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Digital Camera Buyer's Guide

by Andy Resnick
Tags: buyer, camera, digital, guide
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Andre
#37
Sep29-11, 11:51 AM
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Sure you can compare with what we can and I would love to see results of that lens but it's not a game/match. I know that my 7D/100mm macro is not the best in the world, Borek beats it already with the 100mm L-version, but with a 5D mk2 body, results would even be better which would be topped by the A900, since the resolution is a function of both lens resolution and sensor resolution.

But we can compare pix maybe of a yardstick, or matches or playing cards, or a certain common brand of batteries.
Borek
#38
Sep29-11, 01:48 PM
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Andre and I can take a picture of Canon's lens cap
turbo
#39
Sep29-11, 02:19 PM
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Quote Quote by Borek View Post
Andre and I can take a picture of Canon's lens cap
From the inside? Your 100mm macros should deliver equivalent quality, I would think.
Andre
#40
Sep29-11, 02:36 PM
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yes here is mine



Anyway, I would also be interested to see results compared to the Canon MP-E 65mm
Andy Resnick
#41
Sep30-11, 09:22 PM
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Here's some preliminary results using two resolution targets. The first is from Edmund optics and is a chrome on glass variable bar target:



and the second for higher-magnifications is a Richardson Gen III test slide:



The images below are taken from that small region in the dead center.

There's a few things to keep in mind- first, although the targets are specified in terms of a length (for example, 5 line pairs per mm), the proper way to compare lenses is by the angular resolution: line pairs per radian. I didn't measure the object distance so I can't convert the units properly.

Second, the pixelated nature of the CCD results in imaging artifacts, especially aliasing:



In this case, it shows the effect of angular misalignment between the bars and the pixels. A related issue is the Bayer filter, but from the point spread images I took earlier, that issue may not be a significant one.

Lastly, for whatever reason I set the camera to 6 MP instead of the full resolution. This is probably a fatal flaw. In any case... From top to bottom are images from the 100mm, 63mm, and 25mm at full aperture, at the two useful extremes of reproduction ratio. For the 100mm, this is 1x and 1.78x (45 lp/mm and 75 lp/mm), while the 63mm images are at 2.5x and 4.5x (105 lp/mm and 190 lp/mm) and the 25 mm is 10.5x and 28.5x- the largest bars are 2 microns wide (4 microns per light/dark pair):



What I should probably do is re-take these at full resolution...
Andre
#42
Oct1-11, 08:20 AM
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Impressive Andy and yes, resolution is a function of lens resolution and sensor resolution. But maybe this should go in another thread?
Topher925
#43
Oct1-11, 08:47 AM
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I ended up pulling the trigger on a Nikon d5100 w/kit lens and 55-300 DX VR lens last night. Amazon was having a killer deal where I got the stuff above and a camera bag for a little over $900 shipped. While I was leaning more towards getting the K-5, it just seemed like too good of a deal to pass up.
Borek
#44
Oct1-11, 10:00 AM
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Can we find or prepare some kind of test that each one of us could print to take pictures of?
turbo
#45
Oct1-11, 10:04 AM
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How available are bicycle-brand playing cards in Europe? When the cards are new, they are very flat, and the printing quality on the backs is generally excellent and consistent to foil cheats.
Andy Resnick
#46
Oct1-11, 10:13 AM
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Quote Quote by Topher925 View Post
I ended up pulling the trigger on a Nikon d5100 w/kit lens and 55-300 DX VR lens last night. Amazon was having a killer deal where I got the stuff above and a camera bag for a little over $900 shipped. While I was leaning more towards getting the K-5, it just seemed like too good of a deal to pass up.
Excellent- I think you will be very happy with your decision!
Andy Resnick
#47
Oct1-11, 10:28 AM
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Quote Quote by Andre View Post
Impressive Andy and yes, resolution is a function of lens resolution and sensor resolution. But maybe this should go in another thread?
Probably- I think some sort of "shoot out at the PF corral" thread makes sense for this.

Quote Quote by Borek View Post
Can we find or prepare some kind of test that each one of us could print to take pictures of?
All we need is a 'standard object' (or a few objects of different sizes if we want to go beyond macro shooting)

Quote Quote by turbo View Post
How available are bicycle-brand playing cards in Europe? When the cards are new, they are very flat, and the printing quality on the backs is generally excellent and consistent to foil cheats.
This is a good suggestion- there does not appear to be very much fine detail, but it's probably good enough. How about the hologram sticker on credit/debit cards? Just a suggestion for something commonly available....

