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Newbie SLR sharpnes
Hi, I just go a canon 40d. I was messin with it a little and since there is a full moon tonight, I took some shots. I got the 12-85 IS lens. Granted 85 is a little short for the moon but I was a little disappointed at the lack of detail I could resolve. this got me curious so I setup some crude sharpness test. I took shots of a pdf print of the iso 12233 test pattern.

I took shots at open, closed, and mid apertures. aside from the heavy barrel distortion at 17mm all the shots looked pretty close except for the f/22@17 and f/32@85 shots. this seems counter intuitive to me. I thought it would be the opposite. stopped down (aperture closed) I would think that DOF would me large and focus would be "tighter".

Btw, the moon is bright but no stars so I guess there could me some clouds interfering with my shots. I see the detail on the lcd, which is low res, and comes right off the sensor? best shot was at iso100, 1/30, f/16, 85mm, manual focus...

Comments (13)

You will never get maximum sharpness stopped down all the way..

GaryPhotos at http://www.pbase.com/gary_602zAll who wander are not lost!..

Comment #1

Yes, I realize the error in my reasoning now. think back to physics class!... when you focus light through an aperture it basically acts like a low pass filter. the high frequency components in the focus plan are at the edges and of course get chopped off. sorry not the best first post. I'm just excited to learn all I can about my new camera..

Comment #2

PhotonFiend wrote:.

Yes, I realize the error in my reasoning now. think back to physicsclass!... when you focus light through an aperture it basically actslike a low pass filter. the high frequency components in the focusplan are at the edges and of course get chopped off. sorry not thebest first post. I'm just excited to learn all I can about my newcamera.

It's actually a diffraction effect. Here's a good, semi-technical introduction to the subject:.

Http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm.

If you are going to look very closely at the image quality from your lens, you need to be aware that it is sold mainly on it's versatility rather than it's flat-out image quality. Here is a review of your lens from a respected, reliable source:.

Http://www.photozone.de/...anon-ef-s-17-85mm-f4-56-usm-is-test-reportreview..

Comment #3

Any lens beyond about f11.0 is going to run into diffraction distortion. so for max IQ yoiu have to run it at or below f11. also the lenses will hit max IQ 2-3 stop closed from wideopen, or about f8.0. personally, I just use f8.0..

When testing fo sharpness you have to remove ALL OTHER FACTORS. this means putting the camera on a tripod and cable release. if moon shots then what was the atmosphere like? cyrtsal clear and no turbelance, right? and away form any city..

For moon shots with a small lens, and your kit lens is that, you will be enlarging the image a lot and cropping rest of the image. idally you to have enough lens so that you do not crop and use the whole image..

I wrote the following some months ago; it may help answer your questions about moon shots..

To take a picture of the moon you need-.

Long lens 1000mm(35mm equivelent) about.high iso(800?) to force afaster shutter speed..

Exposure-the moon, odd as it sounds is hign noon sunlit. just like noon on earth. we are 240000 miles to moon, BUT earth or moon is 93000000 miles to sun. that determines exposure. as other replyer stated use sunny 16 rule. that is for a full moon 1/iso at f16.

Shoot a very hign shutter speed to start, take more than 1 shot at each shutter speed(3) then go down to about 1/30sec.use stong tripod..

Use cable shutter release or self timer. if self timer this will take a while, and you will have to keep adjusting moon in viewfinder.Use mirror lockup if your camera has it.Turn IS,VR,SR off, your camera is on a tripod..

DO NOT TRUST LIGHT METER IN CAMERA. it is being fooled by all the black sky. even spot meter, if available will not help, it won't go small enough to get moon only. moon is only 1/2degree wide, smaller than any spot meter.get away from city. turbulance and lights are bad news.if 1000mm or so not available, use biggest available. crop in post-processing.not as good as big lens but will work.shoot many pics, you can always delete later..

Happy moon pics. good luck.also-sunny 16 rule-i/iso is shutter speed. if iso is 100 then shutter speed is 1/100about.fstop is 16.0..

The f stop is f16. this a starting point. any lens is not at max sharpness at f16, so adjust fstop to f8 or f11, and move shutter acccordingly..

Check moonrise times in your area. you want about 3 hours after moonrise to start your pic taking. this gives the moon time to get far enough above the horizon to clear the horizontal atmosphere and turbelance..

You also need crystal clear skys. NO rpt NO haze, clouds, or humidity. humidity is noticable if you have corana around the moon, this could also be haze. in which case shoot on another night.happy moon pics..

Garysecond reply-on the subject of lenses-.

I use the bigma(sigma50-500+1.4converter). a smaller lenses will work, you just have to crop. but, if cropping heavily do not expect a lot of detail, you just won't get it. though remember any lens is multiplied by the crop factor. so your 135 becomes about 200-205mm..

I shoot at iso800 and at f8.0 end up at about200th-400th of a sec. when start taking the shot I start at 1/1000 and go down to about a 1/30. I also should three shots at each shutter speed, thus increasing the odds of getting a good one somewhere in the bunch. I expect to hit the good shots as stated at about 200th-400th..

