Canon EF 70-200 mm F/2.8 series USM camera lens...help

[steve51450]

help

I am not that up on Canon lenses so i am a little unsure as which one to go with, so i thought i would list what i want it to do and with what camera.

I will either be using my qsi ccd camera with internal filter wheel and canon adapter so i get the correct back focus or a 35mm chipped ccd (if funds allow it will be the latter)

I want to do widefield to very widefield narrowband imaging and i want it to be sharp in the corners etc as well as be able to work with a full format not just aps size chip

I have looked at the Canon EF 70-200 mm F/2.8 series USM but i am unsure as to which model as they appear to do a couple.

L series usm

L series usm is

Am i correct in saying one is image stabilized and is this necessary for astro work mounted on another scope, does anyone have any experiance with this lens for astro

photography ?

Please excuse my ignorance. Scopes i understand but lenses are a whole new ball game

cheers

steve

[arad85]

IS is useful ONLY when you are handholding the lens and claims to give you an extra 4 stops worth of light before camera shake becomes important. If it will always be on some form of mount, go with the cheaper lens

[Coco]

don't bother with the 70-200 f/2.8 IS L . I have had both copies none IS and IS, neither is good enough wide open to get sharp stars and both suffer from chromatic aberation on stars, so does the 300/2.8 L also

My Sigma 100-300 f/4 EX DG at f4 matches 'my' previously owned Canons and shows very expectable star colours.

The 200 L prime is worth a look as is the 135/2 L but not good wide open , very good stopped down which to me defeats the whole point of owning a fast L lens.

Canon IS will only work on a Canon body.

My friend uses an old Tamron SP 70-210 Adaptall II lens with stunning results. his pictures taken wide open at f/3.5 are awesome. You can pick one of these up for around £60, These old Tamrons SP's are highly regarded.

Adaptall-2.com

Follow the link to SP ( tamrons 'L' equivelent )

Cheers

Guy

[Ben Ritchie]

I love the 70-200L for daylight photography (and would go for the IS for that, especially with the f/4), but it's not perfect for night use. There is CA (as Guy says) although that's not an issue for narrowband, and it's not perfectly flat.

I found a borrowed 135mm f/2 good at f/2.8, have some pics somewhere that i'll try and dig out. Not perfect in the corners but good enough that you won't notice unless you look, resampled to fit on the screen is fine. Most of the fixed FL lenses in the 50 - 200 range need to be stopped down a bit but are still very quick.

The 100mm f/2.8 macro is very sharp, and again CA isn't an issue if you're narrowband. The 50mm f/1.4 is well worth adding to your shortlist for very wide too, there's a f/1.2L version too but expensive. Or the cheap as chips 50mm f/1.8 (the "plastic fantastic") that works very well at f/2.8ish.

[steve51450]

thanks everyboby that has been most helpful

i can have adapters made so any lens will fit my ccd imager so one more question if you please

what are pentax lens like i think its the 6/7 range which is a very large format from what i understand, will i have less issues with these ?

thanks once again

[Catanonia]

Yes IS is Image Stabilisation and really not much good.

I would go for a good F1.4 50mm prime lens and step it to F2 on apeture to get best results.

[brianb]

Yes IS is Image Stabilisation and really not much good.

I would go for a good F1.4 50mm prime lens and step it to F2 on apeture to get best results.

Sorry but I'm going to have to disagree with you on both counts.

Image stabilization is excellent for hand-held shots. There is no benefit when using the lens on a tripod or other mounting but at least you can switch it off. In fact you should switch it off when not required as this prevents the gyro-stabilized elements from drifting, which can cause the appearance of camera shake in very long exposures when solidly mounted.

Canon IS lenses rely on electrical power through the lens/body contacts; if used to image without a EF mount compatible SLR body no electrical power will be available, the lens can only be used at full aperture as there is no aperture control on the lens, and IS will be disabled.

As for the 50mm f/1.4 lens - Canon's version needs to be stopped down to approx. f/4 before it delivers satisfactory star images. At full aperture there is gross coma, considerable astigmatism and a certain amount of spherical aberration - acceptable enough for hand-held available light photography but not, IMO, for AP. Get the EF 50/1.8 instead, it's not perfect either but it's also perfectly adequate when stopped down to f/4, and it's about a quarter the price of the f/1.4 version.

As for the 70-200 lenses - I have a 70-200 f/4L IS, and I've used it for AP, finding it excellent even at f/4, giving small sharp circular star images across the field of a full frame camera. For AP I very much doubt whether it's worth going to the f/2.8 version as, for most people, light pollution will restrict exposures to a few seconds even at f/4 unless anti-pollution filters are used. The extra cost of the f/2.8 version is very significant, as is the weight, something you'll really notice if you try to carry the lens on long daytime trips.

[Catanonia]

Ah, my F1.4 is Sony for my A700.

I stand corrected.

[brianb]

my F1.4 is Sony for my A700.

But 50mm f/1.4 from all the manufacturers are basically the same design, a six or seven element semi-symmetrical type developed in the 1960s ... it's one which might have been good at f/2.8 but has been "stretched" to give extreme speed .... You may be getting away to some extent as you're using a "full frame" lens on a "crop frame" camera i.e. throwing away the edges of the field where the worse aberrations are.

[Catanonia]

But 50mm f/1.4 from all the manufacturers are basically the same design, a six or seven element semi-symmetrical type developed in the 1960s ... it's one which might have been good at f/2.8 but has been "stretched" to give extreme speed .... You may be getting away to some extent as you're using a "full frame" lens on a "crop frame" camera i.e. throwing away the edges of the field where the worse aberrations are.

I do tend to crop out the outer edges when I process.

[steve51450]

thanks all for your help