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Author Topic: More megapixels or better optics?  (Read 17644 times)

Darkly

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More megapixels or better optics?
« on: June 23, 2014, 05:42:15 AM »
I'm still trying to put together a cheap "hobby" rig.

Should I go for cheap lower end compacts (like A2500) around 12MP, or am I better of looking for used older "prosumer" devices like the PowerShot G series? The G7 and SX40 are around 6 MP I believe, and can be had at similar prices as clearance compacts.

From old online reviews of "prosumer" cameras, the pictures up close actually look about as noisy as my old 5MP Pentax Optio 550 compact camera.

But then I don't really know anything about photography and have only limited experience with PhotoScan.

Tyler J

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Re: More megapixels or better optics?
« Reply #1 on: June 23, 2014, 12:41:59 PM »
I can't awnser your question however I'd loke to warn you about something else,
do not make the same mistake I did.

Low end point and shoot camera do not allow ISO/aperture/tv-speed (shutter-peed) management.
Most of them choose for you. so if you have 20 cameras, it is most likely that they will all choose something different.

The canon a2500 is perfect because you can use the CHDK firmware which will allow tv speed, and ISO to be choosen by the user (I don't know about aperture).
« Last Edit: June 23, 2014, 12:47:06 PM by Eildosa »

Marcel

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Re: More megapixels or better optics?
« Reply #2 on: June 23, 2014, 02:33:54 PM »
But then I don't really know anything about photography and have only limited experience with PhotoScan.

My advice would be to first get some more experience with both subjects before spending money on multiple cameras. Get just one camera and shoot some static objects. I think you'll get a much better idea on what is important.

Darkly

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Re: More megapixels or better optics?
« Reply #3 on: June 23, 2014, 07:02:25 PM »
Can't you give me some hints?

I have tried with a single camera and multiple shots, a 14 mp Casio compact that unfortunately does not do raw. What I learned was that you need good lighting, low ISO, a solid ball-joint stand, and a remote trigger. I also learned that even sharp images are surprisingly grainy when you zoom 100%.

Anyway, I can't use a single camera because I want to capture a living human being.

Having read many many threads on this forum, it seems that going for 40+ DSLR's is the best option, but I simply do not have that amount of money to spend on this. Canon compacts with CHDK seems like a workable solution for "hobby project" standards.

That is why I mentioned specifically the A2500, because it seems like one of the reasonable choices.

Again, this is just the due diligence, which of course I did.

So the above is not directly related to my question. My question is simply, if I have a choice between ~10 pieces of 12+ mp resolution compact Canons, or ~10 older prosumer ~7mp Canon ~G7's with supposedly superior optics but much lower megapixel count, which one should I go for?

Darkly

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Re: More megapixels or better optics?
« Reply #4 on: June 24, 2014, 09:58:03 PM »
Nobody has any hints on whether higher megapixels or more expensive optics matter more in photogrammetry? I think in regular photography, better optics wins, but my intuition says megapixels are more important for scanning.

Marcel

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Re: More megapixels or better optics?
« Reply #5 on: June 25, 2014, 07:30:11 AM »
I would choose optics (high quality pixels) over more Megapixels.

But that doesn't answer your question about which camera to pick,  and I don't think anybody can give a meaningful answer without having actually tested and compared both cameras.

It also depends on your subject. For human head scans the lens corner quality might be less important because this part of the frame is filled with the background anyway. So bad optics with good center sharpness might work.

If you are thinking about buying a considerable number of cameras why not buy one of each first and do some testing? You can always sell it later.

mala

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Re: More megapixels or better optics?
« Reply #6 on: June 25, 2014, 04:15:36 PM »
Personally given the choice listed above I would go for fewer but better (i.e. more Mpix and interchangable lenses) DSLRs.

Way back when I first got Photoscan I had just one Canon 450D.... this alone  was easily adequate to complete face scans, provided the person was still as possible and there was adequate lighting.
I then bought more 450Ds on Ebay (pretty cheap) and made a rig of 3 cams, to this I added at a later date more 450Ds..unitl I ended up with 8 x 450D... The results were fine at the time.
I eventually sold all these cameras and the 50mm prime lenses I had bought, back on Ebay...... the thing to remember is that Canon DSLRs in general hold their value pretty well provided they are taken care of,as do the lenses.
At some point you are bound to want to upgrade your cameras for more Mpix, faster shutters,etc...so it is
worth having something that has a resale value.....

Cheers,
mala

Darkly

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Re: More megapixels or better optics?
« Reply #7 on: June 27, 2014, 06:24:26 AM »
Ok, but I'm on a very very limited budget. And I do not really need the textures anyway, I'm only going for an accurate (measurement-wise) 3D model of the human body. Perhaps I should have linked to my original thread, didn't think about that.

