Is the IQ really this different? (Image comparison)

Between the 85mm F1.8 Canon and the Canon 50mm F1.8 Mk I...I took these two images and did nothing but change the distance between me and the subject, and change the lens out...is there something wrong with one of my lenses or is the IQ just that substantially different?

Canon 50mm F1.8 Mk I
ISO: 800
F/3.5
1/125sec
speedlight power: Unknown but stayed the same between images.

I'm sorry they are in Landscape and not portrait, Tinypic decided it looked better sideways. Either way you can see the amount of light let in by the 85mm is WAY higher and the clarity is much nicer too

Surely the flash didn't fire in the 50 1.8 shot?

xarik wrote in post #16680239
is there something wrong with one of my lenses or is the IQ just that substantially different?

Or.......the flash didn't fire! So yes, "IQ" with no light in an extremely underexposed picture will suffer no matter what lens you're using

It did for sure. Nothing changed and I saw it fire. If it didn't fire the image would be mostly black and you wouldn't see anyting

xarik wrote in post #16680254
It did for sure. Nothing changed and I saw it fire. If it didn't fire the image would be mostly black and you wouldn't see anyting

Hate you break it to you but the image is mostly black. Doesn't matter if you saw the flash fire, your camera didn't! So possible sync issue then

was the flash in ETTL mode?

xarik wrote in post #16680254
It did for sure. Nothing changed and I saw it fire. If it didn't fire the image would be mostly black and you wouldn't see anyting

Was the flash on ETTL mode and pointed directly at the subject or bounced?

A underexposed image of this nature has nothing to do with the lenses IQ, it has everything to do with a problem with your exposure. Given that your other settings were the same, the flash settings most definitely weren't. Or, as said above, your flash didn't sync with the camera correctly.

Flash was in full manual (As that's the only option) and it was bounced up with the bounce card out towards my subject. The flash did indeed fire and I had the same results in 2 images from both lenses. I have a couple from the 50mm that just aren't usable while I have others from my 85mm with the same settings that are well exposed. These were all just test shots for taking pictures of a friend tomorrow

xarik wrote in post #16680261
Flash was in full manual (As that's the only option) and it was bounced up with the bounce card out towards my subject. The flash did indeed fire and I had the same results in 2 images from both lenses. I have a couple from the 50mm that just aren't usable while I have others from my 85mm with the same settings that are well exposed. These were all just test shots for taking pictures of a friend tomorrow

Then the aperture blades are stuck on one of the lenses. That, or some other problem pertaining the the aperture. I can't think of any other reason this would happen.

Ok well perhaps there is a either a missfire or the aperture blades are stuck. I've never run into this before as I just got the 85mm a couple weeks ago and have only take like 8 pictures with it :P. I was going to sell the lens but haven't gotten around to it. For now I think I'll shoot with the 85mm and maybe take one or two with the 50mm just to see if it's acting oddly.

xarik wrote in post #16680269
Ok well perhaps there is a either a missfire or the aperture blades are stuck. I've never run into this before as I just got the 85mm a couple weeks ago and have only take like 8 pictures with it :P. I was going to sell the lens but haven't gotten around to it. For now I think I'll shoot with the 85mm and maybe take one or two with the 50mm just to see if it's acting oddly.

There's an easy way to test it, just stop it down to f/4 or so and snap a few shots at the same settings on a well lit subject without the flash. If the exposure looks different, there's a problem with your aperture. I think it's more likely there was something up with the flash though... but I did have a Bower 85mm that had a sticky aperture, with that lens it was very obvious though since it was manual.

Yeh I will have to test this out tomorrow. Unfortunately I'll hardly have any time. I'm pretty nervous about this shoot because one of my speedlites is in my car which is in for repair lol. Also my tripod is in my car too. I'm try to get a dramatic picture of a woman at the piano, any suggestions on settings to darken the background and only use one speedlight? :/

That depends on what light modifiers you have and where you're shooting (IE, window or other light in scene, tight space, white walls, etc?).