New to photos: A few questions

[Prof]

Hey, everyone. I've been trying to learn a bit more about vintage photos. I took photography classes and developed my own film/photos in darkrooms before, but I'm not as familiar when it comes to the collecting world.

I understand the rough descriptions for the four types, the descending values, and know that it's difficult to distinguish at times. Are there any generic tips you'd give to help navigate this stuff?

Regarding sizing: I know that 8x10s didn't become a sort of standard until later. Are there any sizes that should set off immediate red flags as a non-authentic, say 1900-1930 photo?

I had found one a while ago that the owner said was 7x9, but similar authenticated examples that I could find from the 1910s were measuring 6.25x8.25, 6.25x7.5, 6.5x8.5... Is a 7x9 realistic? (I didn't see a ruler next to it, so they may have been rounding as well. But, the question stands.) I was wary, and didn't make an offer.

Regarding News Photos: I've seen plenty online that have the dimension markings, like picas or inches in the borders. Does that sort of marking lend credibility to authenticity/age to you? Obviously that can be faked, or a type 2 could have been used for publication as well.

Cropping/Blowing up of a photo: Say there's a Ty Cobb batting photo that's Type 1, authenticated. Then you find the same photo, but he's slightly blown up to eliminate negative space above his head etc., that could still be a Type 1 assuming it's printed off of the negative during the time period, correct? I would assume it would most likely be a later print though- even if it had news/publication measurements.

Random Question: Can someone tell me what the 5019 / 5 in the bottom left on the back of the photo means? I've seen it on some other photos, with different numbers. Heritage Babe Ruth


I appreciate any information you'd be willing to share.