tom_jenner1

Thanks for the response, Tom.

The 2000 umol number I believe is for 30 degrees lat, equinox, noon. I've also heard 2,200 umol so I'm trying to figure this out.

I believe it's actually an open loop test. There's no feedback process control going on.

Yeah, I've wondered about reflections off the leaf material. My idea was to measure the leaf, move it out of the measuring area then take a grey card measurement.

I've been having a hard time finding an answer. "Ask a physicist" didn't know what a 18% grey card was. I think what I need to do is find a photobiologist who also understands cameras.

Yes, I need empiricism.

Thanks for wishing me luck with Kodak, I'll probably need it!

Yeah, I think I'll contact Kodak for help. It's a rather tricky question because I'm attempting to make photosynthetic active radiation (PAR) measurements. By looking at the specs of PAR meters and sensors made for PAR measurements, I'm thinking my D70s is going to be more accurate.

I could try using the "Sunny 16" rule since full sunlight is 2,000 umol/meter^2/sec-1 and put a grey card next to the plant then meter off that but I'd like to confirm this as a sound testing method. Having a 18% calibrated reference will also allow me to measure the amount of light being reflected from the leaf tissue.

This is kind of technical and I didn't know where to post this. I wish to

convert an 18% Kodak grey card reading (iso, shutter, f stop) to

umol/meter^2/sec-1 equivelent. Any clues how?

I wish to use my camera (Nikon D70s) as a three chanel optical spectrum

analyzer (daylight white balance) to measure light levels with the above

conversion for growing plants using LEDs.

If you look here at

you can see what I'm trying to do.

Well, if we can have digital cameras work in space (Hubble Telescope, etc) and if the vast majority of cosmic rays are absorbed by the atmosphere then it stands to reason that cosmic rays are a complete non-issue in the normal digital photography that we do.

I'm actually working on a neutrino gun, it's going to be a weapon for hardcore pacifists.

OMG! I'm not nor never will be a wedding photographer (I get a lot out of following the wedding forum though) but I mean come on! This is just unprofessional. Even the composition is bad.

I could set my camera to auto everything, hand the camera off to a layman with a five minute lesson in holding the camera and still likely get better shots.

I'm very sorry that your wedding pics came out so bad, you don't deserve this!

I use 2 five watt flexible water sealed solar panels mounted on top of my '81 Volkwagen Westphalia camper van that's hooked into a 20 amp 12 volt gel cell battery.

It's mainly used to run my lap top that has been modified to run strait off the battery. The laptop is an old 266 MHz Toshiba Portege that runs an old copy of Photoshop Elements. The laptop draws only 1.2 amps (when the hard drive isn't running) so I can run the computer for 3-4 hours per day in the summer.

I also trickle charge NiMH batteries and am going to modify my Nikon lithium battery charger to run off the 12 volt battery (I'm an electronics engineer). It should be a simple mod, relativley speaking, although I'll be examining the data sheet to the charging chip first (most have a wide input voltage).

The solar panels saving me a few years ago when I drained my car battery in the middle of the woods. After about three hours of using the solar panels wired to the car battery I had enough of a charge to start my van.

You can buy a lithium battery charger designed for running off 12 volt batteries here:

http://www.centralhobbies.com/Electrical/chargers/Chargers.html

You'll need to rig up you own adapter.

Good luck!

The more I learn about photography, the less serious I take Ken Rockwell.

I personally think he does a disservice to people newer to photography with some of the completely BS advice he gives.

That strobist blog, btw, has good info.

Mmmmm...chocolate muffins!

According to this web site the sync voltage is 5.9 volts which would be safe for your camera.

http://www.botzilla.com/photo/strobeVolts.html

Sigma's web site confirms that it's safe for your camera.

http://www.sigma-photo.co.jp/english/flash/comp_500dg_sup.htm

That large softbox in the busy bee package will come in very handy. It'll be ideal to properly light up a dark wine bottle.

It looks like it boils down to 3 lights and a battery pack or four lights. I've been into studio type photography for about a year now and one of the important lessons I've learned is that more lights is better so that your background can be lit seperately.

The LG4X is a wired remote control with 25 foot cables. This allows the power levels to be set in one location.

Hey Gunpreet,

What we're all trying to tell you is that you're having this problem because of the zoom lens that you're using. Zoom lense are a compromise and one of the compromises, at least in the consumer zoom lenses, is that they tend to have a higher amount of fringing.

