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Getting the subject in focus

 
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MikeUK



Joined: 26 Mar 2018
Posts: 4

PostPosted: Mon Mar 26, 2018 4:43 pm    Post subject: Getting the subject in focus Reply with quote

Hello all,

A little deflated at the moment. I'm new to photography and newer to macro. I've seen some incredible images produced by the lens I have(Canon EF 100mm f/2.8 Macro USM) but I feel a million miles away from accomplishing anything even close.

I don't know how people manage to get something like a bee in focus when I can't even get a multivitamin pill in focus.

Another issue I'm running in to which is probably compounding the problem, is that it's like I'm looking through a slit when it comes to focus.

Any advice appreciated.

P.S. I honestly think my hairline has receded since getting this lens, LOL.
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rjlittlefield
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PostPosted: Mon Mar 26, 2018 7:43 pm    Post subject: Reply with quote

Mike, welcome aboard.

The lens you have will focus from infinity to approximately 5 inches in front of the lens, just by turning the focus ring. At closest focus it has an optical magnification of 1:1, which means that it shoots a frame the same size as the sensor in your camera. If you cannot get any part of your subject in focus, then check to be sure that it's beyond that critical close focus limit.

Quote:
it's like I'm looking through a slit when it comes to focus

That sounds to me like you can get part of your subject in focus, but the in-focus slab is a lot thinner than you hoped.

This is the classic "depth of field problem" in macro photography: the higher the magnification, the relatively shallower the depth of field gets.

There are three main approaches to attacking the depth of field problem:

1. Stop down the lens as far as possible, while still getting the sharpness you need. Beyond a certain point, the image will get blurred from diffraction, and there's nothing you can do about that. For a given size subject, the tradeoff between DOF and sharpness is the same for all lenses and all cameras. Many people believe that small sensor cameras give more DOF than large sensor cameras do, but that's a myth.

2. Choose a composition and viewing angle that will capture the viewer's attention with the in-focus bits. When shooting an insect, or any small animal, it's traditional to focus on the eyes.

3. Use a technique called "focus-stacking", in which you shoot a multitude of pictures focused at slightly different distances, then run the whole collection through clever software that picks out the sharp bits and merges them together to form a single image that is sharp everywhere that any of the inputs was. This is a very powerful technique, but it only works on subjects that will hold still long enough to shoot the stack. Live bees are not typically photographed with focus stacking, but it works great on dead ones.

Quote:
I honestly think my hairline has receded since getting this lens

We don't often hear that symptom. However, macro photography is well known for producing "multifaceted" individuals -- in our cases, that's because of repeatedly smashing our foreheads into hard surfaces at various angles. Rolling Eyes

Welcome to photomacrography.net!

--Rik
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MikeUK



Joined: 26 Mar 2018
Posts: 4

PostPosted: Tue Mar 27, 2018 2:00 am    Post subject: Reply with quote

rjlittlefield wrote:
Mike, welcome aboard.

The lens you have will focus from infinity to approximately 5 inches in front of the lens, just by turning the focus ring. At closest focus it has an optical magnification of 1:1, which means that it shoots a frame the same size as the sensor in your camera. If you cannot get any part of your subject in focus, then check to be sure that it's beyond that critical close focus limit.

Quote:
it's like I'm looking through a slit when it comes to focus

That sounds to me like you can get part of your subject in focus, but the in-focus slab is a lot thinner than you hoped.

This is the classic "depth of field problem" in macro photography: the higher the magnification, the relatively shallower the depth of field gets.

There are three main approaches to attacking the depth of field problem:

1. Stop down the lens as far as possible, while still getting the sharpness you need. Beyond a certain point, the image will get blurred from diffraction, and there's nothing you can do about that. For a given size subject, the tradeoff between DOF and sharpness is the same for all lenses and all cameras. Many people believe that small sensor cameras give more DOF than large sensor cameras do, but that's a myth.

