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10-11-2018, 10:22 PM - 1 Like   #1
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Magmod Modifier Comparisons.

I saw an interesting thread on the Magmod Community Facebook Group the other day that sparked a small amount of controversy. A user uploaded a few images of a mannequin with a fixed camera+flash firing at the mannequin with all the various modifiers attached, these images shot indoor towards the ceiling (so all bounce shots) in a makeshift studio of sorts. The user asked the community to guess which picture had which (if any) modifier attached (magsphere or magbounce) etc. The results were quite interesting with many users getting it wrong. The most pleasing exposed image with the softest shadow was the bare flash shot.

It certainly sparked my interest and as a magmod user I aimed to set out to replicate her findings as well as tinker with a few more modifiers and physical manipulations to see if I could alter or improve the shots.

Below I post the results of my own testing which do indeed reflect an accurate finding the initial magmod user found with her own experiment. To those of you with better technical understanding of photography and lighting in general, the results won't surprise, to those more amateurish (like myself) they might be a bit of an eye opener.

The test was conducted under the following conditions;

Camera+Flash Bracket (with a v6ii and RF60x attached) was mounted on a tripod on my verandah. The mannequin placed a few feet back with a simple blind as a backdrop.
The camera was in Manual mode, 1/60, f4, ISO 200 (the first image is a non flash shot to illustrate the ambient light (lower than I'd normally have but important to really detect what's happening with the flash lighting effects).
TTL mode used throughout, Exposure 0.0
WB set to 5000K, in the Menu I have configured flash use to NOT take over the WB and set to AWB, instead keep it at my 5000K as chosen. I think this is interesting to note as a lot of the 'MagBounce' shots seem to lose their 'warmth'...
The entire test was performed around 3pm, on a dull overcast day, studio environment this was not. However it was completed within 20mins or so and the ambient lighting conditions didn't seem to alter much (and I think the comparison shots reflect this).

I think it's really important to note however that the Magsphere, Diffuser Gel and Magbounce were not all intended to be used in this specific set up way. Different environment, distances to subject and desired effect wanted all dictate their uses.

The Setup



Shot 1, No Flash



Shot 2, Bare Flash, Ceiling Bounced



Shot 3, Magsphere, Ceiling Bounced



Shot 4, Diffuser Gel Only, Ceiling Bounced



Shot 5, Magbounce



Shot 6, Bare Flash, Directly Facing Fwd



Shot 7, Magsphere, Directly Facing Fwd



Shot 8, Diffuser Gel Only, Directly Facing Fwd



Shot 9, Diffuser Gel+Magsphere, Directly Fwd

Curious to understand why this shot would look underexposed. I mean of course the flash has to penetrate two diffusers, but isn't the point of TTL to fire a preflash quickly first, ascertain what is required from that flash output and then for the real shot compensate accordingly to bring the shot into proper exposure? I would have thought this shot would be exposed the same as the rest but the flash fired would have been stronger (requiring a longer recycle time). Hmm...


I decided here to try pulling the maggrip down further on the flash, so that the gap I saw between the Magsphere>Maggrip and where possible flash spill light was slipping out was minimised;

Gap



No Gap, Maggrip pulled down further


To save you scrolling up, here's the shot again from earlier with the magsphere facing the ceiling with the gap existing;


And now below with the gap taken away;



And the same with the Magbounce, with the Gap (as before);


And now without a gap;



I think without the gap the shots are better, softer shadows slightly.

We typically have a small gap there and cannot always have the maggrip that low down on the flash head due to using other modifiers such as maggrids and maggels which are flat.

Anyway, hope you find these results interesting. To my eye bare flash wins, magsphere with no gap a close second, and interesting to note that there is not a dramatic difference between using the diffuser gel and sphere when ceiling bouncing. Magsphere produces a better image if used directly at the subject than bare flash imo, but it's not that profound. All the images look a tad underexposed with a modifier, I think they would have looked better if I had compensated the TTL exposure slightly.

