Radiometer vs Integrator with Photocell

[mimosatexas]

I posted in the shoutbox above, but thought this topic may come in handy to other down the road, so I decided to make a thread.

I just got a 1k MH bulb and ballast from Homer to improve my exposure setup (thanks, you rule!).  I wanted to start exposing more consistently and professionally, and it was suggested I purchase an integrator to measure UV and automate certain things down the road, most likely some kind of shutter, since the MH takes a bit to warm up.  I purchased an integrator off ebay, but it did not come with a photocell, and it seems the photocells are pretty costly, unless the person I spoke with at Douthitt misunderstood what I needed or was trying to sell me more than I need.  I will likely call them back to clarify...but in the mean time:

Since I am not actually using the integrator to automate anything right now, but just using it to measure UV, is there another device that will accomplish this for not much money?  I looked around on good and saw that they make standalone radiometers that measure UV, but they all seem to only measure up to 370nm, and for some emulsions I need to be closer to 420nm.  I don't know what UV my bulb outputs (is there a way to measure this as well?), but I'd like to spend as little as necessary to accomplish my goal of a consistent exposure.

tl;dr Photocell vs. Radiometer vs. - what should I use for better exposure?

[StuJohnston]

The guy at douthitt probably didn't misunderstand you, they are expensive. This project you've started sounds like a giant hassle to be honest, especially since you are only now learning how an exposure unit works.

What I did when I didn't have an integrator was to simply use dual cure that has a decently large exposure margin and use a timer, after using an exposure calculator of course. I never really liked the stencils I got from straight photopolymer emulsions anyhow.

EDIT: I just took a look at the link you put in the shoutbox. There are a couple of problems with using something like that. The first is that the unit would have to be on the vacuum frame and you would have to figure out a way to read it in that position. The other problem is that if you couldn't read it from where you stand, it won't alert you when you reached your target.

on further inspection, it measures mW/cm^2 I may be wrong, but I don't think that's what you want. That's more like putting a dial on your dash that measures horsepower when you wanted a trip meter. I think what you want is something that can measure in mJ.

[mimosatexas]

I started the thread to see if anyone had ideas.  Builds like this are not a hassle to me.  I have build a homemade version of every piece of equipment in my shop, and when I have upgraded I have been a lot more informed about how things work and what I actually need than a lot of the printers I've talked to.  I like the DIY process a lot...

I currently use Aquasol HV with a homemade florescent tube unit and timer, and have for the past 7 years.  It works fine (i can hold plenty of detail on big runs of both discharge and plastisol), but isn't optimal, which is why I purchased the metal halide.  I know how a pre-built expo unit works, but I don't want to pay $1000+ for one of the few that have popped up for sale in my area, most needing work, and being limited to smaller screens (i have a handful of large screens I use for weird personal projects and one offs for some clients.  Not sure why you assume I don't understand the technology because I don't want to shell out for it pre-built...

I will continue to do exposure tests in the way I always have and use a timer to gauge exposure, which works fine, but I know there are better and cheap alternative methods that will account for bulb aging and other variables.  The integrator I got was $25 so it isn't like I made a costly mistake, though not seeing that the photocell was missing was an oversight.  I'm thinking the radiometer is what I'm looking for, but haven't found an affordable one with the right spectrum yet.

[Gilligan]

Have you ever messed with the arduino platform?

Might be able to take one of these and write a program that not only sample/logs/calculates/displays but also could do outputs as well... From simple buzzers and lights to relays to turn off or close a shutter... Which could also be built into the arduino.

[mimosatexas]

EDIT: I just took a look at the link you put in the shoutbox. There are a couple of problems with using something like that. The first is that the unit would have to be on the vacuum frame and you would have to figure out a way to read it in that position. The other problem is that if you couldn't read it from where you stand, it won't alert you when you reached your target.

