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Forum: Flashes, Lighting, and Studio 03-14-2019, 02:36 PM  
Xpro-P TTL Wireless Flash Trigger for Pentax
Posted By mcgregni
Replies: 218
Views: 15,457
Glad to hear the Slow Speed Sync can work with the trigger and AD200. Its an interesting "flash mode", because it is not a mode that affects the flash really at all, but rather the camera behaviours. My understanding is that standard "Flash On" mode is really designed for simple flash only scenes, ie where there is no real attempts to balance ambient and flash light, or outdoors in daylight then only for the most basic fill-in situations. The shutter speeds are related to lens focal lengths and designed to avoid camera shake, assuming handholding. So it is sort of "snapshot" mode. Indoors in low light this mode can produce the typical "party" snapshot look, with bright flashed faces and dark surrounds.


Slow Speed Sync assumes that the photographer wants to take more control and combine a mix of ambient and flash exposures, well suited to indoor events or the classic low light portrait outdoors with a city skyline in behind. The camera manual now warns us to ensure the camera is steadied or on a tripod, as shutter speeds will likely not be hand-holdable.
Forum: Flashes, Lighting, and Studio 03-14-2019, 02:24 PM  
Pre readings differ from Post Playback EXIF under these conditions... what gives?
Posted By mcgregni
Replies: 29
Views: 604
Yes, its good to acknowledge that flash output combines with ambient brightness, so the two are effectively slapped on top of one another. And there is a risk of blow out where flash is introduced on top of, for example, an already naturally bright face ..... however, I wonder if it may be over-promoting the sophistications of our P-TTL metering system a bit too far to suggest that the system can recognise when a flash cannot reduce its output sufficiently, and consequently take a decision to use shutter speed (if allowed) to reduce ambient to a level that would allow the flash to expose correctly ...? That does sound rather far fetched, however of course there's no proof about this as we lack any technical information about this sort of thing.


It sounds to me more like the sort of considered and assessed decision a photographer would have to make when finely tuning things using manual mode!
Forum: Flashes, Lighting, and Studio 03-14-2019, 10:52 AM  
Xpro-P TTL Wireless Flash Trigger for Pentax
Posted By mcgregni
Replies: 218
Views: 15,457
For these modes, if needing to free the shutter speed restrictions then switch the Camera Flash Mode to Slow-Speed Sync.... this is most effective indoors and in low light to create a true balance of ambient and flash exposures.
Forum: Flashes, Lighting, and Studio 03-14-2019, 10:43 AM  
Pre readings differ from Post Playback EXIF under these conditions... what gives?
Posted By mcgregni
Replies: 29
Views: 604
Peter is right with this; its important to keep emphasising that exposure time does not influence the flash exposure level in normal operations .... only in HSS mode will exposure time have an effect on flash exposure.


If the meter detects an overexposure situation even though the flash would output its lowest possible level, then it would need to adjust another variable, ie aperture or ISO, in order to allow a good flash exposure. Which of these varies would depend on the mode of course, and whether ISO is available to vary (auto-ISO parameter settings).


If the need is to reduce flash exposure, and the flash is already at its lowest possible output, then in Av mode the camera only has one thing to vary .... ISO, which would have to be lowered. The only alternative is for the photographer to step back more and increase the distance, then try again with a new pre-flash and test shot.


Regarding shutter speed auto control, then this is determined mainly by the camera flash mode setting and the lens focal length. The system aims to provide a steady handheld shot as the first requirement, and in dim conditions this will result in a poor ambient/flash balance, unless the photographer overrides this with Slow Speed Sync mode.
Forum: Flashes, Lighting, and Studio 03-13-2019, 04:07 PM  
Pre readings differ from Post Playback EXIF under these conditions... what gives?
Posted By mcgregni
Replies: 29
Views: 604
Having a flash ready signal going to the camera through the hotshoe changes everything. The metering system has to decide whether it tries to balance ambient and flash exposures, or whether the flash is going to provide everything.

This depends of course on what restrictions on ambient exposure are being imposed by the program line and ISO parameter settings. The Camera Flash mode and lens focal length will likely have the most impact in practice though.
Forum: Flashes, Lighting, and Studio 03-13-2019, 03:08 PM  
Pre readings differ from Post Playback EXIF under these conditions... what gives?
Posted By mcgregni
Replies: 29
Views: 604
....


Bruce, be fair please, this is what you told us in your first post, so I think we should be forgiven for understanding you are trying to use Av with Auto-ISO.
You may have said you had changed it later, but the posts are quite long, so its likely that people are responding to the opening one primarily.


