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Author Topic: Homemade Cameras  (Read 5264 times)

simplify

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« on: January 24, 2010, 06:55:25 pm »

I am considering a metal shop class at TechShop here in the San Francisco Bay area.  I am particularly interested in making mounts for my P45+ and experimental camera designs.  I remember seeing a post a while back by someone in Scandinavia who's friend was milling him parts related to a MFDB.  Does anyone know of any postings or have any experience making cameras?
Thanks,
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Dick Roadnight

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« Reply #1 on: January 25, 2010, 05:03:00 am »

Quote from: simplify
I am considering a metal shop class at TechShop here in the San Francisco Bay area.  I am particularly interested in making mounts for my P45+ and experimental camera designs.  I remember seeing a post a while back by someone in Scandinavia who's friend was milling him parts related to a MFDB.  Does anyone know of any postings or have any experience making cameras?
Thanks,
The tolerances you have to work to when making mounts for MFD are so tight that you would probably need (someone who has) a precision machine workshop, which TechShop seems to have. It could be some time before you were able to make precision parts, and you would need to produce precision drawings to work from.

I am an experienced and qualified engineer... and I might contemplate making parts for a view camera (without a lathe, milling machine or CNC plasma cutter) but for a MFD I would approach a jeweller/clockmaker.

Most of the Formula 1 cars and Tour de France cycles are built near here, (and when American Ford wanted to win Le Mans they [initially] built the car in the UK)  so if I hope I could get prototypes of anything made.

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elf

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« Reply #2 on: January 26, 2010, 12:05:39 am »

Quote from: Dick Roadnight
The tolerances you have to work to when making mounts for MFD are so tight that you would probably need (someone who has) a precision machine workshop, which TechShop seems to have. It could be some time before you were able to make precision parts, and you would need to produce precision drawings to work from.

I am an experienced and qualified engineer... and I might contemplate making parts for a view camera (without a lathe, milling machine or CNC plasma cutter) but for a MFD I would approach a jeweller/clockmaker.

Most of the Formula 1 cars and Tour de France cycles are built near here, (and when American Ford wanted to win Le Mans they [initially] built the car in the UK)  so if I hope I could get prototypes of anything made.

Why would the tolerances have to be any higher than for a view camera?  With back and front tilts/swings and shifts you should be able to focus an image on any back.
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jing q

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« Reply #3 on: January 26, 2010, 03:10:46 am »

Quote from: simplify
I am considering a metal shop class at TechShop here in the San Francisco Bay area.  I am particularly interested in making mounts for my P45+ and experimental camera designs.  I remember seeing a post a while back by someone in Scandinavia who's friend was milling him parts related to a MFDB.  Does anyone know of any postings or have any experience making cameras?
Thanks,

a sliding back helps, since the focus on the groundglass should be accurate.
Alternatively you could easily just calibrate your experimental camera's helicoid distance through trial and error.

Are you planning to get helicoids?I've been looking for some but not sure where to start.
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Hank Keeton

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« Reply #4 on: January 26, 2010, 01:17:37 pm »

Stateside try SK Grimes in RI. www.SKGrimes.com

Off-shore, but excellent service Stateside is Kim Camera in Korea, via Woo Jean Kim, KimCa9752@HanMail.com.

I've had great experiences with both, and would recommend them highly.
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dergiman

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« Reply #5 on: January 26, 2010, 01:27:59 pm »

Quote from: simplify
I am considering a metal shop class at TechShop here in the San Francisco Bay area.  I am particularly interested in making mounts for my P45+ and experimental camera designs.  I remember seeing a post a while back by someone in Scandinavia who's friend was milling him parts related to a MFDB.  Does anyone know of any postings or have any experience making cameras?
Thanks,

that might have been Graham Mitchell in Estonia a.k.a. foto-z.

Felipe
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EricWHiss

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« Reply #6 on: January 26, 2010, 03:41:29 pm »

Quote from: HankKeeton
Stateside try SK Grimes in RI. www.SKGrimes.com

Off-shore, but excellent service Stateside is Kim Camera in Korea, via Woo Jean Kim, KimCa9752@HanMail.com.

I've had great experiences with both, and would recommend them highly.

SKGrimes does high quality work for a fair price - and what's even better is that they think through projects thoroughly and sort the details.   I'd use them all the time for stuff but I don't like to wait that long.  I sent them a small project last summer and didn't get a quote until about Halloween, then didn't get the parts back until close to Xmas.  Maybe they are faster for some types of jobs they have already done?



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Rod.Klukas

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« Reply #7 on: January 29, 2010, 10:48:05 am »

Quote from: elf
Why would the tolerances have to be any higher than for a view camera?  With back and front tilts/swings and shifts you should be able to focus an image on any back.

The tolerances have to be at least 4 times more precise because film was thousands of an inch thick and the image plane of a digital sensor is 1 micron.  NO slop allowed.
One of the problems for view camera makers trying to transition to making cameras for digital backs is that the back makers are unable to measure exactly, where the image will form because it is slightly below the physical surface of the sensor and again is only 1 micron thick.
To be really sharp and allow for movements on a view camera, a far more precise camera than most is required.
An Arca Swiss, Sinar P series, Linhof 670's or similar are what is required for this.
That is why the cameras such as Arca Swiss RM3d or Alpa 12 max are so excellent as well.
Because they do not have bellows it eliminates one potential for mis-allignment.
Rod
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brianc1959

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« Reply #8 on: January 29, 2010, 08:47:54 pm »

Quote from: [email]Rod.Klukas@cox.net[/email]
The tolerances have to be at least 4 times more precise because film was thousands of an inch thick and the image plane of a digital sensor is 1 micron.  NO slop allowed.
One of the problems for view camera makers trying to transition to making cameras for digital backs is that the back makers are unable to measure exactly, where the image will form because it is slightly below the physical surface of the sensor and again is only 1 micron thick.
To be really sharp and allow for movements on a view camera, a far more precise camera than most is required.
An Arca Swiss, Sinar P series, Linhof 670's or similar are what is required for this.
That is why the cameras such as Arca Swiss RM3d or Alpa 12 max are so excellent as well.
Because they do not have bellows it eliminates one potential for mis-allignment.
Rod

Hi Rod:
Your precision estimate is way too tight, and is at odds with basic optical physics.  Ultimately its the f/# and degree of correction of the lens that really counts.  Pixel thickness isn't relevant to anything involving camera design.

