oldmalky Loc: West Midlands,England.

When using a teleconverter i am told i lose two stops, so if i am on f8 what would i change it to. I also set the camera to A mode, I have an Alpa a200.

CamObs Loc: South America (Texas)

if you have a 2x tele, 2 full stops would be f16

mtnredhed Loc: The part of NorCal that doesn't move

Assuming you mean an Sony Alpha A200 and not an Alpa (which are also very nice cameras).

Losing 2 stops means you have 1/4 the amount of light hitting your sensor. Each stop is either twice the light or half the light*. Learning the history of why we call it F stops is a hoot.

So, if you're using the camera's built in exposure meter, it will automatically compensate.

If you're going manual, then you can think of it as any ONE of the following:

If you were shooting ISO 100, you'd need to go to ISO 400 at the same shutter and aperture. (2x2x100)

If you were at F16, you'd need to be at F8 to keep shutter and ISO constant (F16>F11>F8)

If you were 1/500 of a sec. shutter, you'd need to be at 1/125 of a sec. (4x1/500 or 1/125)

You can also mix and match to the same effect. An example would be changing ISO to 200 and shutter to 1/250 per the example.

*Not really, but we all pretend it does

mtnredhed Loc: The part of NorCal that doesn't move

Wrong direction. They were at f/8. Using the TC would mean they would need to open to f/4 all else being equal.

oldmalky Loc: West Midlands,England.

Sorry it is an alpha a200,and by using a 2xtc i would need to change it to f4 I was despairing of getting an answer so very many thanks. I will try it out tomorrow thanks again.

oldmalky Loc: West Midlands,England.

I attempted to set the camera on the A setting at f4 but i could only go "up" to f16+ I really am a complete novice with settings, I can take pictures and enjoy doing it but i have no idea about the technical side of photography.I bought the 2x converter to help me take pics of birds, butterflies and anything else that appealed to me but it just would not focus.I have tried to get manual focus and that wouldnt work either.

mtnredhed Loc: The part of NorCal that doesn't move

Need to know details on what lens and TC you're using.

oldmalky Loc: West Midlands,England.

My lens is the minolta ZOOM xi af 100-30 the TC is the minolta Mx-AF 2X TELEPLUS MC7.

mtnredhed Loc: The part of NorCal that doesn't move

Kenko seems to own some of the old Minolta biz (the extender) and Sony got the rest. The lens you have should have a minimum fstop of 4.5-5.6. In theory with the TC installed, that should be somewhere around f8+ and F11. You were never going to get F4 or anything close.

Auto focus is probably not going to be an option at those fstops (too dim).

I'm not familiar with the camera, so you're going to need to find someone who is. Might check over at dpreview.com and see the Sony forum. I would almost say that the TC isn't talking to the camera. If you can get the internal metering working, you shouldn't have to compensate. If not, you'll need to meter manually somehow (which doesn't seem like an option for you). It's also possible that your camera is working as designed, and it knows that the min fstop really is f16.

Sorry can't be of more help

oldmalky Loc: West Midlands,England.

Went outside this morning (grey and overcast) with the TC and 100-300 (not the 100-30 another typo)and found it would take a pic at f16 but needed to be worked on,at least i now have a starting point, i have always said i wished i had started 20years ago might have learned some of the technical operations of my camera by now.thank you for your time and help.