Do not shoot if high humidity or haze or any kind of atmosspheric turbelence. it just is a waste of memory and time. I shot originally in a park in Detroit michigan on what I thought was a clear night, forget it. I actually got some good pics 200 miles north on the shore of Lake Huron. much better..

0ne thought, if available you can try putting a 2X converter on the lens, that would get to over 400mm. there are also several moon pic takers that use more than I converter. 2 2Xs or a 2X and a 1.4. it sound odd but the results are worth it. they are better than the crop heavy method..

Do not underestimate how bright a 3/4 or just under full is in terms of brightness. it equal to highnoon on a cloudless day in the summer.focus-.

Put lens on manual focus. then put it on infinity(assuming lens does not focus past infinity,some do) or manual focus..

F16.0 comes from the rule of 16. it is the starting point. if you want f8.0, as I use, then you move the shutter speed accordingly to get back to the EV. it is 1/iso for shutter speed under rule of 16. for f8.0 and iso500, for example, you move 2stops or 1/125. at iso500 the shutter speed is 1/500..

By the way, the above set of instructions work, I just got back from oscoda michigan, I live in detroit, used the same instructions, it worked..

Also, with my setup: pentax *istD, bigma50-500 at 500, 2x converter, this gives 35mm equiv of 1500mm. the moon's size is almost exactly 1/2 of the short side of the frame. in other words, you need all the telephoto power you can get..

The next items I also wrote some time ago. they may you. they are on the next reply...

Comment #4

I wrote the following posts some time ago, they may be of interest..

No matter which dslr you buy..

Heavily consider the following. there are NEW DSLR owners' writing in all over these forums on this subject.when changeing from a p&s to a dslr, there is a huge difference..

When you take p&s out of the box add a memory card and a fully charged battery you can now shoot and take very good pics..

BUT, you cannot do this with dslr. the camera HAS TO BE SETUP first. you have to adjust the contrast/saturation/sharpness/shooting modes(color style or whatever it is called) to your likes. if you don't it is quite likely you will disappointed with results. your p&s will likely outshoot the dslr..

To setup-you have shoot a test shot make ONE adjustment reshoot check pc screen readjust, until you are satisfied. and you do this with each of the adjustment types. then you have all the custom adjustments in the menu to check and if wanted change..

When done you can put the camera into AUTO or PROGRAM and get reasonably nice shots. I would advise at first staying with jpeg. as you learn about the camera and photography you can then go to the other shooting modes and try RAW if you wish..

Dslrs are made to see the shot through the optical viewfinder not through the lcd. this is true of almost all dslrs including the k10d. there was a thread.

Not to log ago about who would want a dslr with a preview lcd, al,most noone wanted one.dslrs and color..

If you mean heavy saturated colors then no dslr is going to do that. they are not made to give strongly saturated colors. they are made to give ACCURATE COLORS. not heavy saturated colors..

This is not the same thing at all. too many people who come from a p&s are very disappointed in th dslr colors, because they are not bright and saturated. this is because they are and have been using a p&s which has been giving them saturated and incorrect clors for so long that they think it is the right look. nothing could be further from the truth. the p&s colors are wrong, wrong. the camera manufactures know that the public buys high megapixel and heavy saturated colors and is what they make and sell to the public..

But the slr/dslr is a whole different world. for the dslr accuracy of the scene in terms of view and color is a religion rpt religion. you want accurate color that is what you are going to get with dslr. but they will not be the bright saturated colors of a p&s. ytou can with adjustments in the menus up the color is dslr, but it will not look the INACCURATE CARTOON COLOR of the p&s..

If you are wishing to buy a dslr for more and brighter color, save you money the p&s is what you want..

Not too long ago a new owner of a dslr was on these forums talking about the poor color of his new dslr. it seems as if he was shooting on an overcast day. many many people replying to him told him that cloudy day shots give the most accurate color, which they do. he couldn't believe and get over that idea. he also owned a p&S previously.you might be interested in this; which I posted a while back..

Http://forums.dpreview.com/...forums/read.asp?forum=1036&message=23677257.

________________to setup for jpeg with new camera-.

There are 4 functions that may be adjusted. the color mode(or whatevr it is called) satuation contrast and sharpening. I assume you are using a calibrated monitor. simply selrect a scene immediately outside your house. hopefully it has lights darks and colors. all settings in the camera are at zero or default.

Go on to each of the other adjustmenty settings. the object is to get the monitor scene as close a possible to the real scene outside. do not be cncerned if the finished monitor scene has enough color for your tastes; the amount of color can be adjusted in pp. you are going for accuracy between the 2 scenes. the real and the one on your monitor.

The adjustment process could take several hours. but once done leave the settings alone. at this point you know that the canera will accurately make the best pics possible of the scene. after I se my dslr up 3+ yrs ago about, I have not ever moved the settings..

If I needed/wanted more color or whatever that is what pp is for. I also try very hard to do my composing in the camera and crop heavily in the pc. my thinking is why buy a 10mp camera and crop away 40%. you are then no better that a 6mp that is not cropped. besides which the cropped 10mp is noisier..

