The Blog of Photographer Jacob Vorpahl.
My obsession with all things related to testing my new G11 continues. Today: ISO.
When I got my G11, and even before I purchased it, I knew that if I wanted to use off camera flash with the advanced point and shoot I’d have to go full manual. I’ve been blessed (and cursed) using a full Nikon spread when it comes to serious photo gear: Nikon D80 with a Nikon SB-24, SB-25, and three SB-800s. Those three SB800s and the D80 work fantastic together: I get full manual and iTTL control wirelessly, all from the camera. Unfortunately, it’s made me use iTTL a lot, and I haven’t developed a good sense for manual light levels.
Knowing this, I decided to go ahead and buy a light meter (thanks for the birthday present sweetheart!) to take out the chimping that I knew would come without one. I ordered a Sekonic L-358 off Amazon last week and it arrived on Monday. I played around with it, than I came back to a question that had me curious when I was looking at buying the G11: I know that DOF (depth of field) is greatly increased because of the smaller sensor size in the G11 compared to a DSLR, but how similar are the light sensitivity levels between the two types of cameras? Does f4 on the G11 let in as much light as the D80 that I own? Only one way to find out.
I took the world’s favorite secret ninja squirrel, Nuts, and I placed him on my dining room table along with an SB800 hooked up to a Skyport reciever. I put the flash on manual and I dialed it all the way down to 1/128, since it was so close and I’d be popping the flash quickly, and my light meter said that a proper exposure at a shutter speed of 1/200 was f4. I had to cap my shutter speed at 1/200 because that’s the D80′s max sync speed (the G11, on the other hand, can hit up to 1/1000 with Skyports). Once I had everything set, I decided testing the aperture would be an easy way to see if the light value was the same, but then I had another thought: what if the ISO responds differently on each camera? f4 is f4, but if ISO 100 looks different on each camera, then what?
So, our test is instead going to look at the difference in ISO sensitivity at 4 ranges: 100, 200, 400, and 800. With everything set up I went ahead and snapped the requisite photos, only to discover afterward that my G11 had an EV adjustment of +.3. Ooops. Fixed that, then went back and did it again. Here are our results:
I’m going to make a small disclaimer for these photos. I used a 17-50mm lens on the D80 and and of course the built in 28-140mm lens on the G11: the perspectives are not entirely the same. It’s not a big deal with the exception that you see more shadows in Nuts’ fur on the D80 pictures because they are at a slightly higher angle, allowing them to see more shadows. Again, it’s not that big of a deal, as long as you remember that caveat.
Now, here, you don’t see too much difference, if any. ISO100 looks to be about the same on both. The colors are different, but that’s because each resolves them differently (both WBs were set on daylight). But, we’re not too concerned with that right now, only the light levels. For now, good.
Results: G11 vs. D80: ISO100 – Same
This is the same as ISO100 as far as difference is concerned. His white stomach looks to be blown out to about the same level in both shots. There may be a little variance in the very center of his stomach, but I think that is caused by the angle of the shot.
Results: G11 vs. D80: ISO200 – Same
Now I think we’re starting to see a little more difference between the two. There’s not too much, but if you look at different areas of Nuts you can see a little more fur blown out. Look specifically at the difference between the “paws” and forehead. Again, it’s too great of a change, but I think we can say the G11 image is a bit more blown out, if only just a little.
Results: G11 vs. D80: ISO400 – G11 a little more blown out
Pushing things to ISO800 makes things a bit more apparent. The G11 is clearly more sensitive at this ISO range. You can see it on the feet, the right paw, and especially, look at the left set of wiskers: in the G11 image, you can barely see the third one (the one closest to the inside of the face), whereas on the D80 image it is more clearly visible.
Results: G11 vs. D80: ISO800 – G11 more sensitive
Now, what kind of conclusions can we draw from this? Is the ISO range on the G11 more sensitive at higher ISO levels? It appears that way, or is there something else at work here?
Most serious camera entusiasts know that the smaller sensor cameras lack the same dynamic range as their DSLR big brothers. What that means is, say there is light throughout the picture that could be rated from 1-10 in terms of power. Whereas a DSLR can successfully capture, say, levels 3-8 before things either go completely white or black, a compact camera can only capture levels 4-7, or maybe even worse depending on the quality of the manufacturer. Perhaps the light sensitivity levels aren’t too different, if at all, but the G11 simply can’t produce detail in highlights in the same range as a DSLR.
Looking at all the pictures, through all the ranges, makes me believe that it may a combination of both scenarios. I think the G11 is a tad, a smidge if you will, more sensitive than the D80, which becomes more apparent at higher ISO ranges. However, I also think it just can’t give the same detail range.
So, what does this mean for you, the photographer? Probably nothing. Seriously, how often are you trying to crazily overexpose a photo like I did above? No, you’re trying to get things exposed for 18% middle gray and for that purpose, the light difference is negligible enough that I wouldn’t even worry about it. However, this does show you limits of what the G11 can do with blown highlights and now you know what you can work with.
I may grab a G11, I sold all my DSLR “Stuff” , 2 D80 bodies W/battery packs, 4 lenses, and various other stuff and I now use a Fuji Finepix S100fs.. Execellent results, built like a tank and a DSLR. So I still need a “pocket” camera, and I need to use off camera flash also at times. I have a very old Kodak Z700 but it is pretty tired and I like your results with the G11.