Question Recommendations for macro lenses

[arphethean]

Does anyone have any recommendations for good true macro lenses for Canon DSLR? 

Ideally more than 100mm due to getting good image scale on small coins

Looking at the sigma 150mm. Any experience of this lens?

 

[Charliemouse]

On 26/03/2023 at 21:19, arphethean said:

Ideally more than 100mm due to getting good image scale on small coins

Sorry to go off on a quick tangent, but I see this misconception frequently.  I will answer your question more directly shortly, but I wanted to cover something first.

Focal length does not mean magnification.

If we are talking true macro lenses from proper lens companies, they are almost always tuned for a 1:1 ratio.  That means that, at their closest working distance, they will reproduce a (e.g.) 22mm sovereign to a 22mm image onto the sensor.  Since a full-frame camera sensor is just 24x36mm, that's a perfect fit and a big image.

It is completely logical to assume a longer lens will magnify more, because longer lenses make distant things closer.  However, the longer the lens, the further the minimum distance you can focus with it.  Therefore, the advantage you gain is lost when dealing with small objects at close range.

What is the most important stat for a macro lens?

The reproduction ratio.

Some specialist lenses, from specialist manufacturers, do higher ratios, typically 2:1 but sometimes as high as 5:1.  I would not recommend going higher than 1:1, unless you want to go down the photography rabbit hole.

Some companies will call something a 'macro lens' when it doesn't achieve 1:1.  It might be 1:2 or 1:3.  Watch out for this.  A lower magnification for the same focal length, means a longer minimum focus distance; see below.

So what does the focal length mean?

The focal length of a lens determines the closest working distance.  In other words, the minimum distance from the lens (or sensor) to the subject, and the subject still be in focus.

A 50mm macro may have a 10cm minimum working distance.  A 150mm macro may have a 30cm working distance.  They vary between lenses.

But at those distances, the image will be the same size/magnification.

What's the best focal length then?

Longer focal lengths (greater than 100mm) are typically used for wildlife, when the photographer doesn't want to disturb the subject.  e.g. photographing insects that may fly off.

Shorter focal lengths are better when you have limited space, and are taking static subjects that you can take time over.

Therefore, the obvious choice for coins is a shorter lens.  Especially if you are photographing down onto a table, a long lens will get very cumbersome because you need to suspend it so far above the coin with a tripod.

Are there any other differences?

For macro photography, the minimum working/focus distance is the only significant difference.

These lenses are useful for other purposes, and typically the longer macros make excellent portrait lenses.  More generally, there is a whole host of differences between focal lengths, which I'm not going to cover here.

Edited March 29, 2023 by Charliemouse

[arphethean]

Thanks for clarifying. Appreciate the in depth explanation

A slightly longer minimum focus is probably also of benefit with axial photography but probably 10cm would suffice. 

Edited March 29, 2023 by arphethean

[Charliemouse]

On 26/03/2023 at 21:19, arphethean said:

Does anyone have any recommendations for good true macro lenses for Canon DSLR? 

Looking at the sigma 150mm. Any experience of this lens?

I use a Sigma 150mm for photographing coins.

But you just said a shorter lens is better for coins.

I already owned it before getting into coins, and I use it for wildlife as well.

However, it is cumbersome with the minimum focus distance of 38cm.  That's the main reason I don't photograph vertically - it's just too awkward.

It takes great pictures.  But if I wanted to buy a macro lens just for coins today, I'd get a shorter focal length.

Recommendations?

I don't have personal experience using any other macro lens.

When looking for new lenses, I usually would first go towards the primary third-party lens companies, i.e. Sigma, Tamron.  The bang-for-buck is so much greater than Canon and Nikon, and in the last decade they have upped their quality so that only the fussiest camera reviewers would notice the difference.

What about the Sigma 150mm?

Sigma 150mm f/2.8 EX DG APO HSM Macro Lens Review (the-digital-picture.com)

A good (older) review, which lists other macros and their minimum distances.  Search out newer reviews for newer lenses.

I believe this is reviewing the actual edition I own, which I think is now the previous generation.  I think the newer model has better autofocus and has vibration reduction; two things I could not care less about with macro photography, but make a better general-purpose lens.

Edited March 29, 2023 by Charliemouse

[Charliemouse]

12 minutes ago, arphethean said:

Thanks for clarifying. Appreciate the in depth explanation

A long minimum focus is probably also of benefit with axial photography so I think I'd still like a 150mm 

What are your thoughts

I'd like to understand why you think that.

If it's just clearance, then a minimum focal distance of 20cm is plenty.  That would give a working distance (the distance from the front of the lens) of about 10cm.

Trust me, trying to get a stable tripod to suspend a DSLR with a 150mm lens above a coin, with a proper macro head, remote, lighting, etc, is a real pain!

