Wednesday, February 26, 2014

Review: Rainbow S4.8mm f1.8 on a Pentax Q

I recently did a review of the Spacecom H3.5mm f1.6 lens and you can pretty much copy whole sections from that review paste it here. I'll be doing some of that so you may get a sense of déjà vu if you've read that other review. Both are C-mount lenses designed to be used on CCTV cameras and there are a lot of similarities between the two, from their strengths, their weakneses and my approach to shooting with them.


The Rainbow lens is pretty small and very light. It's mostly made of plastic aside from the glass elements. Size and weight is just right on the Pentax Q, the lens doesn't dominate the camera. The focus and aperture rings are easy enough to use if you don't mind manual focusing and adjusting the aperture via the lens. They look a lot like the ones on the Spacecom.

The Spacecom lens has a metal mount while the Rainbow has a plastic mount. Not a big deal since both lenses are very light. Except maybe if you're using it for some extreme sports stuff.

As with the Spacecom, I've only been able to use the Rainbow with the Pentax Q using a C-mount to Pentax Q adapter. It cannot be used on a Micro Four Thirds or Nikon 1 camera because of the side of the rear mount. You may be able to modify it to fit but you'd get an image circle in the middle of the frame and just black outside of the circle so I don't know if it'd be worth the effort.


You may be disappointed with the images that this lens produces if you love to view your photos at 100% and examine the tiny details. This is a lens designed for video surveillance cameras and they usually don't require excellent image quality across the frame. If it can catch a bad guy doing some illegal business then it has served its purpose. I don't think it was ever designed for modern day digital stills cameras.

There's a lot of softness across the frame when shot wide open and you'll want to set the aperture ring somewhere past the halfway point of the 'CLOSE - OPEN' labels. So you probably won't be using this for its low light capabilities unless you can get those nice looking soft shots. I haven't done a lot with regards to those kinds of photos but they can be made to look good depending on what you're shooting.

Once you stop it down, you should be able to get some sharp photos. At least they are in the centre of the image. Corners are soft but not as bad as with the Spacecom. Same with chromatic aberration, it's there but mostly noticeable in high contrast scenes or if you're viewing at 100%.

There's noticeable distortion but I've been able to correct these in Lightroom. I mostly just leave the photos alone and don't bother correcting them, I don't mind the look.

The chromatic aberration becomes a non issue and I actually like the corner softness when shooting in black and white. Seems like a nice lens for street photos. It's easy enough to use a smaller aperture and set to infinity focus and a lot of things would be in focus. It works well enough as a 'shoot from the hip' lens.

Minimum focusing distance is pretty good, a bit closer than what you'd get with the Spacecom. It's no macro lens but I'm happy.


I got this as part of a bundle back in January. I paid $85 for 12 C-mount CCTV lenses and included were 6 copies of this lens, 2 copies of the Spacecom H3.5mm f1.6, 1 copy of the Pentax 6mm f1.2 and 3 copies of the Pentax 16mm f1.4. So I'd say that it's extremely good value. As to whether it'd be a good value lens for you, that will depend on how much you can buy it for and how useful a lens like this would be to you.


The Rainbow S4.8mm f1.8 might be a bit redundant if you already have the standard 5-15mm zoom but might be of some use if you bought a Pentax Q with the 8.5mm prime lens like I did.

As with the Spacecom H3.5mm f1.6, this lens has allowed me to empty my brain and just focus on what to shoot instead of how. When using high quality lenses, I'm always trying to get the absolute best image that I can out of it. I know what's possible from them so there's always the quest to get as close to perfection as possible. With lenses such as these, I accept that the images aren't going to be excellent quality and I just make the most of what I have.

I've enjoyed using it when I'm doing random everyday things or going somewhere boring (this happens quite often since I have a very boring life) and I don't need or want to bring my best gear. I don't see myself using this lens for anything really important but there are times when I like to have that cheapie lens character to my photos.

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