No one is denying that its not possible to get some good flash shots using Av with P-TTL modes .... I use that sometimes myself too. But I agree with Steve that it is more suited to "snapshots" .... it is not suited to any situation where we need to take full control over the mix of ambient and flash brightness that is recorded. Whether results in dynamic situations using Av / P-TTL can be more than snapshots really depends on the skill and creativity of the photographer I feel.


Don't forget to check out the impact of the Camera Flash Modes, which can have a major influence on the amount of ambient light allowed to be recorded.


You asked about why the Auto ISO figure was not displayed prior to taking flash pics .... well, its because the figure is not calculated until the pre-flash. And there will be different decisions made based on a range of factors .... camera flash mode, focal length, amount of ambient light are a few of them.
Forum: Flashes, Lighting, and Studio 03-13-2019, 07:09 AM  
Pre readings differ from Post Playback EXIF under these conditions... what gives?
Posted By mcgregni
Replies: 29
Views: 604
I keep on with the same mantra over and over, in any Flash threads that concern automated exposures and auto -ISO .... If we want full and secure control over the images (and Professional work always demands this, regardless of the scenario), then we cannot rely on auto exposure parameters in addition to our P-TTL flash levels.

P-TTL itself, by itself, is a good thing and a useful aid to efficiency, but only when its the one single variable to focus on. Automated flash metering needs a solid, fixed base in terms of the ambient EV, not the least in order to allow the photographer to see clearly the precise effect of their compensation adjustments. Trying to view and assess the impact of multiple automated setting responses, as well as juggle two independent compensation inputs ....well, it's all too much and bound to lead to confusion and inconsistently exposed shots.

I do agree that it's good thing to have a basic underlying knowledge of the key aspects of what the automated systems are trying to do, and what they respond to .... That's why I wrote sections in my Guides that cover Camera Flash Modes, the impact of focal length, ambient brightness, program line, auto-ISO parameters etc. But to understand these basic principles is to ultimately appreciate the liimitations of such an automated approach to what is a very complicated thing; the balance of light and darkness in a scene, and the creative desires of the photographer who needs to take control of that scene and produce an image that records a precisely controlled mix of ambient and flash exposures.

No tiny camera computer brain can do that
Forum: Flashes, Lighting, and Studio 03-13-2019, 04:23 AM  
Pre readings differ from Post Playback EXIF under these conditions... what gives?
Posted By mcgregni
Replies: 29
Views: 604
The camera flash modes are also detailed in a special section early on in the main Guide document (2nd edition). Worth having another stab at understanding it really ...... Honestly, most of your forum threads here are way more complicated than my guides!!

Anyway (and you always knew this was coming!), you asked for the pro view on this. Well I'm not a pro, but I am very sure that the pros wouldn't even be bothering to think about any of this ..... They just wouldn't care .....

Ok, deep breath, here it comes again..... When trying to control and mix ambient and flash exposures, use Manual camera mode and fixed ISO.
Forum: Flashes, Lighting, and Studio 03-13-2019, 03:49 AM  
Pre readings differ from Post Playback EXIF under these conditions... what gives?
Posted By mcgregni
Replies: 29
Views: 604
No, the Camera Flash mode, on your camera .... That is the important setting that influences automated ambient exposures in these circumstances. Still recommending you read up the Supplement section of my guide.
Forum: Flashes, Lighting, and Studio 03-13-2019, 02:53 AM  
Pre readings differ from Post Playback EXIF under these conditions... what gives?
Posted By mcgregni
Replies: 29
Views: 604
As has been explained already, what you see on the screen or viewfinder before firing is not what you will get, because the automated aspects of the exposure settings are not calculated until the pre-flash.

Bruce, you're forgetting about the most important setting here ... What is your camera flash mode. ...?

Don't forget, most of this is covered in my Supplement PDF guide, a whole section on automatic flash photography.
Forum: Flashes, Lighting, and Studio 03-13-2019, 12:36 AM  
3rd Party Flash for Pentax that HSS in Manual Mode (from the hot shoe)?
Posted By mcgregni
Replies: 63
Views: 1,858
You're spreading the confusion Bruce! :lol: I knew this would happen once Godox started to offer more options

Whatever you do I would strongly suggest you go for the neatest, single system choice, and avoid things like trigger stacking and sync cables connecting things etc. Out and about with all your modifiers and stands and handles and stuff, there's more than enough to set up already!
Forum: Flashes, Lighting, and Studio 03-09-2019, 03:05 AM  
Shanny SN600FGZ P-TTL HSS Flash for $120?
Posted By mcgregni
Replies: 132
Views: 18,466
Kobie, thanks for the extra tests and it's good to know more about the Shanny's performance. Right from the time I saw your first video photographing the plant with the street behind, it was clear that the flash was providing a lot of HSS bang per buck!

