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#41 | |||
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eric s wrote:
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Thanks for your input. It's much appreciated and very informative. Geoff |
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#42 |
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but....at f6.3, won't you also get more DOF, which is needed sometimes anyway?
you'll have to excuse me if i missed some points, i haven't read all the posts in this thread...yet... Vito |
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#43 |
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Ya, I meant to say that I need to improve the lighting. It won't effect the focusing, but it could effect the reading. But I really don't think it was that bad that you couldn't tell the difference between the numbers. I hope to do some more tests (at a larger aperture, if I can) and then I'll try to get more & better lights. the problem is that I'm running out of them!
And yes, there is a slight bow in the tape measure. I didn't use it for focusing, so it won't effect that (as I'm sure you are aware) and it isn't bowed that much. And it's consistant across all the pictures. So while it isn't perfect, it won't differe between the shots. I don't own a tsquare... I don't believe. Humm.... <eric puts on thinking cap> No, I don't believe I do, but know where to check. It would be a decent alternative to the yard stick (which would be best, since their numbers are usually printed on and not etched in. The only tsquare I've had was metal and had the marks etched into it.) Eric |
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#44 |
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Well, I was just thinking that the T-Square would be easier to balance on top of the cereal box because of the counterweight of the portion of it hanging down. My T-Square is metal with etched rulings so that might not be as good.
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#45 |
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... missed this whole thread while on vacation :-)
There's a big difference between f/4 - f/5.6, and f/5.6 - f/6.3: o f/4 - f/5.6 is a full f-stop, ie twice the area of the lens barrel! o f/5.6 - f/6.3 is only a 1/3 stop, barely noticeable and not within the adjustment range of the camera @ default (unless you set for it, ie change from a 1/2 to a 1/3) To see the brightness difference, even with the 28-135 IS, put the camera in Av mode and dial in the desired aperture and press the stop-down button on the left side of the camera. Now on a long tele that extra 1-stop translate in a very hefty lens/optics, and we are talking about several magnitudes here in both pounds and $$$. As to the DOF difference it's in the noise! :idea: |
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#46 |
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Eric, I came to the conclusion (about my 100% crop of your shot) that it was indeed much beyond 30 feet, since my Waxwing was 30% and I filled the image at 100% crop. So probably you were like at 50 feet, which gives you a DOF of 3.6 inch. Most importantly, I sincerally believe the "not sharp" 100% crop was due to a slight blur induced by you. Either there was a slight movement when you paned while re-composing, or while you pressed the shutter. Or a combination. This lens is one of the sharpest of them all, it should outclass my Bigma easily by a factor of 2 in terms of sharpness and resolution.
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#47 |
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I have to reply about non L lens for zoom telephoto. The Sigma 50-500 is a nice lens with 2 doublets to kill Chromatic Aberation, which it does nicely. It's also sharp stopped down starting at F/8. Always consider DOF when shooting up close on tiny birds, under 20 feet, F/8 is already at 1.6 inch DOF, at F/11 we're at 2.2 inch DOF, a lens capable of doing F/5.6 will give you 1.2 inch. Unless the bird is posing like in profile, then you will see the entire bird inside the DOF, but if he's facing you, part of the bird will be outside DOF.
So for me, F/4 , F/5.6 is not even an aperture I would use, even if I needed more lights for small birds under 20 feet. But for bigger ones at 40-50 feet, yes F/5.6 would be interesting. Read on the previous page what I mention about "shoot to the right", the key is even at ISO800 with a Canon CMOS, it's quite feasible to do nice noise free shots if only if you employ my post-processing method :homey:LOL Cheers |
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#48 |
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I would not be surprised if it was me that contributed to the less than sharp focus. It was my first time out with that lens, after all. I really posted the picture because it was sharp enough and I liked the pose.
But it's been a very enjoyable discussion (as they usually are here.) Eric Can, I do have to correct you though. The 50-500 is f6.3 at 500. So while the camera reads f5.6, the lens lies.. so when doing DOF calculations use f6.3 to get the proper values. (oops, a reread shows me you didn't *really* say the big mama can do 500 f5.6, you just said that you wouldn't if you could.) And the real benefit of the f4 on the 500 & 600mm is so you can use a teleconverter. I have learned quickly that f4 is not used that often. It can be (especially if you have a professional grade AF systems that does better placement within the DOF) but I don't. Simple as that. Eric |
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