I always thought the photo thing was just her cover story. She was really just checking to see if Luthor knew anything that could threaten her and the Amazons.

Good point.
It's one of the many complaints about BvS that I agreed with regarding Wonder Woman's weird motivations for being around (how do you wipe out a digital file by copying it?!), but if the reason she wanted it was just to have it, then that makes more sense.
How does it feel to be deconstructed?

The picture definitely seems a lot more important than we thought. Originally I just thought it would be more of an easter egg for the Wonder Woman movie, but seeing her looking at it in the movie, it's got a lot more significance.
http://www.astortheatre.net.au/
Support great cinemas.

Who says she doesn't?
The fact that there's no evidence to suggest that she did perhaps?
Also, why would she just ask Lex for the photograph? Why would she just assume that he would give it to her, or that he's someone she can trust with her identity? Obviouusly, the fact that she's not straight-up telling people that she's a 5000 year old Amazon should have been a pretty big clue that she didn't want people to know her identity, but that doesn't seem like the primary reason for her trying to get that photograph back, going by the latest trailer.
On another note, iI don't think the public was EVER aware of her.

Who says she had a solid copy of the photo in BvS?
Who says she doesn't?
We're going by what we 'know'.
It's a DIGITAL COPY she claims he took from her.
She breaks into his server just to steal a friggin' digital image.
She could have just asked him for a print if it's not a big deal that he knows shes Wonder Woman, but the fact that he has it and placed it in a folder with her 'wonder woman logo' on it (did he create it?) seems to indicate that he knew who she was and she didn't want him to leak it. She even lied to Bruce about it.
Why go through all that hassle if hiding who she was is irrelevant?
She could have said:
"Hey Lex, this is Wonder Woman, can you send me a copy of my WWI pic, I lost the original and need to print out another one?"
Nope, she sneaks in and steals it like it's a big secret.
It wasn't about sentimentality it was about hiding her identity because clearly the public isn't aware of her anymore.

Who says she had a solid copy of the photo in BvS?

It obviously has sentimental value for her.
So she had the original photo but wanted a digital one too?
That's what she took. A DIGITAL photo that can be easily copied.
Is she so sentimental that she wants all the digital photos as well as the original one?
That makes no sense, sorry.

No doubt there will be copies of it but you see batman getting it back in the extended cut

But what made no sense was that the photograph was on Lex Luthor Jr's private server in his house. So if it is on a server, it is digital, therefore there can be millions of copies of the file in existence in backups, on the web, the cloud, etc. So getting the picture back is irrelevant in the timeframe that BvS is set in.
A L C _ H _ L - Sometimes alcohol
is
the answer

I think she was taking the photo back the the luvre

Yes it was.

No, it wasn't obvious.

I thought it was obvious in why she wanted the picture for sentimentality in BvS.
If it's all the same to you, I'll have that drink now.-Loki (Marvel's Avengers)

I had it figured out about a year ago.
#fail

It took trailer #2 to happen in order for you to deduce that? That's pathetic.

I considered that myself.
Still I suppose there is no reason it can't be all of the above.

Honestly, I always figured the "Photo" thing was just her cover story. She was just investigating Luthor in general.

Yeah your right, I'll be honest I completely missed that.
Still it makes sense, unless Steve found the secret of immortality, everyone in that picture would have been dead for at least forty years by this point, probably longer.

Her role in BvS was that she wanted to get back that photograph that Luthor had. The trailer for this movie seemed to explain why exactly she wanted it back in the first place.
I thought the photo Luther had was digital.

Because she made the decisionafter a long obvious hiatus and hiding..to help the mankind or not
Man:P

Not me man I am talking about Verdugo he always asks question like these

You seriously funny know why Diana fight doomsday?

Believe me it is

Is that a serious question?
http://www.astortheatre.net.au/
Support great cinemas.