# Flat field correction not working in MRAW
**URL:** https://forums.negativelabpro.com/t/flat-field-correction-not-working-in-mraw/9872
**Category:** Digital Camera Scanning
**Created:** [November 18, 2025, 7:35pm UTC](https://forums.negativelabpro.com/t/flat-field-correction-not-working-in-mraw/9872 "2025-11-18T19:35:28Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@palebluedot](https://forums.negativelabpro.com/u/palebluedot)
#### Post date: [November 18, 2025, 7:35pm UTC](https://forums.negativelabpro.com/t/flat-field-correction-not-working-in-mraw/9872/1 "2025-11-18T19:35:29Z")
Anyone have any thoughts as to why the flat field correction feature in Lightroom would work when the flat field image is RAW but not when it’s taken in MRAW (Canon)?
For context, I’m scanning on a 5DSR with the Valoi Easy35. Never had a problem with flat field correction, but I recently started using MRAW instead of RAW for the smaller file sizes and Lightroom no longer recognizes the MRAW flat field image as valid. However, when I capture the flat field image as a RAW even when the scans themselves are MRAW, it works just fine.
At the end of the day it’s not an issue, I’m just curious why this would be the case.
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### Author:  [@Digitizer](https://forums.negativelabpro.com/u/Digitizer)
#### Post date: [November 19, 2025, 10:21am UTC](https://forums.negativelabpro.com/t/flat-field-correction-not-working-in-mraw/9872/2 "2025-11-19T10:21:45Z")
> [@palebluedot](#):
>
> just curious why this would be the case
Looks like Lightroom isn’t intended/made to deal with non-full-raw FFC reference frames.
Design decision or bug? Who knows.
> [@palebluedot](#):
>
> At the end of the day it’s not an issue
👍
\_\_\_
I’d use full-raw for everything. Why? For ease of scanning and best results. Resizing operations cause data loss that can never be fixed afterwards. It can only get more prominent.
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### Author:  [@Harry](https://forums.negativelabpro.com/u/Harry)
#### Post date: [November 19, 2025, 2:52pm UTC](https://forums.negativelabpro.com/t/flat-field-correction-not-working-in-mraw/9872/3 "2025-11-19T14:52:04Z")
A. I know nothing about MRAW or that camera.
B. I see from DPReview that it has crop modes (I’m assuming MRAW is full frame). Could that be an option that might work with FFC and keep the file sizes down. Your lens might possibly perform better using the crop mode but you’d need different extenders etc for your Valoi setup.