Unsharp photos at 840mm using 1.4x teleconverter

[george013]

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

Why making simple things so difficult?

First the angular movement itself is not important, but the movement per time interval. So let's say the camera moves up and down, left to right with 0.25degrees/second. So will the image on the sensor too. And one can translate that to mm/sec. If you can change your camera from FF to DX, the moving of the image will stay the same. And since she is using one camera, a difference in sensor density is not involved.

She is comparing the quality of the lens and converter and tripod. Looking at a line to be sharp. No framing involved.


George

[William W]

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.

There is relevance and there is association - even if one is using a tripod.

Except you’ve also got to add the factor of the smaller sensor (x1.6) – maybe I think that’s what you meant by doubling it - you assumed that most people use APS-C cameras and the Rule of Thumb is for 35mm Film Cameras, so just double it to be safe.

BTW there is an hint of science (maths) in that old Rule of Thumb. I can’t lay my hands on the document at the moment but my memory tells me the earliest record of that Rule of Thumb was in Popular Photography published around the mid 1930’s. The article discusses hand held portraiture at typical Portraiture distances of about 15 to 20ft and, if one works the calculations backwards using a 135mm lens, an 80 mm lens and a 50mm lens, the Shutter Speeds 1/150; 1/80 and 1/50 sort of fit to what would be “acceptable” to not showing any blur in a ‘typical sized’ print (postcard size then) even for an ‘unsteady’ Photographer’s hands.

***

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.

I concur. It would be good to try it.

What I have found is there is sort of a factor of diminishing returns as the FL gets really long (and perhaps the lens gets heavier and/or more cumbersome).

I have not quantified it, but, to give an example might help – using 5D Series Cameras, I can consistently pull hand held a Tv = 1/400s for a Subject at 25mtrs using a 300mm lens and get acceptable images for good enlargements without using IS. (roughly the 1/FL Rule).

If I engage IS then I can drop to 1/100s for the same shot, so we can say that IS is worth to me “at least 2 Stops”. (There is a reason why I often choose not use IS and that's why I know these facts about what I can do without using it, but that's another story.)

If I plonk a x1.4 Tele extender on the 300mm lens, then to make the same consistently good shots (hand Held) I need Tv = 1/1250s or faster for the same consistency. i.e. I require a little bit more than 1/FL rule.

Note also my preceding comments about the FRAMING – if I am still shooting Subjects at 25metres because I use the x1.4 extender to “get closer”, then the length of any blur will be greater if my hands always tremble at the same rate . . . and remember that the extender as well as adding length also adds a little bit of “wobble” to the camera/lens connection.

So if I engage IS, I still will get a good "2 stops worth" but . . . the longer, heavier, worse balanced, more wobbly lens construct means that I still need a relatively fast Shutter Speed when I am Hand Held.

I have no idea how "efficient/effective" the Tamron VR is, but at 600mm plus a x1.4 on an APS-C Camera that is very "long" - but I agree I would certainly give it a go hand held with the VR engaged, but I suspect the necessary Tv will be very fast, nonetheless.

It's very interesting.

WW

[William W]

Why making simple things so difficult?

Not difficult.

***

First the angular movement itself is not important, but the movement per time interval.

Correct - that's why, (please read again) -

"Let's assume the camera moves 0.25 degrees during the time of the Shutter Release"

***

If you can change your camera from FF to DX, the moving of the image will stay the same.

Indeed correct.

And in the example given it will appear as 131mm at the Plane of Sharp Focus.

And (this is the key point George) . . . if the Subject to Camera Distance remains the same, then the BLUR will take up MORE SPACE in the image made by the CROP camera - hence it will be more noticeable.

WW

[Mike Buckley]

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.

I've always understood that to be true but I've never seen it explained so clearly. Thank you!

