Only select frames discolored w/heavy grain

So I'm new to the site and I have a question. Not a beginning film photographer but sorry if this is a dumb question with an obvious answer. I have problem with only some frames of a 35mm roll being very discolored and a ton of grain and the shots are ruined but its not the whole roll. It seems very sporadic and I know its not my camera settings since multiple photos of the same subject with the same settings will be fine except occasionally one or a few will be ruined as I've described. This also only happens on my Canon AE-1 Program both using the auto functions and the manual functions. It has happened to multiple rolls using this camera and I'm not sure if it's only been on portra 400 or with other rolls (sine I'm not currently able to look at my negatives because I'm away from home for a bit) but I do think it happened to some rolls of fuji 400 as well. Also to add to that a roll from the same pack of 5 of portra 400 used in a different camera did not have the same outcome. All photos came out O.K. So I'm wondering if it has to do with the inner workings of my canon and if anyone has ever seen this before or knows what causes it? I'm thinking maybe a bad shutter? I'm not new to film but not anywhere near professional. Just an enthusiast who understands ASA/aperature/shutter speed relations and other film knowledge.

I'm posting some of the affected photos. The amount of discoloration and grain varies as you can see. The other shots of the same subjects of the photos I've posted have come out just fine, sharp, good color, fine grain etc.

I'll say it first - it's better if we can see a photo of the actual negative, and not a scan of it.

If you have a lightbox, put the negative on it and snap a pic with your phone, or hold it up to a window, or even a TV. If you have a tablet, there are apps that will work (lightbox, or even flashlight).

To me, most of what you're referring to as grain, looks to be digital noise (aka scanner issue).

Did a lab process these for you, or do you process your own? Also, are these images from prints, or did you scan directly from the negatives?

The severely discolored images (#2, 3, 5 & 6) look to be extremely underexposed, hence the color shift and grain in the image. The lab would have processed the film normally, then tried to do the best with the prints it gave you.

It may be your camera shutter is inaccurate at certain speeds, or on auto only, or the lens is not stopping-down correctly.

Are these prints/scans from a lab? If so, they are likely from severely underexposed negatives. Check the negatives themselves to see if that is the case or not. If so, then you need to find the cause of the underexposure.

Best,

Doremus

Kirks518 said:

I'll say it first - it's better if we can see a photo of the actual negative, and not a scan of it.

If you have a lightbox, put the negative on it and snap a pic with your phone, or hold it up to a window, or even a TV. If you have a tablet, there are apps that will work (lightbox, or even flashlight).

To me, most of what you're referring to as grain, looks to be digital noise (aka scanner issue).

Click to expand...

I'm in the process of moving so I don't have my light box and can't get a decent photo but I can see on the negatives themselves they have blurred edges on the frame and are very dense (which means underexposed correct?).

jimjm said:

Did a lab process these for you, or do you process your own? Also, are these images from prints, or did you scan directly from the negatives?

The severely discolored images (#2, 3, 5 & 6) look to be extremely underexposed, hence the color shift and grain in the image. The lab would have processed the film normally, then tried to do the best with the prints it gave you.

It may be your camera shutter is inaccurate at certain speeds, or on auto only, or the lens is not stopping-down correctly.

Click to expand...

These were processed at a lab yes. In the reply I just made I stated how the negatives look. And ya I was thinking my shutter acts up at certain speeds possibly I just don't know which ones or if it was just auto.

milojoinsthecorps said:

I'm in the process of moving so I don't have my light box and can't get a decent photo but I can see on the negatives themselves they have blurred edges on the frame and are very dense (which means underexposed correct?).

Click to expand...

A dense negative is overexposed - an under-exposed negative will be very thin. If those examples above are scans of a very dense negative, the grain and colours are the scanner trying to cope.

Looks to me like you shutter has a speed problem, staying open too long.

Peltigera said:

A dense negative is overexposed - an under-exposed negative will be very thin. If those examples above are scans of a very dense negative, the grain and colours are the scanner trying to cope.

Looks to me like you shutter has a speed problem, staying open too long.

Click to expand...

+1