What do you all think of a Canon A650 for Pano's

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maxlyons
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Re: more=better?

Post by maxlyons » Sun Apr 26, 2009 6:46 pm

All interesting points. It sounds like you and I may have different priorities, and will probably come to different conclusions about the right camera choice for each of us.
I have to ask what would I get if I put a 14mm lens on a 5DMk2 or A900 and upsampled the image. Is it going to look *that* much worse?
For a lot of what I do, the answer is yes. It will look much worse. This image was downsampled from about 1000 megapixels to about 500 for printing this "small". I have a suspicion that the upsampled 21 or 25 megapixel image probably wouldn't look quite as good.

Image

I think the last time I made a print smaller than 20x30 inches was about 2002!

Max

touristguy87
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hm...

Post by touristguy87 » Fri May 01, 2009 12:24 am

that's about 6x6'?

500MP gives about 22kp per side over 70", about 325dpi...not too bad. You could probably stand next to it and not see any pixels :)

Still if you can get 12x15" out of a 24MP image at 300dpi, vs only 8x12" out of 12MP at 300dpi, then it seems like you should upgrade yet again. Or on the other hand, use a 30" diagonal LCD and then there's no need to print at all, and a whole rack full of equipment can take that shot, with the only IQ loss coming out of the smaller format. But in exchange you get the ability to display more images in about the same amount of space, not to mention have a dynamic display. Especially if IQ at viewing-distances of a foot or less are the issue, it doesn't need to be an 8' diagonal print.

...I wonder just how large of a display, at what resolution, I could make if someone gave me, say, $10k to make one?

By the way there are some interesting notes on noise on that link that I put up earlier, one of the points made is that 35mm sensors are too noisy for 14 bits to be of any real significance, as the noise dithers out any difference in tonal resolution. Of course, assuming that the "display" is able to show even 12 bits of tonal resolution per channel. Maybe that''s why Sony stuck with 12-bit A/D in their latest cameras. They also have some interesting notes on NEF compression that shows it to be well worth the use. Actually that's a very well written site. I've seen the same topics discussed elsewhere but this is very clear compared to the others. The real question of course is what is "discernible" to the eye and what isn't, which depends on ones' ability to create an image in the first place...and surely having your rig set up and running and producing panos easily has t count for a lot. I think the software-driven configuration of your current Canon gear has a lot going for it, especially combined with a rack of Canon lenses.

But when it comes to Rebels vs D-series DSLRs? "To each his own" ;) not in my bag, really. But hey, that's the fun part of all this: it's all an expression of artistic talent and technical skill, all mixed together :)

touristguy87
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autofocus issues

Post by touristguy87 » Sat May 02, 2009 2:28 pm

It's generally been my experience that when it comes to selecting cameras, at least for AF, one has to keep in mind that a fair amount of shooting is done in twilight conditions like this, where there isn't something bright, or "lit" or "a light", to focus on:

http://www.flickr.com/photos/touristguy87/3494833728/

So my concern would be that I can get a good AF in these conditions (MF shooters can chuckle with confidence). I know from experience that there are some cameras that I can trust in these conditions, and some, I can't...top of my list of cameras to *not* trust in these conditions would be most if not all CDAF cameras, Rebels and the 10D. From experience. Right here. Out of the 150 or so shots that I took at or near here, in this sequence, the 10D misfocused on about a third of them. I've see it blow focus on a quarter of the shots taken in broad daylight, I've seen it misfocus on just about every damm shot I took, shooting similar scenes at longer focal lengths in even more light than this, while the G9 hit every time on the same shots. I know for a fact that the 400d, at least the one *I* had, would happily misfocus on anything that wasn't a very bright white to dark transition. "near-focus"? Maybe. But still not a good focus.

The 30D and 5D I would trust in conditions like this, having shot them both handheld in much worse and gotten decent results...and I know for sure that a D300 and D700 wouldn't have a problem, for the same reasons. A700 maybe ok, I wasn't lucky enough to have one when I could shoot it without the in-camera NR. Not the most stellar low-light focus but not awful. A200 a little soft but still reliable.

Take your gear out one afternoon and shoot in the near-shadows like this and you will find out in the space of maybe 50 to 100 shots, whether the AF is reliable or not. Unless the AF calibration is wildly-off, or nearly-dysfunctional, and assuming the F# is not too low, it's not an issue of "front-focus" or "back-focus". It's just either hitting focus or missing focus. Front/back focus is only an issue at low focus-distance/FL ratios and low F#s where the DOF is a fraction of the focus-distance, not multiples of the focus-distance. When focusing 50-100 yards away at 35mm and even F2.8, front/back focus is just not a concern, and the camera either hits focus or not.

Surprisingly the G9 focuses ok in low light, while the A650 is not quite as good as the G9 (aside from the fact that the a650s' lens is not as sharp in the corners as the G9's lens, but this isn't a problem unless you need sharp corners..to me the bigger problem is the lack of raw support)...the a650 is passably good in the shadows (it could handle the shot above) but when it gets dark, it's going to misfocus often. The G9 will focus ok as long as it can find something with reasonable contrast. The big problem that remains is that they are both noisy and have low dynamic-range even at ISO80. Compared to a decent DSLR they will not produce a very high-quality image in low light even at lowest ISO, not to mention ISO200 or 400. They simply need light for good results. But this speaks to the bigger problem in that gear can be mismatched to the application, pretty easily. 9 times out of 10 what I get out of a G9 is good enough for me, though in no way can it compete with a decent DSLR and lens in twilight conditions much less at night because of the aforementioned noise and DR problems. Would I shoot panos with it? Hell yeah. Happily. Because when I shoot panos I'm not trying to get micron-level real-world resolution, and at FOVs greater than the normal 35mm FOV it's just fine, at least for me. And it can generate just as much image-data as a D700.

I think the A650 would be great for shooting panos for most people as long as you don't need the remote-control because the A650 doesn't support the Canon remote-control API.

The big thing to remember is that a phase-detect AF system needs edge-contrast to focus (and a specific orientation, to match the PDAF sensor) while CDAF and MF base focus-quality on "overall image quality". There are scales to both of these. Some systems need a lot of edge-contrast, some don't...some measure IQ to a higher degree than others. And since I've yet to see a camera review that actually measures & tests focus-quality, the only way to know is to buy and try, or to take the word of others who have shot that camera. But in the end you still have to be happy with the results that you get. Just remember that results that look ok at 4x3" can look like crap at 8x10". It doesn't take much.

maxlyons
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Forum ban: touristguy87

Post by maxlyons » Sun May 03, 2009 3:10 pm

Please do not respond to touristguy87....he has been banned from this forum.

Max

Melinhead
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my oh my

Post by Melinhead » Mon Jul 27, 2009 6:07 pm

I have been out of the loop for awhile and didn't realize that my little question was going to spark such debate. I did get the A650 and have shot a few pano's in Europe but haven't gotten time to stitch them together yet. Trying to get back into pano's and look forward to cruising the forum again. Thanks all for all the input.
Melinhead

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