spot meter problem?

[chris_4622]

Hi, I think I might have a problem with my Pentax spot meter, but maybe it's with the guy using it. I checked it against the reading in my 35mm manual canon. There was a difference of 1 1/3 stop, the spot meter reading higher. I have noticed my shots seem to be a little on the thin side so yesterday I went out and took a reading of some snow in full sun, opened up three stops and exposed some sheets for testing. I developed one (efke pl 100, pyrocat hd 2:2:100 12 minutes) and though I haven't printed it yet it sure looks too thin. How likely is it that the spot meter is off? I don't have any other meters to check it against so short of sending it out are there any suggestions? If I send it out who is recommended? Thanks,

[tim atherton]

skim through this thread for starters

http://www.largeformatphotography.info/lfforum/topic/504159.html

[Leonard Evens]

If you don't have any other meters, try the following. On a clear sunny day, take a spot reading of the sky, about 45 degrees up and opposite the sun. Avoid any hint of clouds. It should read close to 14. On a specially clear day, it might read slightly under. If there is a trace of haze, it might read higher, but not by too much.

As far as your test with the snow, you are assuming the reading from the snow was Zone VIII. But it could easily have been a bit lower, in which case you would have underexposed. Adams recommends generally determining exposure from the shadows, not the highlights. Finally, the particular developer you used might not give you the nominal film speed. To be sure about it, you have to do careful tests as described in Adms's The Negative and elsewhere.

In principle, it doesn't matter if your meter is right, as long as you arrive at a consistent way to work, including determining your exposure and developing your negatives and making prints. But if your meter is way off, it does make life more difficult. In addition, an error of 1 1/3 stops suggests that the meter has some serious problems and is not linear, i.e., the errors at different intensities are different. It is unlikely that a Pentax digital spotmeter is really that far off, and most likely the problem is your method of using it, but it is good to have an objective test of the meter.

You might try again with your Canon, but make sure you shoose a uniformly lit surface without texture. You can use the spot meter to check the uniformity of the lighting. When making the measurment with the Canon, make sure you are close enough that it doesn't see anything but the uniformly lit surface.

[Joseph O'Neil]

A few years ago, backpacking, I fell into a small river, and my spot meter went for a swim. a few weeks later, after Pentax rebuilt it, it was even better than new, so i tested it beside my then brand new Sekonic incident light meter. the two of them did not match on readings. In fact, i have four light meters in total, including a classic old Weston Master II that looks brand new, and none of them agree with each other.

First, are you shooting B&W or colour. for me, i always use my Sekonic for colour, be it 35mm, 120 or the occasional sheet of 4x5. It's never let me down. Colour film, print, and especially slides, you pretty much can only do it one way (and yes, there are excpetions, but generally speaking)

but for all B&W, which is 99% fo what I shoot 4x5, I always use my spot meter, because there you can start to play with things.

You have to "learn" your spot meter for lack of beter words, what works best for you. You also have to think about what you want to be exposed. for example, i get out there with my analog spot meter, and lets say the range of readings goes from say 9 to 14. if I expose and develop for the shadows - which say might be a 10 or 11 on my meter reading - then will the sky be completely washed out? Maybe that's what I want to begin with.

the "art" of B&W, IMO, begins with your decision on how to expose. I have a shot I perosnally like of a snow sculpture from a contest downown here a few years back. Big, 8 foot high snow lizard. In my shot you can see all the detail in the snow, but the rest of the trees and park in the background is kinda dark, a bit moody even, but that's what I like for this shot. You would almost never guess I took the shot around 3 pm, in full sunlight. Developing in pyro helped too in that case. What I did was meter off the snow, not the grass (well, there wasn't any) or a grey card, but off the snow because that's where the detial was.

so you see, your meter may not be broken, you just have to decide what you want your exposure to be, you have to decide "this is my scale". Take your spot meter outside every day for a week,a nd meter the snow at noon under bright sunlight. does it give you the same, consistant, reading every day? If so, fine, it is working, now you decide, if you are shooting B&W, what you want yoru snow to look like in your prints - brilliant white, slightly grey, dark grey, etc, and then you expose and develop to match. It's your choice, and learning how to do this si all part of the art, mystery, and pain in the ass of B&W.

One last thought - your choice of developer, IMO, affects your exposure. One way to teach yourself just how different - and this will cost you some film and time, but it is worth it, setup a tripod and shoot 8 shots of the exact same thing - be it a building, a pot of flowers, whatever. Develop two sheets in pyro, two in D76, twin in HC-100 and two in Rodinal. or whatever developers you can lay your hands on. the reaosn i say two is for consistancy, and because it's always easy to ruin a sheet here or there. I did this myself once becausse I was having a terrible time, and it worked for me. I also had a Kodak Grey card and Colour scale, which I put into the shot - yes, a colour scale on a B&W shot - it's quite a learnig experience when you are printing.

