Problem with focus

[jackprks]

I have been trying to shoot macros with my sigma 70-300 dg apo macro lens. I have been using auro focus since it has worked with my other lens'. The view finder looks sharp when the focus light blinks and I shoot. When I enlarge the raw image to 100%, they look soft.

I checked the sigma site and looked this lens up. It states that the closest distance with this lens if 59". In macro mode, 37". I was somewhere between 3 or 3 1/2 feet from the subject and not in macro mode. Could this be the problem or would manual focus be the best way to go. I like the af because that is one more thing I don't have to do. I use av mode in order to vary the f stop. I was also using a tripod. :confused: :cry:

[bauerman]

Jack - I have this lens and get great results from my macro work - could you possibly post some examples (with EXIF information) that we could take a look at and that might help us judge what is going on in your situation. You should not have to manual focus all our macro shots - I do not believe that.

Thanks.

[S.Horton]

EXIF is needed and a photo, because this could just be camera shake, the flower moved in the wind, etc...............

[jackprks]

I tried to post this morning but the site was down. I am at work now and will have to wait until tonight to post them. I have already sized and saved the best 2 samples for the web. I will post the exif info and one pic that was sharp, taken with the same lens.

Thanks for your replies. I am just not cerain what caused the problem.

[Cubix Rube]

It sounds to me, like you may have answered your own question in your original post. If the minimum focus distance is 59" when not in Macro mode, and you were 36" - 42" from your subject, and not in Macro mode...;)

[jackprks]

Yet the image was sharp in the viewfinder

[jackprks]

Here are 2 of them. I may or may not have had the lens in macro mode, I am not certain. I have to do these quickly because I do them at work. I have short breaks and do them then.

Daisy-1/25s, f8, iso 100-168mm
Weed-7/200s, f9, iso 100-263mm

[jackprks]

This is one with the same lens, done 3 days before. This one had no problems.

1/100, f11, iso 100-190mm

[braduardo]

I would say it's camera-shake. 1/25 second is WAY too slow for a lens of that length with a subject that can move.

[StewartR]

I would say it's camera-shake. 1/25 second is WAY too slow for a lens of that length with a subject that can move.It's not camera shake because he was using a tripod. And whether or not the subject can move has no bearing on camera shake.

But I agree that 1/25th might be too slow to freeze the motion of the subject.

[cfcRebel]

Jack, you need to increase your ISO (to 400?) to get faster shutter speed. I have used that lens before. The Marco mode is only available between 200mm - 300mm if i remember correctly. When shooting at 300mm, Macro mode, slight shake could blur your shot.

Something for you to experiment:
1. Set it up on a tripod
2. Place your tripod appropriately, depending on the direction of the light
3. Zoom your lens to 300mm, turn on the Macro switch
4. Set your aperture to around f8, ISO400 (in Av mode)
5. Auto focus on your subject. Gently squeeze the shutter button to avoid shake
6. If doubt, use self timer (or cable release) to take the shot, to compare the result

Good luck and post back your experiment result. ;)

[jackprks]

You are correct. This is from the Sigma web site.

"High optical performance is demonstrated throughout the entire zoom range. It also has a switch that converts the lens to macro photography at focal lengths between 200mm and 300mm with a minimum focusing distance of 95cm (37.4 inches). In normal mode the minimum focusing distance is 150cm (59.1 inches) at all zoom settings. Maximum magnification between 200mm and 300mm is 1:2.9 to 1:2."

I guess this is why I was told this lens is not a true macro lens.

[braduardo]

It's not camera shake because he was using a tripod. And whether or not the subject can move has no bearing on camera shake.

But I agree that 1/25th might be too slow to freeze the motion of the subject.

I was actually trying to say it's some of both. I haven't used that particular tripod, but it looks an awful lot like one I had before... (I wasn't a fan) It might be ok with a remote, but if he's pushing the button, you can still introduce a lot of camera shake unless your tripod is very rigid and stable. At 300mm, and that short of distance to the subject, any camera shake (or movement by the subject) will be very dramatic. It might only move 1/4", but it will be very pronounced in the shot.

