We look at the hot kit to get your Pentax DSLR really close to your subject.

Posted: 13/05/2011 - 08:14

If you want to get closer to your subject you need to consider a macro accessory. In this guide we round up all the essential accessories, old and new, for your Pentax film or digital SLR.

1 Macro Lens
2 Bellows
3 Close up lens Set
4 Coupling ring
5 Close up lenses
6 Reversing ring
7 2x teleconverter
8 Extension tube set
9 Standard lens

The 50mm Standard lens

Any lens can be adapted to take macro photos using one of these macro accessories. For this test we used a 50mm f/1.4. It's bright and optically very sharp, so no matter what you put in front or behind you know you're going to get the very best. It also allowed a consistent reference for each accessory so you can see how close each item will go.

The picture on the right is taken with the lens set at its closest focus of 0.45m. See all the comparison photos taken using each accessory at the base of this article.

Macro Lens 

The most obvious option for close up photography is a true macro lens. We say true because many zoom lenses have a macro setting, but this is really just an extended close up. A true macro lens lets you go really close and have at least 1:2 ratio meaning what you capture on your sensor (or film) is just half the size it is in real life. 

Ideally you want to be aiming for life size 1:1 and most true macro lenses offer this capability. We will look at macro lenses in more detail in a future article but for now be aware that they offer the greatest flexibility, being able to focus super close, but also on infinity with typically superb optical quality.

They come in a range of focal lengths from the Pentax 35mm up to the Tamron 180mm. The advantage of a longer focal lengths like the Tamron 180mm is it lets you shoot at the same magnification from a greater distance, so it's ideal for timid insects but sometimes less useful for flowers where you need to get close to isolate specific buds.
The downside of a macro lens is cost. A true macro lens for your Pentax will set you back £400 plus.

Recommended Macro Lens: Tamron 90mm f/2.8 SP Di Macro Lens

Fortunately there are many more less expensive options than macro lenses, and some accessories that will get you even closer, producing larger than lifesize images. Here's our round up:

Close up lens

A single lens that screws onto the front of your existing lens like a filter. It's so much like a filter that people often refer to them as close up filters. A close up lens is like a magnifying glass and lets you go closer to the subject. They come in +1, +2 +3 and +4 dioptre strengths, the larger the number the greater the magnification. 

You can combined different strengths to give a wider variety of combinations. A +1 and +4 add together to give you +5. Some manufacturers sell a set of three in a case. They come in different filter sizes from 49mm to ??mm but stepping rings can be used to fit them on larger or smaller filter thread sized lenses.

Cokin also produce close up lenses for their square filter system, and the advantage of these is you can buy one filter and use it on different size lenses by changing just the filter holder adaptor ring.

Recommendation: Cokin P103 Close Up +3 P series filter

 

Macro + 10 lens

Also a single lens that screws onto the front of your existing lens like a filter. But this one has a 10 dioptre strength, which acts like a magnifying glass and means it can get your lens much closer to the subject. There's a slight loss in quality but the resulting macro shots are worth it. They come in different filter sizes from 37mm to 58mm but stepping rings can be used to fit them on larger or smaller filter thread sized lenses.

Recommended +10 close up lens: Hoya 55mm Macro Close Up +10
 

Reversing ring

This is a low cost option with extreme macro capability. It's an adaptor that fits to the camera body with a filter thread on the other end. You take your lens off the camera attach the adaptor to the body and then screw the lens back on reversed. To get the right adaptor you need to buy one with the correct body mount and the correct filter thread for your lens. They used to be popular in the 70-80s so tend to be made with older camera fittings and smaller filter thread sizes.

Recomendation: JJC 58mm Reversing Ring

 

Extension tubes

A set of three tubes that fit between the camera body and lens to increase magnification dramatically. These offer closer focusing than a macro lens and no loss in optical quality. You can use any combination of tube/s to give a total of seven different magnifications. The light lost as all three tubes is about two stops. Most tubes sold are manual so autofocus and aperture coupling is often lost. The really cheap ones have a screw thread between each tube and bayonet at each end. This makes them slower to split and combine, but much cheaper to produce.

Recommended: Range of Extension Tube options on Amazon

 

Teleconverter

A teleconverter isn't essentially classed as a macro item and not one many think about, but it can make a difference, basically it's magnifying the subject by 1.4x, 2x or 3x depending on which one you buy. So with the camera at a similar distance from the subject the size will be 1.4x, 2x or 3x bigger and effectively a closer sometimes macro shot. The magnification delivers the same value of stops light loss, so a 2x converter will have a two stop light loss.

Recommended: Kenko Teleplus MC7 DG 2x AF Teleconverter

 

Bellows

Bellows offer the greatest magnification and the most flexibility but they are bigger and clumsier to use than other accessories. Bellows fit between the camera and lens and expand and contract to give an infinite range between the compressed and fully expanded state. We extended a set of BPM bellows to show how close you can go. They're prefect for super close-ups of insects etc, but you do lose 3 stops of light when extended. You cant buy these new any more and the old classic BPM ones are manual so you need to use them on a lens with a manual f/stop setting. You can pick automatic Pentax ones up on eBay from time to time.

Recommended: Used BPM Bellows
 

Coupling ring

A coupling ring is a thin ring with a filter thread on each side. This lets you reverse a lens around on a lens fitted to the camera. We reversed the 50mm round on a standard 28-80mm zoom. This option gets you really close but there's some loss of quality at the edges. You need to be sure the combination doesn't vignette. The camera lens needs to have a narrow enough angle to shoot through the centre of the lens on the front. The reversed lens needs to have an aperture ring so you can open up the aperture.

Recommended: There's nothing available new but they appear on ebay from time to time. 

Macro Accessories - Close focusing performance

A Sheffield Edition Monopoly board game - spot the Owls fan! And the main shot is taken with a Pentax K10d with the standard 50mm f/1.4. All photos were at ISO200 and 1/125sec shutter speed. The grid of pics bellow show the same lens with different combinations of accessories and the full frame magnified image. The aperture for the lens with no accessory was f/16 and the distance from CCD to subject was 0.45cm. I've added the aperture and distance for each accessory. As you can see bellows are the master of macro, but you can get pretty close with the 10x macro lens, the extension tube set and the reversing ring.

50mm lens with 2x converter f/16 45cm.	50mm lens with +1 close up dioptre lens. f/16 37cm.	50mm lens with +2 close up dioptre lens. f/16 31cm.	50mm lens with +3 close up dioptre lens. f/16 28cm.
50mm lens with +4 close up dioptre lens. f/16 28cm.	50mm lens with close up dioptre lens set. f/16 22cm.	50mm lens with 13mm extension tube. f/13 25cm.	50mm lens with 22mm extension tube. f/11 22cm.
50mm lens with 31mm extension tube. f/9.5 21cm.	50mm lens with 66mm extension tube set. f/6.7 21cm.	50mm lens with coupling ring. f/16 22cm.	50mm lens with reversing ring. f/9.5 31cm.
Pentax 100mm macro lens. f/16 31cm.	100mm macro lens with 66mm tubes. f/8 34cm.	50mm with 10x macro lens. f/16 15cm.	50mm lens with bellows. f/5.6 28cm.

 

Members photos with related tags: Macro,Bellows

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