Edit: I think it's worth saying that this isn't a "mine's bigger than yours" competition. There's a lot of optics knowledge that goes into setting up and quantitatively evaluating images, and this should be treated as an educational resource.
turbo
#48
Oct1-11, 10:58 AM
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No, Andy, there is not a lot of really fine detail on the card backs, but they could make pretty decent long-distance targets. Just trying to think of something cheap and consistent. I long ago abandoned my wall-sized resolution chart (Edmunds, I think). When I was considering buying a zoom lens for my Olympus kit, I borrowed several from friends, including one who owns a camera shop, and used that chart to put the lenses through their paces. I gave up on the zoom idea right after developing and printing that film.

It was with a bit of trepidation that I jumped in with a Canon 30D and 100-400mm L, because of the expense, but I have a friend on another forum who shoots wildlife/birds from a blind with the 100-400, and the quality is scary-good. Zooms have come a LONG way in the last ~40 years.
Andre
#49
Oct1-11, 02:56 PM
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Quote Quote by Topher925 View Post
I ended up pulling the trigger on a Nikon d5100 w/kit lens and 55-300 DX VR lens last night. Amazon was having a killer deal where I got the stuff above and a camera bag for a little over $900 shipped. While I was leaning more towards getting the K-5, it just seemed like too good of a deal to pass up.
Congrats. I hope you enjoy it. Actually a few years ago I had a similar experience, I was charmed by the multigadget Sony A350 and I had already ordered it (tentatively), I thought that the Canon 450D, the other one of the shortlist, was way too simple and a bit expensive in comparison, then I saw the test results and I never looked at the Sony again.

But that was just a moment in time and Nikon really had no competative model at that time that made it to my shortlist.
Andy Resnick
#50
Oct1-11, 05:49 PM
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Quote Quote by turbo View Post
No, Andy, there is not a lot of really fine detail on the card backs, but they could make pretty decent long-distance targets. Just trying to think of something cheap and consistent. <snip>
I was thinking more and realized that there doesn't have to be fine detail, as long as the pattern edges are sharp- it's still possible to extract the modulation transfer function.

Cards sound good to me- consider that a second. How about the overseas folks?
turbo
#51
Oct1-11, 05:54 PM
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Quote Quote by Andy Resnick View Post
I was thinking more and realized that there doesn't have to be fine detail, as long as the pattern edges are sharp- it's still possible to extract the modulation transfer function.

Cards sound good to me- consider that a second. How about the overseas folks?
Well, I guess a pack of cards isn't that much of an investment, so we could spend a few bucks to split a deck and send one or two cards to others who want to use those as test targets.

I'll send you some money to buy a deck of cards and pay for postage if you want to supply targets to Andre, Borek, and others. I can't get out too much due to my sensitivity to fragrance chemicals, so if you can handle the logistics, I'll pay the cost. It might be better to use cards within a single pack, to keep printing-variables as even as possible.
Andy Resnick
#52
Oct2-11, 06:21 PM
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Quote Quote by turbo View Post
Well, I guess a pack of cards isn't that much of an investment, so we could spend a few bucks to split a deck and send one or two cards to others who want to use those as test targets.

I'll send you some money to buy a deck of cards and pay for postage if you want to supply targets to Andre, Borek, and others. I can't get out too much due to my sensitivity to fragrance chemicals, so if you can handle the logistics, I'll pay the cost. It might be better to use cards within a single pack, to keep printing-variables as even as possible.
I'm not sure I want to open "Andy Resnick's Playing Card Emporium" just yet :) Interested people can buy them directly online, anyways:

http://www.playingcardsandmore.com/b...Fcjc4AodPgS63w

As it happens, I'm teaching the Advanced Optics Lab class next semester, and I've been trying to come up with a few labs to replace the (ahem) useless ones. For example, I'm thinking about a lab that centers on this:

http://www.skymall.com/shopping/deta...769555&c=10323

and a "imaging performance" lab could also be a nice addition. I've come up with a preliminary procedure that I can debut here and see if it's worthwhile to fully develop for the course.

So, for anyone interested in quantitatively measuring the imaging properties of a lens, I'll work to get a rough draft started in a new thread. Details to follow, but all you need to start is a greyscale photo containing a light-to-dark transition.
Topher925
#53
Oct23-11, 01:17 PM
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I know most people here shoot Canikon, but I cant say enough about how much I love my new Pentax. I finally got some time this morning to really try it out and while I'm still learning, I think the results are fantastic. Can't wait to get some nice lenses for it.



Andy Resnick
#54
Oct23-11, 05:29 PM
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Excellent- hope you are having fun!


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