[John 2]

I can only comment from experience Terri and I certainly can't join in the technical discussion above but I used a high end 1.4x converter with the Tamron 150-600mm zoom for about 18 months. In trying to get the best out of the combination I became aware of the fact (apparently) converters work best with fixed focal length lenses and are known to produce inferior results with zooms. Not a universal statement because some Canon and more recently, Fuji zooms have dedicated converters that produce excellent results. That apart, I found that the weight of the lens plus converter meant that it tended to "settle" on the tripod after the head is locked off. This made framing difficult and lacked stability particularly with the lens at full stretch even with a robust carbon fibre tripod that I ultimately acquired to try and improve matters. I finally started to get acceptable results when I resorted to a bean bag as a support. It is stable, quick to set up, light to carry and inexpensive. The tripod only gets a look in for table top and out in the field when there isn't a suitable platform to support the bean bag. The bean bag is a joy to use for instance, in a hide where tripod legs tend to get in the way of everything as you move around. Hope this helps.

[george013]

Not difficult.
....
And (this is the key point George) . . . if the Subject to Camera Distance remains the same, then the BLUR will take up MORE SPACE in the image made by the CROP camera - hence it will be more noticeable.

WW

If the blur takes 10 pixels in crop mode, than it will take 10 pixels in FF mode too. Using the same camera of course. In both situations the blur is 10 pixels. And when viewing on the monitor at 100%, 10 pixels become 10 pixels.
You're talking about printing to a same size. Yes, than the crop image has to be enlarged 1.5 or 1.6 times, and also the blur. But NOT when viewing on the monitor at 100%. And that's what one does when examining a new gear, viewing at 100% on the monitor. The "image sizes" are different.

But this wasn't the question of ts.

George

[Polar01]

Terri I am providing a link to a you tube video on Sharpness with long lens, I found it very interesting, I am looking at getting either the Nikkor 200-500mm or the new Tamron 160-600 in the future. Every piece of info helps, and as I said I found it interesting.

https://www.youtube.com/watch?v=n8HVPrPzpR4

Cheers: Allan

[rpcrowe]

I would NEVER use a "sandbag" simply because the chances of a bag full of sand leaking its contents onto your equipment is well within the realm of possibility, even likelihood. I will use pea-gravel for the same use (weighting down the equipment). The chance of pea-gravel leaking from your bag are (due to the relative size of the gravel) is far lower. And... even if some of the gravel gets out of the bag, it certainly will not damage your equipment...

IMO, the absolute best mount for a long lens is the Manfrotto Gimbal Mount... Yes this is a great mount but, it suffers from Manfrotto's very poor marketing. Not only has Manfrotto changed the name of this mount several times, since I purchased mine several years ago, they use it in what I consider an upside down fashion.



I use mine in this configuration. Not my image but, I included it because it shows using the Sig-Monster which can be 800mm.



Manfrotto also is fairly stupid is touting that their gimbal cannot be used with a flash. It certainly can, with just a slight modification by adding a strip of aluminum stock. As in this illustration (not my image)



The Manfrotto gimbal comes equipped with a long plate mount which you use to configure your camera/lens back and forth so that it is balanced.

When I purchased my Manfrotto mount, it cost less than $100 USD from B&H. It is now more expensive
https://www.bhphotovideo.com/bnh/con...C&A=details&Q=

BTW: this gimbal is also just great for shooting a long lens on a monopod because:
1. you can balance the gear by moving the lens/camera body back and forth
2. you can hold one side of the Gimbal "U" to support your rig

BTW: I use my Gimbal with a Giotto's MT8180 carbon fiber tripod...

[Manfred M]

Terri I am providing a link to a you tube video on Sharpness with long lens, I found it very interesting, I am looking at getting either the Nikkor 200-500mm or the new Tamron 160-600 in the future. Every piece of info helps, and as I said I found it interesting.

https://www.youtube.com/watch?v=n8HVPrPzpR4

Cheers: Allan

Thanks for posting Allan.

While Moose Petersen is an excellent wildlife photographer, I don't think he fully understands what his technique does and how perfecting it will result in a lot of blown shots. By putting his hand on the lens barrel, he is adding mass and through that damping out vibrations. Likewise pushing his eye / head against the viewfinder will result in increase of mass and additional clamping on the setup.

I wonder if he knows that shooting in LiveView will also help, as this reduces the movement in camera significantly as the only moving element is the relatively light weight carbon fibre shutter, rather than the whole mirror assembly?

