Does Pentax F-1.7x AF TC works with M42 lens?

hinman · 04-08-2009, 04:56 PM

I have the Pentax F-1.7x AF TC, while it works great on manual and auto focus K mount lens, it can't seem to operate on AF with M42 lens, is this normal?

The Pentax F-17x AF TC works even with my shameless Tamron 70-300mm f/4.0-5.6 Di LD zoom. When I turn focus ring on my Tamron zoom close to target, the TC will engage into auto focus. And it works similarly on my Komine 200mm f/3.5 in K mount. But when I try it on my Soligor 200mm f/2.8, the AF part does not work and I still get the AF confirmation.

Do you have experiences in using Pentax F-1.7x TC on M42 lens? Please share your experience. If I can get my F-1.7x AF TC to drive the M42 lens with AF, I have more options.

Thanks,
Hin

hinman · 04-08-2009, 05:09 PM

I read somewhere that aluminum foil shorting the contacts in the Pentax F-1.7x AF TC will enable the AF in the TC in steves-cam forum in this thread

Looking for a 300mm Range Telephoto Lens - Pentax Lenses - Digital SLR Cameras - Steves-digicams.com Forums

Quote:

Hi John,

I'd never tried it before, but just did. Using a Pentax M42 S-M-C Takumar 200/4 with an original Pentax M42-K adaptor, the AFA would not actuate until I covered the contacts on the AFA with foil when mounting the lens. The AFA worked as intended with the contacts shorted. Using the foil is not difficult, just take a piece large enough to cover the contact area on the AFA, then hold it in place while you mount the lens. With mine, the foil rotated with the lens as it was turned into the mount on the camera, so I had to offset the foil a bit in the direction opposite to the rotation when mounting the lens.

I'd previously removed the spring lock in the screw to K adaptor, and added a tiny drop of penentrating thread sealer to keep the adapter on the lens, so the adaptor does not lock into the camera mount. I'd previously had some anxiety about accidentally dismounting the lens when focusing, but the thickness of the foil tightens the mount enough that it would not be much of a worry if I used this combo.

I decided early on to concentrate on "A" capable lenses, so all the lenses that I had previously used with the AFA are KA mounts. I may try playing with the few screw mounts that I do still have. . .

There is probably a way to at least semi-permanently alter the screw mt adaptor so it makes the correct contact, but I think I'd just make sure I carried a sheet of foil in my bag.

Scott

I will try it out and report back. If you are aware of other reliable choices other than foil, please comment.
Thanks,
Hin

**dadipentak** · 04-08-2009, 06:31 PM

Originally posted by hinman

I read somewhere that aluminum foil shorting the contacts in the Pentax F-1.7x AF TC will enable the AF in the TC in steves-cam forum in this thread

I will try it out and report back. If you are aware of other reliable choices other than foil, please comment.
Thanks,
Hin

That's right Hin. Remember I worked this through with Mis & Peter's help with the TC you sold me and that 500mm Tak? It's inelegant but the aluminum foil works just fine. I've heard of others who have sanded away the paint on the rear of the M42 lens (too invasive for my taste.) I'm sure there must be a better 21st century solution--perhaps a conductive paint of some sort?

hinman · 04-08-2009, 06:51 PM

Originally posted by dadipentak

That's right Hin. Remember I worked this through with Mis & Peter's help with the TC you sold me and that 500mm Tak? It's inelegant but the aluminum foil works just fine. I've heard of others who have sanded away the paint on the rear of the M42 lens (too invasive for my taste.) I'm sure there must be a better 21st century solution--perhaps a conductive paint of some sort?

Yes, now I remember the thread of discussion. I also remember seeing a suggestion from others in PF lens dicussion using some other form of cut out of either plastic or metallic/magnetic tape from packaged electronic goods. I will experiment.

Dave, I am following your LBA pursue for long lens. Now I understand why you replaces your 500mm Tak with a longer lens. No lens are long and fast enough for birds. We may be in an area that is lacking even when we have plenty of manual focus gear. Though I love manual focus, I find myself needing AF for assistance. My eyesight are getting poorer and I have a difficult time in focusing on the bird's eyes in a far distance as in 30 to 50 feet away. I am using the plain stock screen and manual focusing to get to confirmation is a daunting task especially when the birds are moving.

