I got a weird ultra-grainy look in the dark areas on only some B&W shots and don't know why

Hi there,
I don't have much experience with analog photography and was wondering if you could help with a strange effect on only some shots on a roll I took recently. The film is Ilford HP5 Plus (developed and scanned at a photo shop) and the camera is a Pentax ME.
Most of the shots came out ok in termes of exposure but a few of them have this strange ulta-grainy look in what should be dark areas of the image - I'll post an example of one of the strange images next to one that turned out ok.
If anyone has any ideas about what might have caused it (camera malfunction or me not knowing what I'm doing) I would be very interested!
Thank you

First, the strange exposure :


Then the better exposure from the same roll of film:

Hi, welcome to Photrio!
The problem you're running into is serious underexposure. There's no differentiation in the shadow areas since they received insufficient light on the film. When scanning, you might be tempted to lift those shadows and increase their contrast to recoup this differentiation, but since it wasn't recorded, all you end up with is some grainy base fog plus some scanner noise.

If you correct scan #1 for the actual detail/differentiation on there, you're left with no choice but to set the black point to those last shadow areas and then try to recover as much contrast as possible across the rest of the tonal range:

It's very harsh (and as such it can be a perfectly valid artistic choice); if you want a softer/smoother result, expose more.

The light meter on cameras like your Pentax is easily fooled by relatively small, but very bright areas in the frame, causing the camera to bias exposure towards those very bright areas. This leaves the shadows deprived of exposure. You can either use a handheld (spot) meter, or come to grips with how your camera's meter responds to real-world scenes and use the exposure compensation dial to account for such biases. Reading a basic text on determining correct exposure is also a good idea to start with.

Finally, keep in mind that digital cameras can usually tolerate significant underexposure; it's overexposure that results in unsalvageable blown out highlights. With negative film (both color and B&W), it's the other way around; they can generally tolerate significant overexposure, but underexposure results in blank areas where the shadows are supposed to be. This is something to keep in mind when going from digital to negative film.

Hi Koraks,
Thank you for your reply - it is very instructive!
The camera exposure control was set on "A" so, as you say, it must have been the intense bright spots (very bright southern sun on pale limestone) that messed with the overall exposure.
I think I need to get a better overview of correct exposure and maybe a handheld light meter too!
Thanks again.

Can we see the negatives? I suspect under exposure.

Totally agree with @koraks when he says underexposure, when scanned, results in the grainy look in the shadows.

At first, I assumed the building was brick, and I thought your MX was not likely to underexpose. But then you said the building is pale limestone, so that fits. Remember, your meter assumes all the tones in your scene will average middle gray, so it wants to underexpose when there is an abundence of tones above middle gray.

If you don't mind, can you tell us what number you used to set the ASA dial on your MX? Was it the "box speed" of ISO 400 -- or something else?

And also, it might be a good idea to show the negatives. If you don't have a lightbox, tape the negatives to a window so light shines through them. The questions we are trying to answer: Are these two negatives the only ones that are underexposed? Or are all the negatives somewhat underexposed, and these two are worse than the others?

HugoScott said:

I think I need to get a better overview of correct exposure and maybe a handheld light meter too!

Click to expand...

Before you rush out and buy a handheld light meter, you might investigate the various pros and cons of reflected meters / spot meters / and incident meters.

In the case of your white limestone building, taking a reading from a gray card using your camera's built-in meter might have been helpful. Gray cards are much cheaper than a hand held meter and don't need batteries. But on the other hand, be warned they require good technique.

My personal choice when photographing an unusually light or dark colored subject would be to take an incident reading -- which measures the light falling on the subject rather than reflected light.

runswithsizzers said:

If you don't mind, can you tell us what number you used to set the ASA dial on your MX? Was it the "box speed" of ISO 400 -- or something else?

And also, it might be a good idea to show the negatives. If you don't have a lightbox, tape the negatives to a window so light shines through them. The questions we are trying to answer: Are these two negatives the only ones that are underexposed? Or are all the negatives somewhat underexposed, and these two are worse than the others?

Click to expand...

Hi @runswithsizzers thanks for your reply.

