I often see comments that it is better to crop than use an extender. I disagree and think that the Canon extenders together with the digital lens optimizer in Canon DPP software work very well. I hope this example will be helpful to some.
The advantage from using the extender is more pixels on the bird.
The disadvantages from using the extender include lower contrast at edges in the image and a smaller aperture which requires higher ISO.
I use the Canon DPP digital lens optimizer to remove small aperture diffraction blur. The capture sharpening (Richardson/Lucy deconvolution) in rawtherapee free software also works well. The DPRAW tool or the "clarity" setting in DPP can correct some of the loss of contrast at edges. I use exiftool free software to add IPTC metadata, but for some cameras it can be added using the Canon EOS Utility software.
I have published this photo at https://www.rsok.com/~jrm/2025Jan15_birds_and_cats/2024dec22_chickadee_IMG_2390c.html , https://1-john-moyer.pixels.com/featured/chickadee-2390-john-moyer.html , https://licensing.pixels.com/featured/chickadee-2390-john-moyer.html , https://okla.social/@johnmoyer/113912003640868920 , https://bsky.app/profile/jrm.rsok.com/post/3lgv525qvbk2t , https://www.facebook.com/JohnMoyerPhotography/posts/pfbid0DLcPHMLYx2rC3p4je3zTNNo4wV49G3rsbwCZQuBQeT... , and archived at https://web.archive.org/web/20250115185048/https://www.rsok.com/~jrm/2025Jan15_birds_and_cats/2024de...
I used Canon DPP to process the CR3 raw file. I save the edits as a recipe in a dr4 file. Exiftool can read the dr4 file so that I have a record of the edits. I have placed camera settings and all edits in the table below. I used graphicsmagick free software to place a frame around the image with a caption in the frame.
| ExifTool Version Number | 13.09 |
| File Name | IMG_2390c.JPG |
| Camera Model Name | Canon EOS R5 |
| Software | Digital Photo Professional |
| Modify Date | 2024:12:22 14:15:29 |
| Exposure Time | 1/500 |
| F Number | 13.0 |
| ISO | 500 |
| Date/Time Original | 2024:12:22 14:15:29 |
| Offset Time Original | -06:00 |
| Continuous Drive | Continuous, Low |
| Focus Mode | AI Servo AF |
| Record Mode | CR3+JPEG |
| Metering Mode | Evaluative |
| Focus Continuous | Single |
| Image Stabilization | On (2) |
| Camera Temperature | 29 C |
| Measured EV | 14.12 |
| Measured EV 2 | 30 |
| Canon Firmware Version | Firmware Version 2.1.0 |
| Shutter Count | 22497 |
| Valid AF Points | 1 |
| Image Unique ID | 52a5703634444a4ba1b91d62c962c613 |
| Time Zone | -06:00 |
| Time Zone City | Chicago |
| Daylight Savings | Off |
| Battery Type | LP-E6NH |
| Focus Distance Upper | 9.07 m |
| Focus Distance Lower | 7.89 m |
| Shutter Mode | Electronic First Curtain |
| Add IPTC Information | Enable |
| Measured RGGB | 524 1024 1024 623 |
| WB RGGB Levels As Shot | 1964 1024 1024 1820 |
| Color Temp As Shot | 5357 |
| Per Channel Black Level | 2047 2047 2048 2047 |
| Normal White Level | 13535 |
| Specular White Level | 14888 |
| Linearity Upper Margin | 12735 |
| Picture Style User Def | Standard; Standard; Standard |
| Picture Style PC | None; Standard; None |
| Vignetting Corr Version | 96 |
| Peripheral Lighting Setting | Off |
| Chromatic Aberration Setting | On |
| Distortion Correction Setting | Off |
| Digital Lens Optimizer Setting | On |
| Peripheral Illumination Corr | On |
| Auto Lighting Optimizer | Off |
| Highlight Tone Priority | Off |
| Long Exposure Noise Reduction | Off |
| High ISO Noise Reduction | Off |
| Digital Lens Optimizer | Standard |
| AF Config Tool | Case 1 |
| AF Tracking Sensitivity | 0 |
| AF Accel/Decel Tracking | 0 |
| AF Point Switching | -1 |
| AI Servo First Image | Equal Priority |
| AI Servo Second Image | Equal Priority |
| One Shot AF Release | Focus Priority |
| Auto AF Point Sel EOS iTR AF | Enable |
| Lens Drive When AF Impossible | Continue Focus Search |
| AF Point Display During Focus | Selected (constant) |
| Initial AF Point In Servo | Manual AF Point |
| Subject To Detect | Animals |
| Eye Detection | On |
| Roll Angle | 0.2 |
| Pitch Angle | 19 |
| Focal Length | 800 mm |
| Exposure Mode | Auto |
| Scene Capture Type | Standard |
| Lens Model | EF100-400mm f/4.5-5.6L IS II USM +2x III |
| Keywords | chickadee, Carolina Chickadee, Poecile carolinensis, bird, wildlife, wildlife photography, Oklahoma |
| Location Shown Country Name | United States |
| Location Shown Province State | Oklahoma |
| Description | Carolina Chickadee (Poecile carolinensis) on wild grape vine in Norman, Oklahoma, United States on December 22, 2024 |
| Rights | https://www.rsok.com/copyright.html , Copyright John Moyer, all rights reserved |
| ExifTool Version Number | 13.09 |
| File Name | IMG_2390.dr4 |
| White Balance Adj | Daylight |
| WB Adj Color Temp | 5200 |
| Color Saturation Adj | 1 |
| Unsharp Mask Strength | 1.7 |
| Unsharp Mask Fineness | 1.6 |
| Unsharp Mask Threshold | 4 |
| Shadow Adj | 0 |
| Highlight Adj | 0 |
| Luminance Noise Reduction | 1 |
| Chrominance Noise Reduction | 1 |
| DLO Setting | 70 |
| DLO On | Yes |
| DPRAW Microadjust Back Front | 1 |
| DPRAW Microadjust Strength | 8 |
| Crop X | 1377 |
| Crop Y | 1546 |
| Crop Width | 4800 |
| Crop Height | 3200 |
| Crop Rotation | 0 |
| Crop Angle | 0 |
| Crop Original Width | 8192 |
| Crop Original Height | 5464 |
