Macro but not macro - random close-focus tests on a range of lenses

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 Blue Straggler 09 May 2021

Been playing with lenses mainly as a "de facto" tutorial for a mate who's getting slightly muddled with choices as he enters "dSLR" world. So a little set-up this afternoon, exploring depth of field, closest focus, perspective compression, general quality (sharpness etc). Fringing, flare, vignetting, chromatic aberration, these are things I wasn't particularly testing for but I guess it's all there. No filters on any lenses, no lens hoods, and these are jogs straight off the cameras. All other info in filenames and album description. 

Quite good fun and an interesting bit of revision for me. No great surprise that the only dedicated modern macro lens I have, gave the best quality result....but some good and bad surprises along the way too.

Good: my 24mm prime, and 18-135mm, on the Canon, are both decent for this (the bokeh at f/2.8 at close focus on the 24mm is nice enough although you have to be VERY close to the subject)

"Bad": my 100mm f/2 has a large minimum focus distance (not really "bad" as this isn't what that lens is for)

My several shocking attempts on manual focus are just because I was rushing a bit. This was more for illustrating how well (or not) you can have a defocused background with various lenses, rather than creating absolute technical perfection. Just a quick tabletop test.

Hopefully 21 visible pics but Flickr keeps saying some are public and some aren't and I get confused as to what will be viewable...

https://www.flickr.com/photos/blue-straggler/albums/72157719132615848/with/...

 HeMa 10 May 2021
In reply to Blue Straggler:

Yup. Lots of pics can be seen. And indeed they are a good example of DoF.

The funny thing is that I had a 180mm/f2.8 (IIRC) Sigma on my Pentax. It was a macro lens, and performed well in that. But also worked as a fixed tele, albeit the near 300 or so focus throw made focussing slow.

Btw. The cheapest way into Macro photography is a reversing ring. https://expertphotography.com/reversing-rings-macro-photography/
 

AFAIK you can get a one from Egay/AliExpress for a few quid. And couple it with the nifty-fifty and yer good to go.

 SouthernSteve 10 May 2021
In reply to HeMa:

> The cheapest way into Macro photography is a reversing ring

Or a long tube extension will do a good job without exposing the camera side of your lens to the world. I have a sharp 1:1 105mm f2.8 (fitted with ring flash) that produces a sharp (and large 45 mb files) so I have not used any accessories for years. 

Focus wise it is often easier to go to manual, pick a distance and then move the camera in to stop hunting and stuttering of the focus.

 HeMa 10 May 2021
In reply to SouthernSteve:

True.. I forgot about tube extensions.

that being said, getting a reversing ring and say and old M42 nifty fifty is still going to be cheap. The mount of the nifty fifty (or other ”donor” lens) is irrelevant as you can keep it mounted on the reversing ring all the time.

this has the added bonus, that cheaper stuff (extension tubes and also reversing rings) can have toleranse issues. With the reversing ring, you only need to worry about one interface. But with tubes, it’s two.

In reply to HeMa:

Cheers, I played with tubes and reversing rings a fair bit when I was shooting 35mm film. 

In reply to Blue Straggler:

> No filters on any lenses, no lens hoods, and these are jogs straight off the cameras.

.jpgs, not “jogs”!

 Marek 10 May 2021
In reply to Blue Straggler:

I find - and suspect other do too - that DoF is really hard to guess unless you have a LOT of experience. So one thing I did to help with wildlife photography was to to make simple chart of 'size of target' vs. 'minimum f-number to have it all in focus'. It's bases on the assumption that the target is half the height of the frame. One find is that anything small than a dog (~50cm diameter) can't all be in focus at f4. Anything small than a duck (~13cm diameter) can't all be in focus at f16. So if you're trying to get a good sharp close-up of a bear it's easy, but a bird and you're in trouble. Note also that there no dependency on focal length.

Down with the insects it gets to be really hard work: Using a reversed 50mm on the front of a 400mm, I'm down to a DoF of <0.1mm at f16. Stacking 20-50 images (with a 0.1mm shift in camera-target distance) is the only option.

