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Photo Forum / Film Photography / 35 mm / June 2005Low light
I just checked the light readings on an overcast day with everything on auto comparing the 2 lenses I was planning to take on my trip to Scotland. The Tamron 24-135 3.5-5.6 gave readings of 1/15-1/20 at f3.5 and 24mm & 200 ISO film. The Tamron 70-300 4.0-5.6 gave readings at 70mm of 1/90 & f4.0 with 200 ISO film. So it seems that 70mm is the widest angle I have that will be useful under low light conditions, even with faster film. At the moment it seems the 38mm of my Espio 95WR is the best I have under 70mm. Any suggestions? Price is important. Thanks Mike >I just checked the light readings on an overcast day with everything > on auto comparing the 2 lenses I was planning to take on my trip to [quoted text clipped - 10 lines] > Thanks > Mike Get a roll of film and try it out. See how well you can hand old each lens and see what speed you need to be happy with the results. I am sure that if we all did the same thing, even with the exact same lenses we would have many different answers.  SignatureJoseph Meehan Dia duit Because of neck and shoulder problems I very rarely use a tripod, especially if I need to walk any distance, I have enough problems carrying my backpack camera bag. Luckily I can hand hold steady enough for most shots. I tried a roll each of 200 & 400 speed print film in my Espio 95WR on a drizzly day to try to get close to the light I expected to get in northern Scotland in mid winter and they both came out ok. I was surprised to see that the 24-135 lens seemed to be getting less light through the lens than the P & S. Thanks Mike >>I just checked the light readings on an overcast day with everything >> on auto comparing the 2 lenses I was planning to take on my trip to [quoted text clipped - 15 lines] >that if we all did the same thing, even with the exact same lenses we would >have many different answers. > I just checked the light readings on an overcast day with everything > on auto comparing the 2 lenses I was planning to take on my trip to [quoted text clipped - 7 lines] > At the moment it seems the 38mm of my Espio 95WR is the best I have > under 70mm. Any suggestions? Price is important. Okay, screeching halt here, because there's a flaw in your testing method. A 24mm at f4 and ISO 200 is admitting the same amount of light as a 70mm at f4 and ISO 200 - basically, f4 is f4 no matter what, and it's designed that way. The reason you received different shutter readings is because (almost certainly) you're metering off of subjects with different reflectivity. Remember that the camera meter wants to get a fixed amount of light in, and by default this is a midtone, what's commonly referred to as "18% grey". Should your subject *not* be a nice midtone, the camera is still going to try and make it that. So if it's white, the camera will set a shutter speed to produce it grey on film, underexposing it. And the opposite if it's black. The key is, knowing what method you're using to meter, and then knowing exactly what you're metering from. This is why many photographers carry an 18% grey card in their bags. Not being there I can't say for sure, but the reason you got such drastically different readings from the two different lenses is most likely because the different angles-of-view changed what the meter was seeing - this is, of course, assuming you were aiming in the exact same direction for both ;-). Explaining further: Say you have a white sign against dark background foliage. At 70mm, the sign might fill the metering area, so the exposure is set for the white sign. At 24mm, the metering area is probably now reading a significant portion of the darker foliage, so now the exposure is a lot slower, because the camera is trying to make the dark foliage a midtone, and the little speck of the white sign isn't counting for much. So, provided there's no damage to either of the lenses, they're close enough in performance (lightwise) to choose either - the difference between the maximum apertures of f3.5 and f4.0 is neglible. So take the lens you feel is better suited for your typical shooting style. - Al. SignatureTo reply, insert dash in address to match domain below Online photo gallery at www.wading-in.net What you explained is what I thought happens. The problem came when I tried each lens panning across my front yard in overcast conditions. When set to 24 mm or 70 mm the 24-135 shutter speed didn't get faster than 1/20. The 70-300 showd shutter settings at least twice as fast as as the 24-135. My Espio 95WR (I think its max app is 4.4) indicated that I didn't need the flash for part of the yard, I don't know how slow the shutter speed needs to go before the flash is required. How can an f4.0 and an f4.4 lens attain faster shutter speeds than an f3.5 lens in the same light conditions? In brighter light conditions the 24-135 lens takes good, sharp photos. A few minutes ago I tried both lenses again, still overcast and now just on dusk. With the 24-135 set to 70 mm the aperature was f5.6 and the shutter readings ranged in the 1+ seconds across the yard from foliage to concrete driveway. With the 70-300 lens at 70 mm the readings at f4.0 ranged from 1/6 to 1 sec+. Mike >> I just checked the light readings on an overcast day with everything >> on auto comparing the 2 lenses I was planning to take on my trip to [quoted text clipped - 47 lines] > > - Al. > What you explained is what I thought happens. The problem came when I > tried each lens panning across my front yard in overcast conditions. [quoted text clipped - 9 lines] > How can an f4.0 and an f4.4 lens attain faster shutter speeds than an > f3.5 lens in the same light conditions? Try metering off a gray card. > In brighter light conditions the 24-135 lens takes good, sharp photos. > [quoted text clipped - 61 lines] >> >> - Al. SignatureJoseph Meehan Dia duit > . . . . . . . . . > > How can an f4.0 and an f4.4 lens attain faster shutter speeds than an > f3.5 lens in the same light conditions?. . . . . . . . . There f stop of the aperture merely denotes the physical proportions within the lenses. In motion picture lenses, there is a "T" stop used instead of an "f" stop. That T stop denotes the amount of light transmitted. There can be some variance between a T stop and an f stop, and they will rarely be equal. However, I don't think that is all that is happening. In production lenses, there is enough variation that an f4.0 lens might actually be an f3.8 to f4.2, or even further off. Another factor that you need to consider is that the number of elements in the construction of the lens can affect the amount of light through that lens, meaning that the effective T stop of one lens might be less than another, even if they have the same listed f stop. The last factor is one that should be a little obvious, a wider lens has a different field of view for metering than a longer lens. The wider lens might indeed capture more light, though the meter in the camera might weight that light differently. In other words, some metering in some cameras can be fooled by the amount of light coming through the lens. In your case the wider lens, while you might think it gathers more light from a scene, could be fooling the metering more. Furthermore, the T stop of your wider lens is likely not as good as the longer lens; and the actual variance of the true f stop might be more with that lens over the other. Some lenses have more light falloff at the edges than others, and that difference of falloff can sometimes mean that less light is going through the lens. Something you can try is switching the metering in your camera (if possible) to see if the readings vary more. You can also pick a setting, like f8.0, on each lens and test actual exposures with the same roll of film. Once you test at f8.0, then find the difference (bracketing would be ideal), then you will know in the future how much exposure compensation should be used for each lens. Ciao! Gordon Moat A G Studio <http://www.allgstudio.com> Your two zooms just don't have the speed for dark days, deep shade or inside. You need a fast 50. Round up a 50mm f/1.8 or even better a f/1.4 I went years with a similar lens as my only lens. In fact I still get great results with a 43mm f/1.7 fixed lens Range Finder. > So it seems that 70mm is the widest angle I have that will be useful > under low light conditions, even with faster film. I second. Nikkor 50/1.4 is all I tend to get along with my camera. Zooms come along only if I go someplace by car. Canon and Nikon 50/1.8 are cheap and great also. |
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