Cheers,

Bruce

10-11-2018, 10:51 PM - 1 Like   #2
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Great examples !!!!!!!!!!!!!!!!!!!
10-12-2018, 02:02 AM   #3
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I prefer the bare flash ceiling bounced. But it would be improved with a reflector or secondary LED emitter (as on my Pentax AF360FGZ II) giving a little illumination to the eyes.

The differences in colour balance are surprising.
10-12-2018, 02:20 AM   #4
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QuoteOriginally posted by Paul the Sunman Quote
I prefer the bare flash ceiling bounced. But it would be improved with a reflector or secondary LED emitter (as on my Pentax AF360FGZ II) giving a little illumination to the eyes.

The differences in colour balance are surprising.
Agreed. I surmise that the magsphere, diffuser and bounce all pick up the cooler tones from the material of the modifiers and 'cool' the target down, whereas the bare flash shows the 5000k temp WB as is. And yes, a catch light card might assist with the bareflash shot, tho I don't think Davo (my mannequin ) has very reflective eyes to pick up on that.

10-12-2018, 03:50 AM   #5
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Hi Bruce, just to deal with the question about exposure. ..... The flash exposures are low because of your ambient light settings. Your settings are recording a low amount of ambient light (see your first shot without flash). In this configuration then the P-TTL metering system attempts to create an automatic balance of flash and ambient exposures, which is exactly what we see happening when your flash comes into it

To get the flash metering to fully expose you have to do either two things ....1. Kill off all ambient light, so go to ISO100 and 1/200th (this makes the flash exposure attempt to fully light the scene)....or 2. Open up the ambient exposure much more, say another 3 stops, and this will force the flash metering to again attempt to balance the ambient, but with much more power this time.

As it stands the P-TTL system has done exactly as it was meant to with such a low ambient exposure value. But underexposed flash shots are not really ideal for testing modifiers and effect purposes.
10-12-2018, 04:55 PM   #6
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QuoteOriginally posted by mcgregni Quote
Hi Bruce, just to deal with the question about exposure. ..... The flash exposures are low because of your ambient light settings. Your settings are recording a low amount of ambient light (see your first shot without flash). In this configuration then the P-TTL metering system attempts to create an automatic balance of flash and ambient exposures, which is exactly what we see happening when your flash comes into it

To get the flash metering to fully expose you have to do either two things ....1. Kill off all ambient light, so go to ISO100 and 1/200th (this makes the flash exposure attempt to fully light the scene)....or 2. Open up the ambient exposure much more, say another 3 stops, and this will force the flash metering to again attempt to balance the ambient, but with much more power this time.

As it stands the P-TTL system has done exactly as it was meant to with such a low ambient exposure value. But underexposed flash shots are not really ideal for testing modifiers and effect purposes.
Ah... I think I understand a bit more now.

I was thinking that if I had too strong an ambient light for the test, then the flash power wouldn't kick in that much (as the ambient exposure was already pretty adequate) and therefore that would be harder to see what shadows were being placed where etc. I thought a better strategy was to cut out a fair bit of ambient light and then the TTL system would see it needed quite a bit of work to be done to bring the scene to a decent exposure and therefore do more of the 'work' and by doing that it would be easier to see shadows and where they are placed etc.

But I think i understand a bit more now. If I'm not mistaken it's a bit like this;



I may repeat the test again, this time getting a stronger exposed image with clearer shadows and what they are doing.
10-13-2018, 06:24 AM - 1 Like   #7
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Yes, the level of the P-TTL flash exposure is linked to the level of the ambient exposure, automatically, and we have no way to unlink them (on Pentax that is). By forcing the shutter to 1/60th you are allowing ambient light to record (on your models left side). The metering system sees this and assumes you want that ambient light to be seen. A full flash exposure would blast out that low ambient light and override it, so instead the flash exposure is cut down to try and balance with the ambient. In brighter outdoors light this is what we call "fill in".

Only if the ambient light is exposed much lower (such as almost pitch black) will the metering system assume you want the flash to fully expose the scene .... Then the flash output is automatically increased to the right level to fully cover things with enough light. So in fact we actually control the response ot the P-TTL metering by the amount of ambient light we choose to record

All of this plus plenty more is covered in the Supplement to my "Pentax Flash Guide", in the section "Automatic Flash Photography".
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