Macro Tubes

If you are using a 50mm manual lens with macro tubes how do you calculate the focal length to dial into the camera?

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Regards
Barrie
K20D K200D DA*300 A50/1.7 FA50/1.4 FA135/2.8 FA35 DA70/2.4 DA18-55 DA17-70 DA55-300
Samsung12-24
Tamron 28-300XRDi 70-200/2.8
Sigma 50&105mm Macro 170-500 400/5.6MF 24/2.8

I set mine to the focal length of the lens.

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My FLICKr
My PENTAX GALLERy
Camera: Gripped Pentax K10D MKI (Now with designer red tape door catch)
AF Lenses: 10mm-500mm
Manual Lenses: Pentax M 50mm f4 Macro, Tamron Adaptall 2 SP 17mm f3.5 (151B), SP 35-80mm f2.8-3.8 (01A), SP 90mm f2.5 Macro with 1:1 adapter (52BB), SP 90mm f2.8 Macro (72B), SP 70-150mm f2.8 Soft (51A), SP 70-210mm f3.5 (19AH), SP 80-200mm f2.8 (30A), 6 PK/A Mounts. Pentax A* 300mm f2.8 & Pentax 1.4X-L, 2X-L & AF 1.7X.
Flash: Metz 58 AF-1, Sigma EM 140 DG Macro Ring Flash, Pentax AF-280T, Pentax AF-200T.

NOTE TO SELF: Must stop buying lenses (soon)

So does it not change if you use different lengths of tube? typo

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Regards
Barrie
K20D K200D DA*300 A50/1.7 FA50/1.4 FA135/2.8 FA35 DA70/2.4 DA18-55 DA17-70 DA55-300
Samsung12-24
Tamron 28-300XRDi 70-200/2.8
Sigma 50&105mm Macro 170-500 400/5.6MF 24/2.8

Agreed.

Mine are auto tubes so I just leave them at the focal length set by the camera, which is that of the lens, not had any problems doing this.

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Dont Worry, Be Happy.

You beat me to the post Barrie, no my auto tubes set the focal length of the lens regardless of the number of tubes fitted.

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Dont Worry, Be Happy.

No just give them the focal length since tubes won't change them.
I believe when you use a TC then you should change it though.

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Stefan


K10D
DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ

I can't get my head round this, because are are totally altering the optical relationship between the lens and the sensor.
auto as in auto focus or auto as in "PKA". If it's auto focus then would the camera not just detect the lens without knowing whats going on in between, as happens with auto focus teleconverters? If it's PKA are you not asked to dial in the focal length?

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Regards
Barrie
K20D K200D DA*300 A50/1.7 FA50/1.4 FA135/2.8 FA35 DA70/2.4 DA18-55 DA17-70 DA55-300
Samsung12-24
Tamron 28-300XRDi 70-200/2.8
Sigma 50&105mm Macro 170-500 400/5.6MF 24/2.8

A 50mm lens is a 50mm lens no matter how far away you hold it from the sensor. The focal length doesn't change just because you're using it for macro work...

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Bodies: K10D | MX
Regular Kit Bag: DA12-24 | DA35 | FA43 | FA77 | D-FA100
Raining Kit Bag: DA18-55 | Tamron 70-300
Manual Kit Bag: Super-Takumar 28 | Helios-44 58 | Zeiss Sonnar 135 | Tair-3S 300
Stay-At-Home: Asahi Bellows II | Schneider Componon 50

It's academic anyway if using a tripod. You length you dial into the camera is for the Shake Reduction, but you'll have SR turned off.

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~Pete

Correct It's the engineer in me needing to know how things work.

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Regards
Barrie
K20D K200D DA*300 A50/1.7 FA50/1.4 FA135/2.8 FA35 DA70/2.4 DA18-55 DA17-70 DA55-300
Samsung12-24
Tamron 28-300XRDi 70-200/2.8
Sigma 50&105mm Macro 170-500 400/5.6MF 24/2.8

Yep focal length stays the same but you alter the focus distance.


Don't know about the TC but there is a "chip" in the lens with his data and that gets transferred through the "info-contact"




Focussing just goes through the AF sensor so no need for feedback from the lens about that, however it does give the camera some info about focusing but nothing exciting.

I believe that hardly any TC do give the right focal length automaticly only the Pentax ones does give it through correct so focal length + TC magnification.

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Stefan


K10D
DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ

My tubes are auto and if I am using an A lens or newer then the camera chooses the focal length (which I presume is the lens). If using a M42 or M/K mount then I dial in the lens myself. Never use a tripod and have never had a problem doing it that way. But if it's wrong and I will get sharper shots any other way then all advice gratefully received. (apart from use a tripod).

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My FLICKr
My PENTAX GALLERy
Camera: Gripped Pentax K10D MKI (Now with designer red tape door catch)
AF Lenses: 10mm-500mm
Manual Lenses: Pentax M 50mm f4 Macro, Tamron Adaptall 2 SP 17mm f3.5 (151B), SP 35-80mm f2.8-3.8 (01A), SP 90mm f2.5 Macro with 1:1 adapter (52BB), SP 90mm f2.8 Macro (72B), SP 70-150mm f2.8 Soft (51A), SP 70-210mm f3.5 (19AH), SP 80-200mm f2.8 (30A), 6 PK/A Mounts. Pentax A* 300mm f2.8 & Pentax 1.4X-L, 2X-L & AF 1.7X.
Flash: Metz 58 AF-1, Sigma EM 140 DG Macro Ring Flash, Pentax AF-280T, Pentax AF-200T.

NOTE TO SELF: Must stop buying lenses (soon)

Mike, if your shots get any sharper we'll all be cutting our fingers on them...

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Kris Lockyear
35mm film: too many! Mainly using my LX, along with some others.
LF: Horseman LE 5x4 view camera
Digital: K10D, K20D
AF: DA 12-24mm, 43mm Ltd, DA* 50-135mm f/2.8, Sigma 50mm macro, Mk 1 kit lens.
Manual: SMC-K 200 f/4, SMC-K 135mm f/2.5, SMC-K 50mm f/1.2, SMC-K 35mm f/3.5, SMC-K 15mm f/3.5, SMC-M 100mm f/2.8, Jupiter-9 85mm.