I am building a vacuum frame with a central pivot.  The screens will be vertical when exposed, so the display will be visible through the glass if I end up going with a radiometer.  I also don't plan on using it for every exposure, but rather at standard intervals to gauge the aging of the bulb, or to do on the fly changes to the configuration of the setup (like moving the light closer or further away depending on need).

Thank you for the info on the type of measurement!

[mimosatexas]

Have you ever messed with the arduino platform?

Might be able to take one of these and write a program that not only sample/logs/calculates/displays but also could do outputs as well... From simple buzzers and lights to relays to turn off or close a shutter... Which could also be built into the arduino.

Interesting...I'm reading into it now.  Thanks!

edit: this looks awesome, for a lot more than this project.  Could easily apply to my auto flash idea as well...

[Frog]

I started the thread to see if anyone had ideas.  Builds like this are not a hassle to me.  I have build a homemade version of every piece of equipment in my shop, and when I have upgraded I have been a lot more informed about how things work and what I actually need than a lot of the printers I've talked to.  I like the DIY process a lot...

I currently use Aquasol HV with a homemade florescent tube unit and timer, and have for the past 7 years.  It works fine (i can hold plenty of detail on big runs of both discharge and plastisol), but isn't optimal, which is why I purchased the metal halide.  I know how a pre-built expo unit works, but I don't want to pay $1000+ for one of the few that have popped up for sale in my area, most needing work, and being limited to smaller screens (i have a handful of large screens I use for weird personal projects and one offs for some clients.  Not sure why you assume I don't understand the technology because I don't want to shell out for it pre-built...

I will continue to do exposure tests in the way I always have and use a timer to gauge exposure, which works fine, but I know there are better and cheap alternative methods that will account for bulb aging and other variables.  The integrator I got was $25 so it isn't like I made a costly mistake, though not seeing that the photocell was missing was an oversight.  I'm thinking the radiometer is what I'm looking for, but haven't found an affordable one with the right spectrum yet.

Chromaline used to offer at great discount, a radiometer to help folks optimize the use of their emulsions, and I wish that I had gotten one just for testing purposes. doh!
If nothing else, one could determine hot spots if any to help determine the optimal distance for the particular reflector. For instance, the Olecs come in three flavors. Like wide angle, standard, and telephoto lenses. (With no real reflector, we do use the 1.5 times the diagonal of the exposure area as a rule of thumb, as you mentioned)

At any rate, I don't think that the photo cell was "missing" but is just part of the Olec head unit to which your or a couple of other integrator will connect.

I have no ides how the Nuarc/M&R or Richmond integrators work and where they pick up the light to measure.

[mimosatexas]

I actually found the chromaline UV meter earlier, though I forget what it was called off the top of my head.  Again though, as Stu mentioned, it is measuring intensity (hotspots like you said) rather than UV over time (mJ) as Stu mentioned.

I found this pretty informative paper a minute ago: http://www.eit.com/instruments/UVMeasurementForFormulatorsPart1_PaintAndCoatings.pdf

Definitely helps understand the difference pretty clearly.

edit: found it with a little googlefu: http://www.ebay.com/itm/Chromaline-UV-Minder-Radiometer-Dosimeter-USED-/261323502807

[StuJohnston]

I am building a vacuum frame with a central pivot.  The screens will be vertical when exposed, so the display will be visible through the glass if I end up going with a radiometer.  I also don't plan on using it for every exposure, but rather at standard intervals to gauge the aging of the bulb, or to do on the fly changes to the configuration of the setup (like moving the light closer or further away depending on need).

Thank you for the info on the type of measurement!

I have that type of frame as you may recall and personally, I try not to look at it if possible. The type of radiometers you are looking for are probably more than three hundred bux. I've seen some that have little remote pucks that send a signal to a unit that you could have out of the path of the light, but that would definitely be more than three hundo.

By hassle, I don't mean that you can't meet your goal of having more accurate measurement, but this isn't an equivalent to an integrator hooked up to a lamp that is automated. If you do plan to make something that is automated, a radiometer is just a tangent. While that photocell might be 300 bones, I doubt you will ever have to replace it if you use it like it is in an olec.

