New to Macro Photography - Need Help

[bill_dolphin]

I purchased a Tamron 90mm Macro lens for my Minolta 5D. I hear this is a great

lens. I am a little confused by the concept "minimum focus distance".

Apparently for this lens it is 11.4 inches. Does this mean that his is the

closest I can get to a subject I am photographing in AF mode? I like the idea

of getting some of those great insect shots etc. but if I cant get closer than

11.4 inches, the bug will still look like a dot (or it will have to be a very

big bug). Can I get closer than that in Manual Focus mode? Please advise as to

what this m.f.d. will limit me to for all practical purposes.

 

Thanks

[jmoody]

i'm no good with all the math (any math for that matter), but basically it means that you won't be able to focus clearly manual/automatic on anything that is closer to your lens that 11.4 inches. I don't know what the crop factor on your camera is, but assuming it's at least 1.4, you should have no problem making little bitty bugs look big. Also keep in mind that getting closer than a foot to most bugs will mean that they'll be scared to death, and sure to not stick around long enough for your shot. Sounds like your set up will do fine. Does the lens have a 1:1 ratio?

[jmoody]

thought i'd erased this one, but her's an example from a 105mm sigma macro lens and my digital rebel (1.6 crop factor). the pic is not cropped at all, and I think I might've been about 2-3 feet away (didn't wanna get stung)

 

http://www.photo.net/photodb/photo?photo_id=3828993

[jiun_der_chung]

The Tamron 90mm is a 1 : 1 ratio macro lens. Which basically that based upon the 35mm film negative, you can achieve a life size image (1:1) of whatever you are photographing onto the negative.

 

Of course, when that negative is actually printed, the image of the bug on the print will be many times larger than life size.

 

But as the previous poster quite correctly pointed out, the difficulty with insect photography is not getting so close that you scare the insect off. Often this is what limits the size of the image that you can obtain. The other issue is lighting. Because you need to stop down so much in order to optain a workable depth of view (often down to 22), you really need to be photographing in good light or have a macro flash.

 

Macro photography is fun, it opens up a whole new world of detail. Because you are using the 5D, my advise is to shoot away and experiment.

[mark u]

At closest focus you will fill the frame with a subject that is about 15x22.5mm.

[robert_paul1]

The 'minimum focus distance' is measured from the film (sensor) plane and not the front of the lens. And as you're using the lens on a DSLR with an APS-C sized sensor, which is smaller than a 35mm negative, your image at closest focus will be greater than life-size. True 1:1 will be achieved at a distance further away than the minimum focus distance.

[tommyinca]

To get closer, you can use a Nikon 4T close up lens (via a 55mm-52mm step down ring) or use a 36mm extension tube. Either one of these solution will give you arround ~1.5:1 (1.5X) verse the standard 1X magnification you have now. If you want higher magnification still, I would add a 1.4X tele-converter. This won't get you closer (could be a good thing) but will give you additional 1.4X magnification for a total ~2:1 (2X). 2X is properly as far as I will push a 90mm macro set-up.

[ilkka]

Close up lenses are not good with macros because the front lens is very deep inside the lens barrel. The distance between the close up lens and the front lens becomes big and this greatly reduces the image quality, more so than with a normal lens where the lens is close to the filter threads. It is much better to use an extension tube or bellows set-up with a macro lens. Minolta also makes a special macro lens for larger than 1:1 magnification, but that is expensive.

[dennis_fallon1]

In reply to:

 

"The 'minimum focus distance' is measured from the film (sensor) plane and not the front of the lens. And as you're using the lens on a DSLR with an APS-C sized sensor, which is smaller than a 35mm negative, your image at closest focus will be greater than life-size. True 1:1 will be achieved at a distance further away than the minimum focus distance."

 

Yes, minimum focus distance is from the sensor. But 1:1 is 1:1 regardless of film (full frame) versus APS-C. 1:1 means the lens is reproducing a lifesize image at the film/sensor plane, regardless of how big that film/sensor is. What this means is that for a given composition (what occupies the frame) you'll be able to get further back with APS-C. But that's shooting with a smaller magnification ratio.

 

As others mentioned, at 1:1 (regardless of minimum focus distance) you can fill the frame with an object the size of the APS-C sensor. If your bug is that big, it fills the image; if the bug is smaller, it fills a proportionately smaller part of the image.

 

- Dennis

[bill_dolphin]

Thanks all for your answers. I'm getting the idea now. I thought the mfd was measured from the end of the lens. That it is measured from the sensor makes more sense to me now. I'm guessing that many of the terrific insect and flower shots are achieved by cropping. I'll have to expirement and start posting some photos of my own. With the great respone I got from participants on this board I am sure I'll have the needed guidance. Thanks again to all who responded!