2. Choose a composition and viewing angle that will capture the viewer's attention with the in-focus bits. When shooting an insect, or any small animal, it's traditional to focus on the eyes.

3. Use a technique called "focus-stacking", in which you shoot a multitude of pictures focused at slightly different distances, then run the whole collection through clever software that picks out the sharp bits and merges them together to form a single image that is sharp everywhere that any of the inputs was. This is a very powerful technique, but it only works on subjects that will hold still long enough to shoot the stack. Live bees are not typically photographed with focus stacking, but it works great on dead ones.

Quote:
I honestly think my hairline has receded since getting this lens

We don't often hear that symptom. However, macro photography is well known for producing "multifaceted" individuals -- in our cases, that's because of repeatedly smashing our foreheads into hard surfaces at various angles. Rolling Eyes

Welcome to photomacrography.net!

--Rik


Hello Rik,

Thanks! I've been reading how keeping parallel to the subject where possible helps get more in focus as well. I'll have to try that this evening after work.

I have successfully focus stacked and it does produce some great results.

With my camera being cropped sensor, will that change the working distance of my lens or does that not matter so long as I start getting things in focus?

Lastly would you recommend one of those slider rails? They look good but I think I need a better tripod first. My camera came with a tripod and bag courtesy of Amazon but it isn't brilliant build quality and I worry that the odd load the camera on a rail could put on the connecting bracket to the tripod may not hold and end up breaking my camera or lens.
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ChrisR
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PostPosted: Tue Mar 27, 2018 6:26 am    Post subject: Reply with quote

Quote:
With my camera being cropped sensor, will that change the working distance of my lens or does that not matter so long as I start getting things in focus?

Nope, you just get "the middle out of" what you would have got with a larger sensor.
You can "equate" it several ways, eg it's like using a longer lens at 1.6x the focal length, but the "equatings" are only part of the story.

A focus rail of some sort is desirable.
But on a table-top you only need to keep the camera still. You can focus using the lens control, either by turning it manually or wih software. You can do it with Canon's camera control software, or Helicon Remote, say.

Or you can spend a ton in the more refined corners of the geek universe. Depends on your budget, and aspirations! Achieving pleasing pictures at web size, is very "accessible" .

The most difficult to do reliably, can be in-field pictures in natural light, of flighty subjects. So if you start there, you'll need stamina Smile.
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MikeUK



Joined: 26 Mar 2018
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PostPosted: Tue Mar 27, 2018 3:08 pm    Post subject: Reply with quote

Had better success today with playing around with aperture.

Getting the camera parallel with the subject helped too.
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Overread



Joined: 27 Aug 2017
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Location: UK - England

PostPosted: Fri Mar 30, 2018 5:08 pm    Post subject: Reply with quote

A few thoughts to consider

1) It would be great to see some of your photos (good and bad) along with the details of the settings you used, any lighting, setup and how you went about the shot. It would also help to hear your views on the photo. This shows us what you're doing, how you're approaching things, what results you are getting and what you're thinking about the photo.

This can really help clear up how you are thinking about photography and also what you are doing. It might be one or two adjustments cna get you there, whilst it could also be that you're expecting too much of the lens in the wrong conditions etc... Without photos we can only give general help and guess at common issues people have.

2) Depth of field is razor thin with macro so generally speaking people stop down a lens (smaller aperture - bigger f number) to get a greater depth of field. However, as noted above, the aperture also affects sharpness.
From wide open (biggest aperture - smallest f number) the lens will increase in sharpness and depth of field as the aperture gets smaller (bigger f number). However at a certain point in the lenses range the depth of field will continue to increase, but the sharpness will start to trail off. It will still be more than usable, but will eventually reach a point where the softness is very apparent.

Depending on your desires, standards and even how you view and show your photos; the "limit" is going to vary person to person as well as lens/camera to lens/camera. As a very rough rule of thumb on a Canon* camera I go down to f13 without issue; notice the softness at f16 and any smaller in aperture the sharpness is too soft for me.
However play around and see how you find things.

