I have a Sony Alpha 3000 and bought a Minolta Maxxum 75-300mm but I can't mount it on the camera. Do I need an adapter?
The Sony A3000 utilizes the Sony E-mount. Looks like the Minolta lens uses the older Minolta / Sony alpha mount. It's slightly confusing because the body is called a "Sony Alpha" but the mount isn't an alpha.
You can get the Sony LA-EA3 adapter which will allow you to utilize all the functions of the alpha lens on the A3000 except autofocus. It looks like that lens utilizes the older screw-type focus, which will require the LA-EA4 adapter instead to support mechanical autofocusing.
As lidocaineus says, the A3000 uses the E-mount lens system so an adaptor is needed for use with A mount lenses. However, as the A3000 has an APSC format sensor I believe the LA-EA2 (or discontinued LA-EA1) adapter will be suitable.
Buying a low cost 3rd party adaptor is a very good starting point (see below).
You can 'upgrade' to another adaptor in due course if required. You may well find that a $20 adapter is 'good enough' given cost benefit tradeoff. Details below.
What do I know?: I have not used an A3000 but own a Sony NEX 5N and have used a good range of A-mount lenses with a Sony NEX-5N and an LA-EA1 adaptor with acceptable to excellent results depending on what aspects are being considered.
Sony LA-EAx E-mount body to A-mount lens adapters:
- EA1 EA2 - APSC
- EA3 EA4 - full frame
- EA1 EA3 - very slow contrast focus
- EA2 EA4 - fast phase focus
LA-EA1 and LA-EA2 are for APSC sensor cameras.
LA-EA3 and LA-EA4 are for APSC sensor cameras.
LA-EA1 and LA-EA3 allow slower contrast detect focusing only.
LA-EA2 and LA-EA4 allow much faster contrast detect focusing.
The EA4 is substantially more costly than the EA3.
The EA1 is technically discontinued but can be obtained new and used on eg ebay.
The EA2 and EA4 achieve fast phase detect focusing by adding a partially reflective fixed mirror as in the Sony fixed mirror A-mount SLT cameras. This takes a half stop of light - not usually especially noticeable except in utterly crucial situations.
The LA-EA1-3 adapters will only autofocus "SSM" lenses with internal focus motors. They do not support the manual focusing drive in non-SSM (all older) A-mount lenses.
The LA-EA4 includes a focusing motor for older non-SSM lenses.
All the LA-EAx adapters support camera controlled aperture control of the lens.
3rd party adapters:
A good starting choice is to buy a low cost 3rd party adapter ($10-$30, ebay and elsewhere) that allows mounting of A-mount lenses on E mount bodies such as the A3000. These allow manual control of aperture and manual focusing of A mount lenses. These adapters are a glassless spacing ring with a control to access the lense's aperture control arm.
Very costly 3rd party adapters (Metabones et al) support various focusing modes.
No low cost adapters do (10's of $).
A few adapters in the $100+ range add the contacts necessary to aperture control and support contrast-focus in SSM (only) lenses but do not support phase detect focusing (which needs an 'out of body experience' in the form of a semi-reflective mirror plus phase detect sensors in the adapter.
Any 3rd party adapters that I am aware of will only autofocus "SSM" lenses with internal focus motors. They do not support the manual focusing drive in non-SSM (all older) A-mount lenses.
Only 3rd party adapters with electrical contacts support camera controlled contrast-focusing and aperture control of the lens.
Manual aperture control is not a major disadvantage when the camera is operated in Aperture priority mode. Instead of using the cameras's aperture control function the lenses control is used and the camera still automatically sets shutter speed.
Manual focusing (no AF) is not as great a disadvantage as might be expected due to Sony's (absolutely brilliant) "focus-peaking" system which adds a coloured overlay in the EVF showing in focus areas. This allows DOF to be viewed and focus to be set rapidly and with extremely good accuracy. eg at 10 feet using say 50mm focal length something like a flower stem can be brought into accurate focus with ease. Achieving the same thing by eye based on in-EVF sharpness is much slower, harder and less certain.
My NEX 5N with an EA1 adapter and an SSM lens will contrast focus but I almost always use manual focus-peaking due to speed of focusing, accuracy and the ability to view the DOF achieved (at maximum aperture). With manually controlled aperture (or aperture step down preview) you can see the actual DOF visually. Even with preview at maximum aperture, having the in-focus range highlighted allows you to visually judge the optimum focusing point (centre of hyper-focal distance) when a range of subjects are to be in focus. .