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09/18/2006 01:59:54 AM · #1 |
hello everyone, i'm in need of some help. i think i'm either in a slump, or just...i don't know :)
my shots don't pop anymore. they don't have sharp focus, i don't know if it's my lens, or what. the equipment i have, i would think would be capable of taking absolutely breathtaking group shots, and i'm sure it's able to, but i can't make it. any suggestions would be greatly appreciated. (it's like that w/ my close up portraits too, at times. sometimes they pop, others they don't, more not than do. i don't know what i'm doing wrong.)
here's my setup:
Canon 350d (rebel xt)
Sigma 18-55 EX DC
Sigma 500DG Super Flash
tripod, and remote shutter release cable.
i used this today for this group shot, and they aren't sharp at all. (later i will take a test shot w/ my camera body and my Canon 50mm 1.8 and Sigma 18-55 2.8 at the same settings and compare shots and post them)
but the attached picture is cropped down to size, with a blow up of a 100% selection of a girl's face. the link below is a link to a 1.5mb, full raw conversion jpg with no altering done to it at all.
here's the cropped version:
if you can please tell me something that i'm visibly doing wrong, i would greatly appreciate it. this has me just at a loss what to do. i've tried many different things. aperture priority mode at anywhere from 5-12 or so, w/ varying ISOs to get the shutter speed up to around 1/100-1/120 manual mode to do the same thing.
i greatly appreciate any input anyone can give me. i really need help with this, so if anyone can help me, thank you SOOOO much.
here's the link to the full file.
//www.magnolia-net.com/~jedmag/sigmatest.jpg
thank you so much |
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09/18/2006 02:09:08 AM · #2 |
| The grass looks fairly sharp. Have you tested the lens for front focusing? The other obvious question is how clean are your lens elements and sensor. Also 800 iso is pretty fast to shoot a portrait, I like to be at 200 or lower for crisper detail, but mine is an older sensor. |
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09/18/2006 02:33:32 AM · #3 |
i apologize for my lack of knowledge, but front focusing? how do i test this, and what it is?
i clean my lens, all areas, before a shoot. my sensor i havn't. don't mess w/ it, i suppose i could send it off to get it cleaned out.
but i'm just at a loss. very frustrating.
i have tried at 200, 100, and so on. it was an overcast day today. but even on somewhat sunny days, it does the same.
maybe i'm just having a bad month :) |
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09/18/2006 02:45:47 AM · #4 |
I see this question all the time on another board I post on, dedicated mostly to people photography, something like "my closeups are nice and sharp, but my group shots are not. what am I doing wrong?"
Here is my take -
Your groups shots are not going to be as sharp as your closeups. There just aren't as many pixels to go around in a group shot, and fine details (such as the eyes) will not be as crisp. Usually the people posting this are Rebel (XT) or D50/D70 users. I think this looks pretty good for a Rebel XT shot, where the girls are pretty small relative to the frame. Really, once you make sure that your DOF was sufficient and your focus was in the right place, consider if it is just the limitations of a 8MP camera with such very small detail.
I am absolutely not knocking the Rebel XT or D70. They are great cameras and do a great job. (I did, however notice a HUGE difference in fine detail sharpness when I went to the 5D). How big are you going to print this? Consider how big the print will be and the appropriate viewing distance (you don't hold a 16x20 print up to your face when you look at it, you stand a few feet away). I think with a little USM and a contrast boost, this should print just fine.
As I say, I see this question alot, where talented portrait photographers are thinking they are doing something wrong with their focus on grou shots, and I often post this answer (too few MP) and it is usually not that well received. Just consider how much sharpness/detail your camera is capable of at this distance. You may be doing everything just right.
Liza |
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09/18/2006 03:57:13 AM · #5 |
You're dealing with a number of interrelated problems here: On the processing end, in no particular order, they include:
1. Insufficient density (image too light, light images don't look as sharp)
2. Insufficient contrast/saturation (apparent sharpness is a function of image contrast)
3. Insufficient output sharpening (Images from these cameras NEED to be sharpened in PP, especially when processing from RAW)
On the hardware end, they include:
1. A lack of DOF and/or bad choice of focusing point (the gals on the right are closer to the camera than the gals on the left, and they are sharper; ditto the wall itself)
2. A possibility of a front-focusing lens, assuming you used the center focus point and the camera was autofocusing on the central face (if the lens is out of adjustment, the camera may think it is focusing on that face, but the alignment is such that the focus is actually closer to the camera than that)
3. Most disturbingly, the possibility of an alignment problem with this lens or even with the sensor itself (EVERYTHING on the left side seems soft, suggesting that possibly the plane of the sensor is slightly off parallel with the plane of the lens)
These are not, of course, exhaustive lists; they are just best guesses, I'm not an expert on hardware issues. In any case, see the two examples below processed from your large image.
First I did an autolevel (a big improvement right there in contrast) then I used contrast masking with the highlight mask in multiply layer mode and the shadow mask in soft light layer mode. Finally I did some aggressive USM sharpening. The detail image is 100%.