[Charliemouse]

Taken with the Sigma 150mm.  Definitely benefited from a longer working distance.  Also, a longer focal length gives that buttery smooth bokeh (out-of-focus background).

If you want to photograph things other than coins, I would not hesitate to recommend this lens.

[arphethean]

3 minutes ago, Charliemouse said:

I'd like to understand why you think that.

If it's just clearance, then a minimum focal distance of 20cm is plenty.  That would give a working distance (the distance from the front of the lens) of about 10cm.

Trust me, trying to get a stable tripod to suspend a DSLR with a 150mm lens above a coin, with a proper macro head, remote, lighting, etc, is a real pain!

Thank you. I read your post a bit closer and edited to say probably 10cm would suffice to clear the glass. 

I will maybe see if I can try out a lens first. 

I'm thinking of making a permanent set up, hooked up to the pc to save the headache of fiddling around every time but I guess some adjustment is always necessary. 

Just now, Charliemouse said:

Taken with the Sigma 150mm.  Definitely benefited from a longer working distance.  Also, a longer focal length gives that buttery smooth bokeh (out-of-focus background).

If you want to photograph things other than coins, I would not hesitate to recommend this lens.

Fabulous bokeh indeed. 

[Charliemouse]

2 minutes ago, arphethean said:

I will maybe see if I can try out a lens first. 

I'm thinking of making a permanent set up, hooked up to the pc to save the headache of fiddling around every time but I guess some adjustment is always necessary. 

Trying lenses is always a great idea.  You can usually rent them on a daily basis for a few quid.

A permanent set-up (especially with your throughput of coins) is also an excellent idea.

I will do a post about equipment ideal for coin photography soon.  The world of macro is very different to 'normal' photography, and often has converse requirements.

[Charliemouse]

58 minutes ago, arphethean said:

A slightly longer minimum focus is probably also of benefit with axial photography but probably 10cm would suffice. 

What is the height of DrDaves axial lighting box?  Even more precisely, what is the distance between the surface of a coin in the box, and the top of the clear slide?

That would determine what your minimum working distance needs to be, with a few centimetres to spare, to avoid expensive accidents.

It might be worth adding that detail into your review, for reference.

[arphethean]

Good idea. It's 12cm to be  safe

[arphethean]

5 hours ago, Charliemouse said:

Trying lenses is always a great idea.  You can usually rent them on a daily basis for a few quid.

A permanent set-up (especially with your throughput of coins) is also an excellent idea.

I will do a post about equipment ideal for coin photography soon.  The world of macro is very different to 'normal' photography, and often has converse requirements.

That sounds really useful. In particular I would be interested in your thoughts on lighting as well. 

[arphethean]

4 hours ago, Charliemouse said:

What is the height of DrDaves axial lighting box?  Even more precisely, what is the distance between the surface of a coin in the box, and the top of the clear slide?

That would determine what your minimum working distance needs to be, with a few centimetres to spare, to avoid expensive accidents.

It might be worth adding that detail into your review, for reference.

I believe minimum focus distance is measured from sensor to focal point and with a bulky DSLR body and lengthy lens in front, that could end up being pretty tight even with a 30cm MFD - so that's an important consideration.

[Charliemouse]

7 hours ago, arphethean said:

I believe minimum focus distance is measured from sensor to focal point and with a bulky DSLR body and lengthy lens in front, that could end up being pretty tight even with a 30cm MFD - so that's an important consideration.

There are two relevant values.  Check out the review I mentioned; they actually give both.

1. Minimum focal distance (MFD).  This is the exact distance between the subject in focus and the sensor.  It is used for various technical calculations, but is actually less useful for macro photography.
2. Minimum working distance (MWD).  This is the distance between the subject and the objective lens - i.e. the front surface of the lens.  This is more useful for macro, as it will determine whether it is possible to use things like the axial lighting rig, tripod, etc.

(If the MWD isn't given, use MFD minus the length of the lens.  That will be close.)

Remember, these are minimum distances.  You can always move the camera further away, at the cost of a little bit of image size, if you have the space.

Edited March 29, 2023 by Charliemouse

[Silverlocks]

On 29/03/2023 at 10:59, Charliemouse said:

What is the height of DrDaves axial lighting box?  Even more precisely, what is the distance between the surface of a coin in the box, and the top of the clear slide?

That would determine what your minimum working distance needs to be, with a few centimetres to spare, to avoid expensive accidents.

It might be worth adding that detail into your review, for reference.

The macro lens on my phone will just focus far enough away to take pics of sovs in the box - MWD of 5-6cm or so.  The sovs have to be standing on something, though.  I can't get pics of 1oz silver coins with the lens so I have to take it off for that.  However, this arrangement can't focus properly much further away than this (i.e. you can't get an infinity focus with the lens).

Edited March 30, 2023 by Silverlocks