Is the better optics in order to get better textures, or do they have an effect on the mesh as well? My gut feeling would be the opposite, that higher megapixels are more important for mesh accuracy, and that any lens distortion would be corrected automatically by the PhotoScan process.

I don't have the money for a bunch of DLSRs. The Canon G7, G8, etc are the higher end PowerShots that look a bit like DLSRs but are really "point-and-shoot-ish" with fixed lenses. However, they are supposed to have better quality optics than the regular consumer PowerShots.

So, I'm looking to buy used cameras, and will probably end up with a bunch of different models (all Canon Powershots though). I realize that is a hassle but I can think I can handle it.

Again, the A2500 was only an example of the type of camera I mean. I will buy what I can find as long as it seems good enough.

Kms1

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Re: More megapixels or better optics?
« Reply #8 on: June 27, 2014, 06:53:29 PM »
I started with a 600D canon which is an entry level dslr, managed to get an 'L' lens and the difference in noise and quality of scan between this lense and stock lense is huge. Decent optics are a must, i will do a comparison eventually with a 5DMk2 and 600D using the 'L' lens to see what really matters. I will upload some test images showing the difference between the cheap 18-55mm kit lense and the L lense, both shot in my living room with no lighting

Darkly

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Re: More megapixels or better optics?
« Reply #9 on: June 27, 2014, 07:13:25 PM »
Thanks, looking forward to comparison.

Could you also upload comparisons between the cameras when it comes to mesh accuracy and not texture quality and colors?

Tyler J

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Re: More megapixels or better optics?
« Reply #10 on: June 30, 2014, 11:38:59 AM »
I started with a 600D canon which is an entry level dslr, managed to get an 'L' lens and the difference in noise and quality of scan between this lense and stock lense is huge. Decent optics are a must, i will do a comparison eventually with a 5DMk2 and 600D using the 'L' lens to see what really matters. I will upload some test images showing the difference between the cheap 18-55mm kit lense and the L lense, both shot in my living room with no lighting

Could you give more information about this L lens? I never touch a DSLR before and
plan to buy a 600D.

Marcel

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Re: More megapixels or better optics?
« Reply #11 on: July 01, 2014, 07:51:11 AM »
I started with a 600D canon which is an entry level dslr, managed to get an 'L' lens and the difference in noise and quality of scan between this lense and stock lense is huge. Decent optics are a must, i will do a comparison eventually with a 5DMk2 and 600D using the 'L' lens to see what really matters. I will upload some test images showing the difference between the cheap 18-55mm kit lense and the L lense, both shot in my living room with no lighting

Could you give more information about this L lens? I never touch a DSLR before and
plan to buy a 600D.

The 'L' is just a name for Canons premium/professional lenses. You don't specifically need an L lens however and they are very expensive.

 A prime (non-zoom) 50mm f1.8 lens will have perfect image quality and is one of the cheapest lenses you can buy for a DSLR.

Kms1

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Re: More megapixels or better optics?
« Reply #12 on: July 08, 2014, 03:53:26 AM »
as marcel suggests the L has superior optics, i borrowed the lens so do not have it to do another comparison, the one in question is very expensive so a middle of the range 50mm fixed focus may be better, once i get the lens again i will do a fair comparison between that and the kit lens, if i remember when i used it before i was just starting and used different lighting between the two and raws for the better image, however just looking at the images its obvious the L lens produces better images

Tyler J

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Re: More megapixels or better optics?
« Reply #13 on: July 14, 2014, 04:08:39 PM »
as marcel suggests the L has superior optics, i borrowed the lens so do not have it to do another comparison, the one in question is very expensive so a middle of the range 50mm fixed focus may be better, once i get the lens again i will do a fair comparison between that and the kit lens, if i remember when i used it before i was just starting and used different lighting between the two and raws for the better image, however just looking at the images its obvious the L lens produces better images

Comparaison would be great, thank you very much :D
Could you post screen shot of the resulting 3D model and a full resolution pictures of the same thing with both lens?

mr_cg

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Re: More megapixels or better optics?
« Reply #14 on: November 01, 2014, 04:55:52 PM »
The amount of mega pixels is not only the most important.
I did some tests with pictures with 18m and the same resized to 5m.
Final result almost the same.
You can also achive very good results with Arduino Cam (5M pixels only).

Based on my experience the most important things are:
+ The more pictures ... the better (min. 40-60 pictures per 360° rotation)
+ Good lightning (no shadows)
+ fixed ISO and shutter speed (ISO 100 recommended)
+ The higher the aperture, the better (on DSLR f8 or higher). To get everything sharp.