I have my first shoot out on blue herons this morning with two setup

Tamron 70-300mm f/4.0-5.6 + Pentax F-1.7x AF TC
Soligor 200mm f/2.8 in M42 + Kiron 2x matched mulitplier

I end up using the AF combination as it is easier to make the shot. But when I check the results, it seems my M42 lens has less fringing. All shots still lack detail and have many user errors on focusing

Thanks,
Hin

Last edited by hinman; 04-08-2009 at 08:45 PM.

hinman · 04-08-2009, 07:07 PM

Samples from
Tamron 70-300 + Pentax F-1.7x AF TC

#1
1/400 sec, f/8.0, 510mm, iso 400

#2
1/60 sec, f/10.0, 510mm. iso 125

Samples from
Soligor 200mm f/2.8 + Kiron 2x matched multiplier

#3
1/100 sec, f/8.0, 400mm, iso 250, -1/3 Ev

#4
1/125 sec, f/8.0, 400mm, iso 250, -1/3 Ev

Without AF in the M42 combination, I find it more difficult to follow the bird. And due to the manual diaphragm where the blades are closing down, it is much harder to focus. I often switch to f/2.8, obtain the focus and turn the aperture back to f/8.0 to make the final shot. By the time I am ready to hit shutter, I am most likely move from the focus point. Hence, I am hoping the F-1.7x AF TC help in the AF even when I need to stop-up to get focus confirmation.

Thanks,
Hin

**dadipentak** · 04-08-2009, 08:33 PM

Hin those are terrific--especially considering the lenses you're working with! I can only imagine what you'll produce with a good 300 or 400mm.

hinman · 04-10-2009, 05:04 PM

Originally posted by dadipentak

Hin those are terrific--especially considering the lenses you're working with! I can only imagine what you'll produce with a good 300 or 400mm.

Thank you very much Dave. I am both lacking in skills as much as longer gear for the birds. Here is another 2x TC that I am using heavily for my M42 gear.

Vivitar 2x matched multiplier from Kiron
comes with
Vivitar 70-150mm f/3.8 form Kiron

Hin's cheapo 400mm and 510mm
Soligor 200mm f/2.8 with 2xTC
Tamron 70-300mm f/4.0-5.6 with 1.7x TC
very light and hand-holdable
but IQ can be better

That particular morning, the blue heron stayed very much still for me.

I finally get a chance to try the aluminum foil and AF the F-1.7x can engage in AF with the M42 lens. Quite amazing! Besides allowing the F-1.7x AF TC to work, the foil trick works quite consistent for getting the trap-focus to work on the M42 lens . But it seems like a hassle to put it on. Another caveat noted is on the extra thickness added between the lens and the flush mount.

If anyone knows about other material other than aluminum foil to try that is easier to put on and off, please suggest.

Thanks,
Hin

Last edited by hinman; 04-10-2009 at 07:12 PM.

Sudhakar · 10-13-2009, 01:05 AM

I was not able to take meter reading with green button in M mode for the combination of M42 and 1.7x TC. Not sure what am I missing. Can you confirm it works for you?

madhurvyas · 10-13-2009, 01:35 AM

Hi Sudhakar,
With m42 lenses we can do metering in A mode, stop down wont work.

hinman · 10-13-2009, 01:42 AM

Originally posted by madhurvyas

Hi Sudhakar,
With m42 lenses we can do metering in A mode, stop down wont work.

That is my recommendation to use Av mode. I don't use M mode for M42 lens and I don't remember if stop-down won't work. Stop-down should work in M mode when the M42 lens is in M-diaphragm where you can stop-down the aperture from wide to the selected aperture on aperture ring. I always use Av mode with M42 lens and if you M42 lens has the switch for A/M for auto-diaphragm and manual-diaphragm, always use M for manual diaphragm. When the A/M switch is on A or for those m42 lenses that are defaulted to auto-diaphragm only, the lens can't be stopped down and it meters wide open at its maximum aperture. Alternation and tricks are possible for the Auto-mount lens which is to shorten the pin on lens' back governing the A/M diaphragm mechanics. Or you get one of this M42 3rd party adapter that will depress the pin on your behalf

M42 adapter from Alex with inner ring
Will work with auto-mount M42 lens without alternation

m42 adapter left has inner ring
genuine adapter on right

inner ring will depress pin upon mounting
in effect set to M in the A/M diaphragm auto-mount control

Pin on back in Auto-mount only lens

Also, with M42 lens that I tried on my Photosniper Tair-3 PhS 300mm f/4.5 with 1.7x AFA, I used the common trick of putting in a piece of aluminum foil to aid the connection and the partial AF magic works for M42 lens as if they are K-mount manual lens.