I would not adjust the contrast to get more DR. to me you just have to get ust to the idea that digital has DR limitations. I shoot slides for 32yrs; the DR in digital and slides is about equal. I never had a problem. with DR limits exposure and lighting shoulld/ can be adjusted to compensate. if you want more headroom in your camera for taking jpegs, use adobeRGB color gamut.



_______________.

To put pics on these forums-i have photobucket , post multiple pics all the time.you have to belong/be part of a pic hosting site on the web..

I have IE7, so I simply have the photobucket web site up with my pics open on 1 web page, and the dpreview page I am replying to open on another page. write whatever you wish, go to photobucket(left click once on the pic's url link to make it blue, right click select copy), then on the reply page of dpreview position the blinking cursor where you wish, then right click and select paste, the copied url link will appear. if you want the link to the picture put a semicolon after the url, if you want the actual pic-no semicolon. hit enter, if pc, to move cursor to next line. for any additional pics simply repeat...

Comment #5

Very good writeup, Gary. I have to keep it to review. The forum should have some kind of an FAQ area with this type of stuff.DavidDallas, TX..

Comment #6

Your comments-.

I am with you. I found my self rewritting the exact same replys so when I did a good complete one I simply put them in a folder in my cocuments. I now just copy and paste to my web replys. I now have 24 prewritten replys...

Comment #7

Wow, thanks for the detailed reply. you covered a lot more that just my question, but I ready through it. very helpful. actually what I was confused about is that I have read a LOT of reviews and stuff about lenses and I had the general impression that most lenses get "soft" when wide open. I was ONLY seeing a discernible difference when stopped down. this did not go along with what I had been reading.



Btw, here is a crop of my best moon shot:http://www.flickr.com/photos/23082724@N07/2214363590/..

Comment #8

ANY LENS WILL BE SOFTER, not soft wideopen. the actual difference between the wideopen and f8.0 in terms of softness is why 1 lens costs $1500 and the other $150. the expensive lens lens among other things is reducing the softness of wideopen to a very very small amount..

But please do not think that the lens will be soft wideopen. it is just the lens is producing the sharpest image it can at a wideopen fstop, but not the sharpest. if a lens has a range of fstops from 1.4 to 22, then it will probably reach it's point of max sharpness and image quality somewhere between f4.0 and f8.0. this does not mean that at the other apertures it is unusable due to softness. it is not, just that it's get it's best image somewhere in the range..

For moon shots you do not need dof. and you run into diffraction distorsion beyond f11.0. what you want is max sharpness and quality. for my moonshots I use my sigma 50-500, with either the 1.4 or 2.0 matched converters, at f8.0 not because it gets a lot of light through the lens at that aperature but it is the sharpest at about f8. so for your moon shots use your lens at the sharpest aperture or just put it at f8.0 if you do not know. you can compensate for the aperature by going to a higher iso.



Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window.

High iso is not bad, it just needs some good technique and noise reduction software. below was shot at iso 1600 at the nigara falls butterfly conservatory..

Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window..

Comment #9

Great pics, the butterfly is awesome. I will experiment with higher iso and something around f/8 to see if I can get improvement and I will post. I assume I am still asking for beginner advice and not critique so it will be appropriate to keep things here..

Direct link:.

Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window..

Comment #10

For 85mm, you're not going to get much better..

Also, unless you capture it in a really interesting composition, full moon shots are the most boring. Get it when it's half full and you'll get some nice shadow detail along the terminator..

PhotonFiend wrote:.

Great pics, the butterfly is awesome. I will experiment with higheriso and something around f/8 to see if I can get improvement and iwill post. I assume I am still asking for beginner advice and notcritique so it will be appropriate to keep things here..

Direct link:.

Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window.

Some cool cats that can use your helphttp://www.wildlife-sanctuary.org.

Even if you can't donate, please help spread the word...

Comment #11

Yes, that is why I am posting in the beginner section and not the gallery. I just got my gear so I am learning how to use my camera and lens. this was the most interesting thing I had to photograph at the time so I was just seeing what I could get out of my camera. oh, and about DOF; I realize that this is not needed for the moon but I thought it might also give me a larger margin of error since I was not entirely sure how pin point the focus at the moon. from the tips I have got here I am ready to try again at some more shots...

Comment #12

Understood - just for clarification, I offered my comment merely as a tip, and not critique .

Have fun with your gear - it's always exciting trying out new toys..

PhotonFiend wrote:.

Yes, that is why I am posting in the beginner section and not thegallery. I just got my gear so I am learning how to use my cameraand lens. this was the most interesting thing I had to photograph atthe time so I was just seeing what I could get out of my camera. oh,and about DOF; I realize that this is not needed for the moon but ithought it might also give me a larger margin of error since I wasnot entirely sure how pin point the focus at the moon. from the tipsi have got here I am ready to try again at some more shots..

Some cool cats that can use your helphttp://www.wildlife-sanctuary.org.

Even if you can't donate, please help spread the word...

Comment #13

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This question was taken from a support group/message board and re-posted here so others can learn from it.

 

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