dslr and macro lenses

[TCav]

VTphotog wrote:

TCav wrote: A Macro Lens isa lens that attaches to the camera body, and can focus on objects at short distances.


I would agree with this, though purists argue that the image on the film or sensor must be 1:1. I tend to think of macro as being within an order of magnitude of 1:1, so anything between 10:1 and 1:10 would be macro.

For general macro work, a decent macro zoom lens is more than adequate. The Tamron and Sigma 70-300mm zooms have a 1:2 macro capability with minimum focus distance at just under a meter. The longer working distance allows more flexibility in lighting, and the addition of a 2x teleconverter creates a 1:1 ratio, with no change in min focal distance, at the expense, of course of a couple stops of exposure. Since macro shooting at that level is usually done with tripods, this isn't too much of a problem.

Single focal length macro lenses are almost always sharper, though.

Depth of field with SLR cameras is going to be very small with this kind of shooting; disappointingly so, if you have been using a small sensor camera. One of the nice things about my Minolta D7hi, is having better DOF for macro shots, without having to use f/32.

brian

Thank you, VTphotog, for that explanation.

However, the purpose of my response was simply to help fofa understand the difference betweena 'Macro Lens' and a 'Close Up Lens', not to describe the nuances of what, exactly, constitutes 'Macro'.

TCav wrote:

fofa wrote:

If you stop bugging us, we'll have nothing newto argue about. :-)

See?

[eric s]

TCav wrote:

In Macrophotography, there's almost never enough light, so you'll often be tempted to open the lens all the way. But that will get you almost no depth of field. (Someone posted some macro shots of flowers here some time ago, where the stamen were in focus but the petals were not. That's not enough depth of field.) And the situation will only get worse with extension tubes. At that point, you should consider a ring flash. A ring flash attaches to the end of the lens, andilluminates a subject that is closer to the lens than a shoe mounted flash will. Then you can stop down the lens and get more depth of field.

Why do you feel "the situation will only get worse with extension tubes"? I just wonder what this is in reference to (the size of the depth of field?)

I don't want to spend the money on a macro lens (but the Sigma 150 macro is tempting) so I use extension tubes. I already own the Canon 100-400, and I find the tubes work well with that. I've heard that they can work well with the Canon 28-135 but I've never tried it.

As a note to fofa, extension tubes trade distance focusing for close focusing (reducing the minimum focusing distance) so the subject looks bigger in the frame. They are cheaper than a macro lens, light and small (easy to carry) but they are only as good as the lens you put them on. Put them on a cheap lens and you'll have sharpness issues and larger f-stops will reduce quality even more.

And you still have the small DOF problem. A solution to that problem is to increase the f-stop. But most non-macro lenses have a "quality curve" (as I put it) where they optically start to get better as you increase the f-stop, and then they peak and get worst. It's lens dependent as to where the peak is, but its normally around f/8 to f/11 (if you're lucky.) A dedicated macro lens, though, stays optically great way out into the f/18 range (or even further.) This is part of what you're paying for! And as said by others, you often shoot at f/18 or even more when doing macro.

The downside to increasing the f-stop is you loose light. So you're shutter speed drops. You have two solutions to that problem. Stay steady (use a tripod) and hope your subject stays still (with controlled situations this isn't a problem, with wild animals or outdoors it is.) Or add light by artifically. An off-camera flash bracket can help. The previously mentioned ring lite is good. You can also use a macro twin-lite. A friend who does *stunning* macro work of bugs and lizards uses the twin-lite and does *not* recommend the ring lite. Another friend who does casual macro (but is generally a great photographer) loves the ring lite.

The twin lite (yes, that is how cannon spells it) is here:
http://www.usa.canon.com/consumer/co...p;modelid=7282
The ring lite is here:
http://www.usa.canon.com/consumer/co...p;modelid=8127


You said something I want to correct/adjust:
fofa wrote:

And if I understand the explanation of "working distance" it is basically (I said basically) the distance the camera (not lens front) is from the target for a 1:1 size of the target.

