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Joshua Cadmium

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  1. I just double checked and Formatt is having a 50% sale on all of their Firecrest filters, including clearance ones, until Monday: https://formatt-hitechusa.com/collections/clearance 4x5.65 is $180 and 138mm is $99. The older filters are exactly the same as the newer ones according to this: https://cdn.shopify.com/s/files/1/0267/9934/1677/files/Formatt_Firecrest_Ultra_Brochure_-_Updated.pdf
  2. So, if you can deal with the lack of coverage, you might be okay, but 4x5.65 is the standard for everything besides rotating filters. The market for 138mm NDs is small, so resale will take a hit if you ever decide to step up to 4x5.65. I know Formatt has their 138mm Firecrests on sale for $200, but they've been on sale for a while and no one is buying, if that tells you anything.
  3. Another important point is that 138mm round filters will have less coverage than 4x5.65 filters. Since we are always dealing with rectangular aspect ratios, a 138mm filter in the same 1.4125 aspect ratio of a 4x5.65 filter will cover about a 79.7mm x 112.6mm rectangle A 4x5.65 filter covers a rectangle of 101.6mm x 141.5mm So, 4x5.65 filters offer about 25% more coverage in both directions. But that's at a 1.4125 aspect ratio. As you go wider, the 138mm filter can make up some ground, but it still does not cover as well as a 4x5.65 does. At a 1.85 aspect ratio, a 4x5.65 covers a rectangle of 76.5mm x 141.5mm. A 138mm would cover 65.6mm x 121.4mm. That's about a 15% difference in coverage in each direction. At a 2.39 aspect ratio, a 4x5.65 covers a rectangle of 59.2mm x 141.5mm. A 138mm would cover 53.3mm x 127.3mm. That's about a 10% difference.
  4. I have two of them that I picked up used, so I don't know exactly when they were made. They definitely came from different batches as the engraved font on the aluminum is different, but they were quite similar - about 7 mireds different between the two of them. They do seem to be on the green side by eye and as measured by my lower end Illuminati color meter (they were reading around +1/2 green). They are definitely correcting to daylight kelvin values, though. However, I was not testing them with DLH4s - I was testing them out with Dedocools, which (at least on the one's I own) don't have room for a front filter - the front glass element sticks too far out. I found that I could jam the filter in at an angle and use a cable to keep it from falling out. Partially because of that, I realized that the filter is less green and appears neutral (+0 green) depending on the angle I have it at (while still correcting to daylight.) Dichroic filters work by passing part of the spectrum you want and reflecting less (or none) of what you don't want. They are impacted by the angle of the light as it travels through them, so that's why tilting the filter impacted the color I was getting. So, YMMV on a DLH4, but I hope this might help a little. Also, Dedocools are about as loud as a blowdryer, if anyone was thinking about checking them out. 🙂
  5. Here's a fantastic example of using the Parallel Beam Attachments with DLH4s and the Lightstream Reflectors: In the example, he's only using 4x 150w Dedolights, so only 600w total. Pretty efficient.
  6. Tungsten in general is still the king when it comes to color rendition - it's the only light source besides the sun and fire that gives perfect color. It's 100 CRI, TLCI, CQS, etc. With tungsten Dedolights, you have numerous benefits over regular tungsten lights. Most Dedolights (including the DLH4) use low voltage bulbs that are more efficient than higher voltage bulbs because the filament itself is more compact and doesn't need as much electricity to keep it hot. Because of that, whereas most tungsten units are about 15-20 lumens per watt, Dedolights get up to 35-40 lumens per watt. Dedolights also use aspherical optics that capture all that light and condense it into an even beam. Standard fresnel lenses can be very inefficient, especially when spotted down. Also, Dedolight does has dichroic daylight conversion filters for their tungsten lights, including the DLH4. So, while gelling the light will indeed cut two stops, the dichroic filter will only cut one stop. The bulbs should also not be going away anytime soon. Halogen bulbs are typically still on the market because they are more efficient than non-halogen tungsten. These low voltage bulbs are about double the efficiency of high voltage halogen. Since you were planning on using the Light stream reflectors, Dedolight does have the Parallel Beam Attachment that increases the amount of light when in full spot by 400% (since you use it in the flood position, which gives out the most quantity of light.) Also, while most tungsten units are cheap on the secondary market, I find it telling that Dedolights still hold their value.
  7. Thank you so much for the info! I was actually hoping to hear from you specifically, so that was super helpful.
  8. Anyone want to chime in one way or the other and offer some opinions? 🙂 Basically, would 1-3 lbs of unsupported weight damage the focusing threads if no focusing was actually being done?
  9. I have a Century Double Asphere and a bunch of other heavy wide angle adapters I want to use with a Zeiss 10-100 T1.8 MK II and a 12mm T1.3 MK II. I know that due to the telescoping nature of the helical focusing threads, you shouldn't have anything heavy (or at all) attached to the front of the lens while focusing, like a clip on matte box. I was wondering, though, if the threads would be okay if I prefocused the lens, then attached a wide angle adapter, and then did not focus the lens at all while the adapter was clamped on. (I know I would need to find the exact focus point for non-zoom through adapters, like the Double Asphere, but I'm not worried about that.) With the 10-100, it also has the macro mode, where the focus wouldn't be extended at all and be at its starting point on the threads. I'm also thinking about using an anamorphic adapter, plus a front variable diopter, which would be several pounds hanging off the front. If I went that route, I would have each part individually supported on rods and, again, would not touch the focus at all at that point, but I don't know how safe that would be. Those two lenses currently have perfect focusing, especially for their time and I really don't want to wreck the threads.
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