3) What are you using for lighting. Because of the desire to increase the depth of field by using a smaller aperture (bigger f number) you'll be reducing the amount of light the lens let into the camera. This makes it harder to shoot hand held and keep a fast enough shutter speed without raising the ISO to a higher value. And ISO will sap sharpness the value gets higher and higher (again the limits are mostly personal preference).

Flash lets you use those smaller apertures coupled to a lower ISO for a much cleaner picture. If you've got a live subject and/or you are hand holding flash also helps with freezing motion. Essentially if your settings are such that, without the flash, you'd get a black photo; then all the light from the shot that is captured will be from the flash when the flash is used. Thus that super-fast pulse of light will illuminate and freeze the motion at that split second its used.
This does not mean you can't shoot macro hand held without flash, but that a great many macro photographers do. Even when tripod mounted flash helps when dealing with live subjects and with speeding up the capture process (reduces the chance of wind or small motions blurring a shot if one were otherwise using a very slow shutter speed).

4) Focusing with macro is challenging, but there's a good range of methods you can use to help yourself out including

a) lean on something. Even the ground helps. If you can lean on something that gives you a firm point of contact to help reduce your natural body shaking and motions. Many times I'll use my left hand and put it on the ground/surface and then brace the end of the lens on my hand - my hand then acts like a little tripod and is more stable.

b) Left hand brace technique. This is an extension of the above concept. Essentially you take your left and grasp part of the same object the subject is upon (eg a flower or leaf or stem). At which point the surface the subject is on is now moving in-time with your own body motions, as is the subject. You can then balance and brace the lens on your hand and it should help even out a lot of shake. Of course this works best with insects or subjects in a docile state as opposed to those which are highly active (since disturbance can cause them to move off).

c) Breathing; the body naturally has a pause in motion at the very end of a breath. So if you can time your finger to trigger at that moment it can help lessen your bodies natural shake (this is part of the same theories that snipers use fora clean shot)

d) Squeeze don't press the shutter button. Your hand on the camera can be a huge cause of shake so learn to gradually squeeze the shutter. If you are focusing in manual focusing mode (best way for macro and it sounds like you are?) then a half press of the shutter won't be an issue; you can hold your finger there and then gently close the gap to take the shot.

5) If shooting insects consider the time of day and weather.
Insects are cold blooded and thus warm up with the ambient temperature around them. If you go out to shoot them in the middle of a hot sunny day most will be very mobile and active; making shooting them a much harder challenge.
However if you go out first thing in the morning when its much cooler and the insects have had a long night of the cool already; then they are much more likely to be torpid and thus less likely to react.
Bigger insects can also be caught out with sudden temperature changes during the day. A flash rainfall event can leave insects like bees crashed out on plants as they suddenly find themselves cold.

Windy weather can also affect behaviour. Whilst wind makes many things harder, if you use the left hand brace technique wind can help in so much as it often makes many insects less reactive to disturbance. Your hand causing a little shake on the leaf isn't as worrying to them on a windy day as it is on a very still and calm day. Tough typically wind is an enemy rather than an ally.



Personally I would focus on working with getting good quality single photos. Focus stacking is a fantastic method, but many times you want a good solid single shot first (esp with bugs). Plus as focus stacking is a series of photos; everything you learn about getting a sold single shot will greatly help when you come to move onto stacking a series of shots.



* I make this distinction only because not all cameras report apertures the same way. In macro one "trick" many of the lenses do to focus closer is to reduce their effective aperture and focal length. Canon camera don't report this effective aperture change to the user, the lens remains at f2.8 wide open from infinity to the closest focusing point, even though the effective aperture might be f5.6.
Nikon cameras will, however, report this aperture change to the user, so they might report up to f5.6 when wide open at their closet focusing point.
So even though the camera on the back says they are different the actual aperture is the same. Thus on a Nikon body you might be closer to f16 as the comfortable limit and then f18 as going too far.
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