Getting rid of vignetting? (1 Viewer)

I use a Fuji 31d on my Swarovski AT80 with a swing out adapter by SRB GRiturn.

The eyepiece is the old 20x60 zoom.

This produces a nice clear circle with vignetting. I use the sharpness of the outer rim of the circle as a guide in setting up then use the camera zoom to about one and a half to get rid of the vignetting. Depending on weather etc I have achieved some nice shots.

If I were to switch to a 30 wide eyepiece would it get rid of the vignetting without having to use the camera zoom and if so are there any pros and cons to this?

Looking forward to hearing your views or experiences.
Cheers

Baron Birder said:

If I were to switch to a 30 wide eyepiece would it get rid of the vignetting without having to use the camera zoom and if so are there any pros and cons to this?

Looking forward to hearing your views or experiences.

Click to expand...

Yes, it would get rid of the vignetting, but you would actually get very similar results as with the zoom at 20x + cropping with the camera zoom. Some experienced digiscopers actually prefer the zoom - assuming that the camera lens is good enough zoomed in. My solution to using 20x without vignetting was to get a 20xSW and a camera which doesn't require very much eye-relief. The 20x may not be as versatile for birdwatching as the 30x, but I can get *a lot* wider views than with the zoom (or a 30x wide). Unfortunately the ER of the Swaro 20xSW is slightly limiting for many good digiscoping cameras (like the CP4500), but it might work with your Fuji. You could test the 20xSW - it fits perfectly to the old AT80 body, and even accepts the same SRB adapter as the zoom.

Best regards,

Ilkka :t:

Thanks Ikka

I guess using the wider eyepiece creating no vignetting would give me a better idea of how much it fills the screen rather than having to use the camera zoom which when added to a variable scope zoom over fills it. Any other pros and cons in terms of practical usage

Baron Birder said:

I guess using the wider eyepiece creating no vignetting would give me a better idea of how much it fills the screen rather than having to use the camera zoom which when added to a variable scope zoom over fills it. Any other pros and cons in terms of practical usage

Click to expand...

Baron,

In my use the 20xSW produces clearly the best pics, but I still like the 20-60x zoom very much because of its versatility in birdwatching. If you use the zoom for digiscoping, it is generally recommended to stay at 20x. This is where eye-relief is at its longest and you can see a sharp border between the black "vignetting" frames and the image ring. Black frames are easy to remove with camera zoom. If you zoom with the eyepiece, the eye-relief decreases and you most probably get diffuse edge shadowing, which is more penetrating and difficult to get rid of.

The zoom, 20xW and 30xW all have their pros and cons - and supporters.
- 20xW gives no vignetting at any (?) zoom setting & the widest and brightest views: it works best at close distances, where the subject is large or difficult to get into the viewfinder. You also get fastest shutter speeds and least blurring due to camera shake.
- 30xW gives no vignetting, more power and correspondingly less brightness. 50% more reach is sometimes valuable.
- 20-60x zoom: works VERY well at 20x, but requires camera zoom which brings the image area similar to what you get with the 30xW (and no camera zoom). 60x seldom produces nice, sharp images, but may sometimes be valuable for documenting the records.

I would describe the zoom eyepiece as a 35-105mm "DX" (1.5x crop factor) lens which vignettes at 35-50mm range on a full-frame camera, the 20xW is like a full-frame 28mm lens and the 30x like a 50mm full frame lens - if this analogy makes any sense to anyone . All have their uses, but IMHO a 28mm complements a 35-105mm zoom better than a 50mm.

Best regards,

Ilkka

Thanks again Ikka
I think I will stick with the 20x60 zoom and use the camera at about one and a half to get rid of the vignetting. That way I can always try with the eyepice zoom if the subject is too far at x20.