Tube Camera Oddities

Here's a couple of screenshots from last Saturday's episode of Dad's Army, in particular the 1976 Christmas special.

Noticed watching this on Saturday that some shots, that seem to be from particular cameras, look a bit out of focus (or "noisy") compared to other shots.

This shot for example:
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is followed by this one and the quality in the picture is noticeably sharper than in the previous shot:
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In fact I can tell from just looking at the thumbnails the shot of Captain Mainwaring isn't as clear as the one of Hodges. This issue isn't unique to this particular episode, it happens on quite a few of them but I haven't noticed it on other TV shows that were filmed on Tube Cameras like Fawlty Towers for example, but having said that I believe Fawlty Towers was mostly (but not exclusively) filmed in TC8, whereas Dad's Army seems to have been in TC6 so that might explain that.

I know its unlikely that the hardware would have been 100% identical with various signs of wear, repair and whatever else but wouldn't somebody have noticed that the images from this particular camera were a bit out compared to the rest? Or is it more likely just a quirk of this particular camera?

TC6 and TC8 had the same cameras, Marconi MKVIIs were installed at the beginning of colour working and swiftly replaced by the EMI2001 within a year or so. http://www.tvstudiohistory.co.uk/tv%20centre%20history.htm#tc1,%206,%207

Are all of the shots where you notice a soft picture wides like this one?

Not all wide shots - another episode where I noticed it predominately the effect only happened on the close up shots of one character.

Probably were less bothered about inconsistencies between cameras back then, wouldn't have really shown up once you put it through PAL processing, sent it over the air and watched it on the smaller TVs of the time. The idea of it being seen on big screens in pristine quality 40 years later wouldn't have even been thought of.

They absolutely would have been bothered about inconsistencies like this. However, with the completely analogue nature of tube cameras, where all the settings would drift while running and not all settings were able to be changed remotely or mid scene, there would always be occasions where pictures wouldn't be perfect, but still technically acceptable.

Believe you me - they absolutely were bothered. Engineering maintenance and line-up of studio and OB cameras was taken pretty seriously. However there was only so much you could do - tubes degraded in performance terms, analogue circuits (and most cameras in the 60s and 70s were analogue, though some started to have digital control of analogue processing) similarly weren't always consistent and degraded.

Also because video editing was in it's infancy and expensive shows were often recorded 'as live' - if a camera op missed a cue or was not quite in focus it often had to stand in the final recording. It's far easier now with isso'd cameras and post production methods.