I've said before, but worth saying it again, I doubt there's any value in Bruce making comparisons between 1/1 power and a plus FC setting. The reason is that the base level of the metered P-TTL exposure will vary, it's not a fixed amount, so saying that +3.0 compensation was equal to 1/1 manual can be confusing, as it depends on the situation that the meter was seeing just at that moment.

Having a flash , or trigger, that can be set to+5.0 FC is really meaningless, because if the metering was so off that we needed so much compensation, well we probably should have switched to manual mode anyway ....
Forum: Flashes, Lighting, and Studio 03-07-2019, 12:20 PM  
Lensbaby Lenses with Flash
Posted By mcgregni
Replies: 12
Views: 351
I know my shutter counts with film SLRs were low! If I got 20 well exposed shots out ot each roll of 36, that was pretty good ....I hate to think what that figure would have been if id added manual flash with manual aperture lenses into the mix as well!! .... But then again, plenty of pro photographers back then must have been able to do it!
Forum: Flashes, Lighting, and Studio 03-07-2019, 04:15 AM  
Lensbaby Lenses with Flash
Posted By mcgregni
Replies: 12
Views: 351
Nice effects, very atmospheric, and worth the extra effort with Manual mode flash! Now imagine what this would have been like back in the days of film ....I know for sure I would never have developed many flash skills then, as experimenting and learning would have cost too much in film developing . I know that only through digital could I come to use flash.
Forum: Digital Processing, Software, and Printing 03-07-2019, 02:15 AM  
D FA* 50 now supported by DXO
Posted By mcgregni
Replies: 5
Views: 451
Does the new D FA50 really actually need any software corrections...?
Forum: Flashes, Lighting, and Studio 03-05-2019, 03:32 PM  
Lensbaby Lenses with Flash
Posted By mcgregni
Replies: 12
Views: 351
I think you should stop trying to relate P-TTL automatic outputs to fixed manual flash power levels .... there's really no point, as the two have no theoretical or practical relationship. When using P-TTL with a Pentax flash you have the Range display to guide you (when on camera and straight ahead). All that matters is that the subject distance is within this range. Anything further and you can assume that correct exposure would exceed the flashes maximum output capabilities. But with the metering aspects we can never know for sure whether the flash will actually output its maximum, because the metering may be reducing it somewhat. So its all conjecture, and no help in practice.
Forum: Flashes, Lighting, and Studio 03-05-2019, 01:23 PM  
Lensbaby Lenses with Flash
Posted By mcgregni
Replies: 12
Views: 351
Without the aperture coupling through the mount the camera cannot know the aperture, so P-TTL won't work regardless of what camera mode is used.

Using Av mode with a fully manual lens does not mean that the camera knows, or is controlling, the aperture..... It just means that the Shutter speed (and potentially ISO) is free to float and adjust in response to the light entering the camera. This varies depending on both the actual brightness in the scene and the aperture setting on the lens (assuming fully manual aperture). So the meter is working to control the shutter speed and ISO (which is what normally happens in Av mode with Auto-ISO), but it just cannot control the aperture.

In manual mode the difference is that the shutter speed is fixed by the dial, and only changes with dial adjustments or green button stop down (TV Shifts).
Forum: Flashes, Lighting, and Studio 03-05-2019, 08:39 AM  
Lensbaby Lenses with Flash
Posted By mcgregni
Replies: 12
Views: 351
I think he's probably going to use the RF60x Peter ....
Forum: Flashes, Lighting, and Studio 03-05-2019, 07:16 AM  
Lensbaby Lenses with Flash
Posted By mcgregni
Replies: 12
Views: 351
Manual modes on both camera and flash trigger is probably the way to go, as indeed it is for M and K type Pentax lenses. I don't know if the lensbaby lens behaves any differently, but stop down metering would normally be needed for the ambient exposure values. These days with histograms and instant LCD image reviews, i think most of us would take a quick stab at a manual flash power guestimate, then assess and adjust as needed.

I always establish the ambient EV first and then add the flash contribution on top ..... Ot course if you're indoors and not recording any ambient light then just jump straight to assessing the flash exposure.