Hope this helps you,
Hin

Sudhakar · 10-13-2009, 03:26 AM

Thanks Madhur

Thanks Hinman. Aluminium foil trick works for me (for AF part). I am fine there. It is more about stop down metering. There are some cases Av mode did not give me good results. For M42 lenses generally on my 100Dsuper, I need to use +2 EV to get good results; beyond this I can't adjust the dial further. In those cases, I will try to take stop down meter reading. Individually m42 lens works but when stacked with TC, I could not do. BTW, I use original pentax adapter ring only (for safer reasons :-))

--Sudhakar

hinman · 10-13-2009, 07:31 AM

Originally posted by Sudhakar

Thanks Madhur

Thanks Hinman. Aluminium foil trick works for me (for AF part). I am fine there. It is more about stop down metering. There are some cases Av mode did not give me good results. For M42 lenses generally on my 100Dsuper, I need to use +2 EV to get good results; beyond this I can't adjust the dial further. In those cases, I will try to take stop down meter reading. Individually m42 lens works but when stacked with TC, I could not do. BTW, I use original pentax adapter ring only (for safer reasons :-))

--Sudhakar

I share mostly my m42 experience with K20D. I recalled my time with Pentax K100D with certain M42 lens as in my first try on a Pentacon 50mm f/1.8, I always seem to need to dial in +1.7 to +2.0 Ev compensation. That is just the lens alone and no TC is involved. I was thinking if I actually did it wrong before when I accidentally switched the A/M switch to 'A' instead of 'M' for manual diaphragm control. When A/M is on A for auto-mount diaphragm control, the lens aperture is wide open no matter what aperture you are in. I can't recall now as I don't have the set up to verify. Please check to be sure if your lens has the A/M switch or that it is a lens without the A/M switch and defaulted to Auto-mount. If my memory serves me correctly, I do run into consistent cases of +2.0 Ev adjustment in my K100D with m42 lens.

Also, when you have inaccurate metering, what happens if you switch to M mode and use the stop-down metering method. Do you hear the noise in closing down in diaphragm in small aperture as in f/16? And is the metering worse as in K100D, you don't have Ev compensation in M mode. That got changed in K20D and it is a big plus in K20D to be able to dial in Ev compensation in M mode. That feature was absent even in K10D but added in K20D.

From what I gathered, the metering with M42 lenses is best with K-7 and I hope those metering improvements also prevail in K-x and K-m. Someone who uses k-m can share their m42 experience.

Thanks,
Hin

reeftool · 10-13-2009, 08:00 AM

I have been using tin foil with my 500mm mirror with a T mount. There used to be a metallic paint available in auto stores used in repairing rear window defroster grids but I haven't been able to find any. That stuff should work if it is still being made.

Sudhakar · 02-04-2010, 11:37 PM

After a long time, I pulled my 300/f4 K mount and 1.7x AF TC, as I saw a beutiful bird from my window. Currently my TC is tin-foiled for shorting to work with m42 lenses. General steps of K-mount lenses usage, I switched to M mode on my 100D super and tried to do stop-down-metering via green button and it will not do. I adjusted the aperture between f4 and f32 and took couple fo shots, f32 is also fully blown. I switched to Av mode and as I rotate the dial, I see the shutter speed changing, but when I take the shot, it is fully blown. I believe, it is acting only at f4.

