Vari-focal Lens Question

[justchil 0]

Would a Vari-focal Lens be better vs a fixed lens for a driveway camera? Would it be better for license plates, etc?

[survtech 0]

Yes and no. Properly chosen fixed focus lenses tend to be easier to focus but may not get the exact scene desired, due to the limited selection of focal lengths available. With a fixed focus lens, you may get either too large or too small an area. If it sees too large an area, resolution of the area of interest suffers. If it sees too small an area, you might miss important details.

 

A varifocal lens can be zoomed to view exactly the scene desired but the interaction between zoom and focus makes getting the two right a bit more time-consuming.

 

All else being equal, the picture obtained by properly adjusted varifocal and fixed focus lenses should be equal.

[Nimrod 0]

Fixed lenses can typically be gotten with a lower F stop than varifocal so better low light performance.

[Soundy 1]

Would a Vari-focal Lens be better vs a fixed lens for a driveway camera? Would it be better for license plates, etc?

As survtech indicates, the ONLY functional value difference between fixed and vari-focal is in installation, to let you fine-tune the area of coverage. In actual operation, there should be no real difference (all else being equal).

[rory 0]

Fixed lenses can typically be gotten with a lower F stop than varifocal so better low light performance.

Normally its the other way around, with easy to find varifocal lenses in the F:095/F:1.0 range, and fixed lenses typically F:1.2 and up.

[Soundy 1]

I'd say that really depends - from my collection of used stock, I'd say about 99% of both are no faster than f/1.4... the majority max out at f/1.6 and some of the bigger ones are f/1.8 at best. The only one I can think of off the top of my head that's faster is a fixed 8mm that's f/1.2. I've seen an f/0.95 at one of our suppliers, but never used one.

[Nimrod 0]

I have been able to buy f1.0 fixed lens (CS) fairly easily and cheaply, but i never saw a f1.0 varafocal, they are probably made, but are very expensive.

[rory 0]

I have been able to buy f1.0 fixed lens (CS) fairly easily and cheaply, but i never saw a f1.0 varafocal, they are probably made, but are very expensive.

Dude they are like $40. They are at every distributor, Tamron and Fujinon have had them for years. Basically if you are looking for lower F:stop VF lenses they will typically be in the 3-8mm range. In fact the Fujinon F:0.95 one has been pretty much the same for the past 10 years except it dropped in price and now they have IR models, the Tamron models are IR also.

 

BTW thought you were talking about fixed board lenses, dont know anyone that still buys fixed CS lenses let alone distributors have almost stopped selling them all together since VF lens prices are so cheap now.

[survtech 0]

We still use CS-mount lenses. Most box cameras use them and the Ganz ZCD5000-series mini-domes also accept CS.

 

Really, we would much prefer full size lenses. S-mount board camera lenses typically feel cheap, are more difficult to fine tune zoom and focus, tend to have difficulty maintaining focus over the entire scene and are limited in zoom ratios. Fixed-focus S-mount lenses rarely have irises. Varifocal S-mount lenses offer few focal length options and are not easily interchanged.

[rory 0]

@ Survtech, if your reply was to me, I never said nobody uses CS lenses, I do myself, I said that fixed or MANUAL CS Lenses are not easy to find at distributors, compared to Varifocal lenses (CS Mount).

 

BTW with new (current) Domes and bullets you should be able to interchange M13 Varifocal lenses between at least 90% of them, and buy new lenses that will also fit. But ofcourse box cameras still have a huge advantage over them in that area.