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Using a ring flash and camera settings query

 
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sonyalpha



Joined: 24 Apr 2010
Posts: 916
Location: Middle England

PostPosted: Thu May 06, 2010 2:33 am    Post subject: Using a ring flash and camera settings query Reply with quote

My First techie question on this Forum:

I use a Sony Alpha 300 camera -I have just acquired a used...............Soligor AR 20 T Ring Flash and Light unit; it works well now that I have the correct hot-shoe adaptor for the camera:

Now I am finding problems with the manual camera settings required to get best results; any help and advice offered very welcome.

Thank you

Sonyalpha
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rjlittlefield
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PostPosted: Thu May 06, 2010 10:01 am    Post subject: Reply with quote

What sorts of problems are you having? Overexposure, underexposure, ghosting, color rendition, ... ?

--Rik
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sonyalpha



Joined: 24 Apr 2010
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Location: Middle England

PostPosted: Thu May 06, 2010 11:32 am    Post subject: Reply with quote

Hi Rik,

Thank you for your interest:

I have a feeling that between the old style connector and my more up to date hot-shoe adaptor the TTL isn't working so I will have to rely on working things out from scratch:I can hardly see many of the shots.....and others are too bright.........this one is the only reasonable shot out of a whole batch.......I tried cranking the ISO up with no joy:

The flash is an old one..everything is functioning except the TTL:

Any ideas:

Thanks:

sonyalpha


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Charles Krebs



Joined: 01 Aug 2006
Posts: 5805
Location: Issaquah, WA USA

PostPosted: Thu May 06, 2010 12:09 pm    Post subject: Reply with quote

If this is the unit I think it is then there is no TTL (through the lens) flash metering. The "auto" flash is accomplished via a small sensor on the front panel of the flash, below the flash tube. If this is the case then it would not be surprising if "auto" exposures were all over the place... since the sensor really needs to "see" the light reflected back from the subject. With a 100 or 200mm macro lens at modest magnification this may work pretty well most of the time, but generally I doubt it would give consistently good exposures on auto. (If this is a different flash then forget everything I'm saying here Wink )

Since the flash does not communicate with the camera, you need to be sure that the shutter speed set on the camera is no faster than the maximum shutter sych speed. (This could explain the shots you can "hardly see")

If it has manual exposure settings then it's really not too hard to set things up and use manual flash, especially if you have one or two macro lenses that you will regularly use the flash with.

So what lenses will you be using, and does this flash have a panel where you can set it to "manual" or to different manual power levels? (If so, a photo of this panel or the manual controls would be helpful). Once we know this we can provide more assistance.
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sonyalpha



Joined: 24 Apr 2010
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Location: Middle England

PostPosted: Thu May 06, 2010 2:58 pm    Post subject: Reply with quote



Hi Charles..thank you for your interest in my enquiry....here is the unit I have................Any advice as to what manual setting will work best with it will be of great help:

I notice, that compared to my home-made reflector/diffuser the ring flash shots appear to be very flat:

My camera is a Sony Alpha 300.......lens a Sony 2.8-100 Macro with all three extension tubes fitted:

Cheers!

sonyalpha
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rjlittlefield
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PostPosted: Thu May 06, 2010 3:04 pm    Post subject: Reply with quote

sonyalpha wrote:
the ring flash shots appear to be very flat

This happens because the light comes from all around. You can block a portion of the ring to add some modeling.

--Rik
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DaveW



Joined: 04 Aug 2006
Posts: 1702
Location: Nottingham, UK

PostPosted: Thu May 06, 2010 3:17 pm    Post subject: Reply with quote

As you are using extension tubes I wonder if you are adding the extension factor on for these to get the effective f-number you are working at for calculations, and not just that for the lens alone?

With TTL metering it would normally have allowed for the extra extension, as would TTL flash metering with dedicated flashes since it just meters the light reaching the sensor.

However this obviously does not occur with manual flash, so things need working out using the effective not relative f-number.

DaveW
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Charles Krebs



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Location: Issaquah, WA USA

PostPosted: Thu May 06, 2010 3:36 pm    Post subject: Reply with quote

Can't tell from the picture what manual settings there might be, but this approach might help...

First, when using this flash always be sure that the shutter speed used is 1/160 or slower (1/125 and slower if you have the sensor image stabilization turned on). You want to work in "M" mode, where you will manually set an aperture and shutter speed.

I don't know what the manual mode settings on the flash are. Sometimes it is simply a basic "manual" where the flash fires at full power every time. Sometimes there are settings that allow you to adjust the manual output... something like 1/2, 1/4, 1/8 and such. The basic idea here is that you will run a quick series of tests, at a manual power setting. You should record the magnification used (such as 1:2) and then, while focused on a "medium toned" subject, take a shot at each aperture...2.8, 4, 5.6, 8, 11, 16, 22. Then look at the pictures and determine which f-stop provided the best exposure. From then on, whenever you are at that magnification and have the flash set for that particular manual power level, that should be the f-stop used. You can make up a little sheet and tape it to the flash unit. Test and make up the chart at whatever magnification markings are convenient to see on your lens. Might be something like 1:10, 1:5, 1:4, and so on. Once you have "calibrated" in this way it really becomes simple to just glance at the chart and set the appropriate aperture once you know what the magnification will be for the picture you are about to take.

Chances are pretty good that you will find that the aperture used remains very close to the same value as you go through the focus range. This is because as you go closer the effective aperture becomes smaller, but it is off-set by the fact that flash is moving closer to the subject.

Such a manual "chart" works remarkably well for most subjects. As you become more experienced you may want to "fudge" a little for white subjects and for very dark subjects. You may find you need to stop down 1/2 to 1 stop more than the chart shows if your subject is white, and you may need to open the aperture about 1/2 larger if your subject is very dark.
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Craig Gerard



Joined: 01 May 2010
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Location: Australia

PostPosted: Thu May 06, 2010 7:13 pm    Post subject: Reply with quote

Just another question that may be relevant.

What is the voltage of the Soligor AR 20 T? Does it require a Hot Shoe Safe Sync?

Craig
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Cyclops



Joined: 05 Aug 2006
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PostPosted: Fri May 07, 2010 3:00 am    Post subject: Reply with quote

Oh I wish I could find (and afford) a module for that ringflash I won! Its bugging me now!
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sonyalpha



Joined: 24 Apr 2010
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Location: Middle England

PostPosted: Fri May 07, 2010 11:43 am    Post subject: A Decision and a huge THANK YOU Reply with quote

After much experimenting and taking on board all the valuable feedback from you all I sadly decided to give up on the ring flash..I will keep it on hand for when I wish to record a coin or suchlike:

Or...........if someone in the UK would like it please let me know:

Instead I will stick with my home-made crumpled cooking foil reflector that I much improved today with the addition of two layers of opaque plastic folder cover, this acts as a wonderful diffuser:

Here is the result:


Once again any comments very welcome:

sonyalpha



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