Went back to fundamental question.. How to take meter reading with K-mount lens in combination of Pentax 1.7x AF TC

thanks in advance
--Sudhakar

**Lowell Goudge** · 02-05-2010, 10:19 AM

Originally posted by Sudhakar

After a long time, I pulled my 300/f4 K mount and 1.7x AF TC, as I saw a beutiful bird from my window. Currently my TC is tin-foiled for shorting to work with m42 lenses. General steps of K-mount lenses usage, I switched to M mode on my 100D super and tried to do stop-down-metering via green button and it will not do. I adjusted the aperture between f4 and f32 and took couple fo shots, f32 is also fully blown. I switched to Av mode and as I rotate the dial, I see the shutter speed changing, but when I take the shot, it is fully blown. I believe, it is acting only at f4.

Went back to fundamental question.. How to take meter reading with K-mount lens in combination of Pentax 1.7x AF TC

thanks in advance
--Sudhakar

I don't follow your comments here.
'
The SMC 300F4 does not need tinfoil to focus or meter.

if you are in manual mode, on the K100 super I believe you need to be in manual mode and hit the AE button (i don't think there is a green button, but I could be wrong) This should set the shutter for the aperture selected.

In Av Mode there is no adjustment possible of aperture. The K300F4 will always be wide open no matter where you place the aperture ring, and the camera will always correct for lighting wide open.

Are you sure you are using a K mount lens. Your comments sound more like you have a screw mount 300mm Takumar and an M42 to K mount adaptor.

04-08-2009, 07:07 PM	#5
hinman Veteran Member Join Date: Oct 2006 Location: Fremont, CA Photos: Albums Posts: 3,473 Original Poster	Samples from Tamron 70-300 + Pentax F-1.7x AF TC #1 1/400 sec, f/8.0, 510mm, iso 400 #2 1/60 sec, f/10.0, 510mm. iso 125 Samples from Soligor 200mm f/2.8 + Kiron 2x matched multiplier #3 1/100 sec, f/8.0, 400mm, iso 250, -1/3 Ev #4 1/125 sec, f/8.0, 400mm, iso 250, -1/3 Ev Without AF in the M42 combination, I find it more difficult to follow the bird. And due to the manual diaphragm where the blades are closing down, it is much harder to focus. I often switch to f/2.8, obtain the focus and turn the aperture back to f/8.0 to make the final shot. By the time I am ready to hit shutter, I am most likely move from the focus point. Hence, I am hoping the F-1.7x AF TC help in the AF even when I need to stop-up to get focus confirmation. Thanks, Hin Last edited by hinman; 04-08-2009 at 07:22 PM.

10-13-2009, 01:42 AM	#10
hinman Veteran Member Join Date: Oct 2006 Location: Fremont, CA Photos: Albums Posts: 3,473 Original Poster	Originally posted by madhurvyas Hi Sudhakar, With m42 lenses we can do metering in A mode, stop down wont work. That is my recommendation to use Av mode. I don't use M mode for M42 lens and I don't remember if stop-down won't work. Stop-down should work in M mode when the M42 lens is in M-diaphragm where you can stop-down the aperture from wide to the selected aperture on aperture ring. I always use Av mode with M42 lens and if you M42 lens has the switch for A/M for auto-diaphragm and manual-diaphragm, always use M for manual diaphragm. When the A/M switch is on A or for those m42 lenses that are defaulted to auto-diaphragm only, the lens can't be stopped down and it meters wide open at its maximum aperture. Alternation and tricks are possible for the Auto-mount lens which is to shorten the pin on lens' back governing the A/M diaphragm mechanics. Or you get one of this M42 3rd party adapter that will depress the pin on your behalf M42 adapter from Alex with inner ring Will work with auto-mount M42 lens without alternation m42 adapter left has inner ring genuine adapter on right inner ring will depress pin upon mounting in effect set to M in the A/M diaphragm auto-mount control Pin on back in Auto-mount only lens Also, with M42 lens that I tried on my Photosniper Tair-3 PhS 300mm f/4.5 with 1.7x AFA, I used the common trick of putting in a piece of aluminum foil to aid the connection and the partial AF magic works for M42 lens as if they are K-mount manual lens. Hope this helps you, Hin Last edited by hinman; 10-13-2009 at 01:58 AM.

