Unsharp photos at 840mm using 1.4x teleconverter

[terrib]

I've recently purchased the G2 version Tamron 150-600 with the 1.4x teleconverter specifically designed for the lens. The 1.4x is advertised to have autofocus when used on a Canon 7dII. The lens alone is performing quite well. The autofocus with the 1.4x is slow and requires decent light and I believe contrast to get focus. This was expected. However, even in good conditions my photos are not sharp.

I suspected camera shake, so I set up some controlled tests. On the Tripod with VC off (as the manual instructs). I compared photos taken with a remote shutter release vs pressing the on-camera shutter release and as I suspected, the lens is not missing focus but rather there is significant shake to the camera if I don't use a remote shutter. As you'd expect, it is more noticeable at the long end. But I was rather surprised to find how much difference at the short end. As an aside, I did test with the VC on mode 1 and results were similar. My tripod is a Manfrotto 055xprob. Not a $1000 Gitzo by any means but still not a cheap tripod. I made sure everything was locked down securely. In trying to figure out where the shake was coming from I put it Live View and zoomed in on my subject. It didn't seem to matter where I touched - camera, focus ring, shutter release or legs - there was vibration.

My question is this:

Is it just a given when you get to that long a focal length (840mm on a crop sensor) that a remote shutter release is required? Or does all that extra money spent on Gitzo or RRS legs solve that problem? I don't know that I could ever justify that kind of money on legs but I'm curious.

I've never purchased a teleconverter before because it seemed the limitations didn't justify the expense. At this point I'm thinking my use on a tripod, with a remote shutter, in great light is limited so I may very well be returning it.

thanks all for your insights!

[Stagecoach]

Terri,

Did you use the 'mirror up' function?

Edit...........

I also use the same tripod BUT when using the heavy camera/long lens/TC combination movement is also caused by the lens bracket, head and TC mating face all of which are affected to varying degrees by mirror slap and breeze.

[Saorsa]

Have you tried hanging some weight from the tripod to increase it's mass vs. the camera/lens?

That can increase stability.

Another concern at long FLs is atmospheric distortion.

[Shadowman]

You could try a device such as this to also stabilize the camera body, not useful for quick moving subjects but could help answer your question. There are cheaper devices available.

https://www.bhphotovideo.com/c/produ...C1105202454760

[Black Pearl]

Have you considered using a shutter speed suitable for the focal length in question?

[rpcrowe]

You might look at these setups by Romy Ocon of the Philippines....
http://www.pbase.com/liquidstone/16x_tc

I noticed that he uses a Manfrotto Gimbal as his connection between camera and tripod... I have one of these and it is solid as all get out.

[Pippan]

Could atmospheric conditions/heat haze have anything to do with it at such a long focal length?

[Shadowman]

Have you checked this review?

https://www.youtube.com/watch?v=D0RCvRdHdbM

[Manfred M]

Terri - 600mm x 1.4 (teleconverter) x 1.6 (Canon crop factor) - 1344mm FF equivalent! This is just crazy. No wonder you are having issues. Add that to the Manfrotto 055xprob and even though Manfrotto call it a pro, it is a popular entry level aluminum level tripod (the price gives it away, honestly). I've used that series of tripod and it is not the most rigid unit around, especially if you use the column at all. No wonder you are having issues. Just breath on that setup and you are going to introduce camera shake! That tripod is only rated at around 15.4 lb; that tells me that it is not particularly rigid.

My first question would be what are you shooting to need that long a lens? My initial gut reaction would be that you should be a lot closer to your subject so that you can get away with a shorter focal length. Vibrations and atmospheric distortion are simply going to be a fact of life with your setup.

It has nothing to do with Gitzo (which by the way is owned by Manfrotto and made in the same factory), RRS, Novoflex,etc. It has to do with the robustness of the tripod and of course the head. Carbon fiber damps out more quickly than aluminum. A column free design is much more rigid that a tripod with a column. Large diameter legs and few sections tripods are going to be more rigid than ones that have more sections and smaller diameter legs. You are doing extreme shooting, so you should consider a a tripod and head designed for that level of work. Just as an aside, the tripod I use for extreme work is rated at 66lb (Feisol CT-3372) and my ball head at 50lb (RRS BH-55). I sandbag it for critical shots and remove the column and directly mount on the legs and don't use it for anything that even comes close to that focal length.

[William W]

. . . I suspected camera shake, so I set up some controlled tests. . . I was rather surprised to find how much difference at the short end. . .

My question is this: Is it just a given when you get to that long a focal length (840mm on a crop sensor) that a remote shutter release is required?

