Full frame lens?

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craig223

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Craig
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Hi,
Hope this makes sense? I am quite new to photography (and this forum), I have a Sony A350 and am currently on the steep learning curve that is photoraphy! Whilst searching here for anything sony related I came across mention that a particular lens was not full frame. Apart from focal lengths/ apertures etc I thought a lens was a lens so to speak?

Here is my point. I plan to buy an A900 (or whatever Sony have by the time I have saved and have the experience to jusify it) So do I have to worry about the lenses I have now or may buy now for my A350 not being compatible with a full frame camera?

Will it make a difference? Will I have to repeat lenses for a full frame camera?
How do I even tell what lens is full frame or not?
Lenses I have now are the stock 18-70. Tamron 18-250 F/3.5-6.3, Tamron AF70-300 F/4-5.6Di and a sigma 300-500 (can't remember the other details of it).
Thanks in advance
Craig
 
The term 'full frame' lens refers to fact that the size of the image it projects is large enough to fill a 35mm film frame. For cameras with sensors smaller than the 35mm frame, the lens diameter can be reduced, because the image needed to be projected onto the sensor is that much smaller, thus meaning that less glass is used, less work etc. so that the lens can be made more cheaply. If a non-full frame lens is used on a full-frame camera, it will generally leave dark edges around the image. These could always be cropped off, of course.
 
Hi Craig (and welcome).

Some lenses are only appropriate for a cropped sensor (with Sony it's DT lenses I think) and such lenses won't fit onto full frame..or if they do they won't be suitable for the full frame sensor. I might be mistaken, but non DT Sony lenses might work with all Sony's. Your 18-70 will probably be a DT lens and not suitable for FF..the rest I don't know, but a quick google on them could probably tell you. I am sure a more expereicned togger will be around shortly to give you better info than me!
 
As a very rough guide, any lens that begins with 17 or 18 as the wide end, will generally be for a crop sensor, those that start at about 24 or above are for full sensor.

Lenses designed for full frame will work on a crop sensor, but lenses designed for a crop sensor will not work on full frame, basically the are too close to the mirror and will get hit by it when the shutter is fired, therefore making a grown man or cry.

With the lenses you have, the 18-70 and the 18-250 will not work on a full frame. The 70-300 and the 300-500 will work on full frame.
 
Most dSLRs have a sensor smaller than the area of film exposed in a 35mm SLR and in the early days manufacturers had few, if any, lenses designed for the new format.

Designing specifically for a smaller sensor results in a smaller and lighter lens and completely new lenses were required at the wide angle end, anyway.

Users of film cameras could use their existing lenses on digital bodies with varying degrees of success. As the outer regions of a full frame or medium format lens aren't required to cover a cropped sensor, images from a perhaps below par lens could be expected to be sharper.

Some full frame cameras will switch to allow the use of crop-sensor lenses. You could also crop the vignetting (dark corners and edges) yourself, in an image editor. That is if you particularly want to continue using the lenses in question, rather than relegate them to a 2nd kit.

From your Tamron lenses, the 18-250 is a "Di-II" type, for cropped sensor. The 70-300 is a Di, so can be used on full frame (including the later Minolta film cameras).

Most telephotos (long focal length) are OK for full frame, and so should your Sigma. Sigma use the designation "DC" for lenses which are designed for cropped sensors.
 
Thanks guys,
I have googled as suggested and the issue of vignetting was mentioned, which is croppable but the mechanical issue of protruding further into the camera not!
I have just compared the 18-70 with the 70-300 and there is about 4mm difference
which I had never even considered! Had I have got that far down the road and actually done that I would have definately cried! - I have much to learn!!
 
While the Sony A900 is compatible with the company's DT-series lenses, many of them, if not most, will vignette significantly with the full frame camera, since they were designed to deliver a smaller image circle to the company's APS-C format cameras. When a DT lens is mounted, the camera automatically captures an APS-C sized frame. Only four thin brackets inside the viewfinder indicate where the cropping will occur; it does not gray-out as seen on the Nikon D3. Incidentally, you can choose to shoot an APS-C sized image when a full-frame lens is mounted in Settings menu 4.

From: http://www.imaging-resource.com/PRODS/AA900/AA900A.HTM
 
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