10-13-2009, 07:31 AM	#12
hinman Veteran Member Join Date: Oct 2006 Location: Fremont, CA Photos: Albums Posts: 3,473 Original Poster	Originally posted by Sudhakar Thanks Madhur Thanks Hinman. Aluminium foil trick works for me (for AF part). I am fine there. It is more about stop down metering. There are some cases Av mode did not give me good results. For M42 lenses generally on my 100Dsuper, I need to use +2 EV to get good results; beyond this I can't adjust the dial further. In those cases, I will try to take stop down meter reading. Individually m42 lens works but when stacked with TC, I could not do. BTW, I use original pentax adapter ring only (for safer reasons :-)) --Sudhakar I share mostly my m42 experience with K20D. I recalled my time with Pentax K100D with certain M42 lens as in my first try on a Pentacon 50mm f/1.8, I always seem to need to dial in +1.7 to +2.0 Ev compensation. That is just the lens alone and no TC is involved. I was thinking if I actually did it wrong before when I accidentally switched the A/M switch to 'A' instead of 'M' for manual diaphragm control. When A/M is on A for auto-mount diaphragm control, the lens aperture is wide open no matter what aperture you are in. I can't recall now as I don't have the set up to verify. Please check to be sure if your lens has the A/M switch or that it is a lens without the A/M switch and defaulted to Auto-mount. If my memory serves me correctly, I do run into consistent cases of +2.0 Ev adjustment in my K100D with m42 lens. Also, when you have inaccurate metering, what happens if you switch to M mode and use the stop-down metering method. Do you hear the noise in closing down in diaphragm in small aperture as in f/16? And is the metering worse as in K100D, you don't have Ev compensation in M mode. That got changed in K20D and it is a big plus in K20D to be able to dial in Ev compensation in M mode. That feature was absent even in K10D but added in K20D. From what I gathered, the metering with M42 lenses is best with K-7 and I hope those metering improvements also prevail in K-x and K-m. Someone who uses k-m can share their m42 experience. Thanks, Hin Last edited by hinman; 10-13-2009 at 07:38 AM.

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04-08-2009, 04:56 PM	#1
hinman Veteran Member Join Date: Oct 2006 Location: Fremont, CA Photos: Albums Posts: 3,473	Does Pentax F-1.7x AF TC works with M42 lens? I have the Pentax F-1.7x AF TC, while it works great on manual and auto focus K mount lens, it can't seem to operate on AF with M42 lens, is this normal? The Pentax F-17x AF TC works even with my shameless Tamron 70-300mm f/4.0-5.6 Di LD zoom. When I turn focus ring on my Tamron zoom close to target, the TC will engage into auto focus. And it works similarly on my Komine 200mm f/3.5 in K mount. But when I try it on my Soligor 200mm f/2.8, the AF part does not work and I still get the AF confirmation. Do you have experiences in using Pentax F-1.7x TC on M42 lens? Please share your experience. If I can get my F-1.7x AF TC to drive the M42 lens with AF, I have more options. Thanks, Hin

04-08-2009, 05:09 PM	#2
hinman Veteran Member Join Date: Oct 2006 Location: Fremont, CA Photos: Albums Posts: 3,473 Original Poster	I read somewhere that aluminum foil shorting the contacts in the Pentax F-1.7x AF TC will enable the AF in the TC in steves-cam forum in this thread Looking for a 300mm Range Telephoto Lens - Pentax Lenses - Digital SLR Cameras - Steves-digicams.com Forums Quote: Hi John, I'd never tried it before, but just did. Using a Pentax M42 S-M-C Takumar 200/4 with an original Pentax M42-K adaptor, the AFA would not actuate until I covered the contacts on the AFA with foil when mounting the lens. The AFA worked as intended with the contacts shorted. Using the foil is not difficult, just take a piece large enough to cover the contact area on the AFA, then hold it in place while you mount the lens. With mine, the foil rotated with the lens as it was turned into the mount on the camera, so I had to offset the foil a bit in the direction opposite to the rotation when mounting the lens. I'd previously removed the spring lock in the screw to K adaptor, and added a tiny drop of penentrating thread sealer to keep the adapter on the lens, so the adaptor does not lock into the camera mount. I'd previously had some anxiety about accidentally dismounting the lens when focusing, but the thickness of the foil tightens the mount enough that it would not be much of a worry if I used this combo. I decided early on to concentrate on "A" capable lenses, so all the lenses that I had previously used with the AFA are KA mounts. I may try playing with the few screw mounts that I do still have. . . There is probably a way to at least semi-permanently alter the screw mt adaptor so it makes the correct contact, but I think I'd just make sure I carried a sheet of foil in my bag. Scott I will try it out and report back. If you are aware of other reliable choices other than foil, please comment. Thanks, Hin Last edited by hinman; 04-08-2009 at 05:15 PM.

