75-300 is usm

[Regulus]

These are some out-of-the-camera shots and sections. They are the unenhanced/unsharpened JPG's straight from the SD card. etc.

Taken on the Canon EOS600D with the 75-300 IS USM, which is the lens above the cheapie versions.

Aperture Preferred Auto at f9 (around 1/320sec) and tripod mounted.
I was testing auto-focus with/without the Image Stabiliser, and was interested to see that, with it turned on, over time (3~4 seconds) the image moves slowly a significant distance to the upper right, then slowly re-centres over the following 3~4 seconds. So images taken using the Stabilizer can have entirely different edges depending on when in the cycle you fire the shutter.
Thought that interesting.
But I publish these for Jenchris who seemed unhappy with the focusing performance of the 75-300 that came with her camera kit, so she can compare the performance of a lens that may be a few hundred dollars dearer, yet not the cream of the Canon crop.
I still don't know if the two have similar optical element configurations though.

The full frame shots are reduced from 5184px to 1200px and links are provided to Dropbox to download the full res versions if a closer look is desired.
1/ 75mm full frame 2/ section of 75mm 3/ section of 75mm
4/ 300mm full frame 5/ section of 300mm 6/ section of 300mm

The bridge in the 300mm shot is about 700-800 metres away,
The little Lighthouse in the 75mm shot is about 70mtrs, and the 'Origen' tank is more like 350mtrs

Full Res here:
75mm - https://www.dropbox.com/s/mp6fcr15hzti2i9/75mm%20Test%202.jpg?dl=0
300mm - https://www.dropbox.com/s/ue21g2zliehzk6d/300mm%20Test%201.jpg?dl=0

[Marios]

Hi Trevor

Thank you for putting together this post and sharing your images. The common consensus on any telephoto lens is to avoid pushing it to the extreme of either ends.
Here is online review if your lens you might find interesting..

https://www.youtube.com/watch?v=f-h32WxDtxM

[REVEREND]

Some nice shots there Trevor. I agree with Marios regarding the lens.

Cheers Reverend.

[PeterEde]

I had this lens and found it's sweet spot to be f8 otherwise it was soft.

[Regulus]

Thanks for the link Marios, and I agree with that sentiment, as well as Peter's comment regards the f-stop.
In fact I think I will test that as well to get a definitive answer to where the sweet spot is in this lens. I have known for decades that the extremes of aperture were never going to give the results I would like, and that zooms especially have sweet spots in the zoom range. Inevitable given the compromises made in the optical configurations throughout the zoom.
I have hardly used it so don't have a complete familiarity with it's performance so, I think a few more tests to cover aperture and focal length are probably a quick way to acquire the knowledge.
Thanks for your comments folks.

Trev
Some samples of the lens used at close range. This seems to be where it excels.
1. The Heron at 300mm f10 ISO200 at about 10mtres, and cropped from the centre of the image (about 25% of the total area, and resized to 1200px for upload)
2. Night Heron 300mm f9 ISO400 from 10mtres and a crop of the centre of the original representing about 25% of the total image size, then resized to 1200px

[PeterEde]

Nice shots Trevor . did well through the tree for focus.
The limitations of consumer lens are the sole reason as a photographer that I started buying L glass.
I found too often that consumer lens gave soft images. f8 seems to be the sweet spot for most of these lens but you can not always rely on f8.
Until people use L quality they don't understand that softness can be over come for the whole aperture range of a lens.
Today 50% of my lens collection is L glass and they are used 95% of the time.
Canon 24-70 L f2.8, 100-400 L IS f4.5-5.6, 100mm f2.8 Macro (Many say should be an L lens)
My worst lens for those tight/wide angles is a 10-22mm. It's crap but necessary with a crop camera.
L glass is not cheap. But if you love your photography they are well worth it.

[PeterEde]

Just noticed you said you had IS on while tripod mounted. It's a no no

small copy from photography forum

Image Stabilization is a great feature and is in my opinion well worth paying the extra dollars for – especially if you shoot a lot of lower light shots.
Having said this there is one time when you should definitely switch IS off because it will do more harm than good to your photos – when you’re using a Tripod.
Image Stabilization (and vibration reduction) lenses look for vibrations in your camera in order to reduce it – however if they don’t find any (like when you are using a Tripod) they actually can cause it – and as a result actually cause camera shake.

There are times when IS should not be used.
When using your tripod (as above) as IS is for reducing the shakes at longer focal lengths.
When panning shots at slower speeds. Otherwise you will cause the gyro to topple. this makes the image jump or give a double image.

There is a general rule of thumb to use when using any lens. Keep your shutter speed at least as fast as your focal length is set too. ie if zoomed to 200mm then set shutter to 1/200 or faster. you may need to increase iso to compensate.
This helps reduce how noticeable handshake can be.

Also I found dropbox to be a very lousy storage location when I used it. For my online storage I use flickr.com. Maintains your images in the quality they were uploaded.

[PeterEde]

Another page of interest Re Canon IS lens
Page 4 in particular says don't use IS on tripod.
http://cpn.canon-europe.com/content/education/infobank/lenses/image_stabilisation.do

[Regulus]

Thx Peter, I have started using Flickr too and having a free 1TB of storage there is very nice. Dropbox is usually only used for storing my mp3s, Tablature music for Guitar Pro and my android camera sends a copy of every photo there, whhich has been useful occasionally.
I'll try those shots again without tripod for the IS although, because the camera was body mounted to the tripod, rather than the lens, I thought the vibes I could see in Live View from hand firing the shutter would be enough for IS. But it's worth a second test to find out.
Thanks again for all the help mate.

Trev