No, a remote Shutter release is not "required", but it is useful: Mirror up; Center Counter-weighted Tripod; Sandbag dampening; Mounting via Lens' Mount, etc, are also useful techniques to use when appropriate and possible.

The salient point is, for all practical general photography purposes, when using a very long Focal Length the "vibration" which causes camera movement CAN NOT be totally arrested.

Therefore, whilst we can take prudent measures (such as those already mentioned) to arrest the vibration so that the Final Image does not show a blur - for any given Enlargement and Viewing Distance - often the most effective tool that we will have in our arsenal is the one which Robin mentioned - that is to know and use an appropriate Shutter Speed.

It can be very easy to forget the value of using an appropriate Shutter Speed, for the lens and camera combination, irrespective of Tripods, Image Stabilization; Remote Releases and all that other stuff.

***

Doing the tests you have done are very useful - and also quite enlightening, often doing these practical tests can dispel assumptions and some of the erroneous commentaries found on the www.

***

As a comment for a technique using that lens and a x1.4 tele-converter on a 7D MkII. depending on the Subject, in good light, much depends on the Tripod Head that you are using: no Ball Head that I know of will be suitable, I'd recommend looking at a solid Geared Head - that will be probably three times or more than the price of the Tripod.

Then -

Lower the T. legs to shortest extension
Mount the Lens, not the camera
Do NOT extend the centre column
Three sandbags on the Tripod feet
Small sandbag on top of the centre of the lens
1/2000s would be a good starting point for Tv, I suggest that slower than 1/1000s would be dangerous
The use mirror up and the remote release

Another option is to shoot, without Tripod from ground level, prone; or with the camera and lens supported on a solid base, like a rock wall. In either shooting situation, A Big Sandbag is used as a base, you 'hollow out' a section for the lens barrel and then pack another Sandbag on top of and along the middle of the lens.

In either situation around 1/1000s would be my absolute slowest Tv, and that's based on practical tests similar to yours, my tests used a 100 to 400L and x1.4 and a x2.0 Tele-extenders on APS-C Cameras.

The 7D MkII is pretty good at 3200 ISO, so in good daylight to moderate-heavy overcast, ISO3200 will provide you a range of Aperture from about F/16 to F/8 at as Shutter Speed at or faster than 1/2000s.

That aperture range would be suitable for that particular Lens/Teleconverter application and the Shutter Speed would (I think) be reasonably safe: so, the point is, any quantifying of the shooting parameters starts at choosing the ISO to allow the necessary Aperture and Shutter Speed.

Personally, I wouldn't send back the Tele-converter - it is probably that you haven't given it a good chance to prove what it can do rather than it is not working correctly. On the other hand, I do envy the option that some people have to return gear if they change their mind, I mention that point in passing only - change of mind exchange or refund is not a universal given -

WW

[William W]

Terri - 600mm x 1.4 (teleconverter) x 1.6 (Canon crop factor) - 1344mm FF equivalent! The is just crazy. No wonder you are having issues. . .

Indeed.

Terri please consider my previous is conjunction with and as an addition to Manfred's comments.

Practical advice - I wouldn't buy any new gear, tripods heads or anything - use ISO3200 and a fast shutter speed and DAMP (i.e. sandbags or similar) the tripod you have and use the technique I described - or chuck the Tripod and try a brick wall and lots of Sandbags. . . but a FAST Shutter Speed

If you only have a Ball Head or any Head which if "floppy" then consider mounting the lens's tripod mount direct to the Tripod Centre Column ... I suppose if you do not have a Lens Tripod Mount that is one tool that you do really need.

Let us know how you get on.

WW

[Saorsa]

Indeed.

Terri please consider my previous is conjunction with and as an addition to Manfred's comments.

Practical advice - I wouldn't buy any new gear, tripods heads or anything - use ISO3200 and a fast shutter speed and DAMP (i.e. sandbags or similar) the tripod you have and use the technique I described - or chuck the Tripod and try a brick wall and lots of Sandbags. . . but a FAST Shutter Speed

If you only have a Ball Head or any Head which if "floppy" then consider mounting the lens's tripod mount direct to the Tripod Centre Column ... I suppose if you do not have a Lens Tripod Mount that is one tool that you do really need.

Let us know how you get on.

WW

Don't forget to lower the center column. It causes bad things to happen by giving the weight of the camera and lens a lever arm at the point of greatest stability.

[Saorsa]

Terri,

Can you post a couple of images that you made while testing the use of the remote shutter release?

