Strange problem with istD and external flash AF240ft

What distance are the subjects when using the built-in flash?

The built-in flash is optimized for use between 0.7m (2.3ft) and 4m (13ft).

You could also try adjusting the ISO setting (higher ISO requires less light) or adjusting the EV value to a positive number to increase the exposure.

have you tried cleaning the lens contacts with soft cloth?

ifnot do that.

is there no problem with out the lens in there?

You don't state which Takumar model you have, but your camera is behaving entirely correctly.

The built in flash on the SF10 is automatically disabled when certain lenses are used, this is because the low position and narrow coverage of the flash combined with the size of many lenses causes the light path of the flash to be blocked or the flash coverage will simply be too narrow for some wide angle lenses; this can create vignetting or other dark shadows from the lens to appear in the photo. When a proper SMC-Pentax F lens is used the camera will warn you of this, but third party lenses like the Takumar lack the ability to trigger the warnings.

Built in flash units on all SLR's are just a handy get-you-by feature for parties and snapshots using standard lenses. For all other use, there simply is no substitute for using a proper external flash.

I suggest that you read the manual, if you don't have it then you can download it for free from here.

I trust that my answer has fully resolved your question; if so then please return the favour by rating my answer.

Its it a good camera. So dont try to re-mount the hot shoe by your self. Please contact Pentax service center.

The istD camera requires a flash capable of pttl readings...is the Quantaray a pttl flash unit?

Flash tube is probably burned out.

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.

please do a firmware upgrade

tell us what happened

Yes. The *istD shutter can only provide X-sync for electronic flash up to 1/150 sec. The *istDS reaches 1/180 sec. "High speed" electronic flash is done by strobing the flash repeatedly during the period that the shutter slit is traveling across the focal plane, at th expense of cutting power output quite a bit.

I've found that the *istD underexposes ( as it should metering 18% grey ) light subjects, or with light backgrounds. A white wall using TTL ( AF500ftz ) behind any subject it always turns grey! You need to manually adjust 1 stop over. With dark subjects, overexposing with out blowing out much. If your used to the metering from a PS digi cam the *istD takes a bit of getting used to.