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| Moderated by: chrisbet, | ||
| Author | Post | |||||||||
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TomOC
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My brain has turned to a pretzel. How do you account for the FX/DX factor when using a DOF calculator. There are a bunch of them available (mostly free) for iPhones and Android, but it struck me that I'm not sure whether to calculate for a 35mm or 52mm lens when using a DX camera. I've been assuming that you use the actual lens diameter, but that really gives a huge DOF advantage to DX, doesn't it? Your addled pals, Tom & Lucky  |
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jk
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I think that you have it right. DX has a DOF advantage over FX in relative terms. I know there is an article out there. I just need to dig it out and point you to it. |
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Robert
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In most depth of focus (DoF) calculators there is the opportunity and need to specify the sensor or film format, along with the subject to lens distance*, focal length and aperture. The sensor size or film format is a vital part of the calculation. I don't think you can 'cheat' by using the focal length multiplier of 1.5, which is only intended to give a guide to the field of coverage provided by a given focal length on a DX body compared with the field of view of the same focal length on an FX or 35mm film body. I am sure the parameters of the calculation are completely different. Simple way to check, with a DoF calculator change the format to DX and the focal length to X1.5 and compare the results? Which calculator are you using? JK is right, the smaller the sensor the greater the DoF. That's why tiny format camera's don't need focus and P&S cameras have such great DoF. Small format movie cameras also have the same characteristic. On the other hand large format cameras need careful focusing even for distant subjects. *Not sure where that is measured to? Not critical for landscapes but for extreme close-up's it becomes very important. Most cameras have the focal plane marked but not the lens datum, perhaps because it moves during focus on IF lenses? |
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jk
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See here for good article that explains it all Tom. http://photo.net/learn/optics/dofdigital/ |
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TomOC
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Robert - I'm using two iphone apps ... FOCAL and PHOTO CALC. Neither has a setting for FX or DX and I assume they are both FF 35mm calculators - I guess I really need to track that down. JK - Thanks, I'll have to read that carefully...it's confusing |
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Doug
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If its photocalc from Adair systems (not updated since 2010, better to buy something more recent) then you add cameras using the options button at the bottom Photobuddy seems a good alternative |
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jk
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I use Photobuddy on my iphone and ipad. |
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TomOC
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I think I have that one some where, too... I need to get them all out - pick the best one - delete the rest I really didn't' use them at all with DSLRs, but since getting the Xp1, I've decided to do more zone focus setups and a good calc on my iphone would be great. Let me just ask you this simple question ... When you have a DX lens on and want to check Camera Buddy, do you enter lens size as 35mm or 52mm? I'm using the 35mm (actual size of the lens).Thanks, Tom |
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Robert
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It should be the marked focal length and the actual sensor size. |
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jk
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Robert wrote: It should be the marked focal length and the actual sensor size.Yes that is correct. Dont over-think the problem. Follow the instructions on screen  Sometimes we forget that these softwares/algorithms can make it simpler but we still try to out think them. |
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TomOC
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Hard at work relearning how to effectively prefocus Thanks Tom |
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Squarerigger
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Are you relearning this for a particular project Tom, or just to renew your bag of tricks? |
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TomOC
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Mostly, just for my own enjoyment. I love carrying the Fuji Xpro1 on the street to capture all the great slices of life. I'm no WeeGee but love the fun of shooting. Tom |
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Squarerigger
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I wish you guys would stop talking how great the Fuji x100 and the xpro1 are, it is not doing my desire for a compact walk around camera any good. |
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TomOC
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Gary- All I can say is that it is cheaper and a lot more satisfying than buying a new $500 P&S that DIDN'T really cut it almost every six months - the only one benefiting from all that was B&H Photo and eBay |
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Squarerigger
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Which lens have you found most useful in your walk around photography on your XPro Tom? |
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TomOC
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Gary- I have used them all. But I like the 60mm only for macro. I use the 35mm 90% of the time - makes me think more, is killer sharp and fast. The 18 is also a terrific lens and really good for interiors like museums etc. If you only had one lens it should be the 35mm without any hesitation. Tom |
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Squarerigger
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Thanks Tom. Typically when I go out looking for street shots, I carry camera and one lens. The 35mm would probably be my first choice. That said, why would I get the Xpro vs the X100 with 35mm lens. Big price difference for Xpro w/35mm lens and x100. Is it worth the dollars in your opinion? Well of course it is, you purchased it. Dumb question - sorry. I am trying to justify the extra dollars in my mind and have a hard time doing it. Wait for update of X100 or update of Nikon V1 may be better for someone on a budget. |
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TomOC
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Gary- Well, the x100 is 12mp with 23mm (35 equivalent) fixed lens with some fantastic features. I have had that for almost a year and still use it. The xp1 is almost twice the price (counting one lens) and has the advantage (?) of interchangeable lenses, incredible IQ (not that the x100 is a slouch), a bit more heft (takes it out of the pocket range), much simpler menus and generally a somewhat "better" build. I view the x100 as a 35mm lens in my pocket... The xp1 as a "real" RF type camera to wear around my neck and be "serious" with (all much less serious than a Nikon DSLR . My preferred lens on the xp1 is the 35mm (50mm equivalent) and I really love that focal length on a RF type camera on the street. But I do love them both. I think you can get some pretty good deals right now on the x100 with the rumors of an x200 in the Fall. Tom |
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Squarerigger
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Thanks Tom for the great insight. I think I would be wise to wait until the X200. See how much better it is than the x100 or not. X100 should be a better deal if folks switch to the x200. I am really looking more for something I can pocket and carry on a daily basis. Anyway, thanks and I will follow my own advice and be patient. |
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jk
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Gary I'd say that if you want a serious camera and can live with a fixed lens 23 mm (35mm in FX) then the X100 is great. If you prefer a different focallengththen go for the XPro1 and whatever suits you. In the Fall fuji are bringingout an 18-55 f4 zoom so that gives you all the zoom that you caneffectively use on a viewfinder camera. The XP1 is definitely worth the extra but it is not a DSLR so wont ever deliver fast AF. |
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jk
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TomOC wrote: Gary-Similar numbers for me except that I probably use my 60mm for portrait and macro more. I am going to get a 18mm f2.0 or 14mm f2.8 (when it comes out in October) but I'm thinking that the 18mm may suit me as the 14mm will only equate to a 20mm on FX camera and will probably cost a lot more than the 18mm. Gary if you want a camera that has great lenses is very light and dont need the speed of a DSLR AF functionality then the XPro1 is the answer. My XPro1 with three lenses when I get the 18mm weighs less than my D3 with a light zoom (35-105mm). It really makes for a wonderful travel camera. |
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