The use of extenders in general


takuman

Link Posted 16/03/2017 - 19:54
Evening all. Recently acquired a 1.7 AF Adapter from a fellow member, no problems there at all.
1. Using 50mm 1.7 I set 85mm on the focal length, result:- Excellent.
2. SMC M f4 400mm set 680 on the focal length:- Not so good, but OKish
But then whilst lying in my bath contemplating the meaning of life I had an eureka moment.
3. Aaaaah. that lens has +2 set on fine autofocus. Would that make a difference?
4. I dimly remember/or not, reading that you just dial in the actual focal length of the lens in use?
Advice please.
Just passing thru

McGregNi

Link Posted 16/03/2017 - 21:59
I'm confused ..... how can you have an AF adjustment of +2 with a manual focus lens?
My Guide to the Pentax Digital Camera Flash Lighting System .... Pentax Flash Guide Updated, Articles .... link

Pentax K7 with BG-4 Grip / Samyang 14mm f2.8 ED AS IF UMC / DA18-55mm f3.5-5.6 AL WR / SMC A28mm f2.8 / D FA 28-105mm / SMC F35-70 f3.5-4.5 / SMC A50mm f1.7 / Tamron AF70-300mm f4-5.6 Di LD macro / SMC M75-150mm f4.0 / Tamron Adaptall (CT-135) 135mm f2.8 / Asahi Takumar-A 2X tele-converter / Pentax AF-540FGZ (I & II) Flashes / Cactus RF60 Flash & V6 Transceiver

takuman

Link Posted 16/03/2017 - 22:03
In the morning when I can think straight I will hopefully answer that
Just passing thru

McGregNi

Link Posted 16/03/2017 - 23:08
I suppose you might be able to set the AF fine adjustment, I'm just not sure what effect it could have with an M series lens ....?

I believe the received wisdom regarding Shake Reduction focal length inputs is to use lens plus TC combined focal length figure. It's the magnification that counts, that is what adds to the shaking as the focal length increases, and so the TC has to be factored in also.
My Guide to the Pentax Digital Camera Flash Lighting System .... Pentax Flash Guide Updated, Articles .... link

Pentax K7 with BG-4 Grip / Samyang 14mm f2.8 ED AS IF UMC / DA18-55mm f3.5-5.6 AL WR / SMC A28mm f2.8 / D FA 28-105mm / SMC F35-70 f3.5-4.5 / SMC A50mm f1.7 / Tamron AF70-300mm f4-5.6 Di LD macro / SMC M75-150mm f4.0 / Tamron Adaptall (CT-135) 135mm f2.8 / Asahi Takumar-A 2X tele-converter / Pentax AF-540FGZ (I & II) Flashes / Cactus RF60 Flash & V6 Transceiver

pschlute

Link Posted 17/03/2017 - 07:54
Are you trying to hand hold tha 400mm + 1.7 converter ? That is a tall order.
Peter



My Flickr page

Algernon

Link Posted 17/03/2017 - 08:30
Hi, you do have to set an AF adjustment value for MF. It's because it controls the beep/green light trigger position. To make matters worse the beep (MF or AF) gets triggered in two positions, similar to DOF. One going into focus and one going out and to make matters even worse like DOF it's affected by distance. That's why AF can never work properly A magic wand would be more use.

Pentax users are very DIM and don't realize this CIF has been around since the 80's and they still don't know how to set it up and use it properly

All you can do with any TC is try for a compromise. It's usually better to focus slightly beyond the subject and then let the AF make it's adjustment. Try a few shots at your normal bird distance say 7M at +10, +/-0 and -10. See which is closest and then try a few bracketed shots around that figure untll you get the most hits. Eg. -9, -8, -7, -6 Often DOF will mask most of the errors. Beer bottles are a good target.

I found the DA1.4x TC harder to set up than the 1.7x Adapter on the DA*300mm.

I can't remember any user resolution test shots on any forum where the lens has actually been in focus. A focus rail is the only way to get spot on focus. This site explains why....

http://www.slrgear.com/articles/focus/focus.htm

The Novoflex rail they use for left/right adjustment is the one I use for focussing testing. It allows about 6 inches back and forth.

Live view focussing isn't very good either because the lens is stopped down and there is a big DOF.

