No apeture number

[madrunner]

I have an Alpha 200 DSLR and have purchased an Opteka 650 - 1300mm F8-16 super telephoto zoom lense. The information on Amazon indicated it was ok for the camera.

I am having trouble setting it up

.

When I attache the lense to the camera, switch to maual focus and set dial to M, looking at the screen there is no aperture reading, turning the dial makes no difference. I can alter the shutter speed, (av button and dial) with no problem.

When I take a photo the result is what appears to be an over exposed shot, i.e. all white.

Can anyone help and guide me to set aperure and get a correct picture.

OR is the lense just not compatable

Madrunner

PS with regard to my last question, I would like to thank the person who replied to my question, tried using reply on their message but message was returned as undelivered. mr.

[Watashiwateshdes]

From what I remember from seeing these lenses, the only adjustment part is the zoom ring so assuming that at 650mm it is resulting in a f/8 aperture and 1300mm is yeilding f/16.

You may need to fill in some blanks but this lens does not have any electrical contacts between the mount and the body?

The option that you will need to undergo is dropping your ISO right down if your shutter speed is high enough or raise your shutter speed even higher. The over exposure is going be caused by you. The camera is only reading the light so you need to use the exposure needle to help you ensure that your exposure is somewhere more acceptable.

If you have already done this, please could you provide a sample unedited image. Ideally just a small jpeg straight from the camera. Much easier to explain and help from that.

[Mick2011]

I think this lens uses a T-mount, so there'll be no electronic contacts as such, but it should be compatible. I'm surprised to hear you have very over-exposed shots; the lens is exceptionally dark at f8-f16 and needs a very bright day before you can even see to focus easily. Assuming it's mounted properly, I think you must have used some auto exposure setting, or something in the order of a 1 second exposure, to get a white-out frame..

Making sure the lens mount is properly engaged, and switching everything to manual (focus, exposure mode, ISO, etc) would be the first steps. You then have to figure the exposure manually, as the camera won't be able to give you a light reading. As Watashiwateshdes says, all the camera will do is record the amount of light you set it to receive.

The best way of finding the right exposure is to just.. guess! Fortunately, there are a couple of ways of 'reckoning' exposure according to your subject and conditions. Way before built-in electronic light meters, photographers used the 'Sunny 16' rule which assumed a fixed shutter speed, altering the aperture (f-number) according to the amount of sunlight.

You can adapt this rule to your fixed aperture lens by altering your shutter speed instead. So with your camera zoomed in to 1300mm you have f16, which on a sunny day at ISO100 means your first test should be around 1/100s. If it's too dark, select a longer shutter exposure; too bright, select a shorter one. Or raise/lower the ISO.

Remember that taking shots of the moon (which will be fun with this lens) needs exposures in the order of several seconds, with a higher ISO of between 400 and 1600. And a very steady tripod. This goes for most subjects: you will always need a sturdy support for this lens if you want consistently sharp photos.

Remember the lens will become gradually darker as you zoom in, so exposure will have to change as you move through the zoom range.

Shout up if you need any more help.

Cheers

Mick