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03-03-2015, 09:11 AM   #1
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AF assist light alternatives!??!

Hi there!

I have a K-500 and a Metz flash 48 AF-1, both with latest firmware updates.
The cam is set to P-mode, flash is set to P-TTL, AF to AF.S (no AF.A), kit lens 18-55. No fancy custom settings on cam or flash, except exposure -0,3 to -0,6 on short ranges < 1.5 meters for the Metz.

One problem is that the K-500 does not want to finaly decide which of the assist lights it's going to use: Sometimes it decides for the green LED in the camera, moreoften it uses the red "grid" projected by the Metz. I was unable to find out a rule to predict when it's going to use what - if I could, I would prefer the green internal LED because it's a bit more reliable and faster when it comes to focusing.

However, most times the cam utilizes the Metz grid projection - and then the real problems start:
The beam is very dull and of very poor contrast which makes the cam start hunting most of the times I use that flash.
I already had situations where I removed the Metz and used the internal flash ONLY to get the green LED which makes things easier somewhat (talking about AF!); but in the end it is impossible to use any of these if you are trying to focus on moving objects (kids, pets, partypeople) in low light situations like a softly lit room.

I own a LED-based video light ("continuous light source", so to say) I sometimes used in situations like these, and the results were ok because the thingie gives enough light for the AF - but has no visible influnece on the final picture (the flash is much brighter anyhow).
Unfortunately, people in the room are often annoyed by the vl (which I can fully understand) - and so it's not a real "solution".

Yes, I know, training manual focusing skills could help
Unfortunatly I have to wear glasses that keep me from making full use of the viewfinder
It's ok for everyday situations when taking the glasses off, but it's impossible for me to focus manually that way - and LiveView is not a big help in low light situations.

So, I'm somewhat stuck here because I DO have to rely on the AF.

First question after a long story:
Would it help to replace the flash? The new AF-360 FGZ II is way too expensive for me, but there are some older FGZ models around at ebay I could afford. Will it do better than the Metz? Of course, the Metz is brighter (LZ 48 to 36). But this is not my point!

Second question:
Are there any alternatives to the video light that could serve as assist light? I heard people talking about laser pointers and such, or a small LED torchlight that has a very narrow spot (both would not be pointed directly into people's faces, of course).

Anybody tried things like these already??
I know these are just "workarounds", but I really need some help here and hope you have any suggestions for me how to overcome that problem!

I really wish the good, old IR-beam would return as an additional option - the old cams I had did focus perfectly even in total darkness!

TIA!
Belushi

PS: Sorry for my "buggy" english, I hope it was not too crappy to understand my lines!

03-03-2015, 09:21 AM   #2
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I have used an LED flashlight for AF assist in dark places, and when things locked on I set it to manual focus, turned off the flash light and took the shot when using my K5 in places that I couldn't lock focus.
03-03-2015, 09:53 AM   #3
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First - thank you for the quick reply!!

Well, that's basically what I did with the video light, except I did not switch to manual mode before shooting - kids or pets are usually moving and decline to wait for me taking the picture

The problem with the video light is that it has a wide light angle and does light up much more of the scene than needed - that's the point people get annoyed.

The good thing about it is that I can put it on a "mounting unit" (my dictionary says "mounting rail" or "mounting bar" - I hope you know what I mean). This keeps my hands free for the camera: A flashlight would need me to hold it somehow between two fingers - or tape it to the flash.
That's why I did not give it a serious try it already.

What kind of flashlight did you use?
Wide angle or spot? You know how bright it is?
I have a small Maglite with ~75 Lumen, while the video light has ~ 400. However, the bundled spot of the Maglite seems to be much more blinding than the video light because that one has a diffuser. I think it's not possible to equip the Maglite with something like that...

On the other hand, the wide light angle of the vl may also be the reason why I never noticed the "assistant light" on my pictures. I guess a flashlight like the above would cause visible brighter areas without disabling it before shooting. Did you try that already?

TIA!
Belushi
03-03-2015, 10:46 AM   #4
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I used it on spot normally. It was to prefocus for paranormal investigations. What your issue is is that you don't have an area with enough contrast to be picked up in low light. Red and black were the worst for me.

03-03-2015, 11:38 AM   #5
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Hi again!

No, the common problem for me is "moving targets".
The Metz flash uses some kind of "grid" projected to the surface which basically allows to focus even on a plain surface - the grid pattern itself provides the contrast. Ok, maybe not on black or red areas where the grid would not be visible at all. But in general it's a great idea and should work with almost any scene or surface.

Unfortunately, the pattern is simply way too dark and therefore hard to "see" for the AF. And if the target moves, the AF is not fast enough to capture it - which makes the cam start hunting.

I just want to point out that it's not a problem with the scene itself - there is enough contrast in it: If I use the video light in the same situation, there are no problems at all. Except for the annoyance of the "victims".

It's just that the LED that powers the grid projection of the Metz is way to weak. The flash is aged and there were no real high-power LEDs at that time - compared to nowadays. Maybe I should try to replace it

That's why I think about buying me an AF-360, hoping that the assist light does a much better job than the Metz and allows the focus to also catch moving targets, not only stills.

As said... I vote for the return of IR-AF!

