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05-10-2009, 02:59 PM   #16
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QuoteOriginally posted by heliphoto Quote
I've formulated a theory (more of a guess really) ....
Test it properly, I'd suggest, and write it up. Then it's a proper experiment, repeatable by others. If they too find the same results, it adds to the body of knowledge, and moves out of the realm of speculation into actual theory.

I have no axe to grind on this one - I would imagine Pentax have a reason for their "SR off on tripod" recommendation, but why they won't tell us why they make it seems strange to me.

But until there's proper evidence, conditions repeatable by others, all these ideas about feedback loops and the like remain just speculation. They may even be right, but it doesn't help anyone's understanding until we move away from anecdotes about the odd shot here and there, to a specific set of conditions that anyone can reproduce.

05-10-2009, 04:12 PM   #17
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QuoteOriginally posted by Marc Langille Quote
I'll add to your comments about long lens technique: I don't just do the eye to eyecup! When shooting, it's pressing my face to the camera back...

BTW Josh, you will receive an invite to the exclusive "official photographer of the ugly club" in the mail soon... I have the inside resource to prove it:
...

Cheers,
Marc
Thanks for the additional info Marc - I've just been teaching myself long lens technique lately, so your advice is truly welcome. It'll be good to be in that club - I've been taking ugly pictures for quite a while now ...


QuoteOriginally posted by ChrisA Quote
Test it properly, I'd suggest, and write it up. Then it's a proper experiment, repeatable by others. If they too find the same results, it adds to the body of knowledge, and moves out of the realm of speculation into actual theory.

I have no axe to grind on this one - I would imagine Pentax have a reason for their "SR off on tripod" recommendation, but why they won't tell us why they make it seems strange to me.

But until there's proper evidence, conditions repeatable by others, all these ideas about feedback loops and the like remain just speculation. They may even be right, but it doesn't help anyone's understanding until we move away from anecdotes about the odd shot here and there, to a specific set of conditions that anyone can reproduce.
Well, I may look into this phenomenon a bit more and I may not because to be honest, if I had much tolerance for the rigor and documentation required to be a scientist - I'd have become one (or at least I'd be a test pilot). Most likely I'll leave it as a gedankenexperiment...

Developing repeatable conditions sounds like the work of a scientist, and as you say, Pentax has already done it and whatever their findings they've instructed us to turn SR off when using a tripod. Honestly I have no idea if the real reason has anything to do with my guesswork or if I'm off in Lala land... I just wanted to share my guesswork - maybe someone else has had similar experiences and thoughts. Anyone who knows better is welcome to poke holes in my concept all day .
05-10-2009, 07:33 PM   #18
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QuoteOriginally posted by emr Quote
Oh. I tend to have the habit of half-pressing first and then finding the right composition and moment. Gotta try the direct approach.
Aaargh - somehow I managed to write that exactly backwards. Half-press first is the way to go. I'm fixing it in the original post so no one else gets the wrong idea...
05-11-2009, 09:38 AM   #19
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SR and ST

I find it a shame that SR is turned off when the self timer is engaged. Sometimes I raise the camera on a monopod to get a high overhead, and I have to use the ST to fire the shutter....Chris

05-11-2009, 10:19 AM   #20
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QuoteOriginally posted by Marc Sabatella Quote
Aaargh - somehow I managed to write that exactly backwards. Half-press first is the way to go. I'm fixing it in the original post so no one else gets the wrong idea...
No problem, thanks for the correction. I also removed the quotation the incorrect line.
05-15-2009, 09:00 PM   #21
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Monopod and SR?

I was going to start a new thread, but this seemed an appropriate place to ask:

Do you turn SR on or off when using a monopod?

It seems that some here have done extensive testing with a tripod, but what about its one-legged cousin? Instinct tells me to leave SR on, but I could be wrong - would like to hear from others.
05-16-2009, 10:06 AM   #22
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QuoteOriginally posted by OregonJim Quote
I was going to start a new thread, but this seemed an appropriate place to ask:

Do you turn SR on or off when using a monopod?

