Use of converters
 

Can anyone tell me if there are any hard and fast rules re settings for the camera when using a 1x4 or 2x converter.I know that light stops are lost etc,and that it is probable better to use a 1x4 than a 2x.Would it help to increase the iso settings.Camera used is a 20d and at the moment a 300F4 is lens.But I would like to change to the 400(non is lens) and hopefully try using a 2x converter.But I have never had any success with this converter,so before selling it,would like to see if I can take any decent images,on a bright sunny day ie.
I am not familiar with extensive camera settings,I just tend to use the P mode,and change the iso when needed.
Any tips would be appreciated.
Many thanks,
Christine.

Increasing the ISO setting will be beneficial in that you can get the shutter-speed that you would've had without the teleconverter added... and with the increased magnification, shutter-speed will be even more important.

If the light conditions allow, it's always worth stopping down the aperture as well to give a sharper subject... that's why I'd usually suggest using the camera in AV (aperture priority) mode, then you have a bit more control.

By and large, you shouldn't need to delve into the settings any more with a teleconverter added, its mainly a case of having to have more stability.

cheers
Andy

Andy,many thanks for a simple explanation.Just one question please,stepping down the aperture,does that mean the F stops,and how many stops would you suggest for a bright sunny day,using the 1x4 on say the 400F5 (non is lens).Now you have given me a few tips Andy,will read the cam manual and check out apertures.
Thanks again.

Hi Christine,

Andys comment on shutter speeds is very relevant.

If you can tear yourself away from taking pictures of birds for a while, you can do a few test shots to view on your screen.

Three seperate tests here.

1) With some converters there may be a softening of the image at the sides at full aperture and stopping down one or two f stops will solve that.

So for this you will need a flat object that has detail that would show this effect. A flat panel fence, brick wall, or similar. You MUST tripod mount your camera so there is no shake, line the camera up as square as you can. Select aperture priority and start at the widest aperture. Take a pic. Select 1 stop down and take another, etc So your range would be f4 followed by f5.6 and then f8. You should not need to go further than this.

2) Select an object that has depth and would record sharply in a picture. Even something rested against a brick wall will do here, broom handle is ideal. This test is to show The effect stopping down your lens will have on the zone of sharpness. Set yourself up at least 20 feet away at a fairly sharp angle. Again this is a tripod job. Focus on that object. Set up as before. Aperture priority. f4 then f5.6, f8, f11. When you view these images you will see the zone of sharpness increases as the lens is stopped down.

3) Your the effect of shutter speed when handholding is the last one.

As your set up will greatly magnify your subject so it will also magnify the effect of camera shake. For this any object with sharply defined detail will do. Set your ISO to at least 200, camera on shutter priority, take a set without your converter going from 1/1000 down to 1/250. Repeat with the converter attatched. This should show how slow you can afford to set the shutter speed and handhold for sharp results with your telephoto and with converter attached.

With those results in, it is a case of setting an ISO rating that will allow the setting of sufficent shutter speed for shake free, and aperture to achieve your desired zone of sharpness.

You just have to tear yourself away from the birds for a bit to do it !!

Don

Don,many thanks for the detailed info.Yes,there is a house opposite us ,across the river,which has a red and white lifebelt hanging on the outer wall,so I can practise on that.I will have plenty of time to practise whilst I am waiting for the 100-400 lens to return from the repair people.I think I will still have time to fit a few birds in though!!!.
Again,Don,many thanks,your time and expertise is very much appreciated.

Christine,

Its well worth doing just to help your understanding. It will show what you personally can do hand held. I have read comments about how low a shutter speed has been used. I know my limitations and I'm not that steady. A bit like bins. I was doing a comparison test for someone on BF. I mounted them on tripods to get a direct comparison at various views. Got a field over the fence and a wood about 400 yards beyond. Dare I say it here ... a pair of Goshawks occasionally. Well the upside is I was amazed how much more detail I could see within the wood when tripod mounted, and these are 8x. Never underestimate support. If you hand hold go for the highest shutter speed you can.

Your tests will show that though.

Don

A rule of thumb that I'm sure you have heard is that, for hand holding, shutter speed should be 1 over focal length - a 300mm lens should be a minimum speed of 1/300 second.

This is complicated by 2 things in your case. the 20D's crop factor of 1.6 and the use of a teleconverter ... so:

with the 1.4x teleconverter minimum shutter speed for hand holding: 1/672 second
with the 2x: 1/960

With your 400mm lens these speeds become: 1/896 and 1/1280.

Don't think for a moment that these speeds are on the high side. Remember, you are talking about what has become a 1000mm lens! That's 20x (would you even consider hand holding your scope?)

And as Andy mentioned, stopping down a bit is a good idea. Doing so, it becomes very difficult to obtain these speeds! You will also likely be using manual focus. With all these factors it becomes just about a requirement to use a tripod - and a remote release and mirror lockup is a good idea too.

This is the level where digiscoping takes over from SLR's.

Don and Jim,thankyou for info.Jim,I think I may pass on the mirror lock up,although I have heard it can prevent vibration.But as Don has mentioned ,yes a tripod,must be used,as the 400 lens does not have is,and also I believe it will not auto focus with the converters,so manual focus (in my case),needs a tripod.I am going to start practising next week using the 300 lens .

Hi Christine

I believe the Canon 20D multiplies the focal length of a lens by 1.5 or thereabouts due to the image sensor size, if this is correct then your 400mm f5.6 lens becomes a 600mm f5.6. If you now add a 1.4 converter it becomes an 840mm f8.0 lens. Very useable for wildlife etc.

Hope this is usefull.

nirofo.

thanks,Nirofo,yes,that is interesting.The 1x4 will be all that is needed,as the 2.0 will lose too much light.But f.8 is not very good,so hopefully one may be able to drop the f stop down, to f.4 if this is possible.