 

Bill

[robert_paul1]

"Yes, minimum focus distance is from the sensor. But 1:1 is 1:1 regardless of film (full frame) versus APS-C. 1:1 means the lens is reproducing a lifesize image at the film/sensor plane, regardless of how big that film/sensor is. What this means is that for a given composition (what occupies the frame) you'll be able to get further back with APS-C. But that's shooting with a smaller magnification ratio."

 

Dennis, how does what you say differ from what I posted??? I didn't say that the lens would not shoot 1:1 when used on an APS-C sensor DSLR. My post was in reference to the Minimum Focusing Distance, at which point, the image would be greater than 1:1 on an APS-C sensor, due to the 1.5X magnification of the smaller sensor.

 

Don't try and make it appear that my post was wrong.

[christopher kink www.digi]

Denis and Robert,

 

You're actually both wrong. A lens that produces 1:1 at its minimum focusing distance will produce 1:1 at its minimum focusing distance regardless of the film or sensor size. At the minimum focusing distance, 24x36mm will be "life size" for 35mm, while on an APS-C sensor, about 15x22.5mm will be "life size". However, the distance and magnification will be the same in both cases since magnification at the film/sensor plane is not influenced by crop factor. The magnification scale on the lens will still be accurate, no matter if you use a 35mm or digital camera.

 

-Christopher

[christopher kink www.digi]

Sorry Dennis, didn't mean to spell your name worong.

[jiun_der_chung]

Christopher is absolutely correct, as it is a crop factor, not a magnification factor. However in practice, for subjects that do not require 1 : 1 magnification, the crop factor actually allows you to stay further away and hopefully not scare the creature away.

 

Bill, some of the issues discussed are getting pretty specialised. Yes it is possible to achieve better than 1:1 magnification, but there are quite a few tradeoffs that come with those techniques. In practice, you will be amazed what you can achieve with 1:1 magnification. You will find that in reality, you do not have to do much cropping to achieve very good results.

 

Think of it this way, if you photography a 22mm long bug at 1:1 and fill the frame. You then print that photo at 12x8. You will then be looking at a 12 inch long bug on your wall. Is that enough detail for you?

 

Once again, you will find in practice that there are a lot of other considerations required to produce a good photo. But the Tamron is a great lens so enjoy using it.

[peterblaise]

.

 

Earlier: "...mfd [minimum focus distance]...measured from the end of the lens..."

 

That's MOD - minimum operating distance, the distance from the FRONT of the lens to the principle plane of focus (or subject).

 

With the camera on the floor, I just focus on a film can UPC taped to the 0" end of a tape measure. I reel it in and out across the floor in front of the lens, back and forth from the camera (easily done in the living room) until it's in focus with the lens wound out to MFD minimum focus distance. Then I read the "mod" distance on the tape measure from the 0" end to the lens front. I also measure MFD to the film/sensor plane just for the record, but I hardly ever use the MFR specification to help me in the field. I've done it for all my lenses BEFORE going out and shooting so I know how close NOT to expect them to get. I wish they'd print MOD specs on the lens barrel - a more useful specification to me in the field than the MFD specification.

 

Diopters are fine and loose no light, but, like http://www.lensbabies.com/ you may be dealing with edge softness, NOT what most people expect from one of the world's finest macro lenses like that Tamron 90mm! =8^o But, hey, I have many diopters from +1 to +14 and they are inexpensive (some) and fun, and I find them entirely appropriate for what they do and do well.

 

Extension tubes loose light but add nothing of their own, distortion wise. Yet, with either diopters or extension tubes on top of the macro lens's 1:1 capability, the depth of field and ability to focus is almost nil, so use a focusing rail to move the entire camera to focus.

 

Macro photography can be fun, and as mentioned, distance from the subject with a longer lens is a PLUS, especially for not scaring live subjects (or putting oneself in danger) and for preventing harsh flash or shadows cast from the lens barrel itself across the subject. We had 50mm macros in the old days, but 90mm and even 180mm macros nowadays are as wonderful and as accurate as the ol' 50mm's while additionally increasing the MOD - and that increased MOD is their entire reason for being!

 

Play! Enjoy and share some pictures!

 

- Click! Peter Blaise, Minolta Rokkor Alpha DiMage Photographer

 

PS - Don't forget http://www.google.com/ has a "what is" search feature, and searches like [what is macro photography] http://www.google.com/search?hl=en&q=what+is+macro+photography&btnG=Search and [what is minimum focus distance] http://www.google.com/search?hl=en&q=what+is+minimum+focus+distance&btnG=Search and [what is minimum operating distance macro photography] http://www.google.com/search?hl=en&q=what+is+minimum+operating+distance+macro+photography&btnG=Search bring up a wealth of resources - we're all apparently having much fun! ;-)