Posted by Barbara Graham on January 30, 2011 at 11:35 AM
I'm moving this here at Brad's suggestion from the image post in the Wildlife Gallery so we can continue the discussion here. Thank you, Brad!
My responses to your last questions:
1. Have you used this lens a lot at 250mm? Was the IS on? Handheld or on a tripod?
I got the camera and the lens two or three weeks ago and have been using it constantly since then. IS is always on, and it was on a tripod. Should I really turn IS off when on a tripod? Also, I know I need to get a shutter release cable.
2. How did you get from the cropped size of 4008 pixels down to the final width of 720 pixels? This can be important because if the wrong image interpolation method is selected (in Photoshop's general preferences) you can it can reduce image quality during downsampling.
I used Save for Web, set the largest side to 720, chose JPG and moved the slider to get under 300. I don't know about image interpolation methods.
2. By CR do you mean Adobe Camera Raw?'
Yes.
3. In the second shot the bison is sharper. The grasses show signs of excessive sharpening, but that's for a separate reason (so let's leave that alone for now).
Just FYI, I only did one pass at sharpening, which is PSE9 sharpening at 25%.
Posted by Brad Hill on January 30, 2011 at 9:33 PM
HI Barbara,
Thanks for sending me the original raw file for both the image above and your original post in the Wildlife Gallery. But before I get to those images...responses to your question above: "Should I really turn IS off when on a tripod?"
Whether you should turn the IS (or VR) off when on a tripod varies with the lens. Usually the simplest way to find out is to check the manual that came with the lens. Unfortunately, being a Nikon shooter, I don't know the Canon lenses well enough to say if this particular lens should have the IS turned off when on a tripod. I DO know that many lenses in this focal range perform better when mounted on a tripod if the IS/VR is turned off. I'd recommend doing some test shots with the lens (while mounted on a tripod and see what you discover yourself.
In your original bison post in the Wildlife Gallery I mentioned that the image you posted lacked a bit of critical sharpness. After looking at the original RAW file there's no mystery (and you've done nothing wrong in your processing): the original simply wasn't sharp. I re-processed the raw file (just using default settings in Capture One Pro - no adjustments to ANYTHING made) and then - after cropping the image to reflect your original crop and downsampling the image - I tried several sharpening tricks I have up my sleeve. But, regardless of which method I used, there simply wasn't sufficient detail in the original capture (due to lack of initial sharpness) to allow for a critically sharp image at 720 pixels (see image above).
At this point it's pretty much impossible to say why the initial capture wasn't sharp - it may have been the IS issue I mentioned above, or simply camera shake (despite being on a tripod and having IS, technique is still critical).
I hope this helps (a little!). This experience is probably useful for you in light of your recent "Don't images need to be sharp at 100%?' post in the NPN Discussion forum. This is the kind of image I was referring to when I mentioned that I don't save images unless they're sharp at 100% - as you can see this one has limited use (even at 25% of its original size!).
Cheers...
Brad
Posted by Jim DeWitt on January 30, 2011 at 11:58 PM
Barbara, I can't speak for your equipment, but Olympus specifically instructs users not to use Image Stabilization when using a tripod. I don't know Photoshop Elements well, but in Photoshop itself you get much better results using the Image size command with bicubic sampling turned on, then changing the size in the save to a JPEG. I'd investigate PSE and see if it permits changing image sizes while still in RAW, as opposed to on the way to JPEG.
Posted by Lon Sharp on January 31, 2011 at 10:33 AM
I would be interested in knowing what kind of tripod was used and the circumstance. Were the legs fully extended? Did it have and did you use an extend-capable center column? Bear in mind that most lightweight and inexpensive tripods are not very sturdy, especially with legs extended. Center columns, which look like a handy feature, compound the problem and create additional instability! I honestly believe that flimsy tripods can be worse than none at all, especially if the photographer should choose the alternative of good technique and braced shooting. Excellent results can be had with a long lens using a bean bag off a car window or fence post or handy tree limb or rock or whatever. It may be worth your time to Google "long lens technique" and read a couple of short essays, then make some simple comparative tests.
Posted by Barbara Graham on January 31, 2011 at 10:37 AM
Lon, it's just a cheap Canon tripod. The legs were full extended. It doesn't have an extend-capable center column. And it's definitely not very sturdy. While on some days it's far better for me than shaky hands (which have better days and worse days), other days it's probably not. Thank you for reminding me of that. I'm making a list of things I need, and I somehow forgot that I need a much better tripod. If anybody sees this and knows of the least expensive sturdy tripod I could get, I'd really appreciate the info.
Re: sturdy tripod; I don't know about least expensive, but I would advise to go for either Manfrotto (I think it is called differently in the US, Bogen if I am not mistaken) or Gitzo. Both are not cheap brands, but the best I have seen and used.
Discussion
5 repliesMy responses to your last questions:
1. Have you used this lens a lot at 250mm? Was the IS on? Handheld or on a tripod?
I got the camera and the lens two or three weeks ago and have been using it constantly since then. IS is always on, and it was on a tripod. Should I really turn IS off when on a tripod? Also, I know I need to get a shutter release cable.
2. How did you get from the cropped size of 4008 pixels down to the final width of 720 pixels? This can be important because if the wrong image interpolation method is selected (in Photoshop's general preferences) you can it can reduce image quality during downsampling.
I used Save for Web, set the largest side to 720, chose JPG and moved the slider to get under 300. I don't know about image interpolation methods.
2. By CR do you mean Adobe Camera Raw?'
Yes.
3. In the second shot the bison is sharper. The grasses show signs of excessive sharpening, but that's for a separate reason (so let's leave that alone for now).
Just FYI, I only did one pass at sharpening, which is PSE9 sharpening at 25%.
Thanks for sending me the original raw file for both the image above and your original post in the Wildlife Gallery. But before I get to those images...responses to your question above: "Should I really turn IS off when on a tripod?"
Whether you should turn the IS (or VR) off when on a tripod varies with the lens. Usually the simplest way to find out is to check the manual that came with the lens. Unfortunately, being a Nikon shooter, I don't know the Canon lenses well enough to say if this particular lens should have the IS turned off when on a tripod. I DO know that many lenses in this focal range perform better when mounted on a tripod if the IS/VR is turned off. I'd recommend doing some test shots with the lens (while mounted on a tripod and see what you discover yourself.
In your original bison post in the Wildlife Gallery I mentioned that the image you posted lacked a bit of critical sharpness. After looking at the original RAW file there's no mystery (and you've done nothing wrong in your processing): the original simply wasn't sharp. I re-processed the raw file (just using default settings in Capture One Pro - no adjustments to ANYTHING made) and then - after cropping the image to reflect your original crop and downsampling the image - I tried several sharpening tricks I have up my sleeve. But, regardless of which method I used, there simply wasn't sufficient detail in the original capture (due to lack of initial sharpness) to allow for a critically sharp image at 720 pixels (see image above).
At this point it's pretty much impossible to say why the initial capture wasn't sharp - it may have been the IS issue I mentioned above, or simply camera shake (despite being on a tripod and having IS, technique is still critical).
I hope this helps (a little!). This experience is probably useful for you in light of your recent "Don't images need to be sharp at 100%?' post in the NPN Discussion forum. This is the kind of image I was referring to when I mentioned that I don't save images unless they're sharp at 100% - as you can see this one has limited use (even at 25% of its original size!).
Cheers...
Brad