It seems that some here have done extensive testing with a tripod, but what about its one-legged cousin? Instinct tells me to leave SR on, but I could be wrong - would like to hear from others.
SR on a monopod is OK. Taken with the FA* 300/2.8 + Pentax 1.7 AF TC:


They do not recommend SR on a tripod. However, I have the sharp, low-shutter speed images that have SR enabled while on a tripod:

https://www.pentaxforums.com/forums/post-your-photos/58528-reflections-their-...rd-images.html

https://www.pentaxforums.com/forums/post-your-photos/58779-more-reflections-s...s-part-ii.html

Regards,
Marc
05-16-2009, 10:48 AM   #23
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QuoteOriginally posted by Marc Langille Quote
SR on a monopod is OK. Taken with the FA* 300/2.8 + Pentax 1.7 AF TC:
Thanks, Marc. Love the color rendition on that one! We had a local Civil War reenactment here, too - sadly, I had to work, but could hear the cannons firing 3 miles away.

05-16-2009, 10:58 AM   #24
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Hi Jim,

Glad to help Jim!

Forgot to add: when I mean "OK", I meant it's fine to use SR, not OK results. Obviously technique at 510mm focal is critical. I have several that are pretty good, but nothing like this image at 100%.

Please check out the hummingbird images too - I think you'll be happy with the results at 1/100 sec. and 1/160 sec. in the two posts. Very overcast, near the end of the day, and quite windy. Very sharp at 100%.

Regards,
Marc
05-16-2009, 11:06 AM   #25
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Hi Marc,

Yeah, I understood what you meant. I usually want more than one leg at 510mm anyway. Though, with no wind (and no caffeine), I've done pretty well even at 800mm. Was just curious if SR copes well with 1-axis movement vs. 2.
05-16-2009, 11:14 AM   #26
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I tend to leave SR on all the time when using a monopod or tripod with longer lenses (300/400). I believe it improves results with the monopod. Truth be told my tripod is a lightweight one and it is propoably time to upgrade. For the moment with a 300 or 400mm lens mounted I think SR helps improve the images as I note a fair bit of vibration in the viewfinder from time to time.

Last edited by 8540tomg; 05-16-2009 at 11:17 AM. Reason: typo
05-16-2009, 11:43 AM   #27
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QuoteOriginally posted by 8540tomg Quote
I think SR helps improve the images as I note a fair bit of vibration in the viewfinder from time to time.
Seeing vibration in the viewfinder isn't really an indication of anything.

The sequence is:

- mirror up
- shutter opens
- shutter closes
- mirror down

The vibration caused by the shutter opening and closing is insignificant compared with that caused by the mirror banging up and down (which has its own term - 'mirror slap'),

The 2s and 3s delays are there to let the mirror-up vibration die down.

Vibration that you see in the viewfinder after the exposure, caused by the mirror banging down is completely irrelevant, since the exposure is all finished by then.
05-16-2009, 01:51 PM   #28
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No argument about the sequence Chris. With shorter focal lenghts I would agree with you. I had my 400mm lens in mind when I made the observation above. I seem to use it a lot @ 1/100th of a second and slower. Vibration is noticeable with this focal length in the viewfinder before I trip the shutter on windy days. The combination of K10/battery grip and 400mm lens is quite hefty. My tripod, while not flimsy, is not as rock solid as I would like. It is my opinion, in this particular case, that it helps to leave SR on.

Tom G

Last edited by 8540tomg; 05-16-2009 at 07:39 PM. Reason: typo
05-16-2009, 03:22 PM   #29
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QuoteOriginally posted by 8540tomg Quote
Vibration is noticeable with this focal length in the viewfinder before I trip the shutter on windy days.
Ah well, certainly, if you can see the vibration before taking the picture, it's not mirror slap causing it . I misunderstood your reference to 'vibration'.

QuoteQuote:
It is my opinion, in this particular case, that it helps to leave SR on.
I'd agree with that. As I've commented elsewhere, I've never seen any evidence that SR causes shake on the tripod as others claim, even when I went looking quite carefully for it.

I wouldn't be at all surprised if SR improves the outcome if the shake is visible in the VF.
05-16-2009, 06:10 PM   #30
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The manual recommends turning SR off with a tripod. Not long after I bought my camera there was a total lunar eclipse and like just about everybody I shot several shots at various stages of the eclipse. I had left the SR on and a few of the longer exposures showed obvious motion blur, almost a double image. I posted one of the shots as an example of what can happen and all the folks who insist this is not an issue said leaving the SR on was not the cause of this spoiled shot. I make it a point to turn it off for such shots now and I have never seen this happen since. I took a lot of shots that night and only a couple showed this effect. The SR moves the sensor and its possible that something could cause the sensor to adjust for shake when it doesn't need to and ruin a shot. The manual makes it a point to mention this but for whatever reason some people choose to not believe it.
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