Studio Questions


stub

Link Posted 01/04/2018 - 11:03
Thanks for the reply! I actually want to achieve a white background....

White is what I'm refering to also....

I cant comment on the Cactus triggers Ive never owned one.. My advice to you would be to go for a totally manual system.. A little longer to set up but far far easier to control once you get the hang of it.. And far less expensive.

Certainly wouldn't be using a shoot through umbrella in such an enclosed space.. Maybe go for a beauty dish. Or a small softbox and grid..


Strobes can be very reasonable on the second hand market. you don't need the latest and greatest... But you do get modelling bulbs to see what your doing with shaping the light when setting up.... The Chinese have cornered the new market. Look at the Godox DE300 a great strobe and very reasonably priced.. Cheaper than flash gun in a lot of cases...
K-1Gripped K-1 ungripped K-5ii K7 Various lenses

Stuart..
Last Edited by stub on 01/04/2018 - 11:21

sebas77

Link Posted 01/04/2018 - 11:18
thanks can you suggest any model? Just to give me an idea. I have already the cactuses, so I want to exploit them. I didn't mean TTL I was wrong, I meant remote manual control. However it seems the flashes pre trigger even in this case.

something like this? https://www.amazon.co.uk/gp/product/B0716XQXX6/ref=ox_sc_sfl_title_1?ie=UTF8&psc...

for the softbox you may warned me, I don't remember at all, but I feel I wouldn't have understood what you meant either, now I do.

for the white background, I don't understand the relation with the simple inverse square law, which would make sense to me if I want to achieve a black background, not white...unless you meant to put them closer?

The umbrella is there just because I want to test all the lights, I want to achieve a goal a time and take notes of the results. My first test was to get the 2m wide white background .

I did a quick and dirt test and without much effort I achieved this, but I have to interest in doing random tests, I totally want to master the light


IMGP9550 by sebafoto, on Flickr
Last Edited by sebas77 on 01/04/2018 - 11:35

McBrian

Link Posted 01/04/2018 - 12:05
I'ts not possible to correctly expose subject and background with the same light source[s], you will have to light the background independantley from the subject,
Cheers
Brian.
LBA is good for you, a Lens a day helps you work, rest and play.

sebas77

Link Posted 01/04/2018 - 12:09
McBrian wrote:
I'ts not possible to correctly expose subject and background with the same light source[s], you will have to light the background independantley from the subject,

of course, why did you come to this conclusion? OK I guess because you don't see a white background in the image. Right, actually you may notice there is a light behind the "model". In this case I wasn't going for the white background, I was just testing the trigger, I will post more experiments later!
Last Edited by sebas77 on 01/04/2018 - 12:09

stub

Link Posted 01/04/2018 - 12:09
When you move the light closer the fall off in the light is far greater.. That's why your experiencing grey patches...

https://www.youtube.com/watch?v=xO-J42VM448&t=28s

Look at it as 2 zones of light. Zone 1 the subject and zone 2 the background. Then light them independently.

Don't look at the Neewer lamp you posted. As it doesn't have a recognised mounting bracket for studio softboxes.. You need to get one with a Bowens mount.

https://www.amazon.co.uk/DE300-Professional-Portrait-Photography-WINGONEER/dp/B0...
https://www.youtube.com/watch?v=4h17T2bsYF4
No need for battery charging....

https://www.youtube.com/watch?v=4h17T2bsYF4
K-1Gripped K-1 ungripped K-5ii K7 Various lenses

Stuart..
Last Edited by stub on 01/04/2018 - 12:11

sebas77

Link Posted 01/04/2018 - 12:10
sorry I understand the confusion, damn I am so confusing!!!! I didn't mean to show that photo for the white background :/. I'll do another test later and show you what I can get for the white background.

I still don't understand why you show me the inverse squared law for achieving the white background. The "grey patches" is what I wanted for that test, but again I see the source of confusion. Thanks for the links btw.

P.S.: I do have a white background, but I want to achieve the result with a grey one. IMO my problem is that the slave lights are not powerful enough, but I will show you what I mean
Last Edited by sebas77 on 01/04/2018 - 12:38

K10D

Link Posted 01/04/2018 - 14:49
Not wanting to hijack this thread over chargers so started another.

Best regards
cameradextrous _ Motorcycles etc. link

sebas77

Link Posted 02/04/2018 - 00:04
K10D wrote:
Not wanting to hijack this thread over chargers so started another.

Best regards

link?

K10D

Link Posted 02/04/2018 - 09:43
sebas77 wrote:
K10D wrote:
Not wanting to hijack this thread over chargers so started another.

Best regards

link?

link

Best regards
cameradextrous _ Motorcycles etc. link

sebas77

Link Posted 02/04/2018 - 13:47
OK today I spent a couple of hours testing. My time is very limited and these tests needs time! However I am committed and I will take all the time needed to get to the bottom, so:

I now understand what stub was telling me. You mentioned the light falloff rule to tell me why I cannot achieve the white background, not in order to achieve the white background. That's why I was confused. Yes that's pretty clear especially after the tests. However what I still have to investigate is how the falloff is affected by the distance from the backdrop plus the direction of the light. The closer the light is to the backdrop, the more focused the light and the more intense the falloff are. It's not just a matter of direction, is also a matter of distance. If one just follows the inverse square law, they may think that the closer, the better, while instead the distance must be chosen in relation to the area to light up.