In reply to Marek:

I once had to mount a Zeiss 50mm f/2 (at f/2) on a Nikon-to-C-mount adaptor that inherently acted as an extension tube, to focus an image onto a Peltier-cooled CCD about 25cm from the rear element. The image we were focusing, was the refracted image of a small circular x-ray phospor illuminated by, er, x-rays. It was refracted because for a direct line of sight between x-ray source and sensor, we needed a leaded-glass plug which was a cylinder approx. 20cm in length.

So this was very shallow depth of field macro of a "ghost" image. 

Fine focusing was achieved by shimming the mounting bolts of the camera unit, with Post-It Notes. 

the entire thing was ill conceived because all this stuff was bracketed into a small lead lined cabinet which was moved indelicately every two minutes and the C-mount adaptor and lens set up was a weak wobble point. Luckily the entire project got mothballed after we got paid but before we would have got sued  

Removed User 10 May 2021
In reply to Blue Straggler:

If you want to look at resolution, i.e. the sharpness of a lens I suggest buying a broadsheet newspaper and photographing a double page that's mainly text. Take photos from a distance that's far enough that the text in the centre is just readable. You'll find that the text becomes unreadable as you move out to the corners. You can then change lenses repeat the excercise and compare. Incidentally there's a great piece of software call FastStone for comparing images.

You can do the same sort of thing with a grid of straight lines to compare distortion.

In reply to HeMa:

>

>  With the reversing ring, you only need to worry about one interface. But with tubes, it’s two.

Being totally pedantic, a reversing ring also has two interfaces 😃

In reply to Removed User:

Thanks, I am aware of these things and they suck all the fun out of it 😃

nikkormat 11 May 2021
In reply to Blue Straggler:

I took this about 20 years ago, with a reversed 28mm lens and flash: https://flic.kr/p/24B7dFp

Focusing was not much fun, and working out exposure took some time.

In reply to Marek:

> Down with the insects it gets to be really hard work: Using a reversed 50mm on the front of a 400mm

I never thought about reversing onto the front of another lens! Sounds "fun"

In reply to nikkormat:

> I took this about 20 years ago, with a reversed 28mm lens and flash: https://flic.kr/p/24B7dFp

> Focusing was not much fun, and working out exposure took some time.

I dimly recall trying to reverse a 28mm lens on a 35mm film SLR and the focus distance was "negative" i.e. I could not get close enough to the subject to get it in focus - the lens would hit the subject! Could I be misremembering, and it was not the 28mm lens? Or 28mm on tubes rather than reversed? 

nikkormat 11 May 2021
In reply to Blue Straggler:

In this case I think it was about 6-8cm from the element, but the problem was that the slightest movement of either the web or the camera would throw everything completely out of focus. I think I was at f/22 (and of course you lose the auto iris with a reversing ring, so have to focus wide open then stop down to take) with a GN36 flash a metre away.

In reply to nikkormat:

Cheers. I am going to see what reversing rings and tubes I have in my dusty old kit boxes!

 Marek 11 May 2021
In reply to Blue Straggler:

> I never thought about reversing onto the front of another lens! Sounds "fun"

Standard technique and both lenses are working at their best settings, so the quality is pretty good. Here's an example: https://photos.app.goo.gl/zEYci9TGkbWmGbRi7

That's taken by a G9 with the Panasonic 100-400 zoom lens @ 100mm, f16 (i.e., minimum magnification) and a reversed Canon 50mm f1.8 on the front. Stacked 24 images to create decent DoF. Fly was moved ~0.2mm between each image.

In reply to Marek:

Very impressive! I wonder how I never knew this was a standard technique. Probably simply because “reversing rings” I always saw for sale, were bayonet mount for specific camera mounts rather than (presuming this is what you are on about) a double threaded filter screw-on thingy. Or do you just hold them on with mole grips? 😃

 Marek 11 May 2021
In reply to Blue Straggler:

Mole grips? Ha! No, something like this will do the job: https://www.amazon.co.uk/Pixco-Reverse-Coupling-Reversing-52mm-58mm/dp/B085...

This is the high-tech setup: https://photos.app.goo.gl/ahrHRrC5LdTRdvuD6

I also experimented with using Lumix Tether (remote control Windows app) which allows manual control of the focus stepping (rather than moving the target). It's then easy to automate the whole process with something like AutoStep (Windows GUI automation app). The focus range is a bit limited compared to moving the target, but makes the capture process quite simple for small targets.

Post edited at 22:18

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