 
Robt.
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09/18/2006 04:29:22 AM · #6 |
Ouch. That looks pretty bad...
I'll agree that the first thing that hit my eye was the low contrast too, but it is genuinely soft. Softer than it ought to be too..
The sigma 18-55 isn't an amazing lens, but at f/6.3, it should be performing better than that.
Definitely do some tests on the lenses. Test first for accurate focusing, test second for lens sharpness.
I am not really familiar with that lens, but it's possible that it's not all that sharp at the wide end... Especially at the edges, many lenses in that range have a tough time keeping up.
If you want to do a focus accuracy test, put your camera on a tripod (use mirror lockup if you wish, for this particular test, it's of slightly lesser importance. Mirror lockup is still always a good idea with any lens test though). and get a medium sized peice of paper (A3 if possible) with a rigid backing and place a ruler on top of it. Put the camera on center focus mode (later on you can repeat with the camera in another focusing mode, but it really shouldn't make any difference if it gets it right to start with).
Try to get the angle at around 45 degrees and place the camera at a close distance (around the minimum focal distance of the lens), with the center of the frame on a point roughly in the middle of the ruler. Take three pictures in a row. Move the camera farther away and repeat. Move the camera farther away and repeat.
As you move farther away, you will increase your DOF, so moving too far away will negate the purpose of the test. You still might learn something though.
try the test a few times, using different focal lengths. Experiment. You should get reasonably consistent results.
If the camera is 'locked on' to the point that you chose as the center point for each test, but the focus area is actually in front of that, this is called front focusing. If it is focused on the area behind, it is called back focusing.
There are more in-depth and advanced tests for testing lenses, but that's a simple variant that anyone can do and it's a good place to start.
Message edited by author 2006-09-18 04:30:04. |
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09/18/2006 07:22:14 AM · #7 |
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09/18/2006 10:04:30 AM · #8 |
this is an 800wide resize of another shot i did. i used varying ISOs, i didn't just use 800. i was trying to get good exposure, but around 1/120th or so. is that wrong? if so, i'll change. nothing done but white balance convert from Bibble pro.
 
looks better, but on the big 100% selection, you'll see the lack of detail.
here's the info:
iso 100, F/5 1/60s on tripod.
the movement i'm guessing was the cause, at 1/60th, but i could not get proper exposure readings from anything faster, under exposed.
maybe i'm overanalyzing, which is very possible. i'm bad about doing that :)
thanks so much for all the help. when i have time at work later, i'll answer the other questions that have been asked, in a hurry to get to class |
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09/18/2006 10:12:08 AM · #9 |
The images don't look particularly sharp. Have you got any shots taken with the 50mm 1.8 to do the comparison yet? I think this is most likely due to the lens.
You could try manual focussing too, rather than rely on the autofocus to get it right. This would eliminate any front/backfocus issues.
Since I got my old Manual 28mm lens and adaptor the other day, it has not been off the camera. I love it. You get used to the manual focusing aspect very quickly, especially if the lens is a prime and you dont have to worry about zooming too. |
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09/18/2006 10:15:19 AM · #10 |
Think you should (or should have) expose for the blond girl's hair in the back row. To me, the shot looks overexposed and her hair in particular. Yes the shutter speed is too low. Increase your ISO or decrease your aperture so you can increase your shutter speed. The picutre as is needs a healthy increase in contrast imo.
edit: Re: sharpness, I've found most people (women in particular) don't particularly care for every little imperfection on their skin to be brought into razor sharp focus. A little softness is preferable and, if your lense is like most lenses, you would probably get a nice result at F4 rather than stopping down. You'd also be able to use a quicker shutter speed.
Message edited by author 2006-09-18 10:16:37. |
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09/18/2006 11:06:00 AM · #11 |
Originally posted by Bear_Music:
the gals on the right are closer to the camera than the gals on the left, and they are sharper; ditto the wall itself |
In order to better align the distances between you and all the subjects, the young woman in the "hot pink" should be centered with the middle support brace on the background screen prop. This should keep the ones on the end at equidistant lengths from the camera. Of course, you would risk the chance of having something "growing" out of the top of her head. :-(
Finally, I noticed you used manual white balance. Which setting did you use (or did you calibrate it yourself with a custom setting)?
Message edited by author 2006-09-18 11:08:30.
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09/18/2006 12:12:52 PM · #12 |
| In both the images you posted the left side of the image is way softer than the right. It looks to me like a misalignment in the lens. Has it ever had a knock? Look at the far left of the wall and the flowers in this pic its not DOF or focus point, look at the right side to see that. |
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09/18/2006 12:15:31 PM · #13 |
Originally posted by zardoz:
In both the images you posted the left side of the image is way softer than the right. It looks to me like a misalignment in the lens. Has it ever had a knock? Look at the far left of the wall and the flowers in this pic its not DOF or focus point, look at the right side to see that. |
As a test, take a photo of an empty brick wall from about the same distance as the aforementioned photo. You should then be able to see any discrepancies between the focusing of one side ot the other.