"working distance" is really just the distance from the subject to the camera. I technically doesn't have anything to do with macro. For bird/wildlife photography I talk about working distance in the 18-foot range because that is the minimum focusing distance of my big lens. When teaching I also talk about working distance in relation to scaring my subject (wild animals.) I'll say something like "a comfortable working distance is around 20 feet" - but that is kinda different.

Ok, I'm nit-picking, but I felt I should mention it.

Eric

ps. All the comments about "optically better" and such are relative. I've regularly use over $10,000 of camera gear when I shoot (note, I'm not including what I've sold... just the value of the gear that I physically am using right now.) Clearly, my standards are high enough that I needed to spend that much money to get the quality of result that I wanted. This might *not* be true for you. You have to figure out what enables you to do what you want and what will achieve that at an acceptable quality and price. For example, I didn't spend $1,500 on a really great macro lens even though I could afford it (easily.) Because I just don't care enough about Macro to do it. Instead I own extension tubes and use them on a very good lens (Canon 100-400) and I'm happy enough with the results that I don't spend more money. You need to figure out that point for yourself. Luckily no one in this thread said "you should go buy X" because they really don't know what *your* standards are to say that. They can only say what they are happy with. Ok, I'll get off my soap box now.

[TCav]

eric s wrote:

TCav wrote:

Why do you feel "the situation will only get worse with extension tubes"? I just wonder what this is in reference to (the size of the depth of field?)

The situation I'm referring to is the the reduced depth of field and the insufficient light. When you insert extension tubes, in addition to the closer focusing, you lose depth of field and the amount of light getting to the image sensor is reduced.

I quote from the Kenko DG Teleplus Extension Tube Set webpage: "There is light fall off when using any extension tube, sometimes the equivalent of 3 f-stops of light is lost when using multiple extension tubes together."

The amount of light fall off depends on the lens (I think you can use extensions tubes with any lens, though there may be lenses that you don't want to use them on.), and, unlikewith teleconverters,is probably difficult or impossible to predict. Newer lenses, especially 'digital only' lenses are designed to project the image more perpendicularly to all pixels on the image sensor, whereas older lenses that were designed to work with filmmayproject the image at a more oblique angleat teh edges of the exposurebecause film could handle it. When the lens projects the image at an oblique angle, more of that light is lostinside of the camera body and the extension tubes, so less light gets to the image sensor. But with newer lenses, since the lense is designed to project the image more perpendiculary to all pixels on the image sensor, less light is probably lost to the inside of the camera body.

[fofa]

So with the extension tubes then, is it because you loose light you loose DOF because you have to stop down to compensate for the lose of light?

What are the disadvantage of the close-up lenses (mount on front of a lens).

[TCav]

fofa wrote:

So with the extension tubes then, is it because you loose light you loose DOF because you have to stop down to compensate for the lose of light?

No.A shallower depth of field, and light loss, are two independent cosequences of extension tubes.

With a lens wise open, you will have a shallower depth of field because the focusing distance is less when an extension tube is used.

With a lens wide open, you will have to use a longer shutter speed becasue less light is getting to the image sensor when an extension tube is used.

fofa wrote:

What are the disadvantage of the close-up lenses (mount on front of a lens).

Theyaren't as effective as extention tubes, in that they don't make as big a difference. Also, they attach to the front of a lens, so you need a different set of close up lenses for each size filter mount you have that you want touse for macro work. Extension tubes connect to the camera body, so you only needone set of extension tubes, and they'll work with all your lenses.

Also, close up lenses are additional optical elements, and whenever you add optical elements to an optical system, you decrease sharpness and increase distortion. The effect of a single close up lens won't usually be very significant, but if they aren't good quality and you use them together, it will affect image quality. Extension tubes, on the other hand, don't affect the optics, so if you start with a good lens, you'll get a good image.

But close up lenses are cheaper and simpler to use.