To explain:  the diffraction-limited depth of focus of a perfect lens is approximately equal to the f/# - squared, measured in microns.  So, if you have a lens that is absolutely perfect at f/8 (and you are shooting at f/8), then the diffraction-limited depth of focus is +/- 64 microns (128 microns total, or about 5 thousandths of an inch).  All you have to do is put the sensor surface anywhere within that 5 thousandths envelope bounding the aerial image and the photograph will be as good as it can possibly be (again, assuming you are shooting at f/8).

You might be surprised to learn that very few MF lenses are actually close to perfect at f/8, so in practice the slop is even greater than the above analysis would suggest.  So in reality plenty of slop is allowed!
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brianc1959

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« Reply #9 on: January 29, 2010, 09:02:31 pm »

Quote from: Dick Roadnight
The tolerances you have to work to when making mounts for MFD are so tight that you would probably need (someone who has) a precision machine workshop, which TechShop seems to have. It could be some time before you were able to make precision parts, and you would need to produce precision drawings to work from.

I am an experienced and qualified engineer... and I might contemplate making parts for a view camera (without a lathe, milling machine or CNC plasma cutter) but for a MFD I would approach a jeweller/clockmaker.

Most of the Formula 1 cars and Tour de France cycles are built near here, (and when American Ford wanted to win Le Mans they [initially] built the car in the UK)  so if I hope I could get prototypes of anything made.

Tolerances required for MFD really shouldn't be so extreme - see my post above.  For a camera its mainly important to have some means of adjusting the system after assembly to eliminate tolerance buildup.  The same is true in optics - it makes no sense to blindly over-tolerance the system when you can achieve a better result by using carefully designed compensators to correct for the net effect of *reasonable* tolerances.
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elf

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« Reply #10 on: January 30, 2010, 01:09:18 am »

I don't have any problem focusing an image on the sensor with my spherical pano head: http://smg.photobucket.com/albums/v649/etf...mview=slideshow

I will say that it is hard to get the focus exactly where I want it, but that is a limitation of the Live View, not the alignment of the lens and sensor.  If the Live View had 1080p output, it would be very easy to do swings, tilts, and shifts.

I've been tempted to add a film holder and one of these, http://www.surplusshed.com/pages/item/m3259.html ,  just to see how well it would work.  I'd also be tempted to try a digital back, but $$$ prevent it
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Anders_HK

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« Reply #11 on: February 02, 2010, 01:42:04 am »

Quote from: simplify
I am considering a metal shop class at TechShop here in the San Francisco Bay area.  I am particularly interested in making mounts for my P45+ and experimental camera designs.  I remember seeing a post a while back by someone in Scandinavia who's friend was milling him parts related to a MFDB.  Does anyone know of any postings or have any experience making cameras?
Thanks,

Hi,

With experience from a custom made stitching adapter for my Aptus 65 to 4x5, there are essentially two options;

1) Stitching adapter on 4x5, the critical is that the error tolerance of sensor and groundglass plane versus sliding is small. Mine is approx. 0.07mm which is borderline meaning it works ok with my 72mm XL and 150mm, but not equal well with my 58mm. This is where the difficulty is in making stitching adapters for 4x5... - the tight tolerances! Probably approaching 0.02mm tolerance would be best. The camera itself does not need adhere to 0.02mm. I can focus on my Shen Hao wooden camera! While a complete other issue is that it is simply more convenient to use film in Quickloads in it ~~~

2) Camera body with helical focus. This is more simple (and I have thoughts on one), because there is not need to control swings and tilts, obvious simple if one accept no shift or rise/fall as well. Schneider has recommended me 0.02mm as critical tolerance for adjusted flange focal distance at infinity. Thus... assuming the camera body itself has been fabricated to 'reasonable' tolerances and that the digital back fits snug, it seems all one would need is ensure perfect alignment of lens mount compared to digital back, and make adjustment to the infinity focus of the helical focus...

The last sounds pretty simple to me, since camera body should not need 0.02mm tolerances, but well of material with not excessive expansion. Lens do need to be rather perfect aligned with shims though.

The question I must ask is, how can a company such as Alpa ensure of 0.02mm tolerance with all multiple parts that are connected between lens and back??? Seems dirt easily can account for 0.02mm...

Anders
« Last Edit: February 02, 2010, 01:46:14 am by Anders_HK »
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Dick Roadnight

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« Reply #12 on: February 02, 2010, 05:14:31 am »

Quote from: brianc1959
Tolerances required for MFD really shouldn't be so extreme - see my post above.  For a camera its mainly important to have some means of adjusting the system after assembly to eliminate tolerance buildup.  The same is true in optics - it makes no sense to blindly over-tolerance the system when you can achieve a better result by using carefully designed compensators to correct for the net effect of *reasonable* tolerances.
Most cameras have no adjustment for tolerance build up, but view cameras have (for focus and alignment) so tolerances are not so tight.

...but what I said was

The tolerances you have to work to when making mounts for MFD are so tight...

...and, when making mounts, you need to work to close tolerances just to safely hold your digiback.
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