If you're lens is a problem, then you need to get a different lens. A low cost, high quality lens that won't have these problems is the the 50mm f1.8 prime lens. With a high quality prime lens you won't have this problem in the first place. Problem solved!

There are also a wide variety of low cost prime manual focus lenses that you can use, although they won't meter with your D80 (manual only).

-Tom

You can try a higher F stop.

Better yet, drop $110 on a 50/1.8 lens.

I never use zoom lenses with studio strobes. Even with the 18-70, I'll get fringing on the edge of a white plate on a black background.

Get the 50/1.8

I've found that the Nikon flashes I've opened up do not use a bleeder resistor across the strobe's capacitor. That strobe capacitor does store enough energy to be lethal. If you're not an electronic technician or engineer then you really need to think twice before poking around.

It only takes one shock through the heart to die.

Well, for the money, the best camera I've ever had was a pinhole camera made out of a cardboard box I had laying around that used 8x10 photo paper as a negative with a piece of pin pricked aluminum foil for a lens. A piece of electrical tape was used as the shutter.

Seriously, it took good pictures!

If everyone one bought into this does this mean that everyone would be on the first page? That'd be one long page!

(a little sarcasm to make a point)

Thanks Mars!

I felt really bad for making you feel bad.

You can pick up a tack sharp AIS 55/3.5 macro pretty cheap.

A 50/1.8 AF with extension tubes works good as a macro and is inexpensive.

The 60/2.8 macro would be hard to beat. As mentioned above, is has great build quality. I don't like how heavy it is as a walk around lens.

I picked up my AIS 105/2.5 for $100 and I consider this my best photo related purchase ever. It's very sharp.

You really can't go wrong with this lens.

Mars,

I didn't call you dumb, I called the act of saying that I was helping Ken Rockwell dumb.

But, no the less, it was an unwarranted insult and I offer my apologies to you.

I do disagree that bad publicity is good publicity (and who's they?) unless perhaps one is a c-list celebrity (I wouldn't want Mel Gibson recent publicity!), and I do highly disagree with your notion of not referring at all. If I see something I perceive as wrong I will step in. Silence is betrayal.

Dick and Allen, thanks for the useful tips.

Richard, I've got the 18-70 also. I'll use that lens. Thanks!

I appreciate all of your input!

Mars,

You can be sceptical all you want (it shows free thinking), Rockwell gets enough hits to his website without me "helping" (that part was just dumb...there's opinion for you!).

If you'd read my post just a little more closely, you'll notice I'm stating fact (by Rockwell's own admission) that the man in essence lies on his web site.

Why post a link? Because I'm not going to call a man a liar unless I can back it up.

The ultimate motive for this posting is that Rockwell's site does a disservice to the photo community, particularily to newer photographers who may still be to naive to see through his deliberate gaffes. Is that my opinion? It sure is! I'd rather see people be helped than tricked or deceived.

Sam, the difference between referring someone to photo.net versus Rockwell's site is that when incorrect information is posted to photo.net, there's usually someone there to correct that information (but not always!) rather than having a site where somewone puts up incorrect information as a joke. Intent, if nothing else, makes a difference.

Simon, I agree, some of his stuff is good. I liked his 50mm comparisons, however, since the man admits to deception, how do we know which lens is actually used for what shots? Is it another joke he's playing?

I didn't know where to post this so I just decided on this forum since a lot of

different people read it.

I know there's a love/hate relationship with Ken Rockwell's site but please,

keep in mind, his site is meant to be a joke. I emailed him about some mistakes

and he emailed back "They ARE a joke", refering to his own web pages.

"Read this site at your own risk. I offer no warrantees of any kind, except

that there are many deliberate gaffes, practical jokes and downright foolish

and made-up things lurking."

"...A hoax, like this site, is done as a goof simply for the heck of it by

overactive minds."

http://www.kenrockwell.com/about.htm

At the very least, read the web page you're linking to make sure there's none

of his deliberate, BS mistakes.

I love a good joke but personally I think he does a disservice to the photo

community and his own reputation when he down right makes things up, by his own

admission.

Any thoughts?

Sam, you do realizt that Ken Rockwell's site is meant to be a joke, don't you? I actually emailed him about some mistakes and he emailed me back explaining they were on purpose and that the site was meant to be a joke. I sure wish serious people would quit refering people to this BS site (I'm not trying to be offensive to you Sam :>) )

"Read this site at your own risk. I offer no warrantees of any kind, except that there are many deliberate gaffes, practical jokes and downright foolish and made-up things lurking."

http://www.kenrockwell.com/about.htm