Wednesday, 5 May 2010

Delta DRF-14 Ring Flash for Macro -A Review

I`ve been craving for a ring-flash for a while now, and having got a macro lens, a ring flash was the next logical purchase. The problem was that ring flashes such as the Metz or Sigma ring flashes are pretty expensive. The Sony option (HVL RLAM) is not really a flash at all, and the discontinued Minolta 1200AF ring flash wouldn't do TTL metering without the ultra expensive macro flash controller (MFC-1000). It was only recently that I became aware of the Delta DRF-14 ring flash, and with a Guide number comparable to the Sigma and a price that was less than half, it was too good a bargain to overlook. I have now been using it for a few days and I thought I`d do a little review for those people out there who may be considering purchasing this but don't seem to have much information available on this flash. (The Delta unit may in fact be a re-badged Marumi unit)

What’s in the box:

DSC08849DSC08851

As pictured above, the flash comes in a box that contains the controller unit, connected to the ring light attachment via a coiled extension cable. Also included are adapters for 55, 58, 62 and 67mm lenses and a operating instruction manual.

 

Build and parts:

The first impression I had when I picked up the unit was that it was very light and a bit plastic. It does seem to be made of cheap plastic and doesn't give a strong feel. However, it is extremely light and adds neglible weight (without batteries) to the camera.

In the ring-light attachment is a circular tube, encased in a translucent plastic diffuser and set within a reflector. At the back of the unit is a large plastic ring, to which the 52mm threaded rig is attached. This ring rotates independent of the ring light to tighten the unit on to the lens.

IMG_0003_crDSC08852DSC08853

The controller unit houses the battery compartment and takes 4 AA batteries. There are also two LEDs an On/Off switch and a rather long test button. The head moves up and down to adjust bounce. On the front is the release button, which I find annoying, as it is exactly opposite the test button and more often than not, I end up firing the flash with the test button while trying to remove the flash.

The Fit:

DSC08854

Since most of my lenses are 55mm, i had to use the 55-52mm adapter to attach the flash to the lens. However, it is a bit finicky and takes a bit of work to attach and ensure that it remains in position.

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Once attached, the ring-flash does tend to still rotate and is a bit annoying but one gets used to it. It took me a while to get used to the light source being in front of my lens, and not having to angle the light from on board the camera or a flash bracket, and that gave me a great freedom of movement. Once attached, there is little hassle and since I only use the flash and this lens for macro work, the flash stays attached to the lens. The annoying part is that I cannot put my lens cap on the lens as the front diameter is now no longer 55mm!

The controller, for its part, slots in to the flash attachment without any problem and stays put without any shake. It essentially takes up the space of a normal on camera external flash. What's annoying about this is that its hard to use an angle finder with the flash in place as there is barely any room between the two (but this would be the case with most flashes)

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Specifications:

Camera Type Direct hotshoe contact mount flash
Guide No 14 in meters / 46 in feet at 50mm (ISO 100)
Circuitry IGBT (insulated Gate Bipolar Transistor)
Automatic TTL range 0.9 – 7m / 3.0 – 23ft (F2.0)
Dedication DSLR dedicated mounting
Auto confirmation Indicator Green LED
Auto Standby Approximately 3 minutes
Flash Duration 1/700 sec (full power)
Color temperature 5600k
Number of flashes Approximate 150-300 (Alkaline batteries)
Approximate 100-200 (Ni-Cd, Ni-MH batteries)
Recycling Time Approximate 6 sec (Alkaline batteries)
Approximate 4 sec (Ni-Cd, Ni-MH batteries)
Power source 4x AA Alkaline, Ni-Cad, Ni-MH batteries
Dimension (mm) 70 (W) x 45 (H) x 150 (L)
Weight 250g (without batteries)

As you can see from the specifications above, the duration of the flash is 1/700th of a second. I was recently reading a post discussing the implications of long flash times on image sharpness for macro photography. See here and here. The point was that longer flash durations contribute to motion blur especially when the subject is magnified, as in macro photography, and 1/700th of a second is a rather long flash duration. The longer the duration, the more time there is for motion blur to creep in.

The recharge time of the flash is about 4-6 seconds. This is fine for taking individual shots, recomposing after each click, but will come up short for continuous bursts.

I`ve embedded a scanned copy of the instruction manual below. Strangely it mentions nothing about the bounce head and I haven't been able to figure out the need for a bounce head on a static macro ring flash. Perhaps someone could explain.

Flash Manual

First use impressions:

Switching on the flash takes 5-6 seconds to charge up and light up the red Ready indication LED. As per the instructions, the green LED is meant to light up to indicate that the subject is within TTL range and the exposure is correct. However this only happens once the shutter has been fired, which is self defeating.

When the flash is fired, it lets out two small bursts of light before the final flash, perhaps to check and meter the exposure. This can be quite frightening for insects, but the ones that “survive” the first attempt, tend to ignore it later.

I found that the resulting images obtained with the flash tended to be under exposed and wasnt sure how much an advantage over the in-built camera flash, the ring flash was. hence I decided to set up a small test on a dead bee using different apertures.

The Test:

Below is the bee shot without any flash (1/8th of a second)

No flash f2.8

and these are the results at various apertures, with either the Delta ring flash or the camera’s in-built flash.

Aper-ture Delta Ring Flash Camera Flash
  Guide Number 14 Guide Number 12
F2.8 RFf4 CFf2.8
F4 RFf2.8 CFf4
F8 RFf8 CFf8
F11 RFf11 CFf11
F16 RFf16 CFf16
F22 RFf22 CFf22
F32 RFf32 CFf32

As you may have noted from the images above, there is a definite advantage in using the ring flash. The overall exposure is more pleasing and the shadows are lesser. The bee seems to be more evenly lit using the ring-flash. However, the ring flash seems to be struggling at the smaller apertures of f22-32, which gives me the impression that it it may not be powerful enough in all situations.

Example of real results in the field:

In the field, I have obtained some really nice well lit images using this flash. What strikes me immediately is how even the lighting is. There are almost no shadows and the flash does its job as it is meant to do.

DSC08824.jpgAnt highlightDSC08814.jpg

One drawback of using this flash is the intense glare. The flash produces harsh reflections that can look downright ugly on reflective surfaces of insects. See the “C” like reflection on the termite below. The built in diffuser does little to dampen this and its hard to make a DIY diffuser for a ring flash, but I may need to give it a go.

DSC08878.jpgDSC08803.jpgBalloon-blowing fly!

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More often than not the images were a little underexposed, but this can be overcome by setting the camera’s flash compensation a little higher. Seen below are images taken without, with +1 and +2 flash compensation. However, as the rule goes it is better to under-expose your images than over-expose it, especially when shooting in RAW, so I do not generally change the settings.

Flash compensation = 0 Flash compensation = +1 Flash compensation = +2
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what concerns me is that the spec sheet states that auto TTL works between 0.9m-7m, however, the min distance is a lot less than the min focus distance of a macro lens (approx 0.35m). Does this mean there is no TTL happening during macro photography with this flash at close distances?

Verdict:

The Delta DRF-14 is an inexpensive, option to get over the hassles of a flash bracket and supply uniform lighting for eliminating shadows. However you have to get used to the less than ideal light output and the glare/reflection on shiny surfaces. Although the flash may not be an outright winner, I find that it is great value for money and does a decent job. If I had the money I would have bought a more expensive and more established and dependable brand, but not having that choice I would say this is the next best option. 


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