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12-27-2007, 07:02 PM   #16
mer
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x16 ? This means your bellows should be about 5cm x 16 = 80cm ! Almost a meter... I highly doubt this as most bellows are max 20-25cm... You need 50mm for a 50mm lens to get you to 1:1 , so a 20cm bellows will bring you to about 4x .

12-27-2007, 07:14 PM   #17
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QuoteOriginally posted by mer Quote
x16 ? This means your bellows should be about 5cm x 16 = 80cm ! Almost a meter... I highly doubt this as most bellows are max 20-25cm... You need 50mm for a 50mm lens to get you to 1:1 , so a 20cm bellows will bring you to about 4x .
correct, and an exposure time needing at least an inert subject.. or a good flash setup which i have.. bellows are, to me, just too much of a PITA to use. of course i've never used a tripod for macros either..
12-27-2007, 07:37 PM   #18
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Like I said, I'm still figuring this thing out, lol. It was supposed to come with the manual but it didn't and I can't find one so far.

It's about 1 foot long and at the far end it's marked 16x, 3.0, f=55mm.





I think that means 16x magnification using a 55mm lens and a loss of 3 stops light.

Edited to say I'm probably reading that wrong. I think it's 3x magnification and 16x light loss, however much that is. Also. there's a scale on the other rail that looks like it's 180 cm long, goes to 18.

Last edited by Slick; 12-27-2007 at 07:56 PM.
12-27-2007, 07:59 PM   #19
mer
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1 foot long is about 30cm isn't it .

A 5.5cm lens with 30cm bellows will bring you to 5.45 magnification . Don't worry about the manual , as there are formulas to calculate everything you need.... including light loss/effective f-stop ... just ask .

Have fun

12-28-2007, 08:58 AM   #20
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Thanks everyone, one further question

I finally picked up a manual set of Pentax tubes and the Pentax M 50mm f2 today for 55 euro. The lens came with a hood ( looks like a car tyre) and a uv filter, i wonder if its original?

Anyway, could you tell me once the tubes are in play do i have to adjust the focal length from 50mm when the camera strts up. I wanna play hard in the macro world

Also i have read mixed reviews of this lens and seen MTF results that differ when compared to the other 50mm Pentax primes. Is there a definative conclusion on this as i am starting to wonder if its the runt of the litter?

Thanks again to everyone who contributed to this thread


Peter
12-28-2007, 09:15 AM   #21
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Congratulations.

I'd see how the lens does myself - Stan's site rates the A50/2 highly. And during the time I had both a 50/1.4 and 55/2 screw mount Takumar at hand, I'd have rated the cheaper lens as better in many conditions. For example, my CA torture test showed the 55 beating the 50. But of course I kept the 1.4 and gave the 55 to my brother in law

On your other question - that never occurred to me - you'd think the further the objective is from film, the longer the lens would act, physically I mean?
12-28-2007, 10:20 AM   #22
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Hi Nesster

I could not find anything at Stans concerning the M version of the 50 f2?

The focal length question relates to the shake reduction settings at startup.

Thanks again Nesster

Peter
12-28-2007, 11:19 AM   #23
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I think you can do a pretty good job with extension tubes. I just got a set of Kenko tubes for Christmas. I haven't had time to play with them much yet, but this is a shot of the knob on the top of one of my kitchen chairs. It is definitely a lot closer than 1:1, I'm not sure what it is, I'm not sure how to calculate that, but it gets you pretty close. My set has a 12mm, 20mm, and 36mm, this was taken with all three stacked on my 50mm 1.4 lens.

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12-28-2007, 11:55 AM   #24
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Hi Travis

This is a good example of limeted DOF control for those of us playing with tubes. Keep playin Travis.


Thanks
Peter
12-28-2007, 04:45 PM   #25
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frost on a car roof, yesterday, 50mm M 1.7 mounted normally on 65mm extension. hand held.
I'd say the crystals were 1.5 - 2 mm.
100% crop shows exquisite build up of ice. let me know if you're interested, I'll dig it out.
12-28-2007, 05:28 PM   #26
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QuoteOriginally posted by Spooked Quote
Hi Travis

This is a good example of limeted DOF control for those of us playing with tubes. Keep playin Travis.


Thanks
Peter
Yeah, when you have to get that close you do have a hard time getting a big enough dof, but it can be better than that for sure, that was a f/4.5 I would have stopped down some more, but I didn't have much light.
12-28-2007, 05:51 PM   #27
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QuoteOriginally posted by mer Quote
1 foot long is about 30cm isn't it .

A 5.5cm lens with 30cm bellows will bring you to 5.45 magnification . Don't worry about the manual , as there are formulas to calculate everything you need.... including light loss/effective f-stop ... just ask .

Have fun
here a shot of the cam with a viv105/2.5 macro, 68mm ETs and a 2x TC w/flash. shooting a MM ruler shows it's somewher between 3-4:1 mag.


here's a shot with it. of a dfly eyes.
12-28-2007, 05:54 PM   #28
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QuoteOriginally posted by Spooked Quote
Hi Nesster

I could not find anything at Stans concerning the M version of the 50 f2?

The focal length question relates to the shake reduction settings at startup.

Thanks again Nesster

Peter
i've used it 50/2 on ETs and it's stellar.. very inexpensive also.
12-28-2007, 06:14 PM   #29
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Roy, that shot is so funky its killing me!!! WOW

Thats what i call inspired brother. I am on my way to find me a bug or two.

Thanks for sharing

Peter
12-29-2007, 12:13 AM   #30
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With all the talk about extension tubes, don't totally discount using bellows as part of your macro "quiver". I got my set on eBay for about 40 USD and it is by far my favorite setup for serious macro work.



As you can see, the bellows (Pentax bellows-k) are fairly compact and allow for fine adjustment of both magnification and focus. I have been using a Pentax M 50mm f/1.7, though a moderate tele or dedicated bellows lens might work better from an illumination standpoint.

This setup was used to take the following picture (magnification about 2-2.5:1) of the base of a small maple leaf:



(Straight shot, no crop and no post-processing)

Last edited by stevebrot; 12-29-2007 at 12:46 AM.
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