[Manfred M]

I would NEVER use a "sandbag" simply because the chances of a bag full of sand leaking its contents onto your equipment is well within the realm of possibility, even likelihood. I will use pea-gravel for the same use (weighting down the equipment). The chance of pea-gravel leaking from your bag are (due to the relative size of the gravel) is far lower. And... even it some of the gravel gets out of the bag, it certainly will not damage your equipment...

Lead shot is even more effective as it has all the advantages of pea gravel and has a far higher density. I use my flexible dive weights, which are filled with lead shot, in my sandbags, so don't have to worry about handling the individual pellets. That being said, this material is a lot more expensive than pea gravel, but I already own it.

I do have a couple of super heavy sand filled bags as well, but only use them on the base of the tripod or on light stands where I don't worry about a bit of sand getting out.

[John 2]

I would NEVER use a "sandbag" simply because the chances of a bag full of sand leaking its contents onto your equipment is well within the realm of possibility, even likelihood. I will use pea-gravel for the same use (weighting down the equipment). The chance of pea-gravel leaking from your bag are (due to the relative size of the gravel) is far lower. And... even it some of the gravel gets out of the bag, it certainly will not damage your equipment...

Where did a "Sandbag" come into the equation Richard (or have I missed something)? If you are referring to my recommendation to use a "BEAN" bag to rest on, the beans in question are in fact polystyrene beads. See:

https://www.amazon.co.uk/Prefilled-W...bag+for+camera

I agree that a gimbal mount is very effective, particularly for BIF and I have one but frankly it is about 10x - 15x more expensive than a bean bag and it, with the tripod and a long lens is a heavy burden to cart around the countryside.

[terrib]

Wow, that's a lot of info to digest with my first cup of coffee! Thank you all for your responses. Let me try to answer some points/questions that have been raised. Then, I will conduct some more tests today and post some results.

1. The mount to tripod is via lens foot w/built in arca swiss "plate"
2. The head is a gimbal style Jobu Jr rated at 10lb (my camera lens combo is less than 8) It was locked down in all directions.
3. I did not use mirror lockup or sandbags or other weights and weights would only be practical for testing as I won't be adding them to my load out in the field.
4. First shots outdoors were with clear skies, temp in 60's, no heat waves. Subjects (Canada Geese) were close enough to fill the frame at 840mm.
5. I am shooting wildlife. I've been doing it a while and shoot mostly at 400 or 600mm and usually handheld or resting on a bean bag. I spend a lot of time researching my subjects and doing whatever I can to get closer so I can use the 100-400 lens as it is easiest to handhold. This setup with the 1.4x is for those times when there's the opportunity to shoot something but it's not practical for me to "get closer". It's not a crutch for me. I had already assumed I'd need to be in a locked position, that tracking moving subjects wouldn't be practical.
6. Center column is always down when I use the tripod. But my shots so far have been with legs extended.
7. I can get acceptably sharp images handholding at 600mm (without the 1.4x). When I ordered the 1.4x, I didn't think it unreasonable that I'd get sharp images if I used it on a tripod. I need to do more tests in controlled conditions but I found the autofocus failed/hunted more often if I tried to handhold. Autofocus is slow on the tripod but acceptable with much fewer instances of hunting.
8. Now for the most important point - SS. My outdoor shots of the Canada Geese were not controlled tests. But I had many shots set up as I've described with SS ranging from 1600-8000 which failed. There are a few where focus was just in the wrong place but most were blurred throughout. Thus my first thought that the 1.4x was not focusing properly. Then I found an eagle perched about 200yds away but the light was fading so to be able to see if it was focusing, I used Live View and realized how terribly shaky the setup actually was. Using 2 second timer wasn't long enough (I didn't have my remote sr). Using autofocus and 10 second timer yielded several in focus shots, although grainy given the 6400 ISO. That's when I wondered if the whole problem was shake rather than a focusing failure of the 1.4x and decided to do controlled tests. However, I had to do them indoors due to wind. So the tests I did yesterday did show that with a remote shutter, the 1.4x focused correctly every time. But my shutter speeds were not high enough to resolve the question of whether I can get sharp shots without the remote. They were high outdoors but those weren't controlled tests.

