AndyMan 7 #1 September 21, 2004 I'm having issues with both exposures and depth of field with my Digital Rebel. The results are proving disapointing. I'm setting the camera in TV mode, ISO 100 with a shutter speed of 400 on bright, clear days. My thoughts are the slow film, and slower than normal shutter speed would give me a larger aperature, which would mean a bigger depth of field. That's not happening. 1.jpg (exit) ended up with an aperature of 5.6 and an overexposed horizon. - notice the compresion artifacting in the blue sky, even though I'm shooting large fine. 2.jpg (taking the grip) aperature 4.5, overexposed horizon and underexposed gear. 3.jpg (deployment) aperature 6.3, out of focus. The day was clear, cool, and low humidity. I'm shooting the Sigma 15mm, with the infinity sign lined up with f-stop 8. I'm figuring that this means on this lens everything between roughly 3 feet and infinity should be in focus if I can get aperature to F8... But that's not happening. I'm thinking my only alternative is to set infinity to F5ish, but a: that's not marked on the lens, and b: that'll give me a really short depth of field, which will put me out of focus when I take the hand-dock... Any thoughts? _Am__ You put the fun in "funnel" - craichead. Quote Share this post Link to post Share on other sites
Zee 0 #2 September 21, 2004 A larger aperture (smaller number) will give you less depth of field. Try using auto focus once and see what the difference is. I know tons of people (myself included) who use auto focus in freefall and if you can keep your subject centered, it works quite well. Also, try to take your close up shots while the tandem is facing the sun - helps light up the subject and it also eliminates the over exposure of the sky that you see on the one pic where the sun is coming in from side. Just my two cents - Peace, Z Action©Sports Quote Share this post Link to post Share on other sites
quade 4 #3 September 21, 2004 Quote My thoughts are the slow film, and slower than normal shutter speed would give me a larger aperature, which would mean a bigger depth of field. Larger aperatures (smaller f-stops) mean shorter depth of field. See http://futurecam.com/fStop.html This shot was taken with ISO 200 and 1/500th at f4.0. Focus was set with the infinity mark just slightly short -- about where the IR mark is. Sure, not -everything- is in perfect focus, but . . . Oh, and getting that hand dock in perfect focus . . . is that really required? Having something in the foreground slightly out of focus can give emphasis to the depth just as much as having something in the background out of focus. I mean, do you really see everything in perfect focus extremely close-up and far away?quade - The World's Most Boring Skydiver Quote Share this post Link to post Share on other sites
Zee 0 #4 September 21, 2004 Gee, Quade, couldn't you get just a little closer on that one Action©Sports Quote Share this post Link to post Share on other sites
blazetailman 0 #5 September 21, 2004 Andy, go to a book store and get your hands on a basic photography book. It will demystify a lot. Quade described it but a book will show with diagrams. They shoot and experiment. Its the only way you will learn. Lucky for digital. Not as expensive as film. nice exit shot quade. do you have any pics up from the bigways? I couldn't make it to play. I'll have to relive it in pics.www.canopyflightcenter.com www.skydivesac.com www.guanofreefly.com Quote Share this post Link to post Share on other sites
Deuce 1 #6 September 21, 2004 I think the last one is a shutter speed issue. As to exposure, I suggest using the shutter priority mode. Looking at the pictures you've posted, if you have a range from absolute black to absolute white on the frame, the exposure is OK. If the photo is really overexposed, none of the pixels will be black, likewise if it is underexposed, you won't get to absolute white. The problem is our subject matter, and to a degree, our cameras metering. (I always really preferred the metering on my film Nikons.) With bright, white clouds competing with shadowed faces and gear, we really challenge our cameras, cause we generally don't use lighting equipment. Also, the shot metering can change dramatically from the exit to deployment. Fill flash is a great advantage when shooting close Quote Share this post Link to post Share on other sites
salsicha 0 #7 September 21, 2004 AndyMan, let's go step by step. - overexposed and underexposed areas: check where exactly your camera measures the light. With that measure, the camera will choose the aperture for you. - Out of focus pic – did you shoot in auto or manual focus? If you are using manual focus, probably the image is out of focus because it wasn’t anymore inside the limit you have set. - aperture and depth of field: larger aperture means smaller depth of field, that’s right, but when you use a wide angle lens, this doesn’t function, you’ll always have a bigger depth of field. For example: a 20mm lens with an aperture of f4 has a bigger depth of field than a 50mm lens with the same aperture. - And another thing: the depth of field is not de same before the subject (between it and the camera) and after it. Usually it is 1/3 before and 2/3 after. .___________________ salsicha - shaggy www.skydiveinrio.com Rio de Janeiro - Brazil Quote Share this post Link to post Share on other sites
