Optics Course : Astigmatic fan/Dial : principle behind and how to use.

[@hamedabuhuryra8349]

Sir In the example at 4:49 the vertical meridian is myopic by -1,so sholdn't the horizontally focused rays come on front of the retina as we know that astigmatic lens give focal line parallel to the axis for a point source of light?

[@adelabdelshafik]

would you re see the video up to 6.30 minute , this part explains that each point of the object will be extended in a vertical direction so on looking at a cross, the vertical line of the cross will extend vertically so only its extreme ends will be blurred , on the other hand the horizontal line all its points will extend vertically so the whole line will be blurred. Here we are not dealing with a cylindrical lens. in case of a cylinder we follow rays and see which meridian will come to a focus on the retina. Hope I made myself clear. my regards

[@hamedabuhuryra8349]

@@adelabdelshafik thanks alot dear prof 🌹

[@adelabdelshafik]

@@hamedabuhuryra8349 welcome

[@tarekhussein2186]

Great and simplified Dr Adel .. thanks a lot

[@adelabdelshafik]

Great that you found it useful

[@bladesociety]

Thank you for this excellent explanation, Dr. Abdelshafik. One clarification though. If we follow your explanation with the cross on mark 5:52, shouldn't the blackest line on the astigmatic fan on mark 11:00 be the vertical one as the dots will be perceived as vertical oblongs (I'm referring to the diagram with the horizontal line on the retina)? Thank you so much, Dr, I have understood everything up until this particular point.

[@adelabdelshafik]

" shouldn't the blackest line on the astigmatic fan on mark 11:00 be the vertical one" : would you re phrase, I could not catch your point of view.

[@husseinalshadeedi3024]

Thank you sir for the clear explination

[@adelabdelshafik]

Welcome

[@047heenasingla6]

Thank u so much sir Bcoz of this vedio i could understand why vertical line would be seen more sharp if there is problem in vertical meridian. 🙏🙏

[@adelabdelshafik]

Welcome. Glade to hear your opinion.

[@AbhishekSingh-lu8tw]

Sir, one question 07:21 Why we put cylinder perpendicular to sharp dark line if it indicates astigmatic meridian (axis)? Cylinder axis should be placed correctly waiting for reply

[@adelabdelshafik]

When you apply a cylinder with its axis at 180 degrees, the effect of this cylinder will appear at 90 degrees

[@falahibrahim8447]

Very helpful

[@TrainLiu]

Thank you very much! OTL

[@adelabdelshafik]

welcome

[@karemoptom]

Thanks a lots sir

[@sachinmdesai]

Thanks for the lecture sir

[@adelabdelshafik]

Welcome, glade you find it useful.

[@sachinmdesai]

@@adelabdelshafik Having a good teacher is a valued privilege sir. I and many others like me value your painstaking efforts. Please keep spreading the knowledge to us all. Thanks again!

[@sumitdhingra1619]

hii sir.....please make a video on GHT in detail

[@adelabdelshafik]

kzbin.info/www/bejne/gHyWZJ2Vpbqjb6s

[@AbhishekSingh-lu8tw]

Sir please try to speak louder, not here but in all videos. Except this your videos are perfect. hope you don't mind

[@adelabdelshafik]

OK. Will do

[@AbhishekSingh-lu8tw]

@@adelabdelshafik Make a video on JCC

[@vahidovahido]

Perfect

[@adelabdelshafik]

Thanks, glade you find it useful.

[@learnerstockmkt6143]

hello sir........................ sound is very low

[@adelabdelshafik]

Would watch the video on other device, The sound level is average, would you check again and let me know.

[@learnerstockmkt6143]

@@adelabdelshafik ok sir

[@AbhishekSingh-lu8tw]

Sir you didn't explain MADDOX V test! 😭😭😭