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Focus Trap with Tamron SP 80-200
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PostPosted: Sun Feb 08, 2009 9:05 pm    Post subject: Focus Trap with Tamron SP 80-200 Reply with quote
In the last two days, following the "Focus Trapper" instructions I experienced some focus trapping. Yesterday I had no results and today I noticed the camera run out of batteries... so "no luck" I thought.

Just some minutes ago I was searching for some good shots of the perch or feeder, and "hurra" Laughing I found some unexpected shots of a jay or "ghiandaia" in Italian (Garrulus glandularis). The shot is not perfect and the head is a bit out of focus, next time I will use a higher stop and a higher iso. I really need some more practice.

K100D with Tamron SP 80-200 at 200, f8, 1/125s, ISO 200.



PostPosted: Sun Feb 08, 2009 9:27 pm    Post subject: Re: Focus Trap with Tamron SP 80-200 Reply with quote
[quote="paolo0720"]In the last two days, following the "Focus Trapper" instructions I experienced some focus trapping. Yesterday I had no results and today I noticed the camera run out of batteries... so "no luck" I thought.

Just some minutes ago I was searching for some good shots of the perch or feeder, and "hurra" Laughing I found some unexpected shots of a jay or "ghiandaia" in Italian (Garrulus glandularis). The shot is not perfect and the head is a bit out of focus, next time I will use a higher stop and a higher iso. I really need some more practice.

K100D with Tamron SP 80-200 at 200, f8, 1/125s, ISO 200.

Those 'Focus trap Instructions' are just one persons opinion and in this persons opinion they are very wrong.
Focus trap is a very bad habit to be avoided at all costs.
Focus with any lens on any camera is a very precise yet fairly easy thing especially when you have focus confirmation. The problem with using the focus trap idea is simple. The camera shutter release locks until focus is confirmed, if your pressing the shutter release it goes off as soon as that confirmation is made.
Problem. What has the focus confirmation decided is in focus? Did you stop turning the focus by the time the shutter was released? The answer is its just guess work and you will be lucky to get 50% of shots in focus. It works if you are focusing very slowly and plenty of DOF otherwise it’s a waste of time and is in fact a nuisance.
I find 8 times out of 10 if I leave AF on the camera will not fire because it does not agree with my focus point. I focus adjust the frame a little and the camera is locked and I have missed the shot.
Forget focus lock it does not work and was never designed by Pentax for the use some are putting it too.
Focus confirmation with the camera set to MF does work 100%, use that and your eye.


PostPosted: Sun Feb 08, 2009 10:00 pm    Post subject: Re: Focus Trap with Tamron SP 80-200 Reply with quote
[quote="Rob Leslie"]
paolo0720 wrote:
In the last two days, following the "Focus Trapper" instructions I experienced some focus trapping. Yesterday I had no results and today I noticed the camera run out of batteries... so "no luck" I thought.

Just some minutes ago I was searching for some good shots of the perch or feeder, and "hurra" Laughing I found some unexpected shots of a jay or "ghiandaia" in Italian (Garrulus glandularis). The shot is not perfect and the head is a bit out of focus, next time I will use a higher stop and a higher iso. I really need some more practice.

K100D with Tamron SP 80-200 at 200, f8, 1/125s, ISO 200.

Those 'Focus trap Instructions' are just one persons opinion and in this persons opinion they are very wrong.
Focus trap is a very bad habit to be avoided at all costs.
Focus with any lens on any camera is a very precise yet fairly easy thing especially when you have focus confirmation. The problem with using the focus trap idea is simple. The camera shutter release locks until focus is confirmed, if your pressing the shutter release it goes off as soon as that confirmation is made.
Problem. What has the focus confirmation decided is in focus? Did you stop turning the focus by the time the shutter was released? The answer is its just guess work and you will be lucky to get 50% of shots in focus. It works if you are focusing very slowly and plenty of DOF otherwise it’s a waste of time and is in fact a nuisance.
I find 8 times out of 10 if I leave AF on the camera will not fire because it does not agree with my focus point. I focus adjust the frame a little and the camera is locked and I have missed the shot.
Forget focus lock it does not work and was never designed by Pentax for the use some are putting it too.
Focus confirmation with the camera set to MF does work 100%, use that and your eye.


Hi Rob,
I think there is a sort of missunderstanding, probably due to the lack of explanations. Focus trap, as described in the provided link, consists in leaving the camera "alone" with the focus manually set to predefined distance and with the shutter button pressed by a remote control, when something enter the focus area the camera takes the picture. There many reasons (and not opinions) to use such tecnique. BTW I find your reply unnecessarily harsh.


PostPosted: Mon Feb 09, 2009 12:07 am    Post subject: Reply with quote
My apologies.
The term Focus trap with Pentax DSLRs usually applies to the method I wrote about. Silly me did not fully read the article. I'm wrong.
It does seem as if the article is about pre focusing and setting an aperture to obtain the needed DOF you think your subject may fall into.
I haven’t come across this for many years. It is what we used to do before we could afford telephoto lenses. Yes it works well but because of the limited FOV (Camera is fixed in position) you miss more shots than you get.
Didn’t mean to be harsh and my advice for the focus trapping via the focus confirmation may be worth mentioning anyway.


PostPosted: Mon Feb 09, 2009 1:12 am    Post subject: Reply with quote
Excellent setup, Paolo. Looks like I got a K-series DSLR just in time to try this. Have you noticed what the battery drain is like when the camera is in standby like this?


PostPosted: Mon Feb 09, 2009 9:01 am    Post subject: Reply with quote
This is a great technique, I wish it was possible with Canon cameras. It is one feature Nikon has that Canon does not bother with, which is a pity. I didn't know that Pentax made it available, too.


