The Film Thread: "for sale: packfilm back. never used."

The Something Awful Forums > The Finer Arts > Creative Convention > The Dorkroom > The Film Thread: "for sale: packfilm back. never used."

LooksLikeABabyRat: Jun 26, 2008; Oh dang, I'd nibble that cheese

I have a couple of weird technical questions I can't seem to find an answer to.

I have a Nikon FM, and I had a situation today where I couldn't get a proper light reading at any aperture. I finally got it so 250 was overexposed and 500 was underexposed I think at f/16. Moving the shutter speed dial between the two settings indicated correct exposure, and allowed me to fire the shutter so I took the shot. Does that actually work or does it have to be clicked into either 250 or 500 to be accurate?

Secondly I picked up a cheap Vivitar 200mm prime lens. I tested it indoors and it seemed fine, but when I went outside I couldn't get a correct exposure reading no matter the aperture or shutter speed. Switching to my 50mm in the same spot with similar apertures, I was able to get a correct exposure reading. Is something wrong with the lens, or am I just missing something?

Here are a few shots from my first 3 rolls of film just so there's some interesting content in this post. I just started shooting two months ago.

# ¿ Feb 25, 2015 21:29

Adbot: ADBOT LOVES YOU

# ¿ May 16, 2024 05:29

LooksLikeABabyRat: Jun 26, 2008; Oh dang, I'd nibble that cheese

deaders posted:

I'm not sure about the technical details with that camera but it sounds like you might not have the best understanding of "correct exposure". There are plenty of situations where you want that kind of basic, old-school meter to be reading as over or under exposed, e.g. a dark-coloured subject will be showing underexposure when it is correctly exposed and vice versa. Same thing for back-lit scenes or reflections off water.

The book Understanding Exposure is very helpful if you don't have it already.

I do have that, though I haven't finished reading it. I just thought it seemed weird that I was getting different readings with the same settings on two different lenses.

Back to studying then, thanks.

# ¿ Feb 26, 2015 01:42

LooksLikeABabyRat: Jun 26, 2008; Oh dang, I'd nibble that cheese

Saint Fu posted:

It could have had something to do with the framing of the shot when you were metering. If the camera has a TTL (through the lens) meter, which it almost certainly does, it will meter the scene as seen through the lens. Still, you should have been able to find an aperture/shutter speed combination to get a "correct" exposure with either lens so it's kind of puzzling how you didn't. Doesn't sound like it's anything wrong with the lens though, it shouldn't affect it.

It was incredibly bright outside and I was using ISO 400 film. Maybe that's the problem.

# ¿ Feb 26, 2015 03:02

LooksLikeABabyRat: Jun 26, 2008; Oh dang, I'd nibble that cheese

mulls posted:

Maybe the pin that tells the camera the max aperture or the current aperture setting isn't working or maybe you had depth of field preview turned on which could gently caress with the through-the-lens metering

The second may be the case. The lens is heavy and I'm not confident about where I had my hands placed at the time.

I just pulled the lens out and the pin moves when I adjust aperture. Popped the lens on, focused at a point across the room and set it to a "correct" exposure reading at 4 different apertures without problem.

# ¿ Feb 26, 2015 04:08

LooksLikeABabyRat: Jun 26, 2008; Oh dang, I'd nibble that cheese

mulls posted:

some cameras don't meter right when the DoF preview is engaged because DoF preview stops the aperture down but the meter thinks your lens is at max aperture, so it's getting in f/8's worth of light and pretending it is f/2.8's

It's possible that I had it pressed down, but it seems unlikely. I'll mess around with it tomorrow again and see if I can't figure it out.

# ¿ Feb 26, 2015 05:55

LooksLikeABabyRat: Jun 26, 2008; Oh dang, I'd nibble that cheese

nielsm posted:

The coupling for AI metering is on the edge of the aperture ring itself, not a lever that moves on the lens. The edge of the aperture ring pushes a lever on the camera body, so if one lens was metering wrong all lenses would. There is an aperture lever in the lens, but it only adjusts the actual aperture between the one set on the ring and the maximum. I don't think that lever being out of alignment would cause metering faults. (Check: Set the aperture ring to smallest aperture. Push the aperture lever all the way. Check if any of the aperture blades are still visible through the lens, if they are there is a fault with the lens.)

I don't know about the meter on the original FM, but on the FM2 the meter is 3-part: An up arrow, a down arrow, and a circle between them. When one of the arrows light up, the exposure is wrong by more than 1/3 EI in the indicated direction. When the circle lights up, the exposure is within 1/2 EI of correct.
Any display where the circle is lit is the best possible setting, unless your lens allows aperture adjustment finer than whole stops.

This is almost exactly how metering on the FM works (which the cosmetic difference of there being 3 circles instead of two arrows and a circle; they function the same way).

I just tested again: pointing the 200mm out the window (it's bright and sunny today) I couldn't get the middle circle to light up at f/3.5, f/22, or f/11. When I turned inside and pointed it towards my darker kitchen, I was able to get a circle reading at f/11.

With my 50mm pointed out the window I was able to get the circle at a few different apertures.

I put the 200mm back on and set the ASA to 100 and was able to at least get circle + at a few different apertures pointing out the window. I think I just different film for close ups outside.

Thanks for all the help goons!

# ¿ Feb 26, 2015 19:23

LooksLikeABabyRat: Jun 26, 2008; Oh dang, I'd nibble that cheese

gently caress, I just destroyed an entire roll of film.

# ¿ Feb 27, 2015 01:36

LooksLikeABabyRat: Jun 26, 2008; Oh dang, I'd nibble that cheese

Popped it out of the canister by accident. Forgot to hit the fun rewind button and couldn't figure out why there was so much tension...

# ¿ Feb 27, 2015 04:09

LooksLikeABabyRat: Jun 26, 2008; Oh dang, I'd nibble that cheese

krnhotwings posted:

Sounds to me like you're trying to get a perfect exposure by having the middle-o lit up. Since the shutter speeds and aperture settings (at least for the Nikkor lenses..) go by full-stop increments, you won't always be able to get a "perfect" exposure based on the TTL meter reading, in which case you're just gonna have to settle for under or overexposing a little. But given what you've described (ISO 400, f/16 on a sunny day,) that sounds like the ideal situation to apply the sunny 16 rule, so it sounds to me like your exposure reading was more or less correct. Also, personally, I wouldn't let the shutter dial sit between the indexed speed settings. I'm assuming that it actually works, but I wouldn't rely on it since it's not accurate. Just stick with the full-stop increments.

Just an FYI, the TTL meter reading all depends on where/what you're pointing at. This image is for an FM2, but I'm just gonna assume that the FM works the same way:

See that 12mm circle? The exposure reading is weighted by whatever's in the circle. Since the field of view for a 50mm and 200mm are drastically different, you're mostly like gonna get varied meter readings 'cause what you see in the viewfinder (and therefore, what's in that weighted circle) will be different between the two lenses.

e: On that note, you shouldn't rely 100% on the TTL meter until you understand what it's doing.