Here some tests, in the first early test the lights were too close to the backdrop and the model was to close to the lights (although it is mainly lit by the flash, not the backdrop lights)


IMGP9573.jpg by sebafoto, on Flickr

in the last tests, the lights were around 90CM away from the backdrop, while the model was 2M away from the backdrop. The results are much better, I also added flags on the lights:


IMGP9646.jpg by sebafoto, on Flickr

however like Stub was saying, the area I want to light up is too wide for my lights, I will really likely need another lamp to put on the bottom, also because it could work with wider lens:


IMGP9647.jpg by sebafoto, on Flickr

Next things I will try is to study how to improve light leakage and maybe try with adding a white backdrop and more lights.

About the cactus:

The PTTL pre flash is impossible to use, I think I will ask on the cactus forum if they may do something about it, although it's possible it's a flash limitaton?
What annoys me is that with the flash in M mode, I can still control the zoom from the cactus, but obviously not the power . However I wonder why the zoom is still controlled.
Last Edited by sebas77 on 02/04/2018 - 13:50

McGregNi

Link Posted 02/04/2018 - 14:27
Seb, the Metz flash must be set to P-TTL mode for use with Cactus V6IIs.

You switch between TTL and Manual flash modes on the V6II transmitter unit .... The group button cycles this with each press ....TTL ....M .....Off.
My Guides to the Pentax Digital Camera Flash Lighting System : Download here from the PentaxForums Homepage Article .... link
Pentax K7 with BG-4 Grip / Samyang 14mm f2.8 ED AS IF UMC / DA18-55mm f3.5-5.6 AL WR / SMC A28mm f2.8 / D FA 28-105mm / SMC F35-70 f3.5-4.5 / SMC A50mm f1.7 / Tamron AF70-300mm f4-5.6 Di LD macro / SMC M75-150mm f4.0 / Tamron Adaptall (CT-135) 135mm f2.8 / Asahi Takumar-A 2X tele-converter / Pentax AF-540FGZ (I & II) Flashes / Cactus RF60/X Flashes & V6/V6II Transceiver

sebas77

Link Posted 02/04/2018 - 15:09
Hey MC why do you think I didn't get that? I start to think my English is not good enough .

I said that I have to put the flash in M to suppress the pre flash as I can't work with it. However I am surprised that the zoom is still remotely controllable even in this case.

If I set the flash to M from the trigger as you say the pre flash is still triggered. Maybe it shouldn't and I did something wrong again? I'll try one more time then.
Last Edited by sebas77 on 02/04/2018 - 15:22

McGregNi

Link Posted 02/04/2018 - 15:38
You didn't explain clearly that you were trying a different technical approach in order to remove the pre-flash. So without that exactly explained then you make it easy for people to assume you don't know what you're doing. I can only use the exact words you write to judge, plus memory of problems you've had before.

I agree its a good idea to try in this situation (using the triggers as a basic manual type). However you're not using them as they are designed for, so performance might not be consistent.

If you want to keep your manual strobes fired optically, then you might be better off with a set of Yongnuo triggers and flash that work without any preflash. That way you can keep remote power control over your main light. The Yongnuos are cheap so you might be able to get two flashes

If you need HSS then consider the Cactus RF60x to pair with your V6II, as I believe it does not cause a pre-flash. But I'd confirm this for sure at the Cactus forum.
My Guides to the Pentax Digital Camera Flash Lighting System : Download here from the PentaxForums Homepage Article .... link
Pentax K7 with BG-4 Grip / Samyang 14mm f2.8 ED AS IF UMC / DA18-55mm f3.5-5.6 AL WR / SMC A28mm f2.8 / D FA 28-105mm / SMC F35-70 f3.5-4.5 / SMC A50mm f1.7 / Tamron AF70-300mm f4-5.6 Di LD macro / SMC M75-150mm f4.0 / Tamron Adaptall (CT-135) 135mm f2.8 / Asahi Takumar-A 2X tele-converter / Pentax AF-540FGZ (I & II) Flashes / Cactus RF60/X Flashes & V6/V6II Transceiver

sebas77

Link Posted 02/04/2018 - 15:50
Thanks mc. I get that the cactuses are not well exploited in this case, but I hate that I can't use them to set the flash output power remotely just because of the stupid pre flash. I have simple triggers but I can't change the output with those

sebas77

Link Posted 02/04/2018 - 20:55
I noticed that the new version of the godox slaves come with a sync cord jack and they are more powerful...I may go for this little investment:

https://www.aliexpress.com/item/Godox-SY8000-Photo-Studio-Strobe-Light-E27-Screw...

there is a more powerful version, but I don't think it's worth it honestly, although they have an interesting modelling lighting option:

https://www.aliexpress.com/item/GODOX-K-150A-GODOX-Portable-Mini-Master-Studio-F...
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