both

Best,
Helen

 

[bill schwab]

Don't you mean transmission only?

Doh!!!!

Thanks Helen. I'll make the correction. It is backwards day here today.



Bill

 

[rootberry]

Which is more effective, transmission or reflection?

 

[Nick Zentena]

Transmission for film [Things you look through]
Reflective for paper [Things you look at the reflected light]

 

[rootberry]

See guys, this thread is not worthless- I'm learning at least!

 

[matti]

Would a scanner be able to handle stained negaiteves?

/matti

 

[rootberry]

not a clue. I can't afford a scanner that will do 8x10 negatives, which is all I would want one for..

 

[matti]

Would a scanner be able to handle stained negaiteves?

/matti

I mean as a densitometer.
/matti

 

[Nicholas Lindan]

My firm makes an enlarging meter with 0.01 stop/0.03OD resolution that works as a projection densitometer.

Information is on the web site, please email or call if you need more information. http://www.darkroomautomation.com/ nolindan@ix.netcom.com 216.691.3954

* * *
Any densitometer can be used with pyro stained negatives. With caveats. The stain density the densitometry 'sees' will be different to what the printing paper 'sees'. This is true for any densitometer, the filters in color densitometers are matched to CN or CT film and won’t provide much advantage for pyro. To complicate matters further, variable contrast filters will change the ratio of light transmitted by the stain and light transmitted by the silver. The densitometer will have to calibrated for each film, pyro developer, enlarger, paper and contrast grade/filter.

It is always possible, under fixed conditions, to make a curve of densitometer reading to print density -- which all one is really after in the end.

In general avoid the the small brick-shaped densitometers (many of the X-Rites). They are made for reading 30x40" negatives and proofs in graphic arts and read transmission by placing the negative on a light table. They may be useful to people working in alternative process or ULF as most densitometer can’t take negatives much above 8x10".