Optical effects of telescope's Removable Dewshield

[Fedele]

Optical effects of telescope's  Removable Dewshield
I hadn't fully realized it yet. On the night sky I had guessed it but I had never noticed it (forgive me if sometimes I don't pay attention to the laws of optics). The effect on the field of view of the lRemovable Dewshield position, out or not. 
Same setup: Takahashi TSA120 and Takahashi Abbe Ortho, photo with hand Iphone.
Don't mind the image quality as the telescope is indoors with heat coming out of the balcony. The photo of the cell phone obviously reflects what I see in the eyepiece. 
Another thing that I noticed, besides the slight variations in contrast, brightness and color (which I will quantify later, always on the same terrestrial subject), is the lower sensitivity to turbulence in the image with the Dewshield pulled out. The white lines inside the letters of the writing on the air conditioner are on average more clearly visible with the hood extracted. There are more "calm moment" to see.

Edited March 19, 2022 by Fedele

[JeremyS]

I am not sure what we are supposed to be seeing here. One pic seems to be in better focus than the other. The telescope is not pointing in exactly the same direction in each pic.

[Fedele]

leave the images...i can see this directly at the EP. 

when i change the position of Dewschield the field change. 

is little more large when is out!!

How it is possible?

1) some sort of optic effects of the circular aperture of dewschield?

2) variation in focal lenght? so the triplet moves with Feeschield???? 

 

[Merlin]

The inner surface of the sliding dewschield doesn’t appear to be Matt black.

[mikeDnight]

The images appear the same to me when taking the different positioning of the scope. But its really not possible for the dew shield to increase the field when extended, so there must be something else at play. As for the mat black paint Tak uses, it is the same mat black paint as used in high end japanese cameras, and it really top class at preventing stray light scatter. I can imagine it possible that the extending of the dew shield could improve contrast in a daylight setting.

P.S. 

Tak mat black paint smells fantastic!

[Robindonne]

Maybe they swapped the airco for a different more compact model between photos?