Lens focal length considerations for macro work.

Cluster

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I fancy a go at some macro work and have some fairly obvious choices for a Pentax mount macro lens.
All Sigma, the 50mm f2.8, 70mm f2.8 and the 105mm f2.8 all look to be capable of the jobs that I want them to do (for the moment, general macro work).
I will use it as a prime lens and macro lens on my 35mm MZ-7/5 camera and on my digital K-50/500 (if I ever find a working copy at the right price).

I'm not familiar with how the focal length will affect the working distance (I mean how close the subject must be to the outer element) at 1:1.
Am I correct in thinking that the 50mm will have a closer 1:1 focus than the 105mm for example?
 
The 50 is tough to use at max mag, working distance is annoyingly close, it becomes a challenge to light the subject effectively too.
I'd go for something a bit longer.
 
Working at 1:1 means that the front nodal plane of the lens will be 1 focal length from the plane of focus. The front nodal plane is normally inside the physical lens, but in front of it when the lens is a telephoto design.

In general,double the focal length and double the working distance. Plus change the perspective.
 
If your subject is moving your generally want as long as focal length as possible 105, 150 or even 200mm. If you want insects adding a close up filter to a zoom lens can work well. I used a canon 500d filter on a Nikon 70-200 zoom for years and it worked really well, as most of the time I was working at 1:2 or 1:3 and having the zoom made framing easier. Such filters are a lot cheaper than a dedicated macro lens. Shorter focal length macro lens are generally cheaper, but more difficult to use, I use a 50mm macro for repro work on a copy stand and even here shadowing from the lens can cause shadows on small objects.
 
Cluster said:
I fancy a go at some macro work and have some fairly obvious choices for a Pentax mount macro lens.
All Sigma, the 50mm f2.8, 70mm f2.8 and the 105mm f2.8 all look to be capable of the jobs that I want them to do (for the moment, general macro work).
Click to expand...

I use a Tamron Adaptall-2 SP 90mm f/2.5, which of course can be fitted to just about any film camera with the right adaptor. I also use it with an APS-C digital camera.
It has an optional extension tube which allows 1:1 magnification - without the tube the lens gives 1:2 magnification. However, my eyesight isn't good enough to reliably focus at 1:1
 
I have also used a Tamron SP 90mm which works fine with film but I did have an issue using it on my full frame Canon 6D. I had some glare caused, I believe, by light reflecting back from the sensor not being dispersed on exit from the lens. The explanation given in an article I read is that the behaviour is the result of the outer element of the lens having a flat surface. The shortcoming only seems to apply when the subject contains some bright highlights. Anyway, what I was getting, when photographing small lacquered objects, was a circular hotspot not massively overexposed but enough to show and impossible to correct in post processing. The lens worked fine otherwise on the 6D. In the end I bought a used Canon 100mm macro which I now use in place of both the Tamron and a Sigma 50mm macro. The Canon is a more convenient than the Sigma as it allows me to shoot from further away from the objects.

First photograph using a ring flash, second using two speedlights. At least having to reshoot the object allowed me to improve the result in other respects as well.

Sigma 50mm macro lens

1763977532084.jpeg

Tamron 90mm lens

1763977720681.jpeg
 
I use a SMC Pentax-M 100mm f/4 which is a lovely lens, even if it does only go to 1:2. It's light enough to be very usable hand held for some slightly longer but still close focus images. I'd agree with picking longer lenses though.
 
Kevin Allan said:
I use a Tamron Adaptall-2 SP 90mm f/2.5
Click to expand...
Another vote for this old timer. I've used mine on several film and digital bodies and it does the business...

Camera Canon 5D with Tamron AD2 90mm Macro lens DSC00025.JPG
 
Yes, that's a lens worth consideration. Thanks.
 
Just destroyed my Minolta SRT 101b o_O Put my Vivitar 55mm macro lens on to see what the magnification was like and couldn't get the lens off :headbang: apparently the release mechanism is different to later models erm which I didn't check :rolleyes:
 
I have the sigma 105mm macro. It's great. Used it on a load of different slrs over the years. Minolta/sony fit. I assume the pentax fit is just as good.
 
I have both the 50mm and 100mm Minolta Macro lenses for use on my Dynax cameras. The 100mm gets much more use than the 50mm.

In MF I have a 110mm Macro lens for my Bronica SQ-A which goes to 1:1. It needs to be close to the subject making lighting etc. challenging.
 
Kevin Allan said:
I use a Tamron Adaptall-2 SP 90mm f/2.5, which of course can be fitted to just about any film camera with the right adaptor. I also use it with an APS-C digital camera.
It has an optional extension tube which allows 1:1 magnification - without the tube the lens gives 1:2 magnification. However, my eyesight isn't good enough to reliably focus at 1:1
Click to expand...
There's one of these in the classifieds. No connection, just for info.
 
Depends on your budget the Sigma EX150/2.8 and EX180/3.5 are highly regarded too, both give you more room to work on your subjects. I did own the 180/3.5 but a D810 firmware update rendered it inoperable on that camera.

If you do have a pot of gold hidden somewhere and keen to hunt it down the most revered lens for K-mount macro work is the FA*200/4 but good luck finding one.
 
I have the Sigma 150 f2.8 EX on my Nikon D810 - I do wild flower, orchid, Insect, animal and fungi photography, also some bird shots - the D810 allows me to crop quite a lot and the Sigma 150 gives me the range and the detail needed to support that. Its not a lighweight combo but it is okay for me and I find it flexable on distance due to the image quality of them both, not only close up but at a reasonable distance as well for the more shy subjects.
 
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