Win a Pentax Limited Lens: Raffle Now Live!

loco · 11-30-2011, 12:33 PM

I am real new to hot shoe flashes, so please bear with me if this is a stupid question.

I currently have a Bell & Howell Z680 p-TTL flash. It works great and I have learned to use it manually by referring to the aperture/distance chart included on the display on the back of the flash.

Now, I will soon be getting a YN-560 as a second flash. I want to learn how to use it off camera. In looking at the manual, I notice it does not have a similar display. So ... how does one figure out the proper distance/aperture/power settings when using this flash? Is it a matter of trial and error or do you have to know the guide number and do some math in your head (oh no!)?

Thanks in advance for any help!

alohadave · 11-30-2011, 04:09 PM

A flashmeter is the most sure way of knowing, but if you know the GN, you can work out distances and power levels.

joe.penn · 11-30-2011, 04:24 PM

Originally posted by loco

I will soon be getting a YN-560 as a second flash

Excellent choice Lori, really good manual flash unit especially for macro stuff. As Dave mentioned, you can get pretty precise using the GN/distance/power calculations - trial and error works well also. For macro work, I set the flash at its highest then use ISO to adjust the overall brightness of the composition...

demp10 · 11-30-2011, 04:55 PM

For a given ISO level, the flash will have a different Guide Number (GN) for each zoom setting with the highest at the telephoto setting (typically the advertised one) and the lowest at the wide angle setting. Hopefully the manual will list these values. Keep in mind that these numbers are rarely accurate and manufactures are sometimes generous with their flash output. There are several other conditions that will affect flash output, but the listed values are good starting points.

If they are not listed in the manual then you can guesstimate that at around 35mm zoom it will be one stop less light than the telephoto setting and at 24 you will lose another stop.
So if the YN560 is advertised as GN 58 (m at ISO 100 at 105mm zoom), then it will be around GN 41 at 35mm zoom and around GN 24 at 24 zoom. These are not exact but a good starting point.

The aperture can be calculated by dividing the GN by the distance. If the GN is 58 at ISO 100 with 105mm zoom setting, and the flash is 10m away from the subject, then the proper aperture will be F5.8. Make sure that you measure the distance from the flash to the subject (not camera to subject) and you use the same units (meters or feet) for both distance and GN.
If you try to use both the on camera flash and the new one off camera, things will get complicated and a flash meter will be your best way to determine exposure.

In any event, take a picture with the properly calculated exposure of a subject that has both bright and dark areas. Then look at the histogram. A proper exposure will give an evenly distributed histogram. If it is skewed to either side you should increase/decrease your exposure by opening or closing the aperture. You can also move the flash closer or farther to increase/decrease the exposure.

Experimentation is the best approach without a flash meter. After a while you’ll find what setting to use for most common situations.

loco · 11-30-2011, 05:22 PM

Thanks so much for the replies, everyone! Sounds like there are several ways to do it but some math is involved if you don't want to go the trial and error route. I believe there is a chart in the manual, maybe I will copy that page and keep it with the flash so I can refer to it.

demp10, I honestly didn't know the guide number changes based on zoom but that makes sense. That makes things even more complicated. Thanks for that bit of info and all the other great info you provided as well!

Joe, glad to know you have had a good experience with the flash. I have read lots of good things about it on this forum.

alohadave · 11-30-2011, 07:10 PM

Wait until you start adding modifiers. They can kill 1-3 stops depending on what you are using.

**klh** · 11-30-2011, 08:01 PM - **2 Likes**

I had the same problem. I learned on a manual flash (with only full power), and used the chart at the back to get the right distance and exposure.

I ended up making one for my YN-560 so I wouldn't have to do the math in my head. There's several ways to use it, but usually, I know the distance I want and the flash zoom setting I will be using. Assuming I'm at full power, I find the column with the right zoom, go down and find the distance of the flash to the subject, then look left to pick out an f-stop and ISO. If I want to use less power, for each step down in power, I go up one line.

Confusing to explain, but it works for me.

Attached Images

loco · 11-30-2011, 10:59 PM

Originally posted by klh

I had the same problem. I learned on a manual flash (with only full power), and used the chart at the back to get the right distance and exposure.

I ended up making one for my YN-560 so I wouldn't have to do the math in my head. There's several ways to use it, but usually, I know the distance I want and the flash zoom setting I will be using. Assuming I'm at full power, I find the column with the right zoom, go down and find the distance of the flash to the subject, then look left to pick out an f-stop and ISO. If I want to use less power, for each step down in power, I go up one line.

Confusing to explain, but it works for me.

Wow! klh, thank you so much! This is amazingly helpful! I'll definitely keep this and use it when I get the flash. You are awesome for sharing this. Thanks again!

usrbrv8 · 12-01-2011, 01:18 PM

I thought I would add a little something to this. KLH I took your chart and rebuilt it in Excel, I also took the Guide Number data from the Speedlight.net review and added it to this chart. Then I convert to feet and I also added a calculator portion. Simply specify Flash Power, Flash Distance, ISO, and Zoom and it will tell you the correct aperture.