==
Half Man... Half Pentax

Pentax K-5 and some other stuff

Algi
Last Edited by Algernon on 17/03/2017 - 08:55

takuman

Link Posted 17/03/2017 - 13:41
Algi thanks for that. In my defense at the time of my post I was on the wrong side of a very decent red. Memo to self, wine and Internet are not a good mix. Apologies to all.
Just passing thru

Algernon

Link Posted 17/03/2017 - 14:09
No apologies needed hopefully we've given you some info that you can make use of.

I've never drunk red beer

--
Half Man... Half Pentax

Pentax K-5 and some other stuff

Algi

JAK

Link Posted 17/03/2017 - 14:32
pschlute wrote:
Are you trying to hand hold tha 400mm + 1.7 converter ? That is a tall order.

And that was just in one hand, the glass of red was in the other!
John K
Last Edited by JAK on 17/03/2017 - 14:33

pschlute

Link Posted 17/03/2017 - 17:46
JAK wrote:
pschlute wrote:
Are you trying to hand hold tha 400mm + 1.7 converter ? That is a tall order.

And that was just in one hand, the glass of red was in the other!

Recommended procedure for balance I believe.
Peter



My Flickr page

takuman

Link Posted 17/03/2017 - 18:31
Thank you all for your advice etc. Algi I followed the link you gave but must confess halfway through the red mist descended and I almost lost the will to live. So I will I think experiment until I find the best option for me, my K3ii and the lens I have. Regards to all
Just passing thru

McGregNi

Link Posted 17/03/2017 - 21:16
Algernon wrote:
Hi, you do have to set an AF adjustment value for MF. It's because it controls the beep/green light trigger position. To make matters worse the beep (MF or AF) gets triggered in two positions, similar to DOF. One going into focus and one going out and to make matters even worse like DOF it's affected by distance ....==

Hi Algi, yes thanks, I can see the applications for accurate AF confirmation with a manual focus lens. But .... I did believe that AF fine adjustment required the camera to store the adjustment in its memory, and that surely requires the lens data & ID to be transmitted from the lens ROM, via electronic contacts ..... how can that occur with an M series lens?
My Guide to the Pentax Digital Camera Flash Lighting System .... Pentax Flash Guide Updated, Articles .... link

Pentax K7 with BG-4 Grip / Samyang 14mm f2.8 ED AS IF UMC / DA18-55mm f3.5-5.6 AL WR / SMC A28mm f2.8 / D FA 28-105mm / SMC F35-70 f3.5-4.5 / SMC A50mm f1.7 / Tamron AF70-300mm f4-5.6 Di LD macro / SMC M75-150mm f4.0 / Tamron Adaptall (CT-135) 135mm f2.8 / Asahi Takumar-A 2X tele-converter / Pentax AF-540FGZ (I & II) Flashes / Cactus RF60 Flash & V6 Transceiver
Last Edited by McGregNi on 17/03/2017 - 21:17

Algernon

Link Posted 18/03/2017 - 10:43
I can only speak about my camera the K-5. It has a menu setting 'APPLY ALL' that stores a setting that it uses for any lens not stored separately in it's database.

Usually with M lenses you will only be interested in one main lens possibly a macro so that setting will normally be stored. Most other lenses will be OK if their value is close to that one, there is quite a bit of tolerance with adjustment values i.e. +4 +5 +6 +7 are almost the same. Otherwise the 'APPLY ALL' setting will have to be changed for each lens. I only have one lens that is completely different to most of the others and with 28mm or 35mm lenses I let the DOF compensate for any errors.

--
Half Man... Half Pentax

Pentax K-5 and some other stuff

Algi
Last Edited by Algernon on 18/03/2017 - 10:50

takuman

Link Posted 18/03/2017 - 12:16
Have just tried my 70mm Limited with 1.7x and results in my eyes were excellent. Yes I know, the 70mm is already a cracker. That's all from me now on the subject.
Just passing thru

Algernon

Link Posted 18/03/2017 - 12:32
That gives you a very handy 120mm, which I used to prefer on film over a 135mm because it doesn't flatten the features as much.

--
Half Man... Half Pentax

Pentax K-5 and some other stuff

Algi
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