extension tube tests

[pixmedic]

recently purchased some vivitar N-AF extension tubes (36mm, 20mm, and 12mm) from manicmike and i am finally getting around to actually using them a bit. decided to test them with my 85mm f/1.8 lens.
macro work is a bit interesting. you have to try and compensate for a super thin DOF. tripod and remote cable appear to be a must have. This is definitely a little different than what i am used to. Might take a few attempts to get the fine tuning down, especially getting the focus right. macro focusing is a PITA! live view was my friend for these.

even tho these extension tubes have the electrical connections and will AF, i found AF to be almost useless for these and switched to manual. unlike regular pictures where i would just move the camera to where i want it and focus, i found it easier to set the camera up at the angle i want and move whatever i am photographing around until i hit focus, then make small adjustments with the focus ring. both pictures taken with all three extension tubes connected. no post work done to these except conversion from raw in LR and re-sized for upload. no cropping was done at all.

had to go to f/11 here to get a little more DOF. ISO 1600 SS 1/4
View attachment 64359

f/4 ISO 800 SS 1/5
View attachment 64360

I would love to hear from some macro veterans on how they typically set up their macro shots and what i can do to fine tune the process a little.

 

[Desi]

Love extension tubes, though I would like to get a real macro lens some day.

Yeah, autofocus is counterproductive.

Focus by moving the subject or yourself.

I like using zooms because you can focus by zooming.

Counter-intuitively, the shorter focal lengths give you the most magnification and narrowest DOF......use bigger lenses when you need more DOF.

And.....that sums up my vast knowledge on the subject...

 

[manicmike]

When I used them on my 70-300, I would zoom until I hit focus. That seemed to work pretty well for me. It was definitely fun to shoot macro, but not enough time in my day to learn another style of shooting. They're working alright though?

 

[pixmedic]

When I used them on my 70-300, I would zoom until I hit focus. That seemed to work pretty well for me. It was definitely fun to shoot macro, but not enough time in my day to learn another style of shooting. They're working alright though?

yup. they do appear to be in perfect working order

 

[Overread]

Welcome to macro!

1) Focusing - yep auto focus is not that good with macro and as you've found the value of the metal contacts isn't in the AF its in the aperture control.
Now that aside most macro focusing tends to be done manually; you set the focus on the camera and then:

a) If on a tripod you use a macro focusing rail to move the camera and lens closer or further away until focus lands where you want it. Note I'd recommend Adorama focusing rails or the identical sort sold on ebay - I'd avoid manfrotto (I've not liked its design - well made just not a good design).

b) If hand holding you rock back and forth gently until focus is where you want it.

2) Hand shooting macro tends to require flash since with thin depths of field you'll want the aperture small and thus without boosting ambient light you'll often find it not enough to get a sharp shot.

3) Tripods work well for static subjects and situations where you've time to setup (or for insects a chance to lure the subject to your position). They also mean that you don't have to use flash or can use a greater amount of ambient light in a multi light source situation.
When shooting on a tripod keep a mind to the ground - shooting indoors on carpet can be a nightmare as your body motions will cause the tripod to shift a tiny amount (which is a lot for macro). I've spent ages shooting only to find things were nudged out of focus or where I didn't want it because of this - a good hard floor is ideal (careful of wooden floors- these can also move).

 

[pixmedic]

What is the difference between the different sizes of tubes or using two or all three at a time?

 

[480sparky]

What is the difference between the different sizes of tubes or using two or all three at a time?

More extension = greater magnification.

 

[Overread]

Rough maths for extension tubes is:

[Length of the extension tubes in mm - divided by - focal length of the lens] + native magnification of the lens (at the set focusing point) = magnification :1

For example 100mm of extension tubes on a 50mm lens with a native magnification factor of 0 would be:


[100/50] + 0 = 2:1 or twice life size.

As you can see the more tube length you add the more magnification you get - just as the shorter the focal length the greater.
Note that magnification factor can change within a lens's focusing range so its native magnification is part dependant on where the focus is set to.
In addition remember that more tube extension means more light lost within the setup; as well as a reduced minimum focusing distance and maximum focusing distance. You can end up with the point of focus being inside the lens itself if you use too much on too short a lens (ergo you can never get focused).

 

[apaflo]

I would love to hear from some macro veterans on how they typically set up their macro shots and what i can do to fine tune the process a little.

Don't use extension tubes with IF (internal focus) design lenses. A good multielement diopter is a better choice. A macro lens is even better, of course. Note that for anything near 1:1, as has been noted AF has little value; hence for that type of work an older manual focus macro lens, which is not an internal focus design, is probably best. It will most likely cost a lot less for the same value too.

Zoom lenses and single element diopters are poor choices that are useful only to see if doing macro is something you might enjoy.

Teleconverters are also good for macro work. They don't degrade the image, simply because due to magnification the only part being used is the very sharp image center.

For when a tripod is the way to go... Think about a really heavy duty tripod. If you aren't backpacking a good example might be some of the used Majestic (made by Bencher or Modern Builders) aluminum tripods. The new ones are astronomical, old used ones are well within reach! They've been making exactly the same design for decades, hence there are very good buys on eBay for older used equipment. It is all built like a battleship, so a 30 year old used item is still an excellent tool.

Then consider a Majestic Gearhead. Just be careful not to get the really old version that fits a 1-7/8" column as opposed to the newer 1-1/2" column model 1200. Or a model 1000 if it is used on a regular 3/8" stud mounted tripod platform. Get either a 3x3-5/8" or a 4-1/2 round platform. And on top of that put a 4 way focusing rail.

 

[Overread]

What's wrong with internally focusing lenses and extension tubes?

 

[apaflo]

What's wrong with internally focusing lenses and extension tubes?

The lens is optimized for one specific sensor to lens distance, and using an extension tube puts it at a different distance than where it is designed to work. Using a good multi-element achromatic diopter lense allows the correct sensor to lens distance, plus it doesn't change the effective aperture or focal length, so there is no loss of light either.

Prior to IF designs, lenses were intended to be moved farther from the sensor to bring the focus closer. One problem with that is the difficulty in optimizing for astigmatism at both infinity and at some closer focus. Generally the reason for a specific minimum focus distance would be the design target for astigmatism would be exceeded if the lense were allowed to be moved farther from the sensor. Macro lenses typically were optimized to be sharper close up than at infinity, but general purpose lenses had to be sharp at infinity too.

That is one reason manufacturers today make almost no effort at accessories such as a bellows or extension tubes.

 

[Overread]

But Extension tubes are made - pretty much every manufacturer has them (although Canon tends ot charge a fortune for theirs). I've not heard of the IF limitation before.

However in my view it depends on the focal length of the lens; a good multi-coated lens attachment (eg Canon 500D or 250D - Raynox products like the DCR250) is going to give more magnification on longer focal length lenses; whilst extension tubes are the reverse giving more on shorter focal length lenses. Therefore its party decided by the lens one would use.

The arguments on image quality between macro attachments and extension tubes are somewhat full of drama and bias - I've heard from both die hard camps that their method is the sharpest and my honest opinion is that the differences between the two (when not going into the insane extremes) are likely to be very hard to identify before sharpening and likely impossible after sharpening

Personally I prefer the attachments as they can be taken on and off very quickly without having to remount the lens. They also fit in the pocket very easily too. I'm typically using them on macro lenses though so already have a good magnification as a starting point.