Why are these Doctor Who regenerations the same in (classic) Who?

Question

Why are some Doctor Who regenerations the same in classic Who?

I know in "new" Who regenerations are supposed to be the same but why are the regenerations in classic Who not all different?

For example:

• The Second Doctor's regeneration, 2 regenerates to 3, is the same as the Fifth Doctor's regeneration, 5 regenerates to 6. They both have swirly faces around them.

• The First Doctor's regeneration, 1 regenerates to 2, is the same as the Third Doctor's regeneration, 3 regenerates to 4. They both just morph faces.

Yet every other Doctor Who of (classic) Who is different, is there a reason why these particular Doctors have similar regenerations in classic Who whether in universe or out of universe?

Did the same producers from the Second Doctor era suddenly help with the Fifth Doctor's regeneration or is there another reason that the Doctors mentioned above have so similar regenerations?

Answer 1

It's just a case of practicality and storytelling. Bear in mind the available production technology of the time. When actually shown, the effect is always essentially the same smooth change from one face to the next, just better-presented as technology improves.

• First to Second - both actors available, brighten and cross-fade is an easy effect.
• Second to Third - new actor not available, rotating prism fade-out is an easy effect.
• Third to Fourth - both actors available, use the cross-fade again but in colour looks better without a brighten
• Fourth to Fifth - both actors available, use a slightly fancier cross-fade to incorporate the Watcher (a foreshadowing element)
• Fifth to Sixth - decide to portray the internal process instead, moment of transition obscured
• Sixth to Seventh - old actor not available, use fancy new CGI to obscure the new one's face
• Seventh to Eighth - never had such a large budget, can do a super fancy CGI morph

Then the new series design team went for the whole "streams of orange energy" thing.

A video compilation for reference

Answer 2

The obvious, out-of-universe answer to this question is that each regeneration shown in the early TV show was an example of the visual special-effects of the day. The show has spanned so many decades it is no wonder that the SFX have improved. The newer show since 2005 has also seen improvements in SFX over the seasons, but they appear to have tried to bring some consistency to the visual appearance of regenerations, especially after introducing the concept of 'regeneration energy'. This is the golden energy seen emanating from The Doctor's body before a regeneration before the fiery explosion of the actual regeneration.

'Twice Upon A Time' attempted to address the disparity between old-style regenerations and the new look by faithfully recreating the very first regeneration scene but retconned the account with glimpses of golden regeneration energy before it took place. It wouldn't be difficult for writers to explain away other the look of other past regenerations. The 6th regeneration did seem to show some kind of energy being emitted.

Don't forget also that some early regenerations were described as being "different". For a start, the second regeneration (2nd Doctor to 3rd Doctor) was not actually shown on TV. The series ended with the 2nd Doctor spiralling into an abyss but he never actually changed. The first time we saw the Third Doctor he had already regenerated, and actually a Doctor Who annual contained a story about the 2nd Doctor after the conclusion of his final TV serial which occurs on earth before his regeneration kicks in. Many consider this to be canonical.

Other "different" regenerations include that of the 4th Doctor, who "prepared" for his regeneration in advance and his new form was apparently contained in the form of The Watcher. The 5th Doctor's regeneration was also "different" (his final words are "feels different this time") and instead of seeing him regenerate, we see what is going through his mind as he does. The 7th Doctor's regeneration is also different, as he was "dead" when it happened.

Having already retconned the 1st regeneration and considering the facts that the 2nd, 4th, 5th and 7th regenerations were "different" in various ways, and that the 6th did look like regeneration energy (just not golden) we only really have to look critically at the 3rd. Which isn't so bad.