Sigma 70-300mm lens defaults to manual focus

Sorry, no. If it fit onto a Pentax camera then the lens has a Pentax mount. The Nikon (I assume you mean the D80 digital camera, or perhaps the N80 film camera) has a Nikon mount. Since the Nikon mount has a deeper flange distance than the Pentax mount, there are no adapters available to allow you to fit a Pentax-mount lens onto a Nikon camera.

have you tried cleaning the lens contacts with soft cloth?

ifnot do that.

is there no problem with out the lens in there?

If I am not mistaken all lens can pretty much work with other cameras provide that the attachment is compatible. Having said that with the new SLR cameras with auto focus of the lens the lens itself has a motor and it would be difficult to attach it to a manual SLR. Save yourself the headache and if you can purchase same manufacturer for camera body and lens life would be wonderful. In the past I thought that I could save money and do the swap thing and it just became too much. In addition the new cameras that are out has wonderful features like anti vibration, smooth focusing and the sensors are just dynamite. Good Luck

Is it a pentax fit 600 lens if you can fit it but it wont work the lens is a manual focus lens and has a fixed iris you will have to set the camera to use a manual lens look at the ins book

If u used to have a Pentax camera, i would recommend you buying a Pentax DSLR, because Pentax film lenses still works on Pentax DSLR. I still use some of my prime lenses on my K10D.

Being an SLR camera, you should try another lens. It may be a servo fault in the lens. If the lens is okay, then it can be anything in the lens sensing, lens control drive circuits, and or lens to camera interface area. This would have to be properly diagnosed and serviced.

Jerry G.

please do a firmware upgrade

tell us what happened

i found this which seems similar

http://www.pentaxuser.co.uk/forum/topic/ist-D--HELP-444/p-0#comm_2164

"I know this is late, but the issue sounds to me like the aperture ring is not on A. and if this is a manual lens then you have to set the mode to hyper-program mode and set it to work with "other than A" on aperture."

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this was my issue, i never knew that has i bought the camera 2nd hand without a manual - your issue might be something else but it's worth posting just incase

Go to the following page and select category "cameras", sub category "Digital SLR" & you will find all the *istDS manuals for download: http://www.pentaximaging.com/customer_care/manuals_literature Please update the question & let us know if the information given was useful to you - Good Luck!

That is normal operation, if poped up, the flash fires rapidily in low light to assist the auto focus, on a plain white wall, it can't focus, see the manual on AUto Focus limitations.