I think we all gain a sort of sixth sense for the flash power levels ...eg indoors with my softbox very close to the subject, at ISO 100, F8, 1/180th I start out at 1/8th power and that is usually very close
Forum: Pentax SLR Lens Discussion 03-03-2019, 06:01 AM  
D FA28-105 vs the other 3 Pentax 28-105 lenses
Posted By mcgregni
Replies: 35
Views: 1,616
If you were comparing something like the D FA 50m 1.4 and older FA alternatives, then I think this would be a valid comparison and worthwhile to make ..... But between the D FA 28-105 and it's ancestors then I doubt this is a worthwhile exercise.....

I mean for the money its a no brainer, and probably not worth the effort to try and find the older options? I certainly didn't bother when I had the option to buy new at a discount. Should I have?
Forum: Pentax SLR Lens Discussion 03-01-2019, 12:50 PM  
K1 II - best legacy budget lens on the best price to IQ value ratio for the lowest $
Posted By mcgregni
Replies: 61
Views: 2,774
Don't forget the M75-150 F4.0 ......
Forum: Flashes, Lighting, and Studio 02-26-2019, 09:13 AM  
Shanny SN600FGZ P-TTL HSS Flash for $120?
Posted By mcgregni
Replies: 132
Views: 18,466
Why do you believe P-TTL is not working? What exactly are you doing, and with what settings and equipment (ie lens), when it does not work as you expect?
Forum: Flashes, Lighting, and Studio 02-26-2019, 08:08 AM  
Running & Gunning Softbox?
Posted By mcgregni
Replies: 40
Views: 1,324
Yes, umbrellas are cheap and there's loads to choose from. I think we can pretty much forget about reflective ones for sunny outdoors HSS work however, the power loss is just too great for the light to reach far enough to be practical. Shoot through might work though, and especially if Bruce can use both RF60x's in tandem. The light spread is wide but that might be helpful for the "running and gunning" scenarios where things are quite mobile, so less need for precision.

The realty for me in the Uk is that umbrellas outdoors are impossible due to wind, and unpredictable sudden little gusts that send the brollies flying and I'm jumping to try and grab the flashes before they smash down. Luckily I've only damaged umbrellas so far, not flashes, but I don't take the risks now. My 24' x '24 softbox is stable on a wide legged stand outdoors, but this requires time to set up and exact placement of the subject, so it needs a slower studio like approach to things. But anything smaller is going to produce harder light, and frankly outdoors with a mix of ambient and flash light you're then better off just using on camera bare flash for fill. ......

---------- Post added 26-02-19 at 15:43 ----------

Honestly, I wonder if for the purposes you are thinking of Bruce, whether there's really any point to using a diffuser at all ? Perhaps its just not worth the extra work and consequent power loss …. ?

Here's a few examples of mine where I took the attitude that its not worth the bother. These all mix ambient and flash exposures ( so there's ambient light playing on the faces, but the flash helps it out by reducing contrast) …. they are all taken with bare, direct on camera flash (AF-540FGZII) …. in some there might be a 1/4 CTO gel.




































I'm just not sure if these could really be significantly better if I'd gone to the massively extra effort to use diffusion and managing lightstands etc etc …… ?
Forum: Pentax K-70 02-25-2019, 12:54 AM  
Help choosing a flash for point and shoot and maybe a little more
Posted By mcgregni
Replies: 23
Views: 749
No! Use bounce, swivel and a flag straight away .... The first thing you do.
Forum: Flashes, Lighting, and Studio 02-22-2019, 03:38 PM  
Pentax K1 w/ manual lens won't trigger off camera flash
Posted By mcgregni
Replies: 28
Views: 1,211
I'm not sure if there are yet any "experts" with Pentax DSLRs and the XPro-P ..... It's a very new combination.

The convention with Pentax is that non aperture coupled lenses (ie M, K, M42 types) cause on camera flashes in P-TTL mode to fire at full power. So the advice is to use Manual or auto thrystor flash modes.

I'm not aware of any reporting on the behavior of Radio TTL flash systems in the same configurations. .ie we don't know whether slave flashes in a system such as the Cactus XTTL will fire at full power if the transmitter is set to TTL mode with such a lens ....? It can be tested of course.

It must be something to do with the information from the camera that these triggers need, even if set to M mide. I don't suppose we should assume that they would behave exactly as a P-TTL flash. But there's surely a good chance of firmware being able to correct these sort of issues .....
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