So back to the testing if I can manage to find enough light out of the wind. I will come back with results. (Sorry this is so long but y'all had a lot of points!) Thank you.

[John 2]

Terri, I would never carry weights around the countryside. The "Bean" bag I referred to is to rest the lens on not to stabilise the tripod.

[terrib]

Terri, I would never carry weights around the countryside. The "Bean" bag I referred to is to rest the lens on not to stabilise the tripod.

Yes, I knew what you meant. Thanks. I was referring to the sandbag discussion.

[Saorsa]

Terri, I would never carry weights around the countryside. The "Bean" bag I referred to is to rest the lens on not to stabilise the tripod.

Agree, lugging weight for the sake of lugging weight is pointless. I actually hang my carry bag from the hook at the end of the center column. An alternative is a supermarket plastic bag which you can fill with rocks or dirt.

The Tamron is f6.3 at the long end. The 1.4 TC may move the aperture out of range for AF operations and you may be getting spotty results from that fact.

[terrib]

The Tamron is f6.3 at the long end. The 1.4 TC may move the aperture out of range for AF operations and you may be getting spotty results from that fact.

It may be but Tamron's website compatibility chart says autofocus will be maintained with the camera/lens combination I am using. The max aperture at the long end goes to f9.

[NorthernFocus]

...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...

Welcome to the world of long optics, Terri. Sometimes ignorance is truly bliss. The first time I used live view to set for tuning a 500mm lens I was shocked at how much shake there is. And I use a high quality tripod, RRS lens foot, Wimberly gimbal, etc.

William W's first post is full of good advice. I'll repeat some of it. Another good bit is the recommendation of using a bean bag. Even if mounted atop a tripod.

A better/heavier/more solid tripod does help but doesn't "solve" your problem. Probably the biggest improvement to a tripod is to get one that is tall enough to use without a center column. That type pod is inherently more stable both geometrically(legs spread wider) and mechanically. The single biggest practical improvement that can be done is to increase the weight of your setup. That doesn't necessarily mean the tripod itself has to be heavy. Most pods have a hook under the top where the legs join. You can use the hook to hang weight. The simplest thing is to hang your camera bag. A jug or plastic bag full of water/sand/rocks also works. In my case I often shoot with a second body w/70-200mm lens and I hang it there where it adds weight to my rig and is readily available when needed.

Good technique is somewhat counter intuitive. We have a tendency to keep our hands off of the camera, barely touch it to press the shutter, use a remote release, etc. That all works great with a landscape kit. But with a long lens the opposite is needed. As was pointed out already via the link and Manfred's comment, you can effectively add weight by using your off hand to press down on top of the lens while firmly gripping it with your shooting hand. For me this method also makes it easier to smoothly swing the lens for tracking birds in flight.

Another thing that is counter intuitive is that VR/IS works better if you are holding onto your camera than it does when using a remote release. Generally speaking the electronics work better when there is vibration to correct(like shaky hands). Recall that(for that reason) with the early gen VR/IS systems manufacturers instructed us to turn it off when on a tripod.

Most importantly, as William W recommended, keep ss as high as possible. With a 500mm lens and FF body I try to stay at/above 1/1000s. I'll increase ISO(up to a point) before dropping ss. And when I do go lower on ss I turn on VR.

So to summarize in order of priority:

1) keep ss as high as possible and use VR/IS at lower ss
2) learn/improve technique for steadying the rig with your hands/body
3) use a bean bag if/when possible
4) hang weight on the tripod
5) get a tripod w/out a center column

[george013]

Do I understand you? Does a timer of x sec means a delay of x sec?

George

[NorthernFocus]

Wow. While I was typing there were several more posts including your response, Terri.

Simply put, based on your additional input in the recent post, yes your issue is vibration. You just have to figure out which thing works best for you to get rid of it.

[Mike Buckley]

Wow, that's a lot of info to digest with my first cup of coffee!

Wait until this evening and digest it instead with a glass of wine. The more glasses you consume, the easier the information will be to digest. Whether or not you remember any of it the next morning is irrelevant.