DOF Preview in K110D - lens stays stopped down when unmounted?

fuzzybabybunny · 11-29-2006, 10:34 PM

I have a quick question for a friend who's thinking about getting a K110D.

On Canons, when you press the DOF preview button, and the lens gets stopped down, when you twist off the lens while the button is down, the lens stays stopped down.

I know that Pentax lenses, when twisted off, stop all the way down. Does the same occur in Sigma, Tamron, or Tokina lenses in Sigma mount? Because the ones in Canon mount stay stopped at whatever aperture the DOF preview was set at when twisted off.

This is important for macro work with reverse wide-angle lenses that don't have a manual aperture adjustment ring.

cyberlord · 11-30-2006, 04:12 PM

My Tamron 75-300 LD Macro lens (not the wide angle you were asking about) stays stopped down if pulled off the camera when DOF button is used. I own a DL and not a 110D

I think that function is built in to the lens itself and not the camera.

Maybe some others can reply with other specific 3rd party lenses.

Tim

roscot · 12-01-2006, 08:27 AM

Yes, all A versin and later K mount lens should be stopped down off camera, if the aperture ring is in the A position

fuzzybabybunny · 12-01-2006, 09:48 PM

Erm, lemme try to explain a little bit better.

Say a lens has a minimum aperture of f/22. You want it to be stopped down to f/8 when you reverse mount it. When you DOF preview at f/8 on a Tamron or a Sigma, and then twist the lens off, does it stay stopped down at f/8 or does it stop back down all the way to f/22?

**jfdavis58** · 12-01-2006, 10:22 PM

Most modern lenses for Pentax cameras have a spring loaded mechanism-I've got several Sigmas and Tokinas---applies to all.

They also, typically, have both an "A" stop and traditional "f/" stops (2.8,4,5.6,...). If the aperture ring is in the "A" position the lens stops down to its minimum size (f/22 or similar) because of the spring. If you twist the aperture ring to a particular numbered stop, then that's where the aperture goes.

clm · 12-02-2006, 11:04 PM

Originally posted by fuzzybabybunny

Erm, lemme try to explain a little bit better.

Say a lens has a minimum aperture of f/22. You want it to be stopped down to f/8 when you reverse mount it. When you DOF preview at f/8 on a Tamron or a Sigma, and then twist the lens off, does it stay stopped down at f/8 or does it stop back down all the way to f/22?

If you use a DA or FA-J lens which do not have aperture control rings, it will stop down to the minimum aperture. If you use an older K-mount lens such as K, M, F, or FA or a screw mount Takumar with auto/manual switch, the aperture will stay open to the aperture selected.

11-29-2006, 10:34 PM	#1
fuzzybabybunny New Member Join Date: Nov 2006 Posts: 12	DOF Preview in K110D - lens stays stopped down when unmounted? I have a quick question for a friend who's thinking about getting a K110D. On Canons, when you press the DOF preview button, and the lens gets stopped down, when you twist off the lens while the button is down, the lens stays stopped down. I know that Pentax lenses, when twisted off, stop all the way down. Does the same occur in Sigma, Tamron, or Tokina lenses in Sigma mount? Because the ones in Canon mount stay stopped at whatever aperture the DOF preview was set at when twisted off. This is important for macro work with reverse wide-angle lenses that don't have a manual aperture adjustment ring.

12-01-2006, 10:22 PM	#5
jfdavis58 Site Supporter Join Date: Nov 2006 Location: 13 S 0357397-3884316 Photos: Gallery Posts: 887	Stopping down Most modern lenses for Pentax cameras have a spring loaded mechanism-I've got several Sigmas and Tokinas---applies to all. They also, typically, have both an "A" stop and traditional "f/" stops (2.8,4,5.6,...). If the aperture ring is in the "A" position the lens stops down to its minimum size (f/22 or similar) because of the spring. If you twist the aperture ring to a particular numbered stop, then that's where the aperture goes.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Mirror cycling on optical preview, stopped-down movie recording	bwDraco	Pentax DSLR Discussion	10	09-12-2011 06:50 AM
K5 - DOF preview with MF lenses in aperture mode?	vincechu	Troubleshooting and Beginner Help	5	03-25-2011 01:42 PM
645d DOF preview	Shuttershane	Pentax Medium Format	4	01-01-2011 10:06 AM
Controlling Aperture with DoF Preview Button?	Hello_Photo	Film SLRs and Compact Film Cameras	2	09-04-2010 01:16 PM
*istDL DOF Preview not working & Slow flash pop up.	auspentax	Pentax DSLR Discussion	3	07-07-2010 07:07 AM

11-30-2006, 04:12 PM	#2
cyberlord New Member Join Date: Nov 2006 Location: FWB, FL Posts: 14	My Tamron 75-300 LD Macro lens (not the wide angle you were asking about) stays stopped down if pulled off the camera when DOF button is used. I own a DL and not a 110D I think that function is built in to the lens itself and not the camera. Maybe some others can reply with other specific 3rd party lenses. Tim

12-01-2006, 08:27 AM	#3
roscot Veteran Member Join Date: Sep 2006 Location: Virginia Beach VA USA Photos: Gallery Posts: 1,363	Yes, all A versin and later K mount lens should be stopped down off camera, if the aperture ring is in the A position

12-01-2006, 09:48 PM	#4
fuzzybabybunny New Member Join Date: Nov 2006 Posts: 12 Original Poster	Erm, lemme try to explain a little bit better. Say a lens has a minimum aperture of f/22. You want it to be stopped down to f/8 when you reverse mount it. When you DOF preview at f/8 on a Tamron or a Sigma, and then twist the lens off, does it stay stopped down at f/8 or does it stop back down all the way to f/22?

12-02-2006, 11:04 PM	#6
clm Senior Member Join Date: Sep 2006 Posts: 220	Originally posted by fuzzybabybunny Erm, lemme try to explain a little bit better. Say a lens has a minimum aperture of f/22. You want it to be stopped down to f/8 when you reverse mount it. When you DOF preview at f/8 on a Tamron or a Sigma, and then twist the lens off, does it stay stopped down at f/8 or does it stop back down all the way to f/22? If you use a DA or FA-J lens which do not have aperture control rings, it will stop down to the minimum aperture. If you use an older K-mount lens such as K, M, F, or FA or a screw mount Takumar with auto/manual switch, the aperture will stay open to the aperture selected.