04-08-2009, 06:31 PM	#3
dadipentak Site Supporter Join Date: Jul 2008 Location: Baltimore, Maryland Photos: Gallery Posts: 11,590	Originally posted by hinman I read somewhere that aluminum foil shorting the contacts in the Pentax F-1.7x AF TC will enable the AF in the TC in steves-cam forum in this thread I will try it out and report back. If you are aware of other reliable choices other than foil, please comment. Thanks, Hin That's right Hin. Remember I worked this through with Mis & Peter's help with the TC you sold me and that 500mm Tak? It's inelegant but the aluminum foil works just fine. I've heard of others who have sanded away the paint on the rear of the M42 lens (too invasive for my taste.) I'm sure there must be a better 21st century solution--perhaps a conductive paint of some sort?

04-08-2009, 06:51 PM	#4
hinman Veteran Member Join Date: Oct 2006 Location: Fremont, CA Photos: Albums Posts: 3,473 Original Poster	Originally posted by dadipentak That's right Hin. Remember I worked this through with Mis & Peter's help with the TC you sold me and that 500mm Tak? It's inelegant but the aluminum foil works just fine. I've heard of others who have sanded away the paint on the rear of the M42 lens (too invasive for my taste.) I'm sure there must be a better 21st century solution--perhaps a conductive paint of some sort? Yes, now I remember the thread of discussion. I also remember seeing a suggestion from others in PF lens dicussion using some other form of cut out of either plastic or metallic/magnetic tape from packaged electronic goods. I will experiment. Dave, I am following your LBA pursue for long lens. Now I understand why you replaces your 500mm Tak with a longer lens. No lens are long and fast enough for birds. We may be in an area that is lacking even when we have plenty of manual focus gear. Though I love manual focus, I find myself needing AF for assistance. My eyesight are getting poorer and I have a difficult time in focusing on the bird's eyes in a far distance as in 30 to 50 feet away. I am using the plain stock screen and manual focusing to get to confirmation is a daunting task especially when the birds are moving. I have my first shoot out on blue herons this morning with two setup Tamron 70-300mm f/4.0-5.6 + Pentax F-1.7x AF TC Soligor 200mm f/2.8 in M42 + Kiron 2x matched mulitplier I end up using the AF combination as it is easier to make the shot. But when I check the results, it seems my M42 lens has less fringing. All shots still lack detail and have many user errors on focusing Thanks, Hin Last edited by hinman; 04-08-2009 at 08:45 PM.

04-08-2009, 08:33 PM	#6
dadipentak Site Supporter Join Date: Jul 2008 Location: Baltimore, Maryland Photos: Gallery Posts: 11,590	Hin those are terrific--especially considering the lenses you're working with! I can only imagine what you'll produce with a good 300 or 400mm.

04-10-2009, 05:04 PM	#7
hinman Veteran Member Join Date: Oct 2006 Location: Fremont, CA Photos: Albums Posts: 3,473 Original Poster	Originally posted by dadipentak Hin those are terrific--especially considering the lenses you're working with! I can only imagine what you'll produce with a good 300 or 400mm. Thank you very much Dave. I am both lacking in skills as much as longer gear for the birds. Here is another 2x TC that I am using heavily for my M42 gear. Vivitar 2x matched multiplier from Kiron comes with Vivitar 70-150mm f/3.8 form Kiron Hin's cheapo 400mm and 510mm Soligor 200mm f/2.8 with 2xTC Tamron 70-300mm f/4.0-5.6 with 1.7x TC very light and hand-holdable but IQ can be better That particular morning, the blue heron stayed very much still for me. I finally get a chance to try the aluminum foil and AF the F-1.7x can engage in AF with the M42 lens. Quite amazing! Besides allowing the F-1.7x AF TC to work, the foil trick works quite consistent for getting the trap-focus to work on the M42 lens . But it seems like a hassle to put it on. Another caveat noted is on the extra thickness added between the lens and the flush mount. If anyone knows about other material other than aluminum foil to try that is easier to put on and off, please suggest. Thanks, Hin Last edited by hinman; 04-10-2009 at 07:12 PM.