After they are all devleoped, and you have them in sleves - labeled which ones are which - try printing one of each, and look at the difference. You might be amazed, but more importantly you might learn exactly just how to relate your meter readings to what you want to see under the enlarger. Again, I know it's wasting the better part of a box of film, but you know, in thelong run, what you learn will save you a fortune in lost shots. Just remember, what's is "coorect' is what you decide is correct, what works for you.

Sorry for rambling - still only second cup of coffee this moring. I ain't human until I'm through my second pot.


joe

[Michael Kadillak]

Sorry to have to disagree with you Joe.

If you have two spot meters or two incident meters that do not agree to within 1/3 stop of each other it is not an inconvenience that should be normalized by simple experience or "learning" your meter it is a disaster. What happens when the meter continues on its deviation path from accuracy over time? Do you just keep chasing it with more "experience"?

While it is truly amazing how much elasticity photography affords the error prone consumer cognizant of this condition or not. But are we not a cut above with large format cameras and expensive sheet film? Think about how many other variables are in the equation. Time, temprature, agitation, accuracy of shutter speed and f stop etc. It just makes no sense to not know for sure that where you are placing a tonality with your meter is factually accurate - Period. Iterate your experience off of a consistent reference point and you will be much better off.

A meter is no different from any other mechanical instrument. It needs to be calibrated. And there is no need to continue to be a cheapskate and put it off. Another highly important variable that one must insure with their light meter is LINEARITY throughout the high and low exposure scale.

Suck it up and take the risk out of the equation. Get your meter calibrated. Richard Ritter will accomodate you as other companies will as well.

I purchased a backup spot meter from a guy a while back that claimed that he had used it consistently over the last few years and it was dead on. When it did not agree with my other meter I sent it off to be calibrated and it was off by 2 1/2 stops. Good God! With that kind of accuracy why use a meter at all - just wing it.

There are a few folks that I know that are such consummate shooters that they could get by without taking a meter reading, but they are the exception and surely not the rule.

Cheers!

[Steve Feldman]

Curmudgeon says, "Man who has one watch, always knows the time. Man who has two watches never knows the right time. Man who has a broken watch has the correct time - twice a day."

Photographic Wisdom says, "Man who has one meter always knows the exposure. Man who has more than one meter never knows the exposure."

Corollary to above: "Don't forget sunny 16".

[Gary Griffin]

You might want to look at your development time for the pl 100. J&C recommends for 2:2:100 8 mins.

[Michael Kadillak]

Excellent Advice From Alan Ross's web page on the critical nature of linearity in your metering:

Meter Calibration
According to Ted Orland’s poster Photographic Truths: “No two light meters agree.” Sadly, that does seem to be pretty much the truth – unless you do something about it.

For years I had a pair of supposedly “matched” Pentax digital spot meters that were never closer than 1/3 of a stop from each other - so I had to remember which meter I used for film tests and which one I had in the field. One of these meters had an accident and got sent off to its maker for a rebuild – and came back 2/3 of a stop away from where it had been, now 1/3 higher than the meter it had been lower than! So I sent the other meter off to its maker and after two months got it back about the same as when I had sent it. Which meter was right? I then got a dandy little “Pocket Spot” from Metered Light which sometimes agreed with one Pentax and other times, the other. The Pocket Spot was the only really “linear” meter of the three, yielding nearly identical densities on a roll of 35mm film exposed randomly on plain targets ranging in brightness from about 1 EV up to 18. Last spring I had had it with the three-meter dance and decided to finally standardize on the work of a highly competent, pro-savvy company in Hollywood. Quality Light Metric does the meter calibration for the film industry, and those folks don’t have the time to mess around with equipment that isn’t right. I sent both meters off to Hollywood. The calibration was done in two days at substantially less cost than the “other” place, and both meters now agreed exactly with each other, and while they were still 1/3 stop different from the Pocket Spot, they were now, at least, perfectly linear. The final answer? I sent the Pocket Spot and one of the Pentaxes off to Metered Light and had them tweak the PS to match the Pentax. I now have three meters that all read the same!

My students, naturally, have all varieties of meters in their kits. Sometimes they agree with mine and sometimes not. We can tell pretty quickly whether their gear is linear, and if it is then we know they can rely on the readings, they’ll just have a different film speed than I use. But they’ll wind up with the same exposure!

If you have multiple meters and want to put an end to calibration frustration, just have them all set to the same standard, and make that your own. Contact George Milton at Quality Light Metric, 7095 Hollywood Blvd., Hollywood CA 90028. 323-467-2265. If you Google them, you’ll come up with a bunch of different addresses and phone #s. This is the current info for mail order work.