He is asking about the reason why the fatwa on photography was changed
In fact what you mentioned about the change in the fatwa on photography may not be quite correct. We need to differentiate between two matters when it comes to the matter of photography or image-making.
The first matter is the ruling on photography or making images of animate beings. This is the crux of the matter. What we are referring to is two-dimensional pictures (as opposed to three-dimensional images).
The saheeh Sunnah indicates that these kinds of images are haraam, whether they are on a poster, paper, garment or wall, because it is imitating the creation of Allah.
An-Nawawi (may Allah have mercy on him) said:
Our companions and other scholars said that making images of animate beings is emphatically forbidden and is a major sin, because of the stern warning issued concerning it in many hadeeths. Regardless of whether the final product is something that will be handled in a disrespectful manner or otherwise, making them is haraam in all cases, because it is trying to imitate the creation of Allah, may He be exalted. That applies whether the images are on a garment, carpet, a dirham, dinar or other coin, a vessel, a wall, or anything else.
With regard to making images of trees, camel-saddles and other inanimate objects, that is not haraam. This is the ruling on the issue of image-making.
There is no differentiation in any of these matters between that which has a shadow and that which does not have a shadow.
This is the summary of our opinion concerning this matter, and something similar was stated by the majority of scholars among the Sahaabah, Taabi‘een and those who came after them; it is also the opinion of ath-Thawri, Maalik, Abu Haneefah and others.
Some of the early generation said that it is only that which has a shadow that is forbidden, and there is nothing wrong with images that do not have a shadow. But this is an invalid point of view, because no one doubts that the curtain that the Prophet (blessings and peace of Allah be upon him) objected to because of the images on it was something blameworthy, and its images did not have a shadow. And we should also bear in mind all the other hadeeths which speak in general terms about all images. Az-Zuhri said: The prohibition applies to images in general.
End quote from Sharh Muslim by an-Nawawi, 14/81
We have previously discussed the evidence for the prohibition on image-making and some of the texts of the scholars concerning that in many answers. See the answer to question no. 7222
This is a matter concerning which we know of no fatwa that has been changed, or that anyone who said that image-making is haraam changed his mind and said that it is permissible, or that most muftis were of the opinion that it was haraam but now they think it is permissible. Even if we assume that some such change has taken place, it is very little or is odd and rare, and cannot be taken into account.
The second matter is: does the ruling on image-making apply to specific types of images, such as photographs for example? If it does include that, does this prohibition apply only to a complete image or does it also apply to partial images? And there are other such issues concerning which the faqeehs and muftis differed as to whether the ruling mentioned above is applicable to these modern forms of image-making.
This is a matter concerning which there is a considerable and well known difference of opinion among the scholars. Some are of the view that photographs come under the heading of image-making that is haraam, because it is a kind of image-making and because what is produced by means of it is an image, so it comes under the ruling on images of which the text speaks.
Some scholars are of the view that the reason for the prohibition on image-making, which is imitating the creation of Allah, is not applicable in the case of photography, because it is merely capturing the reflection of a person, so it is permissible and is like looking in a mirror and the like.
This is not the place to discuss that; rather the aim is to point out that there is a difference between saying that there are differences concerning the ruling and saying that there are differences concerning the application of the ruling in specific cases.
We have discussed the ruling on photography in many answers on this site. Please see the answer the questions no. 13633, 10668, and 7918
As this is the case, there is nothing strange about a scholar or mufti having different views concerning new developments. He may have based his ijtihaad at some time on the assumption that the photograph would have to be processed by a human in some way, which is the same as the work of the image-maker, so for that reason he ruled that it is haraam; then things may have changed and equipment may have been developed, so there is no longer any need for human involvement.
In fact we may say, to further clarify this point, that the view of a scholar may change from one time to another on the same issue, and this is nothing new; rather it is something that is well known and well established. The fact that there are two Shaafa‘i madhhabs, old and new, bears witness to that. And the differing reports from Imam Ahmad and others on a single issue are well known.
The examples of that are very well known, and the matter is not to be established on the basis of what this one or that one said; rather what matters what evidence there is to prove a given view.
We ask Allah to help us all to do that which He loves and which pleases Him.
And Allah knows best.