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09/18/2006 01:12:06 PM · #14 |
| You probably focused on the middle person which is fine but since a lens is curved the edges will look soft as the people on the edge techinically are not on the same focal plane or the same distance from the lens. To aviod this shoot a group at F8 or F11 for maximum edge to edge sharpness and have the group bowed more inward. The people on the outside should be closer to your lens than the people on the outside. |
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09/18/2006 01:43:21 PM · #15 |
Originally posted by tmhalling:
You probably focused on the middle person which is fine but since a lens is curved the edges will look soft as the people on the edge techinically are not on the same focal plane or the same distance from the lens. |
I think what zardoz was speaking about was that the left side was a bit out of focus while the right side was good. The nature of a convex lens would have had both sides slightly out of focus (or at least a softer focus).
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09/18/2006 01:57:53 PM · #16 |
Originally posted by lesgainous:
Originally posted by tmhalling:
You probably focused on the middle person which is fine but since a lens is curved the edges will look soft as the people on the edge techinically are not on the same focal plane or the same distance from the lens. |
I think what zardoz was speaking about was that the left side was a bit out of focus while the right side was good. The nature of a convex lens would have had both sides slightly out of focus (or at least a softer focus). |
Exactly my thoughts. If you look, everything on the left-hand side of the image is very soft, from closest point to furthest. Yet on the right-hand side everything is significantly sharper and reasonable sharp all the way from foreground to the building at the back. If it has that kind of DOF on the right it should be the same on the left. |
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09/18/2006 02:03:39 PM · #17 |
Originally posted by zardoz:
Exactly my thoughts. If you look, everything on the left-hand side of the image is very soft, from closest point to furthest. Yet on the right-hand side everything is significantly sharper and reasonable sharp all the way from foreground to the building at the back. If it has that kind of DOF on the right it should be the same on the left. |
This is something I remarked on as well in the originally-posted image. Good to know I'm not imagining things.
R.
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09/18/2006 02:21:29 PM · #18 |
Originally posted by Bear_Music:
This is something I remarked on as well in the originally-posted image. Good to know I'm not imagining things.
R. |
So you did! I missed that. It sure looks like a misalignment to me too. |
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09/18/2006 03:18:21 PM · #19 |
what lens are you using? Sigma makes an 18-55 (cheap) consumer lens and an EX (pro) 18-50 2.8 lens. One is in your profile and you seem to say you ar eusing the cheaper version for these pics.
For groups I've found you need more DOF that F5 - try F8. Somewhat the distance form you to the subject matters as well, but with a group stacked 2 or 3 deep you need a lot DOF than F5.
Using a tripod 1/120 or even 1/60 shold not be an issue - unless the subject moved.
Focus...how did you do it? I used to use the center point and recompose - but that has issues (read all about it)
If the camera does not see enough contrast at the point you are trying to focus on it will NOT focus, or focus well. You find this out when it's too late though!
What works for me is let the camera pick the AF point - and i take 2 or 3 or 4 so it can really think about what it wants LOL And since i've been doing that i've had no problems with OOF group shots.
Using a sigma 18-50 2.8 EX lens
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09/18/2006 03:19:53 PM · #20 |
thank you all so much for the advice...i have a busy day today, but i'm going to try to get something going with it and test it agaist my 50mm 1.8 tomorrow. i'll try the other tests tomorrow that have been given, and post the results.
thanks SO Much. this site has given me more help than i could ask for, and it's greatly appreciate.
i'll post results as i get them. if there's any other ideas, please feel free to throw them out there.
i e-mail where i bought the lens, and going to see about their repair/replacement policy.
we'll see :) |
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09/18/2006 03:56:53 PM · #21 |
here's the full res-shot of the latest one if you want to take a look at it...
//www.magnolia-net.com/~jedmag/sigmatest2.jpg
thanks so much. i see waht you're talking about, the left side is a lot softer. sheesh.
Prof_Fate, i'm using the pro EX DC lens, if that's what you're asking (it's a 2.8) |
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09/18/2006 04:38:40 PM · #22 |
| If you look very, very closely on the left hand side of the full size image you just posted you can see that its not out of focus, its actually a double image. I̢۪m now totally convinced one of the lens elements is out of alignment :-( |
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09/18/2006 04:47:21 PM · #23 |
Originally posted by zardoz:
If you look very, very closely on the left hand side of the full size image you just posted you can see that its not out of focus, its actually a double image. I̢۪m now totally convinced one of the lens elements is out of alignment :-( |
I agree. You have a problem with this lens, unfortunately.
R.
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09/18/2006 04:56:52 PM · #24 |
well, thank you all so very much. i've had it less than a year, and manufacturer's warranty is for one full year. so this is awesome :)
much appreciated. if we all ever meet up, full round on me :)
have a great day everyone. thanks again.
Message edited by author 2006-09-18 16:57:26. |
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