[mtngal]

I'll throw a couple ofcomments into this discussion, only because there's one drawbackto both extension tubes and close-up lenses that hasn't been mentioned. When you use them, you lose the ability to focus to infinity. Now if all you are doing is photographing your tiny subject (I do mostly flowers, to give you a frame of reference) it's not a problem. If you want to take a picture offield of flowersalso, you have to remove the extension tube and remount your lens (or remove the close-up lens). I've taken a number of excellent pictures using a sharp prime lens and a home-made extension tube (which started out in life as a very cheap, poor quality teleconverter that my father had bought 25+years ago), but the fiddling got old after a while, since Itake a lot offlower pictures. Ibought an inexpensive macro lens and have felt much less frustrated (though now a year laterI'm thinking about upgrading the lens). It'spartly a trade-off between cost and convenience.

[TCav]

mtngal wrote:

I'll throw a couple ofcomments into this discussion, only because there's one drawbackto both extension tubes and close-up lenses that hasn't been mentioned. When you use them, you lose the ability to focus to infinity. Now if all you are doing is photographing your tiny subject (I do mostly flowers, to give you a frame of reference) it's not a problem. If you want to take a picture offield of flowersalso, you have to remove the extension tube and remount your lens (or remove the close-up lens). I've taken a number of excellent pictures using a sharp prime lens and a home-made extension tube (which started out in life as a very cheap, poor quality teleconverter that my father had bought 25+years ago), but the fiddling got old after a while, since Itake a lot offlower pictures. Ibought an inexpensive macro lens and have felt much less frustrated (though now a year laterI'm thinking about upgrading the lens). It'spartly a trade-off between cost and convenience.

To be sure.

But I beleive that even a standard lens on anextension tube(s) will get closer than even the 'macro-est' of macro lenses. Close up lenses fall somewhere in between, but if you want to also focus to infinity, close up lenses are easier to remove than extension tubes.

[mtngal]

TCav wrote:

But I beleive that even a standard lens on anextension tube(s) will get closer than even the 'macro-est' of macro lenses. Close up lenses fall somewhere in between, but if you want to also focus to infinity, close up lenses are easier to remove than extension tubes.

It seems to depend on what standard lens you are using, how big the extension tube is and what focal length the macro lens is. For instance, if you take a 300mm lens that has a normal minimum focusing distance of 10-15 feet and add that homemade extension tube, the minimum focusing distance is around 5 feet or so. On the other hand, if you take a 50mm 1.7 lens and add the same extension tube, your minimum focusing distance is really close.

And your point of the close-up lens being easier to remove is really significant!

[TCav]

mtngal wrote:

TCav wrote:

It seems to depend on what standard lens you are using, how big the extension tube is and what focal length the macro lens is. For instance, if you take a 300mm lens that has a normal minimum focusing distance of 10-15 feet and add that homemade extension tube, the minimum focusing distance is around 5 feet or so. On the other hand, if you take a 50mm 1.7 lens and add the same extension tube, your minimum focusing distance is really close.

Yes. I should have made my point clearer. For the same focal length, a standard lens on anextension tube(s) will get closer than even the 'macro-est' of macro lenses.

I used to use a bellows on my srT-101 and -202, and I could focus on the specs of dust on the objective lens of my 50mm f1.4. (As I recall, the depth of fieldwas pretty shallow, too; around1/32".)The same effect should be possible when using extension tubes in combination. I haven't looked, but I don't recall seeing the specifications on any macro lens that listed a minimum focusing distance of zero.

[mtngal]

OK - now I see what you are saying, thanks for explaining what you meant and of course you are right (I tried to say the same thing but not as well as you did).

Originally I thought very little about close-up lenses because of the adding another element aspect. The one I had tried was poor quality and I wasn't impressed at all. However, the macro lens I ended up buying (very inexpensive one) comes with a "matched adaptor" to allow it to go to 1:1 - essentially a close-up filter. It doesn't take away from the sharpness of the lens or cause any flaring or affect the images at all (other than the focus), so I've revised my opinion of them in general. They are much easier to deal with than extension tubeswhen you want to focus to infinity, so I wouldn't necessarily rule them out for macro pictures (though I would buy the best I could find). But it's also one of the reasons why I'm now thinking of upgrading the lens to something else.