[howzitboy]

Something for you to experiment:
1. Set it up on a tripod
2. Place your tripod appropriately, depending on the direction of the light
3. Zoom your lens to 300mm, turn on the Macro switch
4. Set your aperture to around f8, ISO400 (in Av mode)
5. Auto focus on your subject. Gently squeeze the shutter button to avoid shake
6. If doubt, use self timer (or cable release) to take the shot, to compare the result

Good luck and post back your experiment result. ;)

i would do this instead:
1. camera on tripod
2. compose shot
3. iso 100, f8 , shutter "what ever needed"
4. manually focus on subject main point of interest
5. lock up mirror
6. shoot away using cable or self timer.

make sure tripod is sturdy and heavy. hang bag of rocks under center column if more weight is needed (they sell bags for that). make sure subject is out of wind ie NOT moving.

[cfcRebel]

I guess this is why I was told this lens is not a true macro lens.Whether it is a "true" macro lens or not, it's not as important. The most important thing is, do you get the shot that you are after.;)
If my goal is to capture a dragonfly, from head to tail, filling up the whole frame, this lens is more than capable of helping me do that. Some people would argue that is not a "true" macro shot because it's not 1:1 yada yada yada but hey, i've got the shot i wanted. I have used this lens before. I know what it can do. :D

[jackprks]

Thank you all, you have been very helpful.

I will try these suggestions tomorrow, Saturday and then post the results.

[jackprks]

Here are two from today using some of the advice I got from you all. I discovered I couldnt take the lens off of macro. I thought it was stuck, the I retracted the barrel and I could do it. I had trouble centering the subject on the tripod, need more practice I guess. These are right from the camera, just resized for posting.

1/160s, f11, iso 200-300mm
1/200s, f 8, iso200-300mm

[cfcRebel]

Here are two from today using some of the advice I got from you all. I discovered I couldnt take the lens off of macro. I thought it was stuck, the I retracted the barrel and I could do it. I did not get a chance to try that when i had the lens.

The two samples are quite good. A little pp would further enhance the images.
As for centering the subject, do you use a ballhead or 3-way pan head? For macro, it was difficult when i used the pan head to compose my shot. So i switch to ballhead. Much easier when composing a macro shot, for me at least.

[jackprks]

I use the pan head that came with the tripod. It is a cheap one and not as good as the ones uwed in this forum. I have a better one I bought some time ago but can't find it. My wife put it away somewhere. Does a ball head fit any tripod?

I used mirror lock and a wired remote for these pics. I also tried a different weed flower, but the wind kept blowing it around and wasn't able to get a good shot.

[jackprks]

I just ordered a Bogen-Manfrotto 486RC2 Compact Ball Head from Amazon. I have seen this brand quite often in threads I have read. It should fit my cheap and better tripods and make it easier to center subjects for macros. (I hope!!!) ;)

[cfcRebel]

Hopefully you could find the other tripod, the better one that your wife put away, and use it with the new ballhead.
Subject motion is something you need to pay attention to, especially when shooting macro.

[jackprks]

Here a two more. This weed is only about 4" high and the flowers about 3/4" across. I think like most weed/wild flowers they are delicate and quite attractive. c&c welcome.

1/50s, f22, iso 200-300mm
1/200s, f11, iso 200-300mm
both with wired remote, mirror lock and manual focus in av with tripod.

[cfcRebel]

I like the 2nd one better simple because the flowers are isolated better from the green background and the 1st one.
Did you adjust the Contrast/Brightness on these in your pp? The reason i ask is, some highlights are too warm. If these images are straight from camera, then you should underexpose a third, or two thirds, to avoid warm highlight and blown white.

[jackprks]

Yes I did up the contrast, I don't really know what I am doing in cs2 and thought it looked sharper with more contrast. What is meant by "warm highlights"?

Thanks for the critique, I need all I can get.

[Glenn NK]

Didn't notice anyone else mention it, so I will. You will get better results by focusing manually when doing closeups/macro.

[jackprks]

Glenn nk, I did use manual focus on these, is the focusing not right? I do know with this lens at 300mm, the dof is very shallow.

I have been in Victoria and was impressed, the street lights all had flower baskets hanging on them and the amount of building is impressive. Very expensive however. I also watched the nemerous commuter planes arriving and departing constantly.

Thanks for your comments.