Thanks anyhow!
Belushi

PS: Did your investigations come up with something? If yes, I'm interested in seeing the results!
03-03-2015, 12:07 PM   #6
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Mainly shadows and shadows and such that shouldn't be there. I'll have to dig those and the EVPs up.
03-03-2015, 12:18 PM   #7
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See if you can score a (second hand) AF540FGZ (not the 540FGZ/II). It has an auto-thyristor mode in which the AF assist does not work and the camera uses the build in one; works on a K5 so I don't see why it would not work on a K500.

Just in case: a flash with auto-thyristor mode measures the light to determine correct exposure while for pTTL the camera does that.

Two notes:
* To my knowledge, the 360 does not have auto-thyristor mode.
* In my experience, the (red) AF assist of the AF540FGZ is more powerful than the (green) AF assist of the K5

Last edited by sterretje; 03-04-2015 at 08:33 AM.
03-03-2015, 12:31 PM   #8
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QuoteOriginally posted by VoiceOfReason Quote
Mainly shadows and shadows and such that shouldn't be there. I'll have to dig those and the EVPs up.
Ok, I'm curious to see them!

---------- Post added 03-03-15 at 08:58 PM ----------

QuoteOriginally posted by sterretje Quote
Just in case: a flash with auto-thyristor mode measures the light to determine correct exposure while for pTTL the camera does that.
Ah, ok - the good old-fashioned way.
I got the point: In auto-thyristor mode the internal green light would be used which, in my case, works somewhat better than the assist light in the Metz.

QuoteOriginally posted by sterretje Quote
* In my experience, the (red) AF assist of the AF540FGZ is more powerful than the (green) AF assist of the K5
Ok - so I have a look for that one!
The green assist in the K-500 is probably the same (or worse) than the one in the K5. So if you think the red one in the AF540 is better than that green one, it definitely has to be much better than the Metz, right?

Would be great if somebody could confirm that, but Metz flashes don't seem to be very common in the US or Canada.

The AF540 is on ebay for ~230 Euros, so I have to safe some more money. However, with the new FGZ-II around, hopefully some people will swap the "old" flash for the new one and sell their FGZ's!

Thanks!
Belushi

03-03-2015, 06:33 PM   #9
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I've used something like this now and then and it does a great job. Cheapo green laser pointer with star/grid/etc tips you can switch out. One of the ones I have can make basically a grid shape without too much light spillage between the lines. That paints the subject with a nice high contrast, well-lit target, and since it's green, it's presumably much easier on your camera than red or blue would be (since there are 2 green photo sites for each red or blue one)


6 in 1 Ultra Powerful Green Laser Pointer Pen Beam Light Lazer High Power 532nm | eBay
03-04-2015, 05:09 AM   #10
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Jesus... you better NOT point that into people's faces!
Ok, I found these on eBay (Germany) for ~15 Euros; I tink it's worth giving it a try.

But one must really be carefull when using them....

Thanks!
Belushi
03-04-2015, 05:33 AM   #11
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I have the AF360FGZ flash (first version, non-WR) and just gave it a try: It also has a thyristor mode, so you don't need to buy the expensive 540FGZ for this. On the K3, it will use the red pattern projection exclusively when in PTTL (unlike your Metz). When set to A mode (auto thyristor), the green LED of the camera is used.
To my opinion the red pattern of the AF360 works a little better than the green LED in speeding up the focus, and it is also less disturbing. Only problem: At short distances (<1m), the pattern is projected too high (because the flash is quite tall), so it won't assist the central focus point. Need to use to multi-point focus here or one of the upper focus points.

If you are looking for a flash only to use its thyristor mode in combination with the green LED beam, you can buy one of the many old flashes of the film days which can be had for around 10€ on ebay or flea markets. Good examples are the Pentax AF160(S), AF200S or AF200T, or AF280T etc. Basically all the flashes that have this little green (or red) ring on the front where their photo cell is
See here: Flashes (Genuine Pentax - Legacy) - Pentax Camera Accessory Review Database

The Pentax flashes all are fine with DSLRs, but some other old flashes have a very high trigger voltage that might damage modern electronic cameras. This page here (Photo Strobe Trigger Voltages) is a good reference for an ebay search. (my K7 also worked with a ~200V flash, but I think that's not advisable)

A side note about the red AF illumination pattern: It might not appear very bright, but as far as I know, the phase detection AF system also works down into the area of infrared light. What you see might very well be only a fraction of the actual light intensity of the illumination beam, but they designed it this way to be less distracting.
regards,
Alex
03-04-2015, 08:34 AM   #12
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QuoteOriginally posted by alextea Quote
I have the AF360FGZ flash (first version, non-WR) and just gave it a try: It also has a thyristor mode,
Thanks for the addition; I've updated my post.
03-04-2015, 08:48 AM   #13
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QuoteOriginally posted by Belushi Quote
Jesus... you better NOT point that into people's faces!
Ok, I found these on eBay (Germany) for ~15 Euros; I tink it's worth giving it a try.

But one must really be carefull when using them....

Thanks!
Belushi
Mine is about 2 mw (no idea what that one is), and the tip that spreads out the image makes it considerably safer. If it was my 15mw one that's intended for star pointing and so on, that would be much different, you could easily blind someone with that. That said, if you're doing a portrait, tell them to close their eyes, or just use a flashlight. Faces have sufficient contrast. This is more useful for, say, photographing a building.

But of course, the universal warning for lasers should always be observed:
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