10-13-2009, 01:05 AM	#8
Sudhakar Senior Member Join Date: Dec 2008 Location: Hyderabad Photos: Gallery \| Albums Posts: 236	I was not able to take meter reading with green button in M mode for the combination of M42 and 1.7x TC. Not sure what am I missing. Can you confirm it works for you?

10-13-2009, 01:35 AM	#9
madhurvyas Veteran Member Join Date: Jan 2008 Location: Bikaner (Raj)-India Photos: Gallery Posts: 562	Hi Sudhakar, With m42 lenses we can do metering in A mode, stop down wont work.

10-13-2009, 03:26 AM	#11
Sudhakar Senior Member Join Date: Dec 2008 Location: Hyderabad Photos: Gallery \| Albums Posts: 236	Thanks Madhur Thanks Hinman. Aluminium foil trick works for me (for AF part). I am fine there. It is more about stop down metering. There are some cases Av mode did not give me good results. For M42 lenses generally on my 100Dsuper, I need to use +2 EV to get good results; beyond this I can't adjust the dial further. In those cases, I will try to take stop down meter reading. Individually m42 lens works but when stacked with TC, I could not do. BTW, I use original pentax adapter ring only (for safer reasons :-)) --Sudhakar

10-13-2009, 08:00 AM	#13
reeftool Pentaxian Join Date: Dec 2007 Location: Upstate New York Photos: Gallery \| Albums Posts: 9,555	I have been using tin foil with my 500mm mirror with a T mount. There used to be a metallic paint available in auto stores used in repairing rear window defroster grids but I haven't been able to find any. That stuff should work if it is still being made.

02-04-2010, 11:37 PM	#14
Sudhakar Senior Member Join Date: Dec 2008 Location: Hyderabad Photos: Gallery \| Albums Posts: 236	After a long time, I pulled my 300/f4 K mount and 1.7x AF TC, as I saw a beutiful bird from my window. Currently my TC is tin-foiled for shorting to work with m42 lenses. General steps of K-mount lenses usage, I switched to M mode on my 100D super and tried to do stop-down-metering via green button and it will not do. I adjusted the aperture between f4 and f32 and took couple fo shots, f32 is also fully blown. I switched to Av mode and as I rotate the dial, I see the shutter speed changing, but when I take the shot, it is fully blown. I believe, it is acting only at f4. Went back to fundamental question.. How to take meter reading with K-mount lens in combination of Pentax 1.7x AF TC thanks in advance --Sudhakar

02-05-2010, 10:19 AM	#15
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,891	Originally posted by Sudhakar After a long time, I pulled my 300/f4 K mount and 1.7x AF TC, as I saw a beutiful bird from my window. Currently my TC is tin-foiled for shorting to work with m42 lenses. General steps of K-mount lenses usage, I switched to M mode on my 100D super and tried to do stop-down-metering via green button and it will not do. I adjusted the aperture between f4 and f32 and took couple fo shots, f32 is also fully blown. I switched to Av mode and as I rotate the dial, I see the shutter speed changing, but when I take the shot, it is fully blown. I believe, it is acting only at f4. Went back to fundamental question.. How to take meter reading with K-mount lens in combination of Pentax 1.7x AF TC thanks in advance --Sudhakar I don't follow your comments here. ' The SMC 300F4 does not need tinfoil to focus or meter. if you are in manual mode, on the K100 super I believe you need to be in manual mode and hit the AE button (i don't think there is a green button, but I could be wrong) This should set the shutter for the aperture selected. In Av Mode there is no adjustment possible of aperture. The K300F4 will always be wide open no matter where you place the aperture ring, and the camera will always correct for lighting wide open. Are you sure you are using a K mount lens. Your comments sound more like you have a screw mount 300mm Takumar and an M42 to K mount adaptor.