Yes I just used the 400 ASA setting as I don't have a lot of technical knowledge and I thought it's best to start from a standardized baseline.

I'm currently a long way from home but I'll be back in a week or so and will post the negatives on here.

Bracketing the exposure is allowed, just don't tell anyone.

Franklee said:

Bracketing the exposure is allowed, just don't tell anyone.

Click to expand...

Hmm yes, sagely nodding as if I know what that is.

Well, actually I do know, now, because obviously I just looked it up - and yes, if in doubt in a tricky lighting situation it would probably be a good idea to get bracketing.

Though actually knowing what I was doing would mean I'd have fewer rubbish pics on each roll

When using wide-latitude negative film as you are with a camera like this, an easy trick is just to set the film speed one stop slower. Here you would set it to 200. Most negative films will easily handle that.

welcome to photrio...

the pentax me is a fine camera... what you need to learn is how to compensate for the vagaries of light, and increasing or decreasing exposure. Each of the mentioned techniques, will help you accomplish it once you recognize what happening when your taking the picture.

just know that your walking a well trod path and that the reason why there are so many different ways to handle exposure compensation is because we all made the same error, and chose the solution through trial and error that seems best for our photography.

the best thing your doing is taking pictures. the second best is asking questions. good luck

loccdor said:

When using wide-latitude negative film as you are with a camera like this, an easy trick is just to set the film speed one stop slower. Here you would set it to 200. Most negative films will easily handle that.

Click to expand...

HI - thanks!
I'll give that a try with the next roll I use. Funnily enough, someone else just recommended the same tactic!

jvo said:

the best thing your doing is taking pictures. the second best is asking questions. good luck

Click to expand...

Thanks! btw I like your 'agreeable strangers' series

The issue with camera meters (and most basic apps) is that they are black boxes. They give you a setting but hide the raw data, which is why bright limestone scenes often lead to underexposure.

Before spending money on a handheld meter, look for a tool that offers an Advanced View showing the phone's raw auto-exposure data (ISO, shutter, and aperture) in real-time alongside a standardized EV100 value.

Seeing those specific components helps you understand exactly how the meter is deriving the exposure. For a bright limestone scene, you’d expect a reading near EV 15; if the tool shows the phone is seeing EV 17, you immediately know the limestone is fooling the sensor. Using a tool like this as a reference instrument is a great way to learn to judge light manually without flying blind.

smetho said:

The issue with camera meters (and most basic apps) is that they are black boxes. They give you a setting but hide the raw data, which is why bright limestone scenes often lead to underexposure.

Before spending money on a handheld meter, look for a tool that offers an Advanced View showing the phone's raw auto-exposure data (ISO, shutter, and aperture) in real-time alongside a standardized EV100 value.

Seeing those specific components helps you understand exactly how the meter is deriving the exposure. For a bright limestone scene, you’d expect a reading near EV 15; if the tool shows the phone is seeing EV 17, you immediately know the limestone is fooling the sensor. Using a tool like this as a reference instrument is a great way to learn to judge light manually without flying blind.

Click to expand...

Welcome to Photrio.
But I think you misunderstand - @HugoScott is having difficulty with film exposures, not phone exposures.

MattKing said:

But I think you misunderstand - @HugoScott is having difficulty with film exposures, not phone exposures.

Click to expand...

Maybe I misunderstand as well, but I interpreted @smetho's suggestion as using a phone as a learning tool to experience/witness how pointing a camera phone at different scenes to see how it affects exposure, and possibly to also use the phone in lieu of a handheld meter.

Sorry for the confusion, @MattKing. I definitely didn't mean to suggest the phone should be the center of the process. I’m 100% with you that the final exposure on the film is the only thing that actually matters.

I was really just trying to get at what @koraks mentioned: using the phone more as a quick reference instrument when a camera's auto-meter is obviously struggling with something tricky like that limestone. For me, being able to see the actual EV100 and those raw exposure components for a second just helps bridge the gap between my gut feeling and what the camera is doing. It's just a helpful little reality check while you're still training your eyes, I didn't mean to make it sound like more than that! My bad if it came across that way.

No problem - thanks for the clarification!