[William W]

Aside:

Don't forget to lower the center column. It causes bad things to happen by giving the weight of the camera and lens a lever arm at the point of greatest stability.

Yes. Brian, I mentioned that in my Post #10.

Mentioning now, in case you were addressing your comment to me. Good to reiterate to Terri anyway.

WW

[george013]

When analyzing a photo on the monitor at 100% the crop factor isn't an issue. The motion blur for a ff and a crop sensor is the same.

George

[dje]

Just as a matter of interest Terri there used to be a rule of thumb for hand held 35mm cameras that said "use a shutter speed equal to the inverse of the focal length". So if you had a focal length of 840, then your shutter speed should be 1/840 sec or faster. Since digital has taken over, some people have extended this rule of thumb to require the shutter speed to be twice as fast as that predicted from the focal length calculation. These rules have no scientific basis but get you in the right ball park. In your case, that would suggest a minimum shutter speed of 1/1680 sec. This supports Bill's 1/2000 sec figure.

Incidentally if you are using a shutter speed this fast, I wonder whether you might be just as well off hand held with VR ON. Just a thought but you could easily try it out.

Dave

[george013]

Just as a matter of interest Terri there used to be a rule of thumb for hand held 35mm cameras that said "use a shutter speed equal to the inverse of the focal length". So if you had a focal length of 840, then your shutter speed should be 1/840 sec or faster. Since digital has taken over, some people have extended this rule of thumb to require the shutter speed to be twice as fast as that predicted from the focal length calculation. These rules have no scientific basis but get you in the right ball park. In your case, that would suggest a minimum shutter speed of 1/1680 sec. This supports Bill's 1/2000 sec figure.

Incidentally if you are using a shutter speed this fast, I wonder whether you might be just as well off hand held with VR ON. Just a thought but you could easily try it out.

Dave

That rule is meant for handheld. She is using a tripod.

Terri,
A long time ago there was a discussion here on balancing the gear. I did put a link in that discussion which was not liked by many people. I do it again. http://markins.com/charlie/report4e6.pdf. Read it, it explains a lot. For the practical issue you're dealing with now pay attention to page 4.

George

[dje]

That rule is meant for handheld.

Yes George, that's what I said in the first sentence of my post. I was merely trying to emphasise the fact that shutter speed is important to minimise the consequences of camera shake, however it is caused.

[Stagecoach]

What we don't know yet is what Terri is shooting. There's a big difference in technique and options available between shooting far away static buildings at night to small critters you need to track and be able to respond to fast.

[William W]

When analyzing a photo on the monitor at 100% the crop factor isn't an issue. The motion blur for a ff and a crop sensor is the same.

Disregarding resolving power; pixel density and other optic and sensor qualities; that statement is only correct if the FRAMING is kept the same for the two photos (i.e. if the Camera is moved farther away from the Subject to make the shot with the “crop” Camera).

However it occurs to me that as Terri bought a very long lens and also a tele-extender to use on her 7D MkII, then it is UNlikely that she will be moving farther away from the Subject to get the same framing as if she were using a 5D: in fact I think the opposite is more likely and the purpose of Terri buying this gear was to get as much of the Subject in the frame as possible – or in simple terms to get as ‘close as possible’.

Therefore, it is probably very relevant to explain why that statement is NOT true if the Subject to Camera Distance remains the same for two shots, one taken with a 5D (aka “full frame” camera) and the other taken with a 7D (aka a “crop” camera).

If we have an 600mm Lens (such as Terri has) and add a x1.4 Tele-extender and then use that on a 5D, then if the Subject is 30mtrs away, then the FRAMING at the Plane of Sharp Focus is about 1250mm x 833mm.

Let's assume the camera moves 0.25 degrees during the time of the Shutter Release, thus the blur length any edge of the Subject will be about 131mm (relative to the FRAMING dimensions). 131mm Blur is about 10.5% of the width of the Horizontal Framing.



If we now put that Lens and Tele-extender on a 7D and shoot the same Subject at the same distance of 30 metres, the FRAMING at the Plane of Sharp Focus is about 788mm x 524mm.

If the Camera moves the same 0.25 degrees during the Shutter Release, then the Blur length will still be about 131mm, (relative to the Framing) BUT that blur will now be about 16.6% of the Horizontal Framing and as such more obvious to the Viewer’s Eye.

So it doesn’t matter if the two images are viewed at 100% or whatever, if the Subject to Camera Distance is the same and the camera movement is the same, then the relative blur length will always be greater when using the “crop” camera.

WW