12 seconds using a Stellacam III cooled and 18" F4.5 reflector.
Ikagami top, Speco bottom.
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Edited by Daniel Mounsey, 05 August 2014 - 07:06 PM.
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Posted 05 August 2014 - 10:29 PM
Interesting. I enjoy comparisons like this, but I know they can be difficult because of so many variables.
Is the brightness up as far as possible while maintaining the same level of black background?
Any idea why there's a different cast or tint to the Speco image?
Has the Speco had it's black level adjusted?
Is the size difference from cropping for reproduction here, or something else?
Posted 05 August 2014 - 10:52 PM
Posted 17 August 2014 - 08:14 AM
Notes from John Hawk at Cal Arts
The Speco is a surveillance monitor and the Ikagami in its time was a top of the line B&W studio monitor. So the Ikagami gives a little more accurate and refined image. When I did this test I was alone and used the same frozen image on each monitor. I just tried my best to get the best looking image on each monitor. The Speco always has a blue cast to the whites with the Ikagami being more neutral. The Speco appears overall brighter so some prefer it. Finer detail can be observed on the Ikagami which doesn't really show in the pictures, which were taken with an iPhone. Next time I'll use my Canon 7D. As you noticed they do frame the image slightly different. The Ikagami has an under-scan feature that reveals even more of the frame, but the image is slightly smaller. You can get an Ikagami on eBay for a song as who needs a B&W standard definition monitor anymore except an amateur astronomer using a Stellarcam, lucky for us! The nebulosity difference is actually better all around on the Ikagami, it just didn't show on the picture in the spots you pointed out. The Speco also tend to blow out the whites slightly if you want to reveal more fine nebulosity, but has a more punchy look overall. There is no external black level adjustment as in 7.5 IRE on either monitor, just brightness and contrast knobs. Hope this answers your questions.
Posted 17 August 2014 - 10:21 AM
There is a black level adjustment on the Speco ... it's not labeled but it's on the rear panel (I forget what it's actually called ... but it effectively changes the black level). It's a very sensitive adjustment and should only be performed in very small increments. The adjustment can make quite a difference on the visibility of faint details on some monitors. I did the adjustment years ago on my Speco, it made a slightly noticeable difference but it didn't knock my socks off ... other Speco owners have reported big differences.
As a dedicated B/W monitor the Ikagami is likely capable of a bit more resolution resolution (lines horizontally) ... but even with cheap B/W TVs that don't have really good resolution you can often see more faint details than with a color monitor, I think it has something to do with the phosphor coating.
Looking at color vs. B/W is a valuable comparison. If someone goes to the extent of choosing a B/W camera (today for most folks B/W is a choice, a little different from the time when the Stellacams were generally available) I think it makes sense to pair it with a good B/W video monitor to achieve the maximum benefits. You can certainly get some benefits from B/W over color sensors for video but when you display it on a PC (or even a color video monitor) I don't think you're getting all the benefits.
Edited by mclewis1, 17 August 2014 - 10:25 AM.
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