hoym 0 #8 September 21, 2004 Andy, When I jumped a film camera, I almost always used 100 speed film. However, now that I've switched to digital, I've found better results with 200 or 400 ISO settings on this camera. Because I'm after a larger depth of field, I'm looking for 8.0 minimum. I've found some of the results that you are getting, (4.5 - 6.3) don't give me the depth of field that I would like to have. I seem to have better results with Shutter priority rather than Aperature priority. (1/250, 1/320, or 1/400). I tend to mostly be set on 400. I've also found that with a higher ISO setting on the camera, I can quickly dial down the sutter speed for the lower light, inside the plane shots, still get a decent aperature (DOF) and then quickly dial back up before exiting. Another thing to read about and experiment with is the 'Metering Mode' of your camera. I'm guessing that the Digital Rebel has the same feature as the 10D. You have a choice between 'Evaluative', 'Partial', and 'Center-weighted' metering. I've had good luck with Partial Metering which gives the very center of the frame the highest priority when the camera sets exposure. However, I'd like to hear how others are using this setting. Quote Share this post Link to post Share on other sites
sdctlc 0 #9 September 21, 2004 Andy, A lot have already noted the larger aperture (smaller number) gives a less DOF. Here is a very nice on-line calculator for figuring it out. Take a look!! http://www.dudak.baka.com/dofcalc.html Hope it helps.... Scott C."He who Hesitates Shall Inherit the Earth!" Quote Share this post Link to post Share on other sites
AndyMan 7 #10 September 21, 2004 QuoteLarger aperatures (smaller f-stops) mean shorter depth of field I understand that, I just misstated. Smaller aperatures, or larger f-stops are why I'm shooting at 100 ISO and a slower shutter speed... I'm trying to get coax the camera into using larger f-stops, to give greater depth of field. I guess I don't understand how people are able to set focus just shy of infinity - say, with the infinity mark pointing to the 'R' on the Sigma 15, and still get adequate depth of field. Looking at how the marks on my lens are setup, that suggests DOF goes from roughly 4 feet away to infinity, which means I'd need to be always more than 4 feet away from the subject....? _Am__ You put the fun in "funnel" - craichead. Quote Share this post Link to post Share on other sites
hoym 0 #11 September 21, 2004 I think you'll find that if you bump up the sensitivity of the sensor to ISO 200 that at the same shutter speed, (say 1/400), the camera will give you a larger f-stop number (smaller aperature opening) and thus a greater DOF. Another way to obtain a larger DOF... Leave the ISO set to a slower speed like ISO 100 but slow down the shutter speed to say 1/250, and (given the same amount of light source) you will also gain a larger DOF. The biggest difference that you will find is that there may be more movement artifact in the jumpsuits etc., at the slower shutter speed. Quote Share this post Link to post Share on other sites
genoyamamoto 0 #12 September 21, 2004 Quote Looking at how the marks on my lens are setup, that suggests DOF goes from roughly 4 feet away to infinity, which means I'd need to be always more than 4 feet away from the subject....? _Am Yes. it means 4 feet to infinity should look in focus. Hey so do you have your monitor calibrated? I am looking at your photos, and the exposure seems pretty good. Doesn't seem like anything is wrong with your camera. Looking at the histograms in photoshop, they look good too. Gotta go... plaything needs to spank me Feel the hate... Photos here Quote Share this post Link to post Share on other sites
Deuce 1 #13 September 21, 2004 Your 15 has, by design, a very very deep depth of field. If you want blurred backgrounds, and I do sometimes, back way up and use a longer lens. Quote Share this post Link to post Share on other sites
hoym 0 #14 September 21, 2004 That is just a COOOOL shot! -mh. Quote Share this post Link to post Share on other sites
AndyMan 7 #15 September 21, 2004 How long and how close? _Am__ You put the fun in "funnel" - craichead. Quote Share this post Link to post Share on other sites
Deuce 1 #16 September 21, 2004 That's a 100 and I'm about 60 feet away. It's cropped to vertical, but not magnified. Autofocus, shutter priority. For depth of field, I really think it's the only way to go. Quote Share this post Link to post Share on other sites
sdctlc 0 #17 September 21, 2004 QuoteI guess I don't understand how people are able to set focus just shy of infinity - say, with the infinity mark pointing to the 'R' on the Sigma 15, and still get adequate depth of field. Look at the calculator I noted on the other page. It will calculate where infinity in focus starts. I have a 22-55mm lens as it lets me stay with one. I have it on a Rebel 2000 so I picked the lens setting on the attached chart at 22, 24 and 28. As long as your at least focused on at a point beyond the hyperfocal point (noted with the calculator) your good to infinity. The close in focus distance at given aperature is noted in the Near focus.. Scott C. The pics you noted look pretty good though"He who Hesitates Shall Inherit the Earth!" Quote Share this post Link to post Share on other sites
YahooLV 0 #18 September 22, 2004 nah, he like to be on the outside!http://www.curtisglennphotography.com Quote Share this post Link to post Share on other sites
Jaap 0 #19 September 23, 2004 While I was experimenting (well, still am) with this I came across this little gem: f/Calc See for yourself.Chaos, panic, & disorder - my work here is done Quote Share this post Link to post Share on other sites