PostPosted: Mon Feb 09, 2009 10:06 am    Post subject: Reply with quote
I must admit I fail to understand?

Am I missing something?
Why is setting the camera up in a fixed position with the limitations of a fixed small FOV better, when you can have full control of the camera and frame the shot?

I think there will be a lot of "I had no results and today"


PostPosted: Mon Feb 09, 2009 5:27 pm    Post subject: Reply with quote
Rob Leslie wrote:
My apologies.
The term Focus trap with Pentax DSLRs usually applies to the method I wrote about. Silly me did not fully read the article. I'm wrong.
It does seem as if the article is about pre focusing and setting an aperture to obtain the needed DOF you think your subject may fall into.
I haven’t come across this for many years. It is what we used to do before we could afford telephoto lenses. Yes it works well but because of the limited FOV (Camera is fixed in position) you miss more shots than you get.
Didn’t mean to be harsh and my advice for the focus trapping via the focus confirmation may be worth mentioning anyway.


Dear Rob,
I'm really sorry for the missunderstanding and for my disappointed reply. I'm lurking the forum since a couple of year, and I really appreciate all the users and the, very relaxed, atmosphere of the forum itself. Unfortunately, English is not my primary language and so I'm a bit lazy Smile in writing many explanations. I definitely understand and share your point of view!


PostPosted: Mon Feb 09, 2009 8:27 pm    Post subject: Reply with quote
Farside wrote:
Excellent setup, Paolo. Looks like I got a K-series DSLR just in time to try this. Have you noticed what the battery drain is like when the camera is in standby like this?


Hi Dave,
The batteries were not fully charged, they had about 200 shots (about 30% of them with full power flash). Starting from this condition, it took about eight hours to totally discharge the batteries (at 8°C), four hours on Saturday and four on Sunday. Batteries are almost new with three full charge/discharge cycles, so they should be at their maximum capacity.

Next time I will use an AC adapter, but I've found pentax ones are really expensive (about 60€)! Thus I managed to buy one from ABC products... for 15 pounds, I hope it will arrive soon!


PostPosted: Tue Feb 10, 2009 7:47 am    Post subject: Reply with quote
Rob Leslie wrote:
I must admit I fail to understand?

Am I missing something?
Why is setting the camera up in a fixed position with the limitations of a fixed small FOV better, when you can have full control of the camera and frame the shot?

I think there will be a lot of "I had no results and today"


Rob,
Wildlife can be very skittish, most animals have a very keen sense of smell and I will not hang around for long when the human scent is detected. Perhaps with a very long lens many birds can be photographed but with this technique you don’t need a long lens, you can put your camera near the area you want to shoot and capture a close image with a short lens.

I disagree with your argument about missing shots especially when you have your camera targeted on a popular bird feeder. The odds are you will get a few good shots and besides it’s a fun experiment.


PostPosted: Tue Feb 10, 2009 12:25 pm    Post subject: Reply with quote
spiralcity wrote:
Rob Leslie wrote:
I must admit I fail to understand?

Am I missing something?
Why is setting the camera up in a fixed position with the limitations of a fixed small FOV better, when you can have full control of the camera and frame the shot?

I think there will be a lot of "I had no results and today"


Rob,
Wildlife can be very skittish, most animals have a very keen sense of smell and I will not hang around for long when the human scent is detected. Perhaps with a very long lens many birds can be photographed but with this technique you don’t need a long lens, you can put your camera near the area you want to shoot and capture a close image with a short lens.

I disagree with your argument about missing shots especially when you have your camera targeted on a popular bird feeder. The odds are you will get a few good shots and besides it’s a fun experiment.


I see. Could you post results or a link to some of them.
Many of us have a passing interest in Wildlife! Smile


PostPosted: Tue Feb 10, 2009 6:31 pm    Post subject: Reply with quote
Rob Leslie wrote:
spiralcity wrote:
Rob Leslie wrote:
I must admit I fail to understand?

Am I missing something?
Why is setting the camera up in a fixed position with the limitations of a fixed small FOV better, when you can have full control of the camera and frame the shot?

I think there will be a lot of "I had no results and today"


Rob,
Wildlife can be very skittish, most animals have a very keen sense of smell and I will not hang around for long when the human scent is detected. Perhaps with a very long lens many birds can be photographed but with this technique you don’t need a long lens, you can put your camera near the area you want to shoot and capture a close image with a short lens.

I disagree with your argument about missing shots especially when you have your camera targeted on a popular bird feeder. The odds are you will get a few good shots and besides it’s a fun experiment.


I see. Could you post results or a link to some of them.
Many of us have a passing interest in Wildlife! Smile


The OP posted a link witha few shots. Smile


PostPosted: Tue Feb 10, 2009 11:20 pm    Post subject: Reply with quote
paolo0720 wrote:
Farside wrote:
Excellent setup, Paolo. Looks like I got a K-series DSLR just in time to try this. Have you noticed what the battery drain is like when the camera is in standby like this?


Hi Dave,
The batteries were not fully charged, they had about 200 shots (about 30% of them with full power flash). Starting from this condition, it took about eight hours to totally discharge the batteries (at 8°C), four hours on Saturday and four on Sunday. Batteries are almost new with three full charge/discharge cycles, so they should be at their maximum capacity.

Next time I will use an AC adapter, but I've found pentax ones are really expensive (about 60€)! Thus I managed to buy one from ABC products... for 15 pounds, I hope it will arrive soon!

Thanks for that, Paolo. That's longer than I expected. I'll have a look at that AC adapter - if only the makers had some standardisation, I've already got a Fuji AC adapter, but it's entirely different, of course.
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