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Old Mar 1, 2004, 8:31 PM   #1
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Default Help with macro shooting

Hello everyone, I'm having a hard time getting the diamonds in focus on these rings I have to take pictures of. Let me explain my setup... Basically I have the Rebel with a Tamron XR 28-300mm zoom lens at full 300mm zoom. I have the camera set to full manual mode with shutter speed = 1/60th second and aperture of 14.

I'm taking the photos in this photobooth I contsructed using high frequency ballasts (40,000hz) so they don't flicker like conventional fluorescent bulbs, and it's in a photo tent to minimize reflections, etc. I have a tripod setup to shoot the rings from a distance of about 2ft away since the min. focal length is 19" or so for my lens. This is what it looks like:



These are two of the rings I took pictures of:



I can't get the small diamonds in focus no matter how I try. I even tried to manual focus but I couldn't manage to do it. Do I need a dedicated macro lens for this type of work because the tamron just will not focus enough or am I doing something wrong?

Thank you.[/img]
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Old Mar 1, 2004, 8:56 PM   #2
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hmmmmm... sure just looks like your focusing half way "through" the ring... and at 300mm and only 2 feet away the DOF is going to be very shallow.... try a different f-stop?
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Old Mar 2, 2004, 12:25 AM   #3
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I agree with Mr_Saginaw. It looks like you're focusing part way into the ring.

You need a really big DOF, which means a really large aperture. Go upwards of f32 if you can.

If you have to, you might have to take multiple pictures and then shift the DOF across them and merge them in photoshop. I don't know how to do it, but I've seen the results and it can look very good.

When doing macro the DOF can be very, very small (1/4 of an inch is not uncommon.)

You might seriously consider a macro lens, they will be sharper than that len. And they are designed for this job, so they will have a closer min focus.

Eric
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Old Mar 2, 2004, 3:15 AM   #4
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The aperture setting is the AV one right? Is there a way to adjust the f-stop? I don't see that option, sorry if these seem like basic questions.

I had the AV set to 14, I can only change it up to 22. Is there a way to get it to 32? I have the ISO set to 100 currently. Does it have to be higher? I'll try shooting with AV=22 and see how well that works out.
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Old Mar 2, 2004, 10:30 AM   #5
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Quote:
Originally Posted by dotcomguy
The aperture setting is the AV one right? Is there a way to adjust the f-stop? I don't see that option, sorry if these seem like basic questions.

I had the AV set to 14, I can only change it up to 22. Is there a way to get it to 32? I have the ISO set to 100 currently. Does it have to be higher? I'll try shooting with AV=22 and see how well that works out.
Av means aperture which is your f-stop.

You can only go as high as your lens allows you to go. Your lens only goes to 22, so 32 is not an option.

Looking at the pictures, the top of the ring is out of focus. You say that you cannot seem to get it in focus. Are you positive that you're not too close to the subject and exceeding the minimum focus distance?
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Old Mar 2, 2004, 10:35 AM   #6
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ohenry, thanks for the semi-correction for me. I don't know that lens well enough to know what the min aperture is. I guess that is another advantage of a real macro lens... I bet they get some really small apertures.

Eric
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Old Mar 2, 2004, 11:13 AM   #7
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Quote:
Originally Posted by eric s
ohenry, thanks for the semi-correction for me. I don't know that lens well enough to know what the min aperture is. I guess that is another advantage of a real macro lens... I bet they get some really small apertures.

Eric
I don't know that lens either. I was just going off his reply that he couldn't get to f/32. I have the Canon 100mm f/2.8 macro lens. It only goes to f/32 which is the same with all of my lenses (including the EF-S lens). The advantage of a true macro lens is the close focusing and the ability to do 1:1 images. Many of the so-called zoom macros are not capable of achieving 1:1 despite calling themselves macro. It's kind of like low calorie food. You need to read the label to see what the manufacturer considers low calorie and you need to read the specs to see what macro means
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Old Mar 2, 2004, 11:49 AM   #8
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Default Hmmm......

I hesitate to answer this post as I always fear starting a battle. I went to a review site that had several posts listing this lens as a little soft at 300. It would not be as noticeable in a 5X7 landscape but a full frame shot at two feet may be beyond what the lens will do. I think perhaps a shot unzoomed a bit would be a better test of the lenses ability for close=in work. I have a couple macro lenses and even though they say they will focus to infinity it is clear that they don't measure up to primes that are intended for that use. If I only had a few items to shoot I wpuld use less zoom and crop. But as you have a table and lighting it appears you have a serious need, there for I would suggest you purchase a macro lens that will help you extract the most from the rest of your equipment. The frustration will be gone and your joy will return and all of that for the price of a macro lens, pretty cheap really!
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Old Mar 2, 2004, 12:13 PM   #9
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Quote:
The frustration will be gone and your joy will return and all of that for the price of a macro lens, pretty cheap really!
Who needs therapy! All that for the price of a macro lens! I gotta go and get me one.

But seriously, it's a question of the right tool/lens for the job. There are many times when you can get away using something that is "good enough". But there are times when you really should spend the money and get the tool designed for the job... in this case, a real macro lens.

So try it with what you have (which you did.) If you can't get it to work, look into getting the specialized tool.

Eric
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Old Mar 2, 2004, 9:01 PM   #10
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Hi everyone, thanks for the replies. Just to clear it up, I did make sure I was exceeding the min. focus length by using a 2' gap between the lens and the subject, even though the lens only needs 19" and I do get a focus lock, when I'm too close it doesn't lock, so I don't think that's the problem. I even bought a little remote clicker because I thought it was maybe camera shake.

But I guess I do need a dedicated macro lens. This is where I find it confusing.... I'm using the one I have now at 300mm, 24" away. Will a 100mm 14" away or so be that much more "zoomed in" ?? because the 100mm Canon USM f2.8 needs 1 foot, so really... I won't be that much more zoomed in, but it will be more in focus is that right?

But this lens is supposed to do 0.26x full size according to the manufacturer, and the 100mm macro is 1:1, so you'd think it would fill 4 x the size right? This is where the confusion lies...

So my question is.... at 12" how big of an object roughly will fill a full frame? It's very confusing to me a 100mm would be 4x as big as a 300mm.
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