I think I calculated everything correctly, I had to extrapolate on the Speedlights.net data so outside of the GN number data at 35mm and 1/1 power they are averages not measurements.

Let me know if I missed anything.

loco · 12-01-2011, 01:26 PM

Wow, Kyle! I appreciate you doing all that. Sounds like it's great! Unfortunately, I cannot open the file. Says it's corrupt or invalid. May just be me, but I've tried on two different computers. Would love to try this out, though.

usrbrv8 · 12-01-2011, 01:30 PM

I just updated the zip file again there should be a excel 2003 and 2007 file now. Let me know if it doesn't work.

loco · 12-01-2011, 01:55 PM

Still getting invalid or corrupt. It won't attempt to open the file. Maybe someone else should try, though. Could be me. I will try again when I get home tonight. Thanks!

usrbrv8 · 12-01-2011, 02:04 PM - **1 Like**

I put the files up on filesavr, if anyone knows a better place to host them I would be interested:

Excel 2007 version
Free File Hosting and Online Backup Storage.

Excel 2003 version
http://www.filesavr.com/ZLVZT9PI90V81AC

**klh** · 12-01-2011, 02:20 PM

Originally posted by usrbrv8

I put the files up on filesavr, if anyone knows a better place to host them I would be interested:

Excel 2007 version
Free File Hosting and Online Backup Storage.

Excel 2003 version
http://www.filesavr.com/ZLVZT9PI90V81AC

Both files are working for me. Looks good. Thanks.

loco · 12-01-2011, 08:15 PM

A ha! It works for me too, Kyle! Many thanks to both you and klh for coming up with these charts and spreadsheets. This is a huge help!! Members like you is why this forum is so great!

11-30-2011, 12:33 PM	#1
loco Veteran Member Join Date: Mar 2011 Location: Virginia Photos: Gallery \| Albums Posts: 2,846	flash chart? I am real new to hot shoe flashes, so please bear with me if this is a stupid question. I currently have a Bell & Howell Z680 p-TTL flash. It works great and I have learned to use it manually by referring to the aperture/distance chart included on the display on the back of the flash. Now, I will soon be getting a YN-560 as a second flash. I want to learn how to use it off camera. In looking at the manual, I notice it does not have a similar display. So ... how does one figure out the proper distance/aperture/power settings when using this flash? Is it a matter of trial and error or do you have to know the guide number and do some math in your head (oh no!)? Thanks in advance for any help!

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Pentax 67 to 645 conversion chart	elsdad	Pentax Medium Format	8	06-12-2011 02:33 PM
So here's a fun chart...	deadwolfbones	General Talk	30	04-06-2011 12:49 PM
B&W Film Chart	Paleki	Film SLRs and Compact Film Cameras	6	02-01-2011 12:25 PM
MTF chart	garyk	Pentax SLR Lens Discussion	4	05-27-2010 06:27 AM
Camera chart	BadVlad	Canon, Nikon, Sony, and Other Camera Brands	2	05-25-2010 04:00 AM

11-30-2011, 04:09 PM	#2
alohadave Veteran Member Join Date: Jan 2008 Location: Quincy, MA Photos: Gallery \| Albums Posts: 2,024	A flashmeter is the most sure way of knowing, but if you know the GN, you can work out distances and power levels.

11-30-2011, 04:24 PM	#3
joe.penn Veteran Member Join Date: Mar 2011 Location: Maryland (Right Outside Washington DC) Photos: Gallery \| Albums Posts: 2,902	Originally posted by loco I will soon be getting a YN-560 as a second flash Excellent choice Lori, really good manual flash unit especially for macro stuff. As Dave mentioned, you can get pretty precise using the GN/distance/power calculations - trial and error works well also. For macro work, I set the flash at its highest then use ISO to adjust the overall brightness of the composition...

11-30-2011, 04:55 PM	#4
demp10 Veteran Member Join Date: Jun 2011 Location: Atlanta Photos: Albums Posts: 602	For a given ISO level, the flash will have a different Guide Number (GN) for each zoom setting with the highest at the telephoto setting (typically the advertised one) and the lowest at the wide angle setting. Hopefully the manual will list these values. Keep in mind that these numbers are rarely accurate and manufactures are sometimes generous with their flash output. There are several other conditions that will affect flash output, but the listed values are good starting points. If they are not listed in the manual then you can guesstimate that at around 35mm zoom it will be one stop less light than the telephoto setting and at 24 you will lose another stop. So if the YN560 is advertised as GN 58 (m at ISO 100 at 105mm zoom), then it will be around GN 41 at 35mm zoom and around GN 24 at 24 zoom. These are not exact but a good starting point. The aperture can be calculated by dividing the GN by the distance. If the GN is 58 at ISO 100 with 105mm zoom setting, and the flash is 10m away from the subject, then the proper aperture will be F5.8. Make sure that you measure the distance from the flash to the subject (not camera to subject) and you use the same units (meters or feet) for both distance and GN. If you try to use both the on camera flash and the new one off camera, things will get complicated and a flash meter will be your best way to determine exposure. In any event, take a picture with the properly calculated exposure of a subject that has both bright and dark areas. Then look at the histogram. A proper exposure will give an evenly distributed histogram. If it is skewed to either side you should increase/decrease your exposure by opening or closing the aperture. You can also move the flash closer or farther to increase/decrease the exposure. Experimentation is the best approach without a flash meter. After a while you’ll find what setting to use for most common situations.