I wouldn't be surprised if you could make that integrator trigger a relay by testing the output wires with a plain of multimeter, BTW MIDI cables will replace the cables on an olec unit as far as I can tell, or at least they would be useful if you just wanted to DIY something.

Ah, yeah, dosimeter was the thing I was trying to think of earlier. Also super useful if you want to expose in the sun. That chromaline unit looked like a hell of a deal, I wouldn't mind one myself actually.

Have you ever messed with the arduino platform?

Might be able to take one of these and write a program that not only sample/logs/calculates/displays but also could do outputs as well... From simple buzzers and lights to relays to turn off or close a shutter... Which could also be built into the arduino.

That's not a terrible suggestion, but he already has an integrator that does all that and all it needs is a photocell. I actually have one and it's pretty cool.


not quite a tl;dr, but you (mimosa) have addressed some things that I wrote about, but I am not really up to editing my post much at this point.

EDIT: this sort of thing is commonly used to test conveyor uv curing units, but would work to measure your UV density, http://www.ebay.com/itm/UV-Integrator-150-UV-Radiometer-Dosimeter-/320926185826?pt=US_Laser_Pointers&hash=item4ab8b0f962 also called a UV puck

[Gilligan]

Have you ever messed with the arduino platform?

Might be able to take one of these and write a program that not only sample/logs/calculates/displays but also could do outputs as well... From simple buzzers and lights to relays to turn off or close a shutter... Which could also be built into the arduino.

Interesting...I'm reading into it now.  Thanks!

edit: this looks awesome, for a lot more than this project.  Could easily apply to my auto flash idea as well...

Yes, MANY MANY projects can be made with this.  I was building a simple Simon game to test my programming skills as the few projects I had in mind at the time were stupid simple and involved just a few lines of boring code, thanks to all the libraries built in.

My father-in-law recently got a fish weighing set for his bass club.  It has a remote display that uses a black box transmitter that has an arduino in it to read the serial signal and a couple of x-bees to transmit and recieve the data.  And the charged a fortune for it!

[mk162]

here's my take...buy a unit with an integrator built in.  you can find cheap units for $350-$500.  spend the time you would be spending on selling and you will make way more money.

I bought a 7500 watt unit for $1600, it does 2 screens at one time.  i could not have built something for that. 

I don't mind building things, but when I can buy something better for less.

[GaryG]

Yeah we're all tinkerers, but time is money.
Spend it wisely. You could probably use a step wedge monthly or quarterly
and nail times down for regular use.

[mimosatexas]

While I appreciate the advice, buying a pre-built unit isn't the point of this thread.

That said, if I could buy it for less, I would.  Unfortunately, the least expensive 1k MH unit with a vacuum top I have seen within driving distance in the last year and a half of daily searches on craigslist, digitsmith, and forum classifieds was $800 and needed new glass, new blanket, new bulb, new shocks, and that's just what they advertized was wrong with it.  The best deal available right now anywhere within 500 miles (that I can find) is $3k for a mostly working unit.

My situation is a little different from a full time multi-employee shop.  I work part time as a printer and have a full time job and other obligations on my time.  I do not advertize and do not want to advertize until my efficiency allows me to handle more work in a compressed amount of time.  Everything is word of mouth and has continued to build slowly and organically.  I rely on quality products and customer service to keep clients and gain clients.  When there are slow times, I focus on improving efficiency with projects like this, or learning new processes so I can offer a wider array of services.  These are indeed time sinks, but I only use time I have to spare.  I am making the transition to full time at the end of this month, but only because my workload and profitability have forced me to, and I am in a position where I am prepared for the transition.

At some point I'm sure I will have to abandon this kind of incremental growth, but for now it is what I prefer and is working for my situation.

[mimosatexas]

You could probably use a step wedge monthly or quarterly
and nail times down for regular use.

This is what I do currently and what I will continue to do for the time being.  This thread is about improving on that practice though.