Recent content by 138S

koraks, there is a way to safely boost pulsed overcurrent through a LED, it is the way I used in the designs I made for machine vision illuminators, I just copied other popular designs I saw around... > Power source has the Amp capability matching what the LEDs can safely stand, this is a...

A discrete LED can take and unstable amount of current and it requires a regulation, the classic way is a series resistor for the regulation... Anyway you don't need a coil to obtain a regulation, or you may place the coil and the freewheel diode in a way allowing a pulsed operation. In...

The coil and the freewheel diode you add is an smart solution to adjust intensity and to avoid ripples... Anyway let me point that there is an alternative: not avoiding ripples at all and lowering PWM to about 500Hz or 200Hz, allowing the duty cycle duration to be longer than 1ms. This...

Of course the ISO method is not perfect... Probably the ISO method was designed to provide the greatest conceptual simplicity still offering the important information for most of the films. This Delta-X Criterion looks a more refined way, but the ISO method says the exposure that (in standard...

Corel PaintShop is also a nice choice, a single $70 payment, with no subscription.

A problem with old very shutters is that internal contacts usually were intended for higher voltages then the ones sourced by modern flashes. Each metal type requires a certain voltage level to start electrical conduction, it can some microvolts or several volts. Some time the internal mechanism...

The 4990 is a good scanner that will deliver you very good images from 4x5" negatives, you can obtain around 75 effective MPix image quality. The V800 is better for 4x5 becuase it uses a second lens (it has two lenses that are automaticly replaced depending on the situation), while the 4990 has...

This effect is seen mainly in the scene highlights, highlights (high density in the negative, low intensity in the paper) have way lower light intensity in the scene highlights, (1/100 for negative density 2.0D, compared to Zone 0). If you repeat your test with base exposure (say) 1/30...

IMO not dust and not schneideritis... Schneideritis happens in the cylinder, but those dots are in the flange. If you unscreew the retaining ring with an spanner tool then probably you may remove the first glass. The first glass lays between the retaining ring and a flange, that flange has...

Let me add some considerations. The Linhof Technika (2000 model for example) allows 20º tilt/swing in the rear. (http://linhof.com/wp-content/uploads/2015/03/MasterTechnika_classic_2000_e.pdf) while the Horseman allows 10º. Linhof has a revolving back and IMO it also sports quite a...

Of course it would be suitable for stereo photogaphy, optimal distance to subject (for natural 3D feel) would be x30 the separation between the centers of the two lenses, so around 3 or 4 meters, the 1/30 rule... The optimal film format perhaps was larger than 4x5. It could be 5x7 or 8x10...

Also intermitent water bath can be mentioned, the advantage is that it works with the regular developer we may have been using.

The Norma weights around 3.4kg, the new chamonix F2 or a Tachihara weights around 1,5kg... as mentioned in post #8, those additional 1.9kg are important in a 10miles hike... Still some reputed photographers use a Linhof Master Technika that may weight 2.8kg with the rangefinder removed...

This is not an specific recommendation but choice you have... after 40 years (personally, I returned to the darkroom after 25 years...) a way to make a soft landing in the BW it may be having a Variable Contrast head, personally I use an LPL VC6700 that makes 35mm and MF, a good choice if you...

Yes... Probably the "field camera" term is a bit ambiguous. In some context it is a camera that's suitable to use it outside the studio, in other situations the term is used to describe lightweight cameras to hike with... or a heavier camera that is designed to be easy to deploy like the...