11-30-2011, 05:22 PM	#5
loco Veteran Member Join Date: Mar 2011 Location: Virginia Photos: Gallery \| Albums Posts: 2,846 Original Poster	Thanks so much for the replies, everyone! Sounds like there are several ways to do it but some math is involved if you don't want to go the trial and error route. I believe there is a chart in the manual, maybe I will copy that page and keep it with the flash so I can refer to it. demp10, I honestly didn't know the guide number changes based on zoom but that makes sense. That makes things even more complicated. Thanks for that bit of info and all the other great info you provided as well! Joe, glad to know you have had a good experience with the flash. I have read lots of good things about it on this forum.

11-30-2011, 07:10 PM	#6
alohadave Veteran Member Join Date: Jan 2008 Location: Quincy, MA Photos: Gallery \| Albums Posts: 2,024	Wait until you start adding modifiers. They can kill 1-3 stops depending on what you are using.

11-30-2011, 08:01 PM - 2 Likes	#7
klh Loyal Site Supporter Join Date: May 2009 Location: West Lafayette, Indiana, USA Posts: 827	I had the same problem. I learned on a manual flash (with only full power), and used the chart at the back to get the right distance and exposure. I ended up making one for my YN-560 so I wouldn't have to do the math in my head. There's several ways to use it, but usually, I know the distance I want and the flash zoom setting I will be using. Assuming I'm at full power, I find the column with the right zoom, go down and find the distance of the flash to the subject, then look left to pick out an f-stop and ISO. If I want to use less power, for each step down in power, I go up one line. Confusing to explain, but it works for me. Attached Images

11-30-2011, 10:59 PM	#8
loco Veteran Member Join Date: Mar 2011 Location: Virginia Photos: Gallery \| Albums Posts: 2,846 Original Poster	Originally posted by klh I had the same problem. I learned on a manual flash (with only full power), and used the chart at the back to get the right distance and exposure. I ended up making one for my YN-560 so I wouldn't have to do the math in my head. There's several ways to use it, but usually, I know the distance I want and the flash zoom setting I will be using. Assuming I'm at full power, I find the column with the right zoom, go down and find the distance of the flash to the subject, then look left to pick out an f-stop and ISO. If I want to use less power, for each step down in power, I go up one line. Confusing to explain, but it works for me. Wow! klh, thank you so much! This is amazingly helpful! I'll definitely keep this and use it when I get the flash. You are awesome for sharing this. Thanks again!

12-01-2011, 01:26 PM	#10
loco Veteran Member Join Date: Mar 2011 Location: Virginia Photos: Gallery \| Albums Posts: 2,846 Original Poster	Wow, Kyle! I appreciate you doing all that. Sounds like it's great! Unfortunately, I cannot open the file. Says it's corrupt or invalid. May just be me, but I've tried on two different computers. Would love to try this out, though.

12-01-2011, 01:30 PM	#11
usrbrv8 Junior Member Join Date: May 2009 Location: Chicago Posts: 47	I just updated the zip file again there should be a excel 2003 and 2007 file now. Let me know if it doesn't work.

12-01-2011, 01:55 PM	#12
loco Veteran Member Join Date: Mar 2011 Location: Virginia Photos: Gallery \| Albums Posts: 2,846 Original Poster	Still getting invalid or corrupt. It won't attempt to open the file. Maybe someone else should try, though. Could be me. I will try again when I get home tonight. Thanks!

12-01-2011, 02:04 PM - 1 Like	#13
usrbrv8 Junior Member Join Date: May 2009 Location: Chicago Posts: 47	I put the files up on filesavr, if anyone knows a better place to host them I would be interested: Excel 2007 version Free File Hosting and Online Backup Storage. Excel 2003 version http://www.filesavr.com/ZLVZT9PI90V81AC

12-01-2011, 02:20 PM	#14
klh Loyal Site Supporter Join Date: May 2009 Location: West Lafayette, Indiana, USA Posts: 827	Originally posted by usrbrv8 I put the files up on filesavr, if anyone knows a better place to host them I would be interested: Excel 2007 version Free File Hosting and Online Backup Storage. Excel 2003 version http://www.filesavr.com/ZLVZT9PI90V81AC Both files are working for me. Looks good. Thanks.

12-01-2011, 08:15 PM	#15
loco Veteran Member Join Date: Mar 2011 Location: Virginia Photos: Gallery \| Albums Posts: 2,846 Original Poster	A ha! It works for me too, Kyle! Many thanks to both you and klh for coming up with these charts and spreadsheets. This is a huge help!! Members like you is why this forum is so